Enhancing CO2 Electroreduction Precision to Ethylene and Ethanol: The Role of Additional Boron Catalytic Sites in Cu-Based Tandem Catalysts

doi:10.21203/rs.3.rs-3518899/v1

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Enhancing CO2 Electroreduction Precision to Ethylene and Ethanol: The Role of Additional Boron Catalytic Sites in Cu-Based Tandem Catalysts

https://doi.org/10.21203/rs.3.rs-3518899/v1

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The electrocatalytic conversion of carbon dioxide (CO₂) into valuable multicarbon (C₂₊) compounds offers a promising approach to mitigate CO₂ emissions and harness renewable energy resources. However, achieving precise selectivity for specific C₂₊ products, such as ethylene and ethanol, poses a formidable challenge. This investigation advances the concept that incorporating elemental boron (B) into copper (Cu) catalysts can serve as supplementary adsorption sites for *CO intermediates in subsequent reduction reactions, thereby enhancing the selectivity of desirable C₂₊ products. Furthermore, the utilization of a nickel single atom catalyst (Ni-SAC) as a *CO source component elevates local *CO concentration and mitigates the hydrogen evolution reaction. In-situ experiments and density functional theory (DFT) calculations reveal that surface-bound boron units adsorb and convert *CO more efficiently, promoting ethylene production, while B elements within the bulk phase of copper influence charge transfer and lattice alignment, facilitating ethanol generation. In a neutral electrolyte, the bias current density for ethylene production using the CuB₂-Ni_0.05SAC hybrid catalyst exceeded 300 mA cm^-2, and that for ethanol production with CuB₅-Ni_0.2SAC surpassed 250 mA cm^-2. This study underscores that elemental doping in Cu-based catalysts not only induces alterations in charge and crystalline phase arrangement at Cu sites but also serves as supplementary reduction sites for coupling reactions, enabling the efficient synthesis of distinct C₂₊ products.

Physical sciences/Chemistry/Catalysis/Electrocatalysis

Physical sciences/Chemistry/Green chemistry/Sustainability

Physical sciences/Chemistry/Energy

electrochemical CO2 reduction

Boron-doping

Multi-carbon product

Tandem Catalysts

The electrocatalytic conversion of CO₂ into valuable C₂₊ fuels and chemicals, such as ethylene, acetate, ethanol, and n-propanol,^1,2 holds significant promise due to its potential to mitigate CO₂ emissions and generate valuable products utilizing renewable electricity.^3–5 The attainment of high selectivity for specific C₂₊ products is imperative for the commercial viability of CO₂ electrolysis. Copper (Cu) has emerged as a notable electrocatalyst for the efficient conversion of CO₂ into targeted C₂₊ products, with particular focus on ethylene and ethanol.^6–9 Nevertheless, the formation pathways for ethanol and ethylene share common intermediates, posing challenges in selectively producing one product over the other.¹⁰ Various strategies, including surface species adsorption, facet modulation, vacancy engineering, tuning CO coverage, and elemental doping,^11–14 have been deployed to augment the formation of a single product. However, achieving highly selective product generation through modification of the Cu site, involving charge and conformational complexity alone,^15,16 remains a formidable task, necessitating exploration of multisite catalysis.¹⁷

To tackle this challenge, our investigation delves into the disparities in the distribution of heterogeneously doped elements in Cu-based catalysts within the surface and bulk phases, as well as their catalytic advantages in intermediate reaction adsorption, notably *CO. *CO stands as a crucial intermediate in the C₂₊ product generation pathway, and the controlled local concentration of *CO serves to elucidate the catalytic route and extend the catalytic product benefits.^18–20 Consequently, we adopted tandem catalysis, introducing additional sources of CO and customizing Cu-based substrates to facilitate the direct exposure of various catalytic sites to the reaction intermediates.^21–23 In the generation of C₂₊ products, the reaction pathway bifurcates into CO₂ conversion to *CO and the subsequent coupling step of *CO.²⁴ However, the catalytic effects of a single site on CO₂ and CO activation are disparate.²⁵ The tandem catalytic system effectively reduces the energy barrier to CO₂ activation by manipulating the localized concentration of *CO across a spectrum of tailored Cu-based catalysts, thereby playing a pivotal role.^19,26 This approach concurrently enhances our comprehension of the pathways for ethanol and ethylene product formation.

Thus, we employed tandem catalysis by introducing additional sources of CO and tailored cu-based substrates to facilitate direct exposure of different catalytic sites of the catalyst to the reaction intermediates. For the generation of C₂₊ products, the reaction pathway is divided into the conversion of CO₂ to *CO and the subsequent coupling step of *CO, but the catalytic effects of a single site on CO₂ and CO are unbalanced, the tandem catalytic system significantly reduces the energy barrier to CO₂ activation by manipulating the localized concentration of *CO over a variety of tailored cu-based catalysts, and plays a key role. This approach simultaneously enhances our understanding of the pathways of ethanol and ethylene product formation.

In this study, we synthesized a series of tandem catalysts (CuB_x-Ni_ySAC) with varying levels of boron (B) doping using nickel single-atom catalyst (Ni_ySAC) as the CO source. Characterization results confirm that lower B content leads to B enrichment on the catalyst surface, forming atomically dispersed sites. Conversely, higher B content results in B incorporation into the Cu bulk phase, forming a Cu alloy phase. This variance in B content significantly influences the selectivity of the CuB_x catalyst for ethylene and ethanol products. By adjusting the Ni_ySAC ratio, we modulated the local CO concentration, thereby inhibiting the hydrogen evolution reaction (HER) and amplifying the product transition. Consequently, CuB₂-Ni_0.05SAC achieved a Faraday efficiency (FE) of 72% for ethylene, while CuB₅-Ni_0.2SAC achieved 48% for ethanol at high current densities exceeding 400 mA cm^− 2. Experimental and computational findings indicate that surface B doping provided additional *CO adsorption sites, promoting *CO hydrocoupling to yield *HOCCOH, thereby favoring the ethylene pathway. Additionally, the charge and tensile strain induced by B within the Cu lattice enhanced surface-bound *CO coverage, consequently reducing the coupling energy barrier and enhancing ethanol selectivity (Fig. 1). Disparities in the depth of heterogenous element doping in Cu-based catalysts Fig. 1.Schematic illustration of catalyst performance and design.

induced product selectivity divergence, ultimately leading to enhanced the efficiency of FE in the presence of single-atom catalyst. This approach holds promise for the efficient reduction of CO₂ to the desired C₂₊ product.

Catalyst preparation and characterization

We synthesized CuB_x samples and characterized their structures. To prepare the CuB_x catalysts with varying B content, we employed a one-step wet chemical reduction method (Fig. 2a and S2-3).¹⁵ Varying the molar ratio of CuCl₂ and NaBH₄ solutions allowed us to control the B content. Inductively coupled plasma mass spectroscopy (ICP-MS) confirmed the presence of B and its tunability (Table S1). Interestingly, the B/Cu mass ratio (wt. %) increased in the bulk phase with increasing B content, while the B/Cu mass ratio in the X-ray photoelectron spectroscopy (XPS) fine spectra showed a different trend, showing a maximum of 5.4 wt. % at CuB₂, and low to 0.6 wt. % at CuB₅ (Fig. 2b and S4).¹² In order to accurately measure the bulk-phase boron concentration of CuB_x samples, we measured the dissolution time-dependent boron concentration, whose depth of detection was positively correlated with the dissolution time in dilute nitric acid solution indicating surface enrichment of B at lower B doping levels and subsidence into the Cu bulk phase at higher B levels (Fig. 2c).²⁷

Similarly, XPS was used to study the oxidation state and chemical composition of the sample surface.²⁸ In the corresponding B 1s spectra (Fig. 2e), an expected increase in B binding energy with increasing B content was observed. However, it was also accompanied by a relative decrease in the surface B peak with increasing B content. In the Cu 2p_3/2 fine XPS, an attributed peak of CuO is observed at about 933.7 eV, indicating an enhancement of the electron-binding energy of Cu, i.e., an enhanced surface oxidation state. Similarly, the powder X-ray diffraction (XRD) pattern exhibits a transition from the primary Cu crystalline phase to the Cu₂O crystalline phase and finally to the CuO crystalline phase with increasing B content (Fig. 2f), which is consistent with the trend of elevated Cu oxidation state. The magnified Cu(111) facet shows a shift Fig. 2. a) Schematic representation of the preparation and components of CuB_x samples. b) B/Cu wt.% of bulk and surface of CuB_x samples with different B contents measured by XPS and ICP-MS. c) Dissolution time-dependent boron concentration in CuB_x samples measured by ICP-MS. d) k-edge XANES spectra of CuB₂ and CuB₅ samples. e) Boron XPS spectrum of CuB_x samples. f) XRD spectrum of CuB_x samples. (Inside the inset is a zoomed-in Cu(111) peak that is slightly cheaper as the B content changes) g-j) Wavelet transform (WT) –EXAFS Cu K-edge spectra for CuB₅, CuB₂, Cu₂O and Cu foil as a reference. WT maximum positions are indicated as imaginary lines. ‘+α’ indicates that R is not phase-corrected.of the peak to a lower angle with increasing B content, i.e., accompanied by a stretching phenomenon of the Cu-Cu lattice, which can be inferred that B doping into the Cu in the lattice gap.^29,30 We performed X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses (Fig. 2d).³¹ The Cu K-edge white line peak positions confirm the overall Cu valence state between 0 and 1. However, the leading edge position indicates a higher oxidation state of CuB₅ than Cu⁺, suggesting inhomogeneous oxidation in the structure and an enhanced local Cu oxidation state. This observation is consistent with the near-edge first-order derivative diagram of Cu K-edge (Figure S5), where the first-order derivative of CuB₅ exhibits the highest peak at high energy levels. A high-resolution wavelet transform (WT)-EXAFS analysis was performed in both R-space and K-space (Fig. 2g-j). In the lower K-space, the 6.2 Å⁻¹ K peak of the Cu-O coordination signal is not observed, so the O element is Fig. 3. SEM images of Ni-SAC (a), CuB₂(b). c) EDS maps of the corresponding Cu, B. Ni elements of the catalysts after hybridization. d, e) TEM image of CuB₂ and Hybridized catalyst, respectively. not present in the bulk phase of CuB_x. Combined with the previous XRD patterns, we can infer that doping B into the crystalline phase of Cu occupies an O vacancy similar to that of Cu oxide crystals. Meanwhile, increasing the B content also leads to the appearance of new peaks of Cu bonded to lighter elements in the low K region. Moreover, as the peak height increased, it indicated an increase in Cu-B bonding. In the high K space, Cu-Cu coordination is observed, and the Cu-Cu bond in CuB_x moves to higher energy space, indicating elevated Cu-Cu bond energy, electron transfer to the surrounding environment, and elevated oxidation state. The results of EXAFS curve fitting for CuB₂ and CuB₅ showed that the coordination numbers of metal Cu-Cu were 8.0 and 3.2, respectively, and the average bond lengths were 2.58 Å and 2.82 Å, respectively (Fig. 5b, S6-7 and Table s2-3).

We utilized a previously synthesized Ni-SAC catalyst with the "Ni-N₂C₂" configuration, known for its robust CO₂ catalytic performance under neutral conditions.³² High-angle annular dark-field scanning transmission electron microscopy (HAADF-TEM) images provided confirmation of the monodispersion of Ni atoms in the Ni-SAC (see Figure S1). In contrast, CuB₂ displayed a distinctive porous morphology, featuring a specific surface area (S_BET) of 24.5 m³/g, as measured in Figure S8. This porous structure exhibited a prominent hysteresis loop curve, indicative of the presence of micropores and mesopores around 1.3 nm and 100 nm, respectively (refer to Fig. 3b). Notably, Ni-SAC displayed a thin sheet with an interlayer convolutional morphology (as observed in Fig. 3a). The hybrid catalysts were created by mixing CuB_x and Ni-SAC, and energy-dispersive spectroscopy (EDS) elemental mapping confirmed the relative independence of Cu and B elements from C and Ni elements (Fig. 3c). The morphology of CuB_x remained largely unaltered both before and after assembly (as depicted in Fig. 3d-e).

Performance for CO-to-ethanol and ethylene electroreduction

The CO₂RR performance of the synthesized catalysts was tested in a flow cell in 0.5 M KHCO₃ electrolyte (Figure S9). Gas chromatography (GC) analysis revealed the presence of H₂, CO, methane (CH₄), and ethylene (C₂H₄), while headspace injection GC analysis detected methanol (CH₃OH), ethanol (C₂H₅OH), and n-propanol in the liquid phase products. Initially, we investigated the effects of different B doping levels on the CO₂RR performance (Fig. 4a). Among the catalysts tested, CuB₂ demonstrated the highest C₂₊ faradaic efficiency (FE) of 67% at a voltage of -1.2 V vs. RHE, with a current density exceeding 250 mA cm^− 2. ³³ CuB₂ and CuB₅ exhibited specific ethylene-ethanol product transition patterns, resulting in a reduction in FE of C₂H₄ from 46–34% and Figure 5. a-b) In situ Raman spectra of the CuB₂ and Cu samples working at different potentials in 1 M KHCO₃.c-d) In situ ATR-FTIR spectra of CuB₂ and CuB₅ from 2500–1000 cm^− 1 working at different potentials in 1 M KOH. OCP means open circuit potential. an increase in ethanol selection by 10%. These observations echoed the differences in B-element content between the surface and bulk phases of CuB₂ and CuB₅, as characterized earlier. To enhance this effect, we prepared hybrid catalysts with different ratios of Ni-SAC to CuB_x (Fig. 4b), achieving ethylene yields up to 72% at a Ni-SAC to CuB2 mass ratio of 0.05, at -1.2 V vs. RHE, with a maximum current density close to 450 mA cm^− 2. Ni-SAC was used as a substrate as well as an indirect source of CO, and the separate reduction product monitoring of Ni-SAC showed only H₂ and CO, the latter with a Faraday efficiency (FE) of 85 ± 1% at -1.2 V vs. RHE and a partial current density of 120 mA cm^− 2 (Figure S10).

To study the reaction kinetics of the catalyst, Nyquist plots were measured at open-circuit potential. Electrochemical impedance spectra (EIS) analysis (Figure S16) revealed that the addition of Ni-SAC effectively reduced the charge transfer impedance (R_ct) at the operational voltage. Considering the reactant mass transfer equation Z_Re = R_Ω + R_ct − 2σ²C_d, where σ represents the mass transfer rate from the reactant to the reaction interface during the reaction process, the indirect CO generation by adding Ni-SAC improves the transfer efficiency of CO diffusion to the Cu reaction interface.^34–36 Furthermore, we measured the electrochemically active surface area (ECSA) of the catalysts, which indicated the homogeneous dispersion of CuB_x by the carbon carriers effectively enhanced the reactive area of the catalysts, leading to increased mass transfer rates and subsequent enlargement of the active surface area (Figure S17).

Despite a decrease in current density and FE_C2+ yield with increased Ni-SAC content impregnated with CuB₂, the biased generation trend for C₂H₅OH and CO products remained consistent. We conducted coordinated CO₂RR testing of CuB_1 − 5 and Ni-SAC ratios with different mass fractions of 0.05, 0.1, and 0.2. Surprisingly, the different Ni-SAC

ratios amplified the tendency for ethanol-ethanol product differentiation, with the highest Figure 6. a) Average bond energies of individual B atoms corresponding to the layers of the Cu lattice when different numbers of B atoms are inserted through them. b) Gibbs free energy step diagram for the transition of *co to ethylene ethanol differentiation intermediates (*HCCOH and *HCCHO). c) The Gibbs free energy of adsorption of *CO at the B site and the Cu site changes when a B atom is inserted into the interlayer of the crystalline phase of Cu as well as without the addition of B. d) Electron density difference plots for the Cu-B bonding configuration and when it adsorbs *CO. e) The Gibbs free energy step diagrams for final C₂₊ product differentiation at the B site of Cu-L0, and at the Cu site of Cu(111), and of Cu-L1. f) The optimal ethylenic ethanol product differentiation routes and atom migration steps. ethylene selectivity of 72% observed for CuB₂-Ni_0.05SAC and 46% for CuB₅-Ni_0.2SAC (Fig. 4d, 4f and S11-14). Further product distribution analysis indicated that in the hybridized Ni-SAC system, FEs of H₂ were significantly lower compared to the unhybridized condition, while FEs of CO were elevated and the catalytic activity of CO₂ was enhanced (Fig. 4c and S15). This suggests that the tandem system of indirectly generated CO inhibits the hydrogen evolution reaction (HER) and reactive energy barriers for CO generation. Moreover, the results of FEs ratios of C₂₊/CO indicate that a majority of the formed *CO is inclined to participate in the C-C coupling process, promoting sustained generation of ethylene products with a specific localized CO coverage. However, as the CO source hybridization ratio increased continuously, the CO conversion ability weakened, while CuB₅ in a higher local CO environment favored the differentiation pathway towards ethanol products. The bias current densities of the best two samples at different bias voltages are displayed in Fig. 4f. To evaluate the CO₂RR performance, we compared the performance of the CuB_x-Ni_ySAC catalyst with other top catalysts reported in the literature (Fig. 4e).^{11,14,18,25,37–45} The stabilized CO₂RR properties of CuB₂-Ni_0.05SAC and CuB₅-Ni_0.2SAC were tested at a constant voltage of -1.2 V vs. RHE. As shown in Fig. 4g, the bias current densities of the products remained above 200 mA cm^− 2 for 10 hours. The morphology of the catalysts remained largely unchanged after a long period of CO₂ electrolysis (Figure. S18). In summary, the CuB_x-Ni_ySAC catalyst shows great promise for the conversion of CO₂ to C₂₊ products.

In suit characterization of the CuB _X

we utilized in situ Raman measurements to investigate the conformational and phase transitions of the CuB₂ catalyst during the CO₂ reduction reaction (CO₂RR), as depicted in Fig. 5a.^43,46–49 Initially, at the open-circuit potential (OCP) before CO₂RR initiation, the Raman spectrum in Fig. 5b reveals two distinct peaks around 520 cm^− 1, corresponding to the A1g mode of Cu₂O. These peaks gradually decrease as a negative potential is applied, concomitant with the emergence of a rotational vibrational peak at approximately 280 cm^− 1, indicating the involvement of CO in the reduction reaction. Further reduction of the applied potential to -1.0 V vs. RHE leads to nearly complete disappearance of the Cu₂O peak on the copper catalyst. Combining this with our previous XPS and XRD characterizations, it is evident that B is present within the oxygen vacancies of CuB_x. Additionally, under highly negative potentials, B plays a role in stabilizing the + 1 valence state of CuB_x compared to the pure Cu catalyst. Solid-state Raman spectra for both Cu and CuB₂, as shown in Figure S19, confirm distinctive Cu-B bond peaks at around 820 cm^− 1. In contrast, in situ Raman spectra of Cu do not show any discernible presence of the Cu-B bond. During continuous CO₂RR, two characteristic Raman peaks at approximately 1900 cm^− 1 and 2130 cm^− 1 become evident, corresponding to Cu-surface bridge adsorption and top-adsorption C = O stretching vibrations, respectively. Notably, on the CuB₂ catalyst, a novel C = O adsorption site appears at around 2000 cm^− 1, suggesting that B functions as an additional adsorption site to stabilize *CO. This intermediate, crucial for the coupling of C = C, is likely instrumental in the formation of C₂₊ products. Further in situ characterization is necessary to determine the influence of B content on the differentiation of C₂₊ products.

To comprehend the disparate CO₂RR performance of CuB₂ and CuB₅ catalysts, we employed surface-enhanced Fourier Transform InfraRed-based spectroscopy to identify crucial adsorbed intermediates within the electrocatalytic process.^16,50–52 In Fig. 5c and 5d, we observed the corresponding CO₂ adsorption peaks at 2360 cm-1 for both samples, and the one for CuB5 is significantly stronger than that for CuB₂, which indicates the rapid conversion of CO₂ on CuB₅. The absorption bands at 2050 cm^− 1 correspond to surface-bound CO (*CO) and at 1723 cm^− 1 to C = C-coupled *CHO material. Interestingly, the higher *CO peak mirrors that of CuB₂ indicating additional *CO sites and that the conversion of *CO on CuB₅ is more favorable to *CHO. This observation is consistent with the subsequent pathway of ethanol generation by the Cu-L1 model. The stretching vibrations (V_s) at 1610 cm^− 1 *CO = CO, 1290 cm^− 1 *CO = COH, and 1084 cm-1 *C-OH indicate that both samples have similar reaction intermediates in their respective reaction pathways. However, CuB₅ exhibited more robust Vs for *C-OH, reflecting its enhanced ethanol selectivity. In addition, the bending vibration (V_b) of *C-O-H at 1390 cm^− 1 in CuB₅ showed significantly stronger absorption peaks compared to CuB₂, indicating the importance of this intermediate for ethanol production. Notably, the trend of absorption peak intensities assigned to the *CHO and *COCOH species closely matches the trend of selectivity for the C₂₊ product, emphasizing the validity of our peak assignments.

Theoretical calculations

We employed first-principles Density Functional Theory (DFT) calculations to investigate the structural stability of B atoms within the bulk phase of Cu. These computations were based on experimentally determined variations in B content under strongly reducing conditions (Fig. 6a). Specifically, we introduced 1, 2, 8, and 16 B atoms into discrete layers of the Cu (4 × 4 × 6) crystalline phase and subsequently determined the optimized geometries, as depicted in Figure S20-21. Remarkably, the atomic radii of B are considerably smaller than those of Cu. Computational analyses reveal that B atoms are densely clustered and distributed within the layers of the Cu crystalline structure. Subsequent to these optimizations, we conducted bond energy calculations for the B atoms. The Fig. 6a showcases the average bond energies of individual B atoms in various layers within the crystalline phase and sheds light on the optimal structural configurations of B atoms at different B contents. Consistent with the experimental findings, at low B atom concentrations, the atoms predominantly adhere to the surface. Conversely, at higher B atom concentrations, clusters are distributed within the bulk phase of Cu.

Based on the experimental results of the changes in product selectivity associated with different levels of B distribution within the Cu crystalline phase, we designed three catalytic configurations; Cu(111), Cu-L0 (low B content) and Cu-L1 (high B content). The structural configurations of both Cu and Cu-L0-5 are listed in Figure S22. According to the free energies of individual B atoms calculated in the Fig. 6a, Cu-L0 is the introduction of individual B atoms on the surface of the crystalline phase of Cu(111), and Cu-L1 is the insertion of eight B atoms through the L1 layer of Cu(111). We then performed first-principles DFT calculations to explore the pathways of C₂₊ product formation. Previous DFT studies have emphasized the efficacy of the Ni-N₂C₂ SAC in converting CO₂ to CO products.³² Therefore, we first discuss the unique adsorption properties of *CO on these three catalytic configurations. As shown in Fig. 6c, the Gibbs free energy of *CO adsorption on Cu(111) was − 1.605 eV. When single B atom is introduced on the Cu-based surface, the differential density of adsorption charge on the Cu site is concentrated on *CO, which is unfavorable for the retention of *CO, while the B site exhibits a strong adsorption of *CO, which is lower than the Gibbs free energy of *CO adsorption on Cu(111) of 0.65 eV (Fig. 6b). Therefore, the B site on Cu-L0 can be used as an additional adsorption site for *CO for subsequent C₂₊ product conversion.

To delve further into the impact of B on Cu sites within the Cu crystalline phase, we analyze the pathway from *CO to the intermediate *HCCHO (Fig. 6d). In previous calculations, we addressed the sequential problem of proton charge transfer, manifesting as the optimal reaction pathway involving H addition followed by transition state (TS) coupling.⁵³ Notably, the C = C coupling process, being heat-absorbing and influenced by external factors, serves as the rate-determining step (RDS) in this system. The free energy of this coupling process on the Cu site changes from 0.43 eV to 0.42 eV with the introduction of higher B content, indicating that *CO is more likely to generate C₂₊ products on Cu sites with CuB₅. Interestingly, when we employed the B site on CuB₂ for additional *CO adsorption, it exhibited lower energy barriers (*COH,TS and coupling) due to stronger *CO_L adsorption on B. Experimental in-situ Raman results also indicated enhanced *CO adsorption. Furthermore, the stronger B-CO bonding raised the difficulty of hydrogenolysis of *COH to dehydrate. This resulted in an alternative pathway involving H addition, followed by hydrogenolysis to produce *HCCOH, which had lower energy compared to *HCCHO by 0.33 eV. This suggests the advantage of B as an adsorbate site for *CO in facilitating the differentiation of C₂₊ products, the corresponding divergent charge differential distributions of *CCO and *HOCCOH are also shown in Fig. 6b.

Next, we needed to continue exploring the intermediate pathways for C₂₊ product differentiation on three catalytic configurations. Specifically, we focused on the corresponding reaction energies for the generation of ethylene and ethanol products after initiation with *HCCOH and *HCCHO (as shown in Fig. 6e). In the Cu(111) and Cu-L1 configurations with *HCCHO as the promoter at the Cu site, *H tends to be added to C due to the relatively weak Cu-CO bond energy. This leads to an increase in the energy of *HCCHOH on O, and an increase in the free energy of the ethylene pathway by 0.15 eV compared to the ethanol pathway. This suggests that C₂₊ product partitioning at the Cu site facilitates the protonation of C and subsequent retention of -OH in Cu-C-O, which is essential for subsequent ethanol formation. In the Cu-L1 configuration, the presence of interlayer B elements leads to lattice expansion and the formation of electronically delocalized domains within the Cu crystalline phase, as observed by XRD and XPS experiments. Calculations show lower interstitial adsorption energies, indicating higher stability. In the presence of B, the free energy change of the C₂₊ product is 0.07 eV lower than that on Cu(111), indicating that B doping enhances the catalytic activity of CO₂RR. Notably, the free energy change of the *HCCOH pathway is usually lower than that of *HCCHO, and the subsequent hydrogenation and dehydration processes become easier due to the addition of H on O, resulting in a continuous decrease in the overall stepwise trend. Since H-O- leaves easily with O, the -OH group cannot be favorably retained, ultimately leading to ethylene production.³⁹ The optimal ethylenic ethanol product differentiation routes and atom migration steps are shown by us in Fig. 6f. Throughout the reaction pathway, when B is deposited on the C surface as an adsorption site for *CO, the total free energy change of *CO during ethylene production is minimized and the reaction step shows a decreasing trend. Our experiments confirmed that B was deposited on the surface only at low concentrations, indicating effective but limited reaction sites. Consequently, the C₂₊ selectivity efficiency increases significantly when an additional source of *CO generation is introduced.

In this research, we investigated the efficient conversion of CO₂ into C₂₊ products using CuB_x-Ni_ySAC tandem catalysts. By tuning the B doping levels and the ratio of Ni-SAC, we achieved high selectivity for ethylene and ethanol, with faraday efficiencies of 72% and 48%, respectively. Our study revealed the importance of B doping in enhancing the adsorption of *CO and influencing the pathways for C₂₊ product differentiation. The tandem catalyst approach, incorporating an additional source of *CO generation, provided valuable insights into improving CO₂ electrocatalysis and holds promise for the sustainable production of C₂₊ products from carbon dioxide.

Synthesis of CuB _x

CuB_x samples were prepared by a simple one-step method using copper chloride (CuCl₂) and sodium borohydride (NaBH₄) as precursors. Due to the low solubility of boron in copper, CuCl₂ was immediately added to a highly concentrated solution of sodium borohydride to maximize the alloying of boron with copper. First, a quantitative amount of CuCl₂ and NaBH₄ solid powder was dissolved in chilled water (~ 0°C). Next, 2 ml of a certain concentration of CuCl₂ solution was quickly injected into a rapid injection of NaBH₄ (5 M, 2 ml) solution until no bubbles were produced. The obtained precipitate was subsequently washed three times with 150 ml of water (50 ml each time) and once with 50 ml of acetone to completely remove unreacted precursors and other possible by-products. Then, the powder was immediately dried under vacuum overnight. The amounts of CuCl₂ for the different B-doped Cu samples were as follows: 400 mg for CuB₁, 300 mg for CuB₂, 200 mg for CuB₃, 100 mg for CuB₄, 50 mg for CuB₅.

Synthesis of Ni-SAC

According to our previous report, Ni-SAC was initially synthesized by preparing a "precisely pre-buried" Ni-salen crystalline polymer, followed by high-temperature pyrolysis to obtain Ni-SAC. In the synthesis process, 1,2,4,5-benzenetetramine hydrochloride (59.0 mg, 0.208 mmol) was dispersed in a 50 mL hydrothermal kettle containing a mixture of 1,3,5-trimethylbenzene and ethanol solvent (8.4 mL) in a 2:1 ratio. After adding triethylamine (120 µL, 0.832 mmol), the mixture was subjected to ultrasonic mixing for 5 minutes. Subsequently, Ni(OAc)₂·4H₂O (102.88 mg, 0.416 mmol), 3,3'-dialdehyde-4,4'-dihydroxybiphenyl (100 mg, 0.416 mmol), and aqueous acetic acid solution (1 mL, 6.0 M) were added to the hydrothermal kettle, and the resulting mixture was sonicated for an additional 5 minutes. Finally, the mixture was heated to 80°C for 5 days to synthesize a reddish-brown solid. The solid was filtered, washed with ultrapure water, anhydrous ethanol, tetrahydrofuran, and acetone, and then dried under vacuum at 160°C for 12 hours to obtain a reddish-brown powder.

To perform high-temperature pyrolysis, 8 mmol of sodium citrate was pyrolyzed in a tube furnace under an argon atmosphere at 800°C for 1 hour. The resulting black solid product was washed with a 0.5 M HCl solution and ultrapure water to remove inorganic impurities. After drying at 70°C, PC scaffolds were obtained. Then, PC (10 mg), dicyandiamide (125 mg), and Ni-salen crystalline polymer (50 mg) were added to a mortar and ground for 30 minutes. The resulting powder was placed in a tube furnace and heated to 650°C under an argon flow rate of 100 mL/min. After 200 minutes of pyrolysis, Ni-SAC was obtained.

Characterization

The powder XRD patterns were collected on a SmartLab 9 kW instrument using Cu Kα radiation. The SEM images were obtained using a field emission environmental scanning electron microscope (Quanta 200FEG). The TEM images were obtained on a JEM–2100 microscope at an acceleration voltage of 200 kV. The HAADF–STEM observations were performed using an FEI Themis Z instrument. An PerkinElmer NexION 300X ICP-MS spectrometer was used to quantify metal contents. The XPS profiles of the studied materials were acquired using a Thermo Scientific K-Alpha instrument equipped with an Al-Kα radiation source. The Raman spectra were recorded on a Beijing Zolix Instruments, Inc. equipped with two edge Rayleigh filters and an interference filter for plasma line removal. The synchrotron radiation experiment was performed at the easyXAFS300 of Quantum Design company, American, in which, measurable energy range: 5KeV ~ 18KeV, the test mode is transmission mode.

Electrochemical in situ ATR-FTIR test

Electrochemical in situ Attenuated Total Reflection Flourier Transformed Infrared Spectroscopy (ATR-FTIR) was employed to trace the signals of the intermediates using a Nicolet Nexus 670 Spectroscopy equipped with a liquid nitrogen-cooled mercury-cadmium-telluride (MCT) detector. An ECIR-II cell equipped with a Pike Veemax III ATR in a three-electrode system was provided from Shanghai Linglu Instrument& Equipment Co. To improve the signal intensity, the monocrystal silicon was initially coated with a layer of Au using the chemical plating method. Then, 20 µL catalysts ink was dropped on the surface of the Au film and served as the working electrode. Platinum sheet and Ag/AgCl electrode were used as counter electrodes and reference electrodes, respectively. Before the test, the CO₂ feeding gas was purged into the electrolyte and continuously bubbled during the measurement. The dropped catalysts was electroreduced at -0.4 V vs. RHE for 30 min to be active for the test. The potential-dependent in situ ATR-FTIR tests were carried out with LSV test from − 0.4 V to -1.4 V (vs. RHE) with a scan rate of 5 mV s^–1.

Electrochemical in situ Raman test

The in-situ Raman measurement was carried out on a Raman spectroscopy equipped with 532 nm laser (RTS2-301-SMS, Zolix Instruments, Inc.). The measurements were performed in an electrochemical cell with a Pt wire and a Ag/AgCl electrode as the counter and reference electrode, respectively. For Potential-resolved operando Raman spectroscopy, the collection time was 20 min, The exposure and accumulation times were 10 seconds.

Electrochemical measurements

All the electrochemical CO₂ reduction measurements were conducted in a flow cell controlled with an electrochemical workstation (CHI760E). The flow cell consists of three independent chambers: catholyte (gas diffusion electrode, SGL Sigracet 28 BC), gas, and anolyte (Platinum flakes, 1 mm in thickness), as shown in Supplementary Figure S8. The Ag/AgCl reference electrode is placed into the catholyte chamber through a drilled top hole. An anion exchange membrane (Fumasep FAB-PK-130) is employed to separate the anolyte and catholyte chambers. The working electrode was prepared by spray-coating a pre-made catalyst ink via an airbrush on the gas diffusion electrode with a size of 2*0.5 cm². The catalyst loading is 1mg cm^-2 to ensure similar particle density. 0.5 M aqueous KHCO₃ solution was circulated into both the anode and cathode chambers at a constant flow rate of 20 ml min^-1 with the assistance of a dual-channel peristaltic pump. A high-purity CO² gas flow of 10 cm³ min^-1 was supplied to the gas chamber controlled by a digital mass flow controller (Horiba). The gas products were quantitatively analyzed using gas chromatography equipped with both flame ionization and thermal conductivity detectors (Fuli GC9790 Plus). The liquid products were collected after at least 3 h of electrolysis and quantitatively analyzed using ¹H NMR spectroscopy with H₂O suppression. 300 µL electrolyte mixed with 10 µL dimethyl sulfoxide (20 mM) and 200 µL D₂O was used as the internal standard. All the potentials were converted to RHE, according to the equation

E (vs. RHE) = E (vs. Ag/AgCl) + 0.059 pH + 0.198.

Electrode intrinsic properties of the analyzed materials were evaluated on a three-electrode system using an Ag/AgCl electrode as the reference electrode, graphite as the counter electrode, and a KHCO₃ solution (0.5 M) as the electrolyte. The flow rate of CO₂ was maintained at 20 mL min^− 1 by a mass flowmeter during electrochemical measurements. The LSV measurements were conducted at a scan rate of 5 mV s^− 1 in a KHCO₃ solution (0.5 M). The ECSAs of the prepared catalysts were compared by measuring their double layer capacitances calculated from the corresponding cyclic voltammetry curves in the potential window from − 0.05 to 0.05 V vs. RHE. The EIS experiments for CO₂ reduction at the open-circuit potential were performed at a small (5 mV) AC voltage in a frequency range from 10 MHz to 100 kHz.

The FE of the gas products was calculated as follows:

$$\text{FE=}\frac{{\text{Q}}_{product}}{{\text{Q}}_{\text{total}}}\text{×100%=}\frac{\text{(}\frac{\text{v}}{\text{60 s }{\text{min}}^{\text{-1}}}\text{)×(}\frac{\text{y}}{\text{24000 }{\text{cm}}^{\text{3}}\text{ }{\text{mol}}^{\text{-1}}}\text{)×N×F}}{\text{j}}\text{×100%}$$

Where v is the CO₂ flow rate (20 mL min^− 1); y is the concentration of gas in a 1 mL quantitative loop (ppm); N is the electron transfer number; F is the Faraday constant (96485 C mol^− 1); and j is the total current density (A cm^− 2).

The FE of the liquid products: Q_product and Q_total were obtained using the following equations:

$${Q}_{product}={Z}_{product}\times F\times {N}_{product}$$

$${\text{Q}}_{\text{total}}=I\times t$$

Therefore, FE_liquid can be written as

$${FE}_{\text{l}\text{i}\text{q}\text{u}\text{i}\text{d}}=\frac{{Z}_{product}\times F\times {N}_{product}}{I\times t}$$

Z _product is the number of electrons exchanged for the product formation; N_product is obtained by quantifying the DMSO solution in the H-NMR spectrum as an internal reference calibration.

Electrochemical active surface area (ECSA) calculation

The ECSAs of catalysts were calculated based on their electrical double layer capacitor (Cdl), which were obtained from CV plots in a narrow non-Faradaic potential window from 0.05 to -0.05 V (vs. RHE). The measured capacitive current densities at 0 V were plotted as a function of scan rate and the slope of the linear fit was calculated as Cdl. The specific capacitance was found to be 60 µF cm^− 2, and the ECSA of the catalyst is calculated from the following equation:

ECSA = C_dl / (60 µF cm^− 2) cm²

The intrinsic activity was revealed by normalizing the current to the ECSA to exclude the effect of surface area on catalytic performance.

DFT calculations

First-principle Computational procedure

The plane-wave Vienna Ab-initio Simulation Package (VASP) was applied in all first-principles calculations using projector augmented-wave pseudopotentials with the GGA-type PBE functional.^54,55 A model with periodic boundary conditions was used, and the plane wave energy cutoff was set to 450 eV. The reciprocal space for all calculation systems was a Monkhorst–Pack k-point grid with dimensions of 4×4×6. To prevent interactions between replicas along the z-direction, vacuum spacing of at least 20 Å was used between the adjacent images.

The adsorption energy was calculated by the following formula:

E_a = E_final −E_substrate − E_adsorbate

where E_a, E_final, E_substrate, and E_adsorbate are the adsorption energy of the adsorbate on the substrate, total energy of the adsorbate on the substrate, total energy of the substrate, and total energy of the adsorbate, respectively.

The free energy of this reaction was computed via the following equation: ∆G = E_a + ∆Z_PE − T∆S, where ∆G, ∆Z_PE, and ∆S represent the Gibbs free energy, zero-point energy, and entropy, respectively.

Data availability

The data supporting this study are available within the paper and the Supplementary Information. All other relevant source data are available from the corresponding author upon reasonable request.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Nos. 22063005, 21907048 and 22064012), the Natural Science Foundation of Jiangxi Province (Nos. 20202BAB 203009 and 20171BAB213014), the Postdoctoral Research Project of Jiangxi Province (No.2020KY17) and Interdisciplinary Innovation Fund of Natural Science, Nanchang University (No.9167-27060003-ZD2101).

Author Contributions

H.W. conceived the project and supervised the research work. F.Y. designed and conducted most of the experiments of this project. F.Y. performed the STEM measurements and analyzed the results. H.W. and F.Y. designed the computational studies and analyzed the computational data. All authors discussed the results and assisted during manuscript preparation.

Competing interests

The authors declare no competing financial interest.

Dinh, C.-T., et al. CO < sub > 2</sub > electroreduction to ethylene via hydroxide-mediated copper catalysis at an abrupt interface. Science 360, 783–787 (2018).
Jin, J., et al. Constrained C2 adsorbate orientation enables CO-to-acetate electroreduction. Nature 617, 724–729 (2023).
Nitopi, S., et al. Progress and Perspectives of Electrochemical CO2 Reduction on Copper in Aqueous Electrolyte. Chem. Rev. 119, 7610–7672 (2019).
Zhong, M., et al. Accelerated discovery of CO2 electrocatalysts using active machine learning. Nature 581, 178–183 (2020).
Bushuyev, O. S., et al. What Should We Make with CO2 and How Can We Make It? Joule 2, 825–832 (2018).
Ma, W., et al. Electrocatalytic reduction of CO2 to ethylene and ethanol through hydrogen-assisted C–C coupling over fluorine-modified copper. Nat. Catal. 3, 478–487 (2020).
Zhang, B., et al. Highly Electrocatalytic Ethylene Production from CO2 on Nanodefective Cu Nanosheets. J. Am. Chem. Soc. 142, 13606–13613 (2020).
Wang, J., Tan, H.-Y., Zhu, Y., Chu, H. & Chen, H. M. Linking the Dynamic Chemical State of Catalysts with the Product Profile of Electrocatalytic CO2 Reduction. Angew. Chem. Int. Ed 60, 17254–17267 (2021).
Arán-Ais, R. M., Scholten, F., Kunze, S., Rizo, R. & Roldan Cuenya, B. The role of in situ generated morphological motifs and Cu(i) species in C2 + product selectivity during CO2 pulsed electroreduction. Nat. Energy 5, 317–325 (2020).
Kuang, S., et al. Asymmetrical electrohydrogenation of CO2 to ethanol with copper–gold heterojunctions. Proceedings of the National Academy of Sciences 120, e2214175120 (2023).
Wei, P., et al. Coverage-driven selectivity switch from ethylene to acetate in high-rate CO2/CO electrolysis. Nat. Nanotechnol. 18, 299–306 (2023).
Wei, D., et al. Decrypting the Controlled Product Selectivity over Ag – Cu Bimetallic Surface Alloys for Electrochemical CO2 Reduction. Angew. Chem. Int. Ed 62, e202217369 (2023).
Guo, C., et al. Electrocatalytic Reduction of CO2 to Ethanol at Close to Theoretical Potential via Engineering Abundant Electron-Donating Cuδ + Species. Angew. Chem. Int. Ed 61, e202205909 (2022).
Zhang, T., Yuan, B., Wang, W., He, J. & Xiang, X. Tailoring *H Intermediate Coverage on the CuAl2O4/CuO Catalyst for Enhanced Electrocatalytic CO2 Reduction to Ethanol. Angew. Chem. Int. Ed 62, e202302096 (2023).
Yao, K., et al. Mechanistic Insights into OC–COH Coupling in CO2 Electroreduction on Fragmented Copper. J. Am. Chem. Soc. 144, 14005–14011 (2022).
Zheng, M., et al. Electrocatalytic CO2-to-C2 + with Ampere-Level Current on Heteroatom-Engineered Copper via Tuning *CO Intermediate Coverage. J. Am. Chem. Soc. 144, 14936–14944 (2022).
Masel, R. I., et al. An industrial perspective on catalysts for low-temperature CO2 electrolysis. Nat. Nanotechnol. 16, 118–128 (2021).
Li, F., et al. Cooperative CO2-to-ethanol conversion via enriched intermediates at molecule–metal catalyst interfaces. Nat. Catal. 3, 75–82 (2020).
Yin, Z., et al. Hybrid Catalyst Coupling Single-Atom Ni and Nanoscale Cu for Efficient CO2 Electroreduction to Ethylene. J. Am. Chem. Soc. 144, 20931–20938 (2022).
Ding, L., et al. Over 70% Faradaic Efficiency for CO2 Electroreduction to Ethanol Enabled by Potassium Dopant-Tuned Interaction between Copper Sites and Intermediates. Angew. Chem. Int. Ed 61, e202209268 (2022).
Ma, Y. B., et al. Confined Growth of Silver-Copper Janus Nanostructures with {100} Facets for Highly Selective Tandem Electrocatalytic Carbon Dioxide Reduction. Adv. Mater. 34, 2110607 (2022).
Wu, G. L., et al. Selective Electroreduction of CO2 to n-Propanol in Two-Step Tandem Catalytic System. Adv. Energy Mater., (2022).
Lin, Y. R., et al. Vapor-Fed Electrolyzers for Carbon Dioxide Reduction Using Tandem Electrocatalysts: Cuprous Oxide Coupled with Nickel-Coordinated Nitrogen-Doped Carbon. Adv. Funct. Mater. 32, 2113252 (2022).
Gao, W., Xu, Y., Xiong, H., Chang, X., Lu, Q. & Xu, B. CO Binding Energy is an Incomplete Descriptor of Cu-Based Catalysts for the Electrochemical CO2 Reduction Reaction. Angew. Chem. Int. Ed, e202313798 (2023).
Sun, W., et al. V-Doped Cu2Se Hierarchical Nanotubes Enabling Flow-Cell CO2 Electroreduction to Ethanol with High Efficiency and Selectivity. Adv. Mater. 34, 2207691 (2022).
Zhang, Y., et al. Multicarbons generation factory: CuO/Ni single atoms tandem catalyst for boosting the productivity of CO2 electrocatalysis. Science Bulletin 67, 1679–1687 (2022).
Zhou, Y., et al. Dopant-induced electron localization drives CO2 reduction to C2 hydrocarbons. Nat. Chem. 10, 974–980 (2018).
Platzman, I., Brener, R., Haick, H. & Tannenbaum, R. Oxidation of Polycrystalline Copper Thin Films at Ambient Conditions. J. Phys. Chem. C. 112, 1101–1108 (2008).
Ma, W., et al. Copper lattice tension boosts full-cell CO electrolysis to multi-carbon olefins and oxygenates. Chem, (2023).
Feng, J., et al. Improving CO2-to-C2 + Product Electroreduction Efficiency via Atomic Lanthanide Dopant-Induced Tensile-Strained CuOx Catalysts. J. Am. Chem. Soc. 145, 9857–9866 (2023).
De Luna, P., et al. Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction. Nat. Catal. 1, 103–110 (2018).
Liu, X., et al. An accurate “metal pre-buried” strategy for constructing Ni–N2C2 single-atom sites with high metal loadings toward electrocatalytic CO2 reduction. J. Mater. Chem. A 10, 25047–25054 (2022).
Kibria, M. G., et al. Electrochemical CO2 Reduction into Chemical Feedstocks: From Mechanistic Electrocatalysis Models to System Design. Adv. Mater. 31, 1807166 (2019).
Taberna, P. L., Simon, P. & Fauvarque, J. F. Electrochemical Characteristics and Impedance Spectroscopy Studies of Carbon-Carbon Supercapacitors. J. Electrochem. Soc. 150, A292 (2003).
de Levie, R. On porous electrodes in electrolyte solutions: I. Capacitance effects. Electrochim. Acta 8, 751–780 (1963).
Largeot, C., Portet, C., Chmiola, J., Taberna, P.-L., Gogotsi, Y. & Simon, P. Relation between the Ion Size and Pore Size for an Electric Double-Layer Capacitor. J. Am. Chem. Soc. 130, 2730–2731 (2008).
Chen, J., et al. Accelerated Transfer and Spillover of Carbon Monoxide through Tandem Catalysis for Kinetics-boosted Ethylene Electrosynthesis. Angew. Chem. Int. Ed 62, e202215406 (2023).
Yang, Z., et al. CeO₂/CuS Nanoplates Electroreduce CO₂ to Ethanol with Stabilized Cu + Species. Small 19, 2303099 (2023).
Xu, A., et al. Copper/alkaline earth metal oxide interfaces for electrochemical CO2-to-alcohol conversion by selective hydrogenation. Nat. Catal. 5, 1081–1088 (2022).
Wang, X., et al. Efficient electrically powered CO2-to-ethanol via suppression of deoxygenation. Nat. Energy 5, 478–486 (2020).
Ma, G., et al. A hydrophobic Cu/Cu2O sheet catalyst for selective electroreduction of CO to ethanol. Nat. Commun. 14, 501 (2023).
Wang, X., et al. Identifying an Interfacial Stabilizer for Regeneration-Free 300 h Electrochemical CO2 Reduction to C2 Products. J. Am. Chem. Soc. 144, 22759–22766 (2022).
Wang, Z., et al. Localized Alkaline Environment via In Situ Electrostatic Confinement for Enhanced CO2-to-Ethylene Conversion in Neutral Medium. J. Am. Chem. Soc. 145, 6339–6348 (2023).
Zhang, J., et al. Steering CO2 electroreduction pathway toward ethanol via surface-bounded hydroxyl species-induced noncovalent interaction. Proceedings of the National Academy of Sciences 120, e2218987120 (2023).
Lin, Y., et al. Tunable CO2 electroreduction to ethanol and ethylene with controllable interfacial wettability. Nat. Commun. 14, 3575 (2023).
Fang, M., et al. Hydrophobic, Ultrastable Cuδ + for Robust CO2 Electroreduction to C2 Products at Ampere-Current Levels. J. Am. Chem. Soc. 145, 11323–11332 (2023).
Wang, M., et al. Tuning C1/C2 Selectivity of CO2 Electrochemical Reduction over in-Situ Evolved CuO/SnO2 Heterostructure. Angew. Chem. Int. Ed 62, e202306456 (2023).
Chang, X., Vijay, S., Zhao, Y., Oliveira, N. J., Chan, K. & Xu, B. Understanding the complementarities of surface-enhanced infrared and Raman spectroscopies in CO adsorption and electrochemical reduction. Nat. Commun. 13, 2656 (2022).
Qi, K., et al. Unlocking direct CO2 electrolysis to C3 products via electrolyte supersaturation. Nat. Catal. 6, 319–331 (2023).
Zi, X., et al. Breaking K + Concentration Limit on Cu Nanoneedles for Acidic Electrocatalytic CO2 Reduction to Multi-Carbon Products. Angew. Chem. Int. Ed 62, e202309351 (2023).
Zhuansun, M., et al. Promoting CO2 Electroreduction to Multi-Carbon Products by Hydrophobicity-Induced Electro-Kinetic Retardation. Angew. Chem. Int. Ed 62, e202309875 (2023).
Zhou, X. L., et al. Stabilizing Cu2 + Ions by Solid Solutions to Promote CO2 Electroreduction to Methane. J. Am. Chem. Soc. 144, 2079–2084 (2022).
Yu, F., Liu, X., Liao, L., Xia, G. & Wang, H. Multilayer-Cavity Tandem Catalyst for Profiling Sequentially Coupling of Intermediate CO in Electrocatalytic Reduction Reaction of CO2 to Multi-Carbon Products. Small 19, 2301558 (2023).
Kresse, G. & Hafner, J. Ab initio molecular dynamics for open-shell transition metals. Phys. Rev. B 48, 13115–13118 (1993).
Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996).

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Supportinginformation.docx
Supplementary Information

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Enhancing CO2 Electroreduction Precision to Ethylene and Ethanol: The Role of Additional Boron Catalytic Sites in Cu-Based Tandem Catalysts

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Abstract

Figures

Introduction

Results and Discussion

Catalyst preparation and characterization

Performance for CO-to-ethanol and ethylene electroreduction

Theoretical calculations

Conclusion

Methods

Synthesis of Ni-SAC

Characterization

Electrochemical in situ ATR-FTIR test

Electrochemical in situ Raman test

Electrochemical measurements

Electrochemical active surface area (ECSA) calculation

DFT calculations

First-principle Computational procedure

E_a = E_final −E_substrate − E_adsorbate

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1

Enhancing CO2 Electroreduction Precision to Ethylene and Ethanol: The Role of Additional Boron Catalytic Sites in Cu-Based Tandem Catalysts

Status:

Version 1

Abstract

Figures

Introduction

Results and Discussion

Catalyst preparation and characterization

Performance for CO-to-ethanol and ethylene electroreduction

Theoretical calculations

Conclusion

Methods

Synthesis of Ni-SAC

Characterization

Electrochemical in situ ATR-FTIR test

Electrochemical in situ Raman test

Electrochemical measurements

Electrochemical active surface area (ECSA) calculation

DFT calculations

First-principle Computational procedure

Ea = Efinal −Esubstrate − Eadsorbate

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1

E_a = E_final −E_substrate − E_adsorbate