Design of Co‐Cu Diatomic Site Catalysts for High‐efficiency Synergistic CO₂ Electroreduction at Industrial‐level Current Density

Abstract

Single atom catalysts (SACs) have been widely studied in the field of CO 2 electroreduction, but industrial-level current density and near-unity product selectivity are still difficult to achieve. Herein, a diatomic site catalysts (DASCs) consisting of Co-Cu hetero-diatomic pairs is synthesized. The CoCu DASC exhibits excellent selectivity with the maximum CO Faradaic efficiency of 99.1 %. The CO selectivity can maintain above 95 % over a wide current density range from 100 mA cm À 2 to 500 mA cm À 2 . The maximum CO partial current density can reach to 483 mA cm À 2 in flow cell, far exceed industrial-level current density requirements (> 200 mA cm À 2 ). Theoretical calculation reveals that the synergistic catalysis of the Co-Cu bimetallic sites reduce the activation energy and promote the formation of intermediate *COOH. This work shows that the introduction of another metal atom into SACs can significantly affect the electronic structure and then enhance the catalytic activity of SACs.

Why Is C–C Coupling in CO2 Reduction Still Difficult on Dual-Atom Electrocatalysts?

“…For a surface with *OCHO formation as the more favorable initial step, the selectivity would be determined based on the subsequent hydrogenation. The above analysis reveals that the surface states of DACs involve a surface preadsorbed with *CO, which coincides with the experimental fact that CO is generally the main product of DACs. − …”

“…Interestingly, the main product of these three catalysts is CO, which is consistent with the experimental observations (Figure ). − Specifically, when the energy required to form *COOH is lower than *OCHO, it is generally more favorable for the subsequent reaction to produce CO (e.g., Fe/Fe–N 6 –C with preadsorbed *CO in Figure c and Figure S9 in the Supporting Information). As the degree of difficulty in forming these two intermediates is equivalent, further hydrogenation is more advantageous to convert *COOH to *CO, rather than *OCHO to *HCOOH (e.g., Fe/Ni–N 6 –C with preadsorbed *CO, Figure d and Figure S10 in the Supporting Information; Ni/Ni–N 6 –C with preadsorbed *CO, Figures e and Figure S11 in the Supporting Information).…”

“…Until now, most DACs have been used in electrocatalytic CO 2 reduction reactions (CO 2 RR), with the preliminary expectation of yielding a high quantity of multicarbon products (e.g., ethane and ethanol). , Because DACs can provide two metal sites to enrich surface *CO coverage, C–C coupling seems achievable. , However, multicarbon products have been rarely observed on DACs experimentally. Herein, we summarized 11 typical CO 2 RR experiments reported to date on M–N–C DACs, as shown in Figure . − Notably, CO was identified as the main product on almost all homonuclear and heteronuclear DACs. The optimal potential for achieving a Faradaic efficiency of >95% is approximately −0.8 V vs reversible hydrogen electrode (RHE).…”

“…Comparison of CO Faradaic efficiency for various DACs reported in the past three years. The experimental data were extracted from refs − . The inset shows a typical M–N–C DAC where orange, blue, and silvery spheres represent the metal sites, the coordinating N, and the carbon substrate, respectively.…”

Sustainable high-energy radiation powering selective CO2 reduction to CH3OH over atomic dual-metal-sites embedded metal-organic framework

“…When a transition metal promoter like nickel (Ni) is introduced, dual-metal-sites are formed in their respective single-site forms. This structure can cooperate to optimize interactions between the adjacent active sites and reactants on the catalyst surface, minimizing the overall endothermic energy of essential C1 intermediates (CO* COH* CHOH CH 2 OH) in the CO 2 reduction process [27][28][29] . Therefore, we took the view that developing Cu-based atomic dual-metal-sites implanted MOFs could increase and tune the CO…”