Theoretical Investigation of Cu–Au Alloy for Carbon Dioxide Electroreduction: Cu/Au Ratio Determining C₁/C₂ Selectivity

Abstract

Copper−gold alloy exhibits excellent catalytic performance for the carbon dioxide electroreduction (CO 2 ER) reaction, but the mechanism of the effect of the Cu/Au ratio on the selectivity of C 1 /C 2 products has not been carefully investigated. In this work, ( 100) and ( 111) surfaces of three CuAu alloys with different Cu/Au (3:1, 1:1, 1:3) ratios are constructed. The properties of CuAu surfaces like density of states, Bader charge, and the whole CO 2 ER to C 2 H 4 and C 2 H 5 OH mechanisms are investigated. Our calculation reveals that the adsorption capacity of the catalyst surface for the intermediates *COOH and *CO is enhanced with the increase of the Au ratio. The calculation results show that the Cu1Au1(100) surface has the highest activity for CO 2 ER to CO (U L = −0.32 V). Furthermore, the Cu3Au1(100) surface exhibits the best coupling performance, and ethanol is the dominant product for CO 2 ER to C 2 products. Our work provides a useful guideline for further developing CO 2 ER electrocatalysts.

Unraveling the Selectivity and Synergistic Mechanism of Cu-Based Alloys for CO2 Reduction

“…The results show that Ag-, Au-, In-, and Sn-doped alloys are mostly distributed on the right side of the volcano curve as a result of the weaker adsorption energy for *C. This makes the protonation of CO 2 (g) to *COOH become the rate-limiting step for producing CO, HCOOH-1, and C 2 -2 on these alloys. Researchers have found the formation of *COOH being the rate-limiting step on Sn@Cu(111) in the CH 3 OH pathway and Cu–Au alloy, which agrees well with our results. The rate-limiting step of the C 2 -1 process (C 2 via *COH) is the hydrogenation of *CO to *COH.…”

“…On the basis of this, the limiting potentials (U L ) for key elementary steps can be obtained to estimate the thermodynamically favorable reaction pathway (Table S2 of the Supporting Information). Panels b and c of Figure 2 45 and Cu−Au alloy, 46 which agrees well with our results. The rate-limiting step of the C 2 -1 process (C 2 via *COH) is the hydrogenation of *CO to *COH.…”

Theoretical Insights into Enhancing Catalytic Performance of Al–Cu Alloy for CO2 Electroreduction toward Ethene Production

“…The selectivity toward ethylene rather than ethanol is determined by preferential dehydroxylation of *CH 2 CHOH and *CH 2 CH 2 OH on Cu(100) and Al 3 Cu­(100), respectively, as shown in Figure b, which is different with the evolution of *CHCOH discussed in previous work . It is noticed that the breaking of the C–O bond in each oxygenated C 2 intermediate such as *CHCOH, ,, *CH 2 CH 2 OH, , and *CH 2 CHO − results in the high selectivity toward C 2 H 4 , and ethanol can only be achieved by ensuring that all oxygenated C 2 species are inclined to hydrogenation rather than dehydroxylation. Thus, high selectivity toward ethanol is more difficult than that toward ethylene, which requires more precise catalyst regulation to ensure the stability of C–O bonds.…”