Operando Investigation of Ag‐Decorated Cu₂O Nanocube Catalysts with Enhanced CO₂ Electroreduction toward Liquid Products

Abstract

Direct conversion of carbon dioxide into multicarbon liquid fuels by the CO 2 electrochemical reduction reaction (CO 2 RR) can contribute to the decarbonization of the global economy.H ere,w ell-defined Cu 2 On anocubes (NCs, 35 nm) uniformly covered with Ag nanoparticles (5 nm) were synthesized.W hen compared to bare Cu 2 ONCs,t he catalyst with 5at% Ag on Cu 2 ONCs displayed atwo-fold increase in the Faradaic efficiency for C 2+ liquid products (30 %a t À1.0 V RHE), including ethanol, 1-propanol, and acetaldehyde, while formate and hydrogen were suppressed. Operando X-ray absorption spectroscopyrevealed the partial reduction of Cu 2 O during CO 2 RR, accompanied by ar eaction-driven redispersion of Ag on the CuO x NCs.D ata from operando surfaceenhanced Raman spectroscopyf urther uncovered significant variations in the CO binding to Cu, whichw ere assigned to AgÀCu sites formed during CO 2 RR that appear crucial for the C À Ccoupling and the enhanced yield of liquid products.

Catalyst Design for Electrochemical Reduction of CO2 to Multicarbon Products

“…In practical electrochemical tests, the Cu 3 Ag 1 catalyst showed 63% FE for CO 2 to alcohol and an alcohol partial current density of 25 mA cm −2 at −0.95 V versus RHE, corresponding to a 126-fold enhancement in selectivity and 25-fold increase in activity compared with the bare electrodeposited Cu matrix. Herzog et al [91] investigated the morphology, chemical state, composition, and adsorbates of the well-defined Cu 2 O nanocubes (35 nm) uniformly covered with Ag NPs via ex situ, in situ, and operando characterization techniques under CO 2 RR conditions. Particularly, the redispersion was found for Ag NPs on Cu and a certain CuAg miscibility.…”

Operando‐Untersuchung von Ag‐dekorierten Cu2O‐Nanowürfel‐Katalysatoren mit verbesserter CO2‐Elektroreduktion zu Flüssigprodukten

“…[22] Additionally, Ag incorporation in Cu weakens the binding energies of the reduced aldehyde intermediates and inhibits their further reduction to ethanol and 1-propanol as demonstrated in a recent DFT study. [23] However, the structural analysis of the catalysts showed that the surface partially consists of Cu/Ag areas, which also leads to the formation of ethanol and 1-propanol at the Cu sites, since they are expected to have higher binding energies for the oxygenated intermediates as compared to the Ag-Cu mixed regions. Therefore, having Ag/AgCu/Cu interfaces as active surface sites appear to enhance the yield of C2+ liquid products.…”

Enhanced Ethylene Formation from Carbon Dioxide Reduction through Sequential Catalysis on Au Decorated Cubic Cu2O Electrocatalyst

“…Therefore, a sequential-sites mechanism was adopted to illustrate the increased FEs of C 2 products on CuAu, CuAg, Cu x Zn, Ag/Cu 2 O catalysts. [47][48][49] Beyond that, the stability of Cu 2 O could be improved by introducing metal nanoparticles on Cu 2 O surface, such as our previously reported Cu 2 OÀ Au catalyst and nanoporous CuÀ Ag alloy catalyst. [12,23] In present work, we prepared the novel Au x Cu 2 O (x represents the molar mass of the introduction of Au) catalysts by the galvanic replacement reaction between cubic Cu 2 O and HAuCl 4 , and then the co-existence active sites of Cu + and Cu 0 on Au x Cu 2 O catalysts were generated by performing a repeated linear voltammetry (LSV) reduction before CO 2 RR.…”

“…When the second metal (Au, Zn, Ag) is introduced as an active promoter that forms more CO and could help generate a high flux of CO, so that neighboring Cu may have more opportunity to participate in C−C coupling. Therefore, a sequential‐sites mechanism was adopted to illustrate the increased FEs of C 2 products on CuAu, CuAg, Cu x Zn, Ag/Cu 2 O catalysts [47–49] . Beyond that, the stability of Cu 2 O could be improved by introducing metal nanoparticles on Cu 2 O surface, such as our previously reported Cu 2 O−Au catalyst and nanoporous Cu−Ag alloy catalyst [12,23] …”