TY - JOUR

T1 - Can the CO2 Reduction Reaction Be Improved on Cu

T2 - Selectivity and Intrinsic Activity of Functionalized Cu Surfaces

AU - Christensen, Oliver

AU - Zhao, Siqi

AU - Sun, Zhaozong

AU - Bagger, Alexander

AU - Lauritsen, Jeppe Vang

AU - Pedersen, Steen Uttrup

AU - Daasbjerg, Kim

AU - Rossmeisl, Jan

PY - 2022

Y1 - 2022

N2 - Cu is currently the most effective monometallic catalyst for producing valuable multicarbon-based (C2+) products, such as ethylene and ethanol, from the CO2 reduction reaction (CO2RR). One approach to optimize the activity and selectivity of the metal Cu catalyst is to functionalize the Cu electrode with a molecular modifier. We investigate from a data standpoint whether any reported functionalized Cu catalyst improves the intrinsic activity and/or multicarbon product selectivity compared to the performance of bare Cu foil and the best single crystal Cu facets. Our analysis shows that the reported increases in activity are due to increased surface roughness and disappear once normalized with respect to electrochemical surface area. The intrinsic activity generally falls below that of the bare Cu foil reference, both for total and product-specific current, which we attribute to nonselective blocking of active sites by the modifier on the surface. Instead, an analysis of various polymer diffusion coefficients indicates that the modifier allows for easier diffusion of CO2 compared to H2O to the surface, leading to greater selectivity for CO2RR and C2+ products. As such, our analysis finds no catalyst for CO2RR that intrinsically outperforms bare Cu.

AB - Cu is currently the most effective monometallic catalyst for producing valuable multicarbon-based (C2+) products, such as ethylene and ethanol, from the CO2 reduction reaction (CO2RR). One approach to optimize the activity and selectivity of the metal Cu catalyst is to functionalize the Cu electrode with a molecular modifier. We investigate from a data standpoint whether any reported functionalized Cu catalyst improves the intrinsic activity and/or multicarbon product selectivity compared to the performance of bare Cu foil and the best single crystal Cu facets. Our analysis shows that the reported increases in activity are due to increased surface roughness and disappear once normalized with respect to electrochemical surface area. The intrinsic activity generally falls below that of the bare Cu foil reference, both for total and product-specific current, which we attribute to nonselective blocking of active sites by the modifier on the surface. Instead, an analysis of various polymer diffusion coefficients indicates that the modifier allows for easier diffusion of CO2 compared to H2O to the surface, leading to greater selectivity for CO2RR and C2+ products. As such, our analysis finds no catalyst for CO2RR that intrinsically outperforms bare Cu.

KW - CO2 reduction

KW - electrochemistry

KW - copper catalyst

KW - molecular modifiers

KW - surface roughness

KW - intrinsic activity

KW - diffusion

KW - benchmarking

KW - ELECTROCHEMICAL REDUCTION

KW - CARBON-DIOXIDE

KW - ELECTROCATALYTIC PERFORMANCE

KW - POLYCRYSTALLINE COPPER

KW - METAL-ELECTRODES

KW - ELECTROREDUCTION

KW - MORPHOLOGY

KW - CATALYSIS

KW - ETHYLENE

KW - PRODUCTS

U2 - 10.1021/acscatal.2c04200

DO - 10.1021/acscatal.2c04200

M3 - Journal article

VL - 12

SP - 15737

EP - 15749

JO - ACS Catalysis

JF - ACS Catalysis

SN - 2155-5435

IS - 24

ER -