Manipulating Cu Nanoparticle Surface Oxidation States Tunes Catalytic Selectivity toward CH₄ or C₂₊ Products in CO₂ Electroreduction

Abstract

Herein, a facile seed‐assisted strategy for preparing Cu nanoparticles (NPs) with polyvinyl pyrrolidone (PVP) capping is presented. Compared to the Cu NPs with deficient PVP protection, the Cu NPs capped with a sufficient amount of PVP remain almost completely as Cu0 species. In contrast, the Cu NPs that are considered PVP deficient form an oxide structure in which the inner layer is face‐centered cubic Cu and the outer layer is, at least in part, made up of Cu2O species. Furthermore, to eliminate CO2 molecule diffusion and simultaneously obtain significant current density (200 mA cm−2) for industrial applications, a flow cell configuration is used for carbon dioxide electro reduction reaction (CO2RR) testing in 0.5 m potassium hydroxide solution. The Cu NPs with zero valence deliver Faradaic efficiencies (FEs) for the CO2 reduction to CH4 of over 70%, with a current density exceeding 200 mA cm−2, outstripping the performances of the majority of the reported CO2 electrocatalysts. Interestingly, the distribution of products catalyzed by the Cu NPs with +1 valence includes multicarbon products (C2+) such as C2H4, C2H5OH, CH3COOH, and C3H7OH with combined FEs of >80%, with current densities of up to 300 mA cm−2. The above results unambiguously establish that surface oxidation of Cu species plays a crucial role in the CO2RR.

Boosting CO2 electroreduction towards C2+ products via CO* intermediate manipulation on copper-based catalysts

“…DFT results showed that the coexistence of Cu + and Cu 0 on the catalyst surface is beneficial for C-C coupling. 107,108 Therefore, increasing the Cu + content and stability in Cu catalysts has been developed as an important strategy to enhance their C 2+ selectivity.…”

Cu/PCN Metal-Semiconductor Heterojunction by Thermal Reduction for Photoreaction of CO2-Aerated H2O to CH3OH and C2H5OH

“… 2 Cu-based electrocatalyst studies indicated that CO 2 reduction inclines to multicarbon products (C 2 + ) on Cu + sites. 20 , 21 This progress reveals distinct impacts of the Cu valence in semiconductor materials on the photoreaction products.…”

Stabilization of Cu+ via Strong Electronic Interaction for Selective and Stable CO2 Electroreduction

“…[12][13][14][15][16] Moreover, regulating the valence state of copper or optimizing the distribution of multi-valent copper in CuO x catalysts has been reported to enhance the overall CO 2 RR performance. [17][18][19][20][21][22][23] Specifically, based on density functional theory (DFT) calculations, Goddard et al suggested that the interfaces between Cu + and Cu 0 regions could promote C 2 + production. [24] Wu et al reported that Cu surfaces with coexistent Cu 0 and Cu + surprisingly alter the CO 2 reduction mechanism and improve the C 2 product selectivity in the CO 2 RR.…”