Geometric Modulation of Local CO Flux in Ag@Cu₂O Nanoreactors for Steering the CO₂RR Pathway toward High‐Efficacy Methane Production

Abstract

The electroreduction of carbon dioxide (CO2RR) to CH4 stands as one of the promising paths for resourceful CO2 utilization in meeting the imminent “carbon‐neutral” goal of the near future. Yet, limited success has been witnessed in the development of high‐efficiency catalysts imparting satisfactory methane selectivity at a commercially viable current density. Herein, a unique category of CO2RR catalysts is fabricated with the yolk–shell nanocell structure, comprising an Ag core and a Cu2O shell that resembles the tandem nanoreactor. By fixing the Ag core and tuning the Cu2O envelope size, the CO flux arriving at the oxide‐derived Cu shell can be regulated, which further modulates the *CO coverage and *H adsorption at the Cu surface, consequently steering the CO2RR pathway. Density functional theory simulations show that lower CO coverage favors methane formation via stabilizing the intermediate *CHO. As a result, the best catalyst in the flow cell shows a high CH4 Faraday efficiency of 74 ± 2% and partial current density of 178 ± 5 mA cm−2 at −1.2 VRHE, ranking above the state‐of‐the‐art catalysts reported today for methane production. These findings mark the significance of precision synthesis in tailoring the catalyst geometry for achieving desired CO2RR performance.

Steering surface reconstruction of copper with electrolyte additives for CO2 electroreduction

“…c Comparison of our work with previous studies on the electrocatalytic CO 2 -to-CH 4 reaction in a flow cell with partial current densities over 100 mA cm −2 (Refs. 46 , 59 – 66 ). …”

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

“…158 Therefore, a sufficiently high coverage of CO* on Cu is an important condition for C–C coupling and increasing the coverage of CO* is conducive to reducing the energy barrier of C–C coupling. 63,159–161 It was found in an experiment that whether on Cu derived from Cu 2 O or single-crystal Cu, the initial potential to form C 2 H 4 was 300–400 mV higher than the potential to produce CO during the CO 2 RR, and the CO yield decreased after the evolution of C 2 H 4 . This indicates that sufficient CO should be guaranteed before the formation of C 2 H 4 .…”

“…39 Besides, when the distance between the CO formation sites and CO deep reduction sites in the cascade do not match the CO diffusion distance and moderate coverage, the C 2+ production will be dominated by C 1 . 161,212…”

Rational Design and Synthesis of Ag−Cu2O Nanocomposites for SERS Detection, Catalysis, and Antibacterial Applications

“…In their recent work, Xiong et al implemented an Ostwald ripening-based strategy to obtain yolk-shell Ag@Cu 2 O nanocomposites. [34] Pre-synthesized 70 nm Ag nanocubes were first coated with a Cu(OH) 2 shell by dispersing the nanocubes in an aqueous solution containing Cu(NO 3 ) 2 and (NH 4 ) 2 SO 4 , followed by addition of NaOH. The presence of (NH 4 ) 2 SO 4 was noted to facilitate the nucleation and assembly of Cu(OH) 2 exclusively on the surfaces of the Ag nanocubes.…”

“…Xiong and co-workers demonstrated the use of their yolkshell Ag@Cu 2 O nanocomposites (Figures 5a-c) as CO 2 RR catalysts for the production of methane (CH 4 ). [34] In the electrochemical reduction of CO 2 to CH 4 , the hydrogenation of *CO to *CHO is a key intermediate step; hence, an optimized *CO coverage on the catalyst surface is necessary to achieve the best CH 4 selectivity. It was noted that a high *CO coverage can promote CÀ C coupling that leads to the formation of multicarbon products (C 2 + ), whereas a low *CO coverage might not be competitive enough for HER.…”