Synthesis of AuX (X = Ni, Ga, Mo, Zn, and Cr) Alloy Aerogels as High-Performance Electrocatalytic CO2 Reduction Reaction Catalysts.

Abstract

Electrocatalytic CO2 reduction reaction (eCO2RR) into value-added chemicals is highly desirable to mitigate the global warming effect and energy crisis. Metal aerogels, as featured by a self-supporting structure, large specific surface area, outstanding conductivity, and a hierarchical porous structure, are ideal electrocatalysts in eCO2RR. Herein, we report a simple and general strategy for constructing a series of Au-based alloy aerogels which contain Au with another metal including Ga, Ni, Mo, Zn, and Cr, respectively. For the first time, the electrocatalytic activities of AuGa aerogels, AuNi aerogels, and AuMo aerogels for CO2RR were studied in detail. The resultant Au81Ga19 aerogel achieves a 95.2% Faradaic efficiency (FE) at -1.16 V versus reversible hydrogen (vs RHE) in H-cells. Impressively, a total 99.4% FE for C1 products (CO + HCOOH) with a current density of 100 mA cm-2 at -0.6 V vs RHE and a large current density of 228 mA cm-2 can be achieved at -0.9 V with a 72.3% FE for the C1 product in a flow cell. Electrochemical characterization and theoretical calculations further revealed that the outstanding performance of the Au-based aerogels was derived from the large specific surface area, abundant grain boundaries, low interfacial charge transfer resistance, and synergetic effect. Overall, this study provides a promising alternative to engineer alloy aerogel electrocatalysts for highly efficient CO2 electroreduction.