Electrochemical conversion of CO2 into HCOO-in a synergistic manner by a nanocomposite of Zn2SnO4/ZnO

Abstract

Exploring environmentally friendly nanomaterials as alternatives to toxic metals for electrocatalytic CO2 reduction into formate is very important. Designing a nanocomposite catalyst with different phase components is an underlying strategy to achieve prominent catalysts for electrochemical CO2 reduction owing to the potential capacity to regulate electronic structure by interfacial interactions. Herein, we report a novel nanocomposite with components of cublic-like Zn2SnO4 and nanosheet-structured ZnO (Zn2SnO4/ZnO) as an efficient electrocatalyst for the CO2 reduction reaction (CO2RR). This strategy can reduce the use of toxic metals and the cost of the catalyst. The composite exhibited a maximum faradaic efficiency (FE) of 98% for the C-1 product, and even approached 90% for formate production at -1.0 V versus the reversible hydrogen electrode, along with excellent durability. In constrast, the maximum FEHCOOH of a single ZnO component or Zn2SnO4 component were both <50% over the potential window. Coupling of X-ray photoelectron/adsorption spectroscopy and electrochemical measurements revealed interfacial charge transfer and oxygen vacancies to result in an optimized electronic structure of Zn2SnO4/ZnO. This was favorable for an HCOO* intermediate-involved reaction pathway, together with an enlarged electochemcial active area, which boosted the selectivity and activity of formate synergistically.