Hybridization of Defective Tin Disulfide Nanosheets and Silver Nanowires Enables Efficient Electrochemical Reduction of CO2 into Formate and Syngas.

Abstract

Integrating the defect engineering and conductivity promotion represents a promising way to improve the performance of CO2 electrochemical reduction. Herein, the hybridized composite of defective SnS2 nanosheets and Ag nanowires is developed as an efficient catalyst for the production of formate and syngas toward CO2 electrochemical reduction. The Schottky barrier in Ag-SnS2 hybrid nanosheets is negligible due to the similar Fermi level of SnS2 nanosheets and Ag nanowires. Accordingly, the free electrons of Ag nanowires participate in the electronic transport of SnS2 nanosheets, and thus give rise to a 5.5-fold larger carrier density of Ag-SnS2 hybrid nanosheets than that of SnS2 nanosheets. In CO2 electrochemical reduction, the Ag-SnS2 hybrid nanosheets display 38.8 mA cm-2 of geometrical current density at -1.0 V vs reversible hydrogen electrode, including 23.3 mA cm-2 for formate and 15.5 mA cm-2 for syngas with the CO/H2 ratio of 1:1. A mechanistic study reveals that the abundant defect sites and carrier density not only promote the conductivity of the electrocatalyst, but also increase the binding strength for CO2 , which account for the efficient CO2 reduction.