Multi-morphology CuS catalyst for selective electrocatalytic of CO2 conversion to formate.

The excessive consumption of fossil fuels leads to a large amount of carbon dioxide (CO 2) being released into the atmosphere, destroying the natural balance of the carbon cycle system, causing the greenhouse effect, and aggravating global climate change. Electrocatalytic CO 2 reduction (E-CO 2 R) to produce value-added chemicals and synthetic fuels can not only solve the excessive emission of CO 2 but also realize the regeneration of carbon fuel. Given the unclear relationship between morphology and performance of copper-based catalysts for E-CO 2 R. The morphology of CuS nanomaterials prepared under different sulfur sources is different, which affects the performance of E-CO 2 R. In this study, a series of CuS nano-catalysts with multiple morphologies were prepared by using different sulfur precursors and surfactants based on morphology and structure regulation strategies, and E-CO 2 R performance tests were conducted to determine the structure-activity relationship between morphology and formate selectivity. Flower spherical morphology exhibited better Faraday efficiency for formate, followed by nanoparticles and finally nanospheres. After the surfactant was added, the morphology of CuS changed differently, such as adjusting the particle size of nano-flowers, alleviating the agglomeration of nano-particles, and forming hollow nano-spheres or composite morphology. These changes increased the electrochemical surface area and improved the performance of the electrocatalytic preparation of formate from CO 2 R. Density functional theory (DFT) was used to explain the reaction mechanism of E-CO 2 R to formate on different Cu surfaces, and the linear relationship between the work function corrected by sulfur content on each surface and the binding energy of *CO 2 was quantified. Bader charge analysis demonstrated that the stability of *OCHO was related to the algebraic sum of S and intermediate charges on each surface, and the formation energy of CO product intermediate *COOH was linear with that of HCOOH product intermediate *OCHO. [Display omitted] • Morphology-controlled CuS catalyst for selective electrochemical CO 2 reduction of formate. • The Faraday efficiency of formate formation reached 79.7 % at －1 V vs RHE. • DFT reveals the mechanism of S doping on Cu surface for electroreduction of CO 2 conversion. [ABSTRACT FROM AUTHOR]