One-pot hydrothermal synthesis of transition metal sulfides-decorated CuS microflower-like structures for electrochemical CO2 reduction to CO

Abstract

Electrochemical CO2 reduction (ECR) to value-added products is regarded as a sustainable strategy to mitigate global warming and energy crisis, and designing highly efficient and robust catalysts is essential. In this work, transition metal sulfides (TMS)-decorated CuS microflower-like structures were prepared via the one-pot hydrothermal synthesis method for ECR to CO, and the influence of TMS doping on ECR performance was demonstrated. Characterization of the catalysts was performed using XRD, FESEM-EDS, N2 physisorption, and XPS, revealing the successful loading of TMS, the formation of microflower-like architectures and the generation of sulfur vacancies. Electrochemical tests demonstrated that doping ZnS, Bi2S3, CdS and MoS2 improved the intrinsic CO2 reduction activity of the CuS catalyst. Particularly, the MoS2-CuS composite catalyst with imperfect petal-like structure showed uniform distribution of edge Mo sites, which worked synergistically with the formed grain boundaries (GBs) and undercoordinated S vacancy sites in promoting CO2 activation, stabilizing *COOH adsorption, facilitating *CO desorption, and lowering the energy barrier of the potential-limiting step for improved CO selectivity. The MoS2-CuS catalyst achieved a maximum CO selectivity of 83.2% at –0.6 V versus the reversible hydrogen electrode (RHE) and a high CO cathodic energetic efficiency of 100%. At this potential, the catalyst maintained stable catalytic activity and CO selectivity during a 333-min electrolysis process. The findings will offer a promising avenue for the development of efficient and stable catalysts for CO production from ECR.