Developing an efficient and cost-effective catalyst is of the highest interests for electrochemical reduction of CO2. Nanostructured silver (Ag) represents one candidate due to its efficiency of selective formation of CO that is comparable that of the well-known expensive gold (Au) catalysts. However, the mass-specific efficiency and suppression of the competitive hydrogen evolution reaction (HER) of the available Ag nanostructured catalysts are not ideal yet for electrochemical CO2 reduction. In this presentation, we demonstrate a new type of porous Ag nanostructures with two-levels of porosity, exhibiting the larger hollows for efficient electrolyte diffusion and the smaller pores for exposing the highest surface area. The porous Ag nanostructures are synthesized from in-situ electrochemical reduction of silver benzenthiolate nanoboxes constructed from the well-organized nanoplates. Such synthesis results in the Ag surfaces to be covered with benzenthiolate, which influences the adsorption energy of active species involved in both CO2 reduction and HER to improve the selectivity of CO2-to-CO conversion. The results reveal tremendous enhancement of mass efficiency reaching upto 500 A/g for CO2 reduction. In the presence of surface benzenethiolate adsorbates, the electrochemical CO2-to-CO conversion efficiency maintains as high as close to the unity even at high overpotentials, where HER is usually difficult to suppress. This work highlights a promising way to design a cost-effective catalyst toward an efficient and selective electroreduction of CO2.

3D-porous plate-like Ag nanostructures for efficient CO2 electroreduction

2019 Fall National Meeting

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