AuCu Catalysts with High Activity and Selectivity for Electrochemical Reduction of CO2 to CO

Abstract

As the extensive usage of fossil fuels, the concentration of CO2 in the atmosphere has increased, and global warming becomes a critical problem. Recently various studies have been conducted to reduce the concentration of CO2. One attractive method to solve this problem is the electrochemical reduction of CO2. It produces feedstocks and useful fuels of C1 chemistry, such as CO, CH4, CH3OH and HCOOH at room temperature and ambient pressure. Among the useful products, the CO is known to have the economic benefit because the market price of CO is higher than other products. However, the electrochemical reduction usually suffers from huge energy losses due to the high overpotential originated form chemical stability of CO2. Therefore, development of a highly active catalyst is essential. Currently, Au-based and Au-based bimetallic catalysts are commonly used to convert CO2. To obtain highly activity and selectivity, the various investigates are being conducted to control properties, which their morphology, size, composition, facets and oxidation states. In addition, these properties can effect intermediate adsorption, grain size and electrochemical surface area.Herein, AuCu nanoparticles were directly fabricated on carbon paper substrate by using electrodeposition method. The electrodeposition parameters such as precursor concentration and deposition time were changed to control the morphology and composition of AuCu catalysts. The AuCu nanoparticles were used as cathode for electrochemical carbon dioxide conversion in 0.5 M KHCO3 in H-type cell which was separated by proton conducting membrane. At a certain condition, the CO Faradaic efficiency of ~80 % was achieved at a potential of -0.7 VRHE. Further post-treatments such as anodizing or annealing methods were performed to change the control properties of the catalyst. And then, modification on catalytic performance was observed.