Development and investigation of cathode catalyst for electrochemical and photoelectrochemical carbon dioxide conversion to useful fuels

Abstract

$CO_2$ is a major contributor to global warming and greenhouse effect. To reduce the accumulation of $CO_2$ in the atmosphere, various strategies for $CO_2$ conversion into fuels have been developed. Photoelectrochemical and electrochemical system is highly desirable due to its ambient reaction conditions, high energy efficiency and sustainability. However, since $CO_2$ is extremely stable, the primary obstacle for success these systems is to find suitable catalyst having good catalytic activity, selectivity, and stability. Herein, design strategies of catalysts for highly efficient photoelectrochemical and electrochemical $CO_2$ reduction are developed and their catalysis are also investigated using physical characterizations, electrochemical analyses, theoretical calculation, and etc. As a cathode material for a photoelectrochemical system, i) various transition metals decorated layered $CuO/Cu_2O$ films and ii) polypyrrole-coated p-ZnTe electrode (PPy/ZnTe) were developed and their catalytic activities were investigated. Deposition of the transition metals and polypyrrole effectively enhanced $CO_2$ con-version to fuel in terms of faradaic efficiency and production rate. In electrochemical $CO_2$ reduction system, the correlations of $CO_2$ conversion selectivity on Sn and Zn electrodes with their chemical and crystal structures are demonstrated. Based on this design strategy, i) a hierarchical Sn dendrite electrode with high oxygen content and ii) hexagonal Zn catalyst with high (101) concentration was synthesized. Furthermore, both of these elec-trodes exhibits a superior production rate with high selectivity and unprecedented stability toward $CO_2$ reduc-tion reaction.