Toward Excellence in Photocathode Engineering for Photoelectrochemical CO_2 Reduction: Design Rationales and Current Progress

摘要

Photoelectrochemical CO_2 reduction reaction (PEC CO_2RR) is a promisingtechnology which offers the possibility of a carbon-neutral solar fuel productionvia artificial photosynthesis. The challenging proton-coupled multielectrontransfers with high energy barriers in CO_2RR however pose as a huge hindranceto the technology, which demands strict specifications in the designof photocathode materials so as to improve PEC performances. This reviewunderscores effective design strategies and current material progress for thejudicious assembly of photocathode materials for CO_2RR. The review beginswith elucidating the fundamental principles of CO_2 reduction process andphotocathode electrochemistry. Based on these, the design criteria and tradeoffsin the design of PEC CO_2RR photocathodes are highlighted. The variouspromotive strategies for photocathodes and their underlying rationales such asdoping, defect engineering, nanostructuring, cocatalyst loading, passivation,heterojunction formation, and innovative multijunction configurations are furtheroutlined and design propositions in the area are provided. Following that,various photocathode semiconductor materials categorized into photovoltaic(PV) grade (silicon, Ⅲ-Ⅴ semiconductors, chalcogenides) and non-PV grade(metal oxides) materials are summarized and extensively discussed, along withtheir recent advances. Finally, perspectives on the design of photocathodes forCO2RR and new paradigms in the field are put forward.