Current dilemma in photocatalytic CO2 reduction: real solar fuel production or false positive outcomings?

Abstract

Solar driven carbon dioxide (CO2) recycling into hydrocarbon fuels using semiconductor photocatalysts offers an ideal energy conversion pathway to solve both the energy crisis and environmental degradation problems. However, the ubiquitous presence of carbonaceous contaminants in photocatalytic CO2 reduction system and the inferior yields of hydrocarbon fuels raise serious concerns about the reliability of the reported experimental results. Here in this perspective, we focus on the accurate assessment of the CO2 reduction products, systemically discuss the possible sources of errors in the product quantification, elaborate the common mistakes spread in the analysis of reaction products obtained in 13CO2 labelling experiments, and further propose reliable protocols for reporting the results of these isotopic tracing experiments. Moreover, the challenges and cautions in the precise measurement of O2 evolution rate are also depicted, and the amplification of the concentration of O2 in photoreactors well above the limit of detection is still demonstrated to be the most effective solution to this troublesome issue. We hope the viewpoints raised in this paper will help to assessment the reliability of the reported data in future, and also benefit the beginners that intend to dive in the photocatalytic CO2 reduction area.Graphical abstract