Interface engineered metal oxide heterojunction nanostructures in photocatalytic CO2 reduction: Progress and prospects

The current surge in atmospheric CO2 poses a critical challenge to global climate stability. To combat this, effective strategies for capturing and utilizing CO2 are imperative. Among the available strategies, photochemical reduction emerges as a highly promising avenue. However, achieving efficient CO2 reduction with superior product selectivity demands well-designed photocatalysts. In this review, we provide an overview of recent advancements in designing and fabricating metal oxide-based heterojunction nanocatalysts, including novel types such as high-entropy oxides and MXenes, over the past five years, assessing their effectiveness in photocatalytic CO2 reduction. Emphasis is placed on understanding the roles played by oxygen vacancies and structural defects in enhancing the CO2 adsorption capacities of metal oxides. Considering the critical role of carrier recombination processes in photocatalytic efficiency, we delve into the formation of junction potential, as well as the separation and recombination of charge carriers at heterojunction interfaces, elucidating their impact on the CO2 reduction capabilities of metal-oxide heterostructures. Finally, we address the current challenges and prospects of harnessing such heterojunction nanostructures for CO2 photoreduction.