In-situ synthesis of WO3–x/MoO3–x heterojunction with abundant oxygen vacancies for efficient photocatalytic reduction of CO2

Abstract Photocatalytic conversion of CO2 into valuable fuels is considered to be a promising approach for developing renewable and sustainable energy. However, due to poor light harvesting, low charge-separation efficiency and insufficient reaction sites on the surface of photocatalyst, the overall conversion efficiency is facing great challenges. Herein, we reported a novel WO3−x/MoO3−x heterojunction photocatalyst with abundant oxygen vacancies via a facile in-situ solvothermal process to tackle all of the aforementioned issues. Due to the well-matched band gap between WO3−x and MoO3−x, the resultant WO3−x/MoO3−x heterojunction can not only extend the optical response to overlap the NIR region, but also greatly promote the separation of electron-hole pairs. Meanwhile, the improvement of specific surface area and the creation of surface oxygen vacancies endow WO3−x/MoO3−x heterojunction with enhanced CO2 adsorption and activation capacities. As a result, WO3−x/MoO3−x heterojunction exhibits a significant improvement in the photoreduction activity of CO2. And its CO productivity is 40.2 μmol·g−1·h−1, which is 9.5 times higher than that of the pristine MoO3−x nanosheet. This strategy might provide a novel way to improve the comprehensive performance of photocatalysts and develop renewable energy sources.