Synthesis of Bi2WO6 with gradient oxygen vacancies for highly photocatalytic NO oxidation and mechanism study

We successfully synthesized the Bi2WO6 (BWO) with gradient concentration of oxygen vacancies and exhibited the excellent photocatalytic NO oxidation activity. And the oxygen vacancy introduced in photocatalyst is a popular method to enhance the photocatalytic performance. The formation of oxygen vacancy defects in BWO is responsible for the tuning band structure and modifying surface chemical state to improve carriers separation efficiency, enlarge visible light absorption range and facilitate reactant activation, which is unambiguously verified by the UV-vis DRS, XPS, EPR and DFT calculations. Moreover, the role of surface oxygen vacancy defects and reaction mechanism of photocatalytic NO oxidation were discussed in detail by combing the in situ DRIFT and theoretical calculations. This work could be broadly used to the design and synthesize high efficient photocatalysts and pave a way to understand the reaction mechanism of NO oxidization.