Flower-like Bi2WO6 with oxygen vacancies achieving enhanced photoelectrocatalytic performance

A series of flower-like Bi2WO6 with oxygen vacancies were produced through an etching process at room temperature using NaBH4 as reducing agent. The structure and morphology were further confirmed by XRD, SEM, HRTEM and XPS. The performance of photoelectrochemical (PEC) water splitting for all samples was investigated by evaluating the charge-transfer resistance, electrons lifetime and photoinduced carrier density. The results demonstrated that the Bi2WO6 with appropriate concentration of oxygen vacancies exhibited higher PEC properties than pure Bi2WO6 and the enhanced PEC performance of the Bi2WO6-x was ascribed to the presence of oxygen vacancies. The oxygen vacancies can introduce impurity levels under the conduction band which can act as electron trapping centers in Bi2WO6-x resulted in the band gap narrowing, which accelerates the separation and transfer of charges and reduced the recombination of photogenerated electron-hole.