Preparation of direct Z-scheme Bi2WO6/TiO2 heterojunction by one-step solvothermal method and enhancement mechanism of photocatalytic H2 production

Direct Z-scheme Bi2WO6/TiO2 heterojunction photocatalyst was prepared by one-step solvothermal method. The catalyst was characterized by XRD, TEM, XPS, UV–Vis DRS, photoluminescence spectroscopy and photoelectrochemical studies. The photocatalytic hydrogen production experiments show that Bi2WO6 did not generate H2 and the H2-production rate of TiO2 is only 0.1 mmol⋅g−1h−1. The hydrogen production rate of the Bi2WO6/TiO2 heterojunction photocatalyst reaches 12.9 mmol⋅g−1h−1, which is 129 times that of TiO2. Compared with TiO2, the enhanced H2-production activity of the heterojunction catalyst can be attributed to the wider light absorption range and the efficient separation and migration of carriers at the close contact interface between Bi2WO6 and TiO2. Based on the work functions of Bi2WO6, TiO2 and their heterojunctions, combined with the results of electron paramagnetic resonance spectroscopy and Mott-Schottky measurements, the photocatalytic H2 production mechanism of Z-scheme heterojunction Bi2WO6/TiO2 was proposed. This work provides an easy and simple way to design a binary Z-scheme photocatalyst with efficient catalytic H2-production activity without electron mediators.