Oxygen vacancy induced robust interfacial electric field for efficient photocatalytic hydrogen peroxide production

Photocatalytic production of hydrogen peroxide (H2O2) can convert low-density solar energy into storable chemical energy by only utilizing water and oxygen as feedstock, and sunlight as stimulator. However, it is encountered a great deal of hurdles for further improving the photocatalytic H2O2 production, such as the narrow light absorption range of a single semiconductor, low separation efficiency of photogenerated electron-hole pairs and limited surface active sites. Although construction of heterojunction is an effective tactic to modulate the charge transfer path and improve the utilization of visible light, realizing close interfacial contact with strong interfacial electric field (IEF) remains challenging. Herein, we construct a chemically bonded heterojunction, abbreviated as BON-Ov/CN, which consists of g-C3N4 and Bi2O2(NO3)(OH) decorated with oxygen vacancies (Ovs) to solve all the above problems in one fell swoop. The optimal BON-Ov/CN exhibits a photocatalytic H2O2 production performance of 706.2 µmol L-1, which is 19.1, 14.9 and 4.9 times higher than that of BON, BON-Ov and CN, respectively. It was demonstrated that the largely enhanced catalytic activity is attributed to the type-II heterojunction between BON-Ov and CN. In particular, the introduction of Ovs on BON can induce a strengthened IEF to boost the interfacial directional charge transfer and enhance its surface active sites to some extent. This study offers a fresh perspective on improving interfacial charge migration of heterojunctions by vacancy-induced IEF regulation strategy.