Ultra-efficient post-treatment flame method to introduce abundant oxygen vacancies in BiVO4 photoanode toward solar water splitting

Oxygen vacancies (OVs) are widely introduced into metal oxide photocatalysts to improve their light absorption, carrier mobility, and surface reaction. It is still challenging to use typical OV generation strategies for achieving high efficiency, low cost, and good controllability. Here, we develop the controllable and ultra-efficient post-processing flame method to introduce rich OVs into monoclinic BiVO4 photoanode in 20 s. The experiment parameters including the fuel-to-oxygen equivalence, distance, and annealing time were governed to adjust the electronic structure and PEC performances of the resultant BiVO4 photoanodes. As a result, the photocurrent density was enhanced up to 3.14-fold, and a high photocurrent density of 3.07 mA cm−2 was achieved. The introduction of OVs improves the carrier transport, adsorption, and activation of OH– ions, confirmed by experimental and computational results. Furthermore, the presented flame strategy exhibited great versatility in the configuration of OV-enhanced metal oxide photoanodes such as Fe2O3, WO3, and TiO2.