Microwave-assisted synthesis of ZnO/BiNbO₄ heterojunctions for enhanced hydrogen production

This work introduces a novel heterojunction between ZnO and BiNbO₄, prepared through a microwave-assisted technique that significantly reduces time and energy consumption for the synthesis. The used method requires 48 minutes to obtain vertically aligned wurtzite ZnO films and 30 minutes to obtain globular orthorhombic/triclinic BiNbO₄. The heterojunction exploits the suitable band alignment of ZnO and BiNbO₄ to construct an S-scheme structure, achieving enhanced charge separation and transfer. The prepared ZnO/BiNbO₄ heterojunction was used as a photoanode for water photosplitting, exhibiting a fourfold increase in photocurrents for oxygen evolution compared to pristine ZnO. The heterojunction has also demonstrated photocatalytic activity for hydrogen production that is 3.5 and 2 times higher than that of bare ZnO and BiNbO₄, respectively. These findings highlight the promising potential of ZnO/BiNbO₄ heterojunctions for advanced photocatalytic and photoelectrocatalytic applications, particularly in hydrogen production.