Otmane El Ouardi¹, Adnane Maimoune¹, Marina Ratova², Mohammed Makha¹, Peter Kelly², Jones Alami^1
1University Mohammed VI Polytechnic, Benguerir, Morocco
²Manchester Metropolitan University, Manchester, United Kingdom
Bismuth vanadate (BiVO₄) has emerged as a promising candidate for photocatalytic and photoelectrochemical (PEC) applications, particularly in solar water splitting. In this study, we integrate Density Functional Theory (DFT) simulations with experimental deposition techniques to enhance the photocatalytic performance of BiVO₄ thin films. DFT calculations reveal that the monoclinic scheelite structure of BiVO₄ possesses a narrow band gap (2.44 eV), low hole effective masses, a large dipole moment, strong visible light absorption, and an optimal valence band edge position—key features that contribute to its excellent photocatalytic activity as a photoanode. Additionally, the tetragonal zircon phase, with its light electron effective masses, well-positioned conduction and valence bands, and direct band gap, shows potential as a photocathode for solar water splitting.
Experimentally, BiVO₄ thin films were deposited using DC magnetron sputtering (DcMS) and High-Power Impulse Magnetron Sputtering (HiPIMS). We systematically examined the evolution of structural, compositional, and morphological properties of the films, and evaluated their photocatalytic activity under various deposition and annealing conditions. Our findings demonstrate the significant influence of deposition parameters and post-deposition annealing on the crystallinity, surface roughness, and band gap of the films. Notably, HiPIMS-deposited films exhibited superior photocatalytic activity compared to those deposited via DcMS, with annealing further enhancing performance. This study underscores the critical role of deposition techniques and thermal treatments in optimizing BiVO₄ thin films for high-efficiency solar water splitting, providing a pathway for advancing photocatalytic materials for sustainable energy applications.