Photocatalytic Water Splitting Using Heterogeneous Bismuth Vanadate Nanostructures

Solar-driven photocatalytic water splitting represents a pivotal pathway toward clean and sustainable hydrogen fuel generation. In this study, we synthesized and characterized monoclinic bismuth vanadate (BiVO₄) nanostructures with controlled morphology through a facile hydrothermal approach and evaluated their photocatalytic efficiency under simulated visible-light irradiation. The introduction of reduced graphene oxide (rGO) as a co-support significantly enhanced charge-carrier mobility and suppressed electron–hole recombination, resulting in a hydrogen evolution rate of 104.2 μmol h⁻¹ g⁻¹ and an apparent quantum yield (AQY) of 6.8% at 420 nm—approximately 2.1-fold improvement over pristine BiVO₄ nanoplates. Comprehensive materials characterization using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectroscopy (DRS), and Tauc plot analysis confirmed a narrowed optical band gap of 2.31 eV in the composite, enabling broader visible-light harvesting. Electrochemical impedance spectroscopy (EIS) and transient photocurrent measurements verified substantially reduced interfacial charge-transfer resistance. Stability tests over 20 hours demonstrated robust catalytic activity with less than 9% performance degradation, validating the structural integrity of the heterostructure. These findings provide mechanistic insight into interfacial charge dynamics and establish a design framework for high-performance visible-light photocatalysts.