Enhanced Photocatalytic Seawater Splitting Using Cu-Doped TiO₂ Nanoparticles Anchored on Nb₂O₅

Hydrogen production from seawater via the photocatalysis process presents a sustainable way to resolve environmental as well as energy issues. In this study, an efficient Cu-doped TiO2 (CuT) and Nb2O5-based heterojunction was synthesized for hydrogen production from seawater. CuT was synthesized through the hydrothermal method and then formed a heterojunction with Nb2O5 through the impregnation method. X-ray diffraction (XRD) analysis reveals the anatase phase of CuT and the orthorhombic phase of Nb2O5 and its structure is retained after the formation of a heterojunction. Photoluminescence and ultraviolet–visible (UV–vis) analysis showed a lower recombination rate of e–/h+ pairs and a higher absorption of light, respectively. These outcomes were further confirmed using electrochemical analysis. The formation of the heterojunction resulted in an improved specific surface area of 146.62 m2 g–1. The synthesized heterojunction (CuT/10-Nb2O5) exhibited superior activity compared to CuT and Nb2O5, achieving a hydrogen production rate of 1589.01 μmol g–1 h–1 in the presence of ethylene glycol (10 vol %) as a sacrificial reagent. Furthermore, the effect of various sacrificial reagents was evaluated for seawater splitting. Additionally, the heterojunction demonstrated good stability in seawater, with only approximately an 11% reduction in activity after the fourth cycle.