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

Abstract

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.