Ion-selective β-Ga2O3 based heterostructures for durable seawater splitting

Photoelectrochemical (PEC) seawater splitting provides a promising approach for solar-driven hydrogen production using Earth's most abundant water resource. However, chloride-induced corrosion and parasitic chlorine evolution remain major barriers to practical implementation. Effective photoanodes must simultaneously maintain catalytic activity, resist degradation in saline environments, and enable solar energy utilisation. In this work, we design a two-dimensional heterostructure combining Rh-doped β-Ga2O3 and porous O-shaped graphitic carbon nitride (g-C3N4), which together address these challenges. The g-C3N4 overlayer functions as an ion-selective barrier that permits water transport while blocking Cl− ions. Meanwhile, Rh doping activates lattice oxygen redox in β-Ga2O3, reducing the overpotential of the oxygen evolution reaction. The heterostructure also supports visible-light absorption and efficient charge separation due to type-II band alignment and interfacial orbital mixing. This integrated design provides a stable, selective, and solar-responsive platform for seawater splitting. It offers a practical strategy for mitigating chloride corrosion and enhancing catalytic performance, with implications for scalable hydrogen production in real-world saline environments.