Visible Light-Induced Photocatalytic Hydrogen Generation from Seawater Using Ternary Indium Sulfide/Indium Oxide/Gold Nanocomposites Obtained via Microwave-Assisted Synthesis

Photocatalytic water splitting under visible light represents a promising pathway toward achieving future net zero-emission renewable energy. However, the development of this energy source faces a challenge owing to the scarcity of freshwater resources. The direct application of actual seawater in photocatalytic hydrogen generation is scarce. This study reports a simple and rapid microwave-assisted synthesis to fabricate a ternary indium sulfide/indium oxide/gold (In₂S₃/In₂O₃/Au) nanocomposite photocatalyst. The microwave-assisted synthesis can be performed with precise temperature control in less time. Binary In₂S₃/In₂O₃ nanosheets were first synthesized via a one-pot microwave-assisted synthesis, which exhibited an efficient spatial separation of electrons and holes than individual In₂S₃ or In₂O₃. The incorporation of Au nanoparticles onto nanosheets enhanced visible light absorption and decreased electron-hole pair recombination. In₂S₃/In₂O₃/Au nanocomposites demonstrated remarkable effectiveness in seawater splitting to generate hydrogen with a high hydrogen evolution rate (1.604 mmol h^-1 g^-1) under low power (5 W blue light and a maximum absorption wavelength of 420 nm) visible light irradiation and low carbon emission for sustainability in water splitting materials. This work has achieved an excellent solar-to-hydrogen conversion efficiency and apparent quantum efficiency of ∼2.11% and ∼5.06%, respectively. The ternary nanocomposites show a high degree of reusability under repeated testing cycles, suggesting their potential and practical application for sustainable hydrogen production in the seawater environment.