Recent progress in metallic-oxygen semiconductors systems towards solar-hydrogen production and investigating mechanisms through different characterization techniques

Renewable energy is the only viable way to effectively address the global challenges of energy crisis and climate change. Among different resources of renewable energies, artificial photosynthesis is considered as the potential candidate to mitigate both challenges simultaneously by converting solar energy into chemical energy. Hydrogen (H₂) energy is the first choice in the conversion and utilization of solar energy since it can be carried out at room temperature with the advantages of environmentally friendly and low-energy consuming. Up to now, numerous metallic-oxygen group semiconductors have been designed as photocatalyst to produce H₂ from water under light irradiation. However, the conversion efficiency of solar energy to H₂ energy is still very low, which is closely related to light absorption properties, electron hole separation, and surface reaction efficiency. Based on this, this review aims to summarize the strategies developed to improve the H₂ production efficiency by photocatalytic water decomposition from the perspective of band structure regulation, photogenerated charges separation efficiency, and surface reactivity. Besides, the review highlights characterization methods involved in investigating and studying the photocatalytic mechanism trilogy. This review provides detailed understanding about designing photocatalytic systems and predicting the efficiency to researchers from different field of science. It also discusses that how to study the effective theoretical basis and analytical methods for selecting photocatalytic H₂ production materials based on metallic-oxygen group semiconductors.