The rapid global population during this decade is instigating a substantial surge in demand for global energy resources. Nevertheless, the depletion of fossil fuels, including petroleum, coal, and natural gas, is progressively increasing. Furthermore, the detrimental environmental pollution from conventional energy resources poses a significant challenge. For those reasons, research on sustainable energy sources such as H2 production by photocatalysts is becoming a hot topic due to its eco-friendliness and sustainability. The discharge of an enormous quantity of untreated azobenzene into the environment gives rise to many significant environmental issues and complications. In order to address these concerns and maximize economic advantages, there has been considerable scientific interest in employing metal oxide and sulfide nanocatalysts under mild conditions for the hydrogenation of azobenzene, leading to the production of aniline and hydrazobenzene. This approach is highly efficient and reproducible, making it a significant focus research field for researchers. In this chapter, we would like to summarize the requirements of H2 production and organic chemicals conversion. Besides, we also discuss promising photocatalysts for H2 production and hydrogenation of azobenzene, such as TiO2, Zn(O,S), CdS, and NaNbO3. To enhance our comprehension of H2 production and the hydrogenation process of azobenzene, the possible mechanisms and detailed performance analyses was discussed. Additionally, we provide an overview of potential application prospects for future research.