Growing urbanization associated with the consumption of nonrenewable energy resources (i.e., fossil fuels: coal, oil, and natural gas) is leading to serious environmental problems. Therefore, the world needs to develop green, sustainable, and affordable energy sources as alternatives to fossil fuels. Hydrogen gas is considered an auspicious renewable energy carrier to supply the world energy demand and reduce greenhouse gas emissions. It can be produced by various methods, using renewable or nonrenewable resources. This chapter gives an overview on various technologies of renewable hydrogen production via water splitting, with a focus on solar hydrogen production as a greener approach. Moreover, innovative technologies of hydrogen production via seawater splitting and utilizing organic waste are reviewed. Photocatalytic seawater splitting is regarded as an ideal water-splitting method using the most abundance resources on Earth (seawater and solar irradiation). In addition, simultaneous hydrogen production and water treatment are achieved when waste rich in nitrogen and chlorine act as sacrificial electron donors. Finally, an overview of the various state-of-the-art semiconductor nanomaterials used in this field is given with highlights on the green processing of these materials by utilizing natural resources and efficient-energy techniques. Metal oxide/metal oxide hybrid, metal chalcogenides, metal-organic frameworks, and metal-free semiconductor nanomaterials are promising water-splitting materials to be reviewed in this chapter.
Sustainable Materials and Green Processing for Energy Conversion, Volume , 1 January 2022,