Green Hydrogen from Water Splitting Using Metal Oxide Nanocatalysts

The production of green hydrogen by water splitting with metal oxide nanocatalysts is a dynamically advancing domain, concentrating on improving efficiency and sustainability. Recent improvements emphasize the application of diverse metal oxide nanostructures that enhance the kinetics of hydrogen evolution reactions (HERs) and oxygen evolution reactions (OERs). The development of efficient catalysts is essential for large-scale hydrogen generation. S. Marimuthu et al. synthesized nanoclusters of earth-abundant transition metals (Fe, Co, Ni, Cu) on nickel oxide nanosheets have demonstrated encouraging outcomes, with low overpotentials of around 62.0 mV for the HER and around 380.0 mV for the OER. F. T. Inchaurregui et al. presented Zn-Al-In mixed metal oxide nanocomposites triggered by visible light generated up to 372 μmol h −1 g −1 of H 2 , indicating significant photocatalytic activity. The interaction between metal and metal oxide improves the binding affinity of hydrogen and hydroxyl ions, thereby promoting effective water splitting. Metal oxide nanoparticles such as TiO 2 and ZnO harness solar energy to facilitate the water-splitting process, demonstrating their potential for sustainable hydrogen generation. Although the emphasis on metal oxide nanocatalysts is encouraging, obstacles persist in scaling these technologies for broad use, especially concerning cost and stability in practical applications. In this chapter, we discussed the properties of hydrogen, like high energy density, high thermal conductivity, and wide flammability range. We also briefly discuss various methods of water splitting. The main focus of this chapter is water splitting with different types of metal oxide nanocatalysts. Despite these advantages, hydrogen has some limitations, which we also discuss with future perspective.