Role of nanocomposites in hydrogen production

Energy supply mainly relies on traditional sources such as fossil fuels. These fuels pose a severe threat to the environment and public health due to the emission of greenhouse gases during combustion. Thus it is essential to seek clean and renewable alternative energy sources that can substitute fossil fuels and satisfy an ever-growing global energy demand. Hydrogen (H2) has been demonstrated as an environmentally clean and renewable energy source that can replace fossil fuels in the coming days. Among various available techniques, water splitting is the most promising and economical approach for hydrogen production. Efficient catalysts are highly desirable in water-splitting reactions to implement large-scale H2 production. Nanocomposites as catalysts have attracted much interest in recent years due to their larger surface area, versatile structures, and formation of well-interfaced heterojunctions. In this chapter, we discuss the photocatalytic and electrocatalytic water-splitting method for hydrogen evolution reactions on nanocomposite-based catalysts. The key challenge in photocatalytic H2 generation is adopting an ideal photocatalyst that is able to electrolyze water using a substantial fraction of sunlight. Similarly, designing a suitable electrocatalyst that can lower overpotential and enhance reaction kinetics is crucial for electrocatalytic H2 production. Additionally, a detailed discussion has been presented on why the nanocomposites are imperative in electro-/photocatalytic water-splitting reactions to produce H2 gas.