Engineering Graphene Structures for Enhanced Photocatalytic Activity

Graphene-based photocatalytic hydrogen generation is an exciting research field that explores the use of graphene and graphene-based materials as catalysts to produce hydrogen gas through the process of photocatalysis. By harnessing light energy, these materials can split water molecules into hydrogen and oxygen. Graphene, with its unique properties as a single layer of carbon atoms arranged in a two-dimensional lattice, shows great promise as an efficient platform for capturing and utilizing light energy. Its high surface area, excellent electrical conductivity, and wide light absorption range contribute to its potential in photocatalysis. Various graphene-based materials, such as graphene oxide (GO), reduced graphene oxide (rGO), and graphene quantum dots (GQDs), have been studied for their photocatalytic hydrogen generation properties. These materials can be modified by incorporating additional elements or functional groups to enhance their photocatalytic activity. The photocatalytic process for hydrogen generation involves three main steps: light absorption, charge separation and migration, and redox reactions. Graphene-based materials absorb light energy across a wide spectrum, exciting electrons and creating electron–hole pairs. These charged particles separate due to inherent potential differences, with electrons migrating to catalytic sites on the graphene surface while holes move toward water molecules. The excited electrons on the graphene surface then reduce protons from water, forming hydrogen gas, while the holes oxidize water molecules, generating oxygen gas. To enhance the efficiency of graphene-based photocatalytic systems, researchers employ strategies such as incorporating cocatalysts like metal nanoparticles or semiconducting materials onto the graphene surface to improve charge separation and catalytic activity. Doping graphene with heteroatoms or functional groups also modifies its electronic structure, leading to enhanced light absorption and charge transfer. Additionally, controlling the morphology of graphene-based structures, such as nanosheets, nanowires, or hierarchical assemblies, increases the surface area and provides more active sites for catalytic reactions. Graphene-based photocatalytic hydrogen generation offers numerous advantages for clean and sustainable energy production, including high efficiency, low cost, and stability compared to traditional catalysts. In this chapter, we provide an overview of engineering graphene structures for this purpose and propose strategies and challenges to optimize graphene-based materials, enhance catalytic activity, and scale up production processes for practical applications.