Strategies for Enhancement of Photocatalytic Activity

There are several strategies or approaches to enhance the efficiency of graphene-based photocatalytic materials. Scientists are attempting all possible ways and means towards the enhancement of photocatalytic efficiency of carbonaceous materials like quantum dots modification, tailoring the band gap, synthesizing composites with suitable partners, modifying the fabrication methods and control parameters, bio-catalysts coupling, doping with suitable materials, constructing suitable heterojunctions, modifying surface morphology, to name a few. In this chapter, certain important strategies are discussed with appropriate references. In quantum dots, as there are fewer electrons than the bulk, it consists of fewer distinct quantized energies within the density of states for individual zero-dimensional systems. Due to the quantum confinement phenomena, the two-dimensional characteristics of the graphene quantum dots (g-QDs) can be altered to change the energy band gap between 0 and 6 eV. The g-QDs consist of several desirable features over the quantum dots of a conventional semiconductor like low toxicity, persistent fluorescence qualities, and better water dispersion etc. In addition, the surface modifications of g-QDs can regulate the oxidation process. The graphene quantum dots address the drawbacks of conventional photocatalyst mechanisms like quick rate of electron–hole recombination and increase active sites and thereby increase absorption rate. Typical graphene quantum dot photocatalysts when combined with semiconductors offer better photocatalytic capabilities.