Effect of External Electric/Magnetic Field on Photocatalysis for Green Hydrogen

Considering light as an inexhaustible source of renewable energy, several chemical reactions are regulated by light. Photocatalysis is one such promising approach to convert solar energy to chemical fuel. The generation of green hydrogen via photocatalytic water splitting is one of the state-of-the-art techniques for sustainable energy development. The drawbacks of photocatalytic water splitting in terms of poor efficiency, high overpotential, stability to acidic electrolytes and selectivity has been addressed by various ways. Among many strategies, the application of an external field like electric/magnetic or electromagnetic resulted in improved efficiency. Very few reports are available on this topic. Particularly the mechanistic details in terms of intensity, frequency, and direction of the externally applied field are missing. Moreover, the design of a new strategic catalyst which can perform better under the influence of an external field is not covered systematically. In this chapter, we demonstrate the effect of external electric and magnetic fields as well as the synergistic effect of combining electric and magnetic or electromagnetic fields on the photocatalytic process. The foundation of this chapter depends on three fundamental steps, optical absorption, charge carrier generation/separation, and catalytic reactions under external applied field. We also include the strategies to answer various unsolved questions and potential challenges for further utilization of external fields in photocatalysis.