Engineering the solid–liquid interfaces for photoelectrochemical water reduction

Photoelectrochemical (PEC) water splitting can directly convert solar energy into storable and transportable clean hydrogen fuels, which is one of the effective ways to solve the energy and environmental crisis. However, the efficiency of PEC water splitting is limited by the complex reactions at solid–liquid interfaces, including serious recombination of photogenerated charges, high overpotential, and slow gas desorption. In this chapter, we focus on the PEC water reduction reaction at the solid–liquid interfaces, and discuss the mechanism of the interfacial reaction in detail. In addition, the main modification strategies of the solid–liquid interfaces for enhancing PEC water reduction are described, including: (i) the surface modification of hydrogen evolution reaction co-catalysts; (ii) surface state passivation and protective layer deposition for water reduction reaction; and (iii) composition engineering of the electrolyte during PEC water reduction.