Recent Advances in Earth-Abundant Heterogeneous Electrocatalysts for Photoelectrochemical Water Splitting

Photoelectrochemical (PEC) water splitting has been considered as the most promising strategy to obtain hydrogen fuels and oxygen. Developing earth-abundant heterogeneous electrocatalysts with high catalytic activity and stability is of great importance for achieving highly efficient water splitting. Here, an overview of the recent developments in the earth-abundant heterogeneous electrocatalysts for PEC water splitting is presented. The main earth-abundant electrocatalysts for the PEC hydrogen-evolution reaction (PEC-HER) include transition-metal dichalcogenide (TMD)-based materials, transition-metal carbides/phosphatides, and N-doped graphene, whereas the earth-abundant PEC oxygen-evolution reaction (PEC-OER) electrocatalysts are focused on mixed transition-metal oxides, TMD-based materials, and transition-metal-and/or heteroatom-doped carbon catalysts. In addition, earth-abundant bifunctional (HER/OER) electrocatalysts, including NiFe layered double hydroxide and Co-Mn oxide nanoparticles/nitrogen-doped carbon frameworks, are introduced for overall water splitting. The strategies for improvement of the catalytic performance and the composition/structure-catalytic-activity relationships are highlighted. Finally, current existing challenges and the future research directions for enhancing the PEC water-splitting performance of earth-abundant heterogeneous electrocatalysts are provided.