Role of Cocatalysts on Hematite Photoanodes in Photoelectrocatalytic Water Splitting: Challenges and Future Perspectives

The efficiency of a nanostructure applied to photo-electrocatalysis is fundamentally governed by the capability of the nanostructure surface to sustain a reaction without the occurrence of electron trapping or a recombination of the photogenerated holes. This Minireview summarizes the latest progress in the use of cocatalysts on hematite electrodes and their application in water splitting induced by sunlight. The major drawback of hole diffusion through a solid-liquid interface is addressed through the selection of the best cocatalyst for increasing the efficiency of an iron-based material. Finally, the most promising modification routes and outstanding materials for enhancing the low kinetics of the oxygen evolution reaction during sunlight-driven water oxidation reactions in hematite are provided and those materials that may have a significant impact on the overall photoelectrochemical performance are discussed.