Revisiting strategies to improve the performance of hematite photoanodes for water photoelectrolysis.

Photoelectrochemical (PEC) water splitting is emerging as a sustainable approach for producing green hydrogen. The design of efficient photoanodes is the key for the step forward technological application in which morphology optimization and defect engineering play central roles. In this perspective, the intricate interplay between morphology optimization, band engineering and chemical modifications is critically discussed. First, a brief introduction of the relevant aspects of semiconductors applied in PEC devices is provided. Then, a critical analysis of the influence of morphology and chemical modifications is presented, with hematite employed as a model system. Lastly, insights into future directions and outlooks for existing challenges on the development of photoelectrochemical devices for water splitting are displayed.