Photoelectrocatalytic water splitting offers a promising approach to convert sunlight into sustainable hydrogen energy. A thorough understanding of the relationships between the properties and functions of photoelectrocatalytic materials plays a crucial role in the design and fabrication of efficient photoelectrochemical systems for water splitting. This review presents the advances in the development of efficient photoelectrocatalytic materials. First, the fundamentals involved in the photoelectrocatalytic water splitting are elaborated. Then, the critical properties of photoelectrocatalytic materials are classified and discussed according to the associated photoelectrochemical processes, including light absorption, charge separation, charge transportation, and photoelectrocatalytic reactions. The importance of heterointerfaces in photoelectrodes is also mentioned in conjunction with the illustration of some functional interlayer materials. Finally, some strategies that can be employed in material screening and optimization for the construction of highly efficient photoelectrochemical devices for water splitting are also discussed.

Electrochemical oxidation deprotonation of surface species on a transition metal electrode is crucial for the oxygen evolution reaction (OER). However, the relation between the electrode surface characteristics and the OER activity are not well understood. This work presents operando Raman spectroscopy, X-ray photoelectron spectroscopy, and an electrokinetic study on three typical Ni or NiFe electrodes with adjustable OER activities. The decoupled OH − /e − transfer electrochemical oxidation of surface Ni species and its influence on the following OER on Ni and NiFeO x electrodes are revealed. The NF(R)-Fe electrode with (2.69) OH − /(2) e − transfer of electrochemical oxidation is the closest process approaching the ideal Nernstian process, which resulted in a less negatively charged OER-active surface and facilitates further OH − attachment. The NF(R)-Fe electrode with a smaller pK a value has an easier and prepositioned deprotonation process in the OER cycle, which displays the fastest kinetics and best performance for the oxygen evolution reaction.