Recent progress on molecular catalysts integrated photoelectrochemical systems for water oxidation

The major limitations of photoelectrochemical (PEC) water splitting lies in the currently unsatisfying efficiency and stability of the semiconductor materials-based water splitting systems. By addressing these limitations, the immobilization of the molecular catalysts on semiconductor photoanodes to establish a hybrid inorganic-organic PEC system has attracted an increasing research attention. It is crucial to choose a suitable molecular catalyst and effectively couple it into a hybrid photoelectrode system. In this review, focusing on the water oxidation process, molecular catalysts integrated photoelectrochemical water oxidation systems are highlighted from the perspective of the roles of molecular catalysts and the integration strategies in the hybrid system. The most recent advances are summarized with various case studies presented, based on which perspectives are proposed to provide guidance toward the rational design of an integrated system for future development.