As demand for sustainable energy grows, green hydrogen becomes crucial for reducing emissions. Utilizing solar energy, photocatalytic (PC) and photoelectrocatalytic (PEC) water splitting are among the most promising and efficient approaches. However, PC/PEC water splitting faces challenges, including catalysts with limited competence and poor stability due to charge-carrier recombination, high overpotentials, and sluggish reaction kinetics. Loading co-catalysts onto the target semiconductors (SCs) offers the simplest and most effective strategy to provide more active sites, alleviate the kinetic barriers, and enhance efficiency and stability. Lately, many reports have explored various aspects of co-catalyst decoration, while few have focused on platinum group metals (PGMs). PGMs are known for their superior catalytic activity, excellent charge separation, and long-term stability, spotlighting their impact in PC/PEC applications. This review summarizes the role of PGMs as effective co-catalysts in improving the performance of well-known SCs, including metal oxides, sulfides, and nitrides. Furthermore, the review highlights the competition between PGMs and transition metals (TMs) as co-catalysts, thereby further magnifying the benefits of PGMs in terms of performance and stability. Finally, it examines new approaches for PGM recycling that reduce costs and enhance sustainability.
Chamani et al. (Mon,) studied this question.