Carbon-based catalysts for photoelectrochemical water splitting: advancing carbon–neutral hydrogen production

The production of hydrogen using renewable energy sources requires efficient and stable catalysts. However, the development of such catalysts is hindered by the lack of efficient photo/electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), as well as an insufficient understanding of the reaction mechanisms. This review comprehensively summarizes recent progress in photo/electrochemical hydrogen production technology and fundamental knowledge of reaction mechanisms. Specifically, it discusses recent developments in carbon-based materials for water splitting, with a focus on photoelectrocatalysts. The review highlights advancements in C-doped metal oxides, carbon quantum dots (CQD), MOF/COF-derived carbon, carbon nanotubes, graphene, carbon nitride-based materials, and strategies to enhance their catalytic activity and conductivity. Furthermore, integrating carbon-based materials with semiconductors and co-catalysts is explored to optimize overall performance. We outline practical routes to improve charge transfer and stability across carbon-based photoelectrocatalysts, providing a concise roadmap toward scalable and sustainable water splitting.