The role of extremely low-dimensional carbon materials in the design of sustainable catalysts for water splitting

Abstract

The transition to green hydrogen fuel systems is a promising avenue towards carbon neutrality, with catalytic water splitting (WS) emerging as a potential solution. However, the utilization of expensive and unstable catalysts in WS poses significant challenges to the sustainability and long-term effectiveness of hydrogen generation systems. In this context, extreme low-dimensional carbon materials have garnered significant attention due to their potential to offer high performance, long-term durability, and affordability. This review provides a comprehensive overview of recent advancements in the field, focusing on carbon quantum dots (CQDs), carbon nitride QDs, MXene QDs, biomolecules, polymers, and single-atom catalysts (SACs) based on transition metals embedded in sustainable carbon supports. These carbon materials offer several advantages, including high surface-to-volume ratios, sustainable precursors, and tunable optoelectronic properties. Notably, biomolecules have emerged as a scalable and facile alternative to traditional metal-organic complexes, achieving comparable efficiencies with ecofriendly process. Polymers, when employed as co-catalysts or overlayers, have demonstrated remarkable stability, exceeding 200 h. While pure carbon catalysts exhibit high stability, their performance is relatively limited. In contrast, SACs, incorporating less than 5 % content of transition metals into sustainable carbon substrates, offer a promising solution, combining high efficiency, low cost, and high stability. This review highlights the significant potential of low-dimensional carbon materials to revolutionize hydrogen generation technology. Future directions, such as optimizing synthesis techniques, enhancing charge transfer, and improving stability, will be crucial to realizing the commercial-scale production of sustainable hydrogen fuel.