A Roadmap of Sustainable Hydrogen Production and Storage: Innovations and Challenges

The present review offers a strategic roadmap for overcoming conventional photocatalyst limitations and emphasizes recent advancements in hybrid photocatalysts, thereby addressing electrode and topology-associated challenges for sustainable hydrogen (H₂) production and storage. Unlike traditional reviews, this paper explores the latest developments in hybrid photocatalysts and provides a thorough analysis of H₂ fuel technology, including water splitting, photocatalytic reactions, and storage issues. A detailed analysis of photoelectrochemical (PEC) water splitting, which mimics photosynthesis, to produce carbon-neutral H₂ and the importance of optimizing PEC devices with co-catalysts are highlighted. Advanced photocatalyst designs, including Z-scheme and S-scheme heterojunctions, doping, surface modifications, and copolymerization, are discussed and the impact of various materials, such as conjugated microporous polymers (CMPs), covalent organic frameworks (COFs), graphdiyne, MBene, TiO₂-based compounds, metal sulfides, and group III-V compounds, on PEC activity is examined. Furthermore, this review highlights strategies for improving photocatalyst performance, such as targeted doping, vacancy creation, and hybrid composite formation. Recommendations include designing cost-effective efficient hybrid photoelectrodes, maximizing light utilization, and simplifying PEC cell design. By addressing H₂ storage, transport, and conversion challenges, this review not only covers critical aspects of H₂ production but also provides a roadmap towards achieving a sustainable hydrogen future.