Emerging 2D and layered materials for high-efficiency photoelectrocatalytic hydrogen generation

The development of highly efficient, stable, and scalable photoelectrode materials is paramount for developing photoelectrochemical (PEC) water splitting as a sustainable and practical approach for hydrogen production. The rapid progress in two-dimensional (2D) and layered materials, combined with innovative synthesis methodologies and sophisticated interface engineering strategies, is projected to drive substantial breakthroughs in solar-driven hydrogen generation, contributing to the global transition toward sustainable energy solutions. A diverse range of 2D and layered materials, including transition metal dichalcogenides, transition metal oxides, MXenes, graphene, nitrides, carbides, and their hybrid architectures, have demonstrated outstanding potential in enhancing PEC performance. These materials exhibit exceptional optical absorption properties, efficient charge carrier transport, and remarkable catalytic activity, making them highly attractive for next-generation PEC systems. Similarly, layered transition metal chalcogenides and metal-based layered double hydroxides have emerged as promising candidates for photoelectrode applications due to their high surface area, tunable electronic structures, and superior charge separation efficiency. Furthermore, heterostructured photosystems, intentionally engineered through precise interface modulation, have shown notable efficiency in accelerating charge transfer kinetics and mitigating charge recombination losses. In this regard, these layered materials have proven to be a versatile and robust platform for the fabrication of spatially controlled multilayered nanoarchitectures. Such an approach enables precise regulation of material composition, interfacial properties, and thickness, thereby optimizing light harvesting and charge carrier dynamics to achieve enhanced photocatalytic efficiency. This review provides an in-depth evaluation of emerging 2D and layered materials for PEC hydrogen evolution, emphasizing their structural advantages, intrinsic charge transport mechanisms, and synergistic interactions within heterostructured architectures. Additionally, critical challenges related to long-term stability, large-scale fabrication, and integration into existing PEC systems are thoroughly examined to offer insights into future research directions and practical implementation strategies.