Hybrid 2D material–plasmonic nanocomposites for efficient Solar-to-hydrogen conversion

Hydrogen is a pivotal clean energy carrier with immense potential for decarbonizing transportation, industry, and large-scale energy storage. However, conventional hydrogen production technologies remain constrained by high costs, limited solar utilization, sluggish reaction kinetics, and scalability challenges. Plasmonic materials have emerged as a transformative strategy to address these limitations by enabling efficient light–matter interaction at the nanoscale. This review comprehensively examines the role of plasmonic composites in enhancing hydrogen production through photocatalytic, photoelectrochemical, and electrocatalytic pathways. The fundamental principles of localized surface plasmon resonance (LSPR), hot-carrier generation, plasmon decay dynamics, near-field electromagnetic enhancement, and thermoplasmonic effects are discussed to establish the mechanistic basis of plasmon-assisted hydrogen evolution. Advanced material systems, including noble and non-noble plasmonic metals, bimetallic alloys, two-dimensional materials, MXenes, doped graphene, transition metal chalcogenides, perovskites, and metal–organic frameworks, are critically evaluated. Emerging low-cost plasmonic materials, including doped metal oxides and transition metal nitrides and carbides are also evaluated for their potential in scalable hydrogen production applications. Particular emphasis is placed on hybrid architectures such as metal–semiconductor, metal–metal, metal–2D, and metal–MOF systems that promote efficient charge separation, hot-electron injection, and synergistic catalytic activity. The review further analyzes key hydrogen production routes, including photocatalytic water splitting, photoelectrochemical cells, thermoplasmonic reforming, and light-assisted electrolysis. Comparative analyses with conventional PEC and thermal HER systems are provided to highlight the performance advantages of plasmon-assisted approaches. Challenges related to material stability, interfacial degradation, sintering, cost, and large-scale implementation are highlighted, along with structural and interfacial limitations affecting long-term performance. Emerging strategies involving interface engineering, defect control, and computational design are discussed. In addition, the role of structure–activity relationships in guiding material optimization is briefly addressed. This review outlines pathways toward efficient, durable, and cost-effective solar-to-hydrogen systems by integrating plasmonic fundamentals with practical hydrogen technologies. The growing importance of non-precious plasmonic materials for sustainable and scalable hydrogen production is also emphasized.