Renewable hydrogen production from lignocellulosic biomass: A critical review of thermochemical and advanced light/electricity-driven pathways

Hydrogen (H 2 ) production from lignocellulosic biomass offers a promising carbon-neutral option for reducing emissions. Existing studies examine thermochemical, photocatalytic, and electrocatalytic routes separately, lacking a unified framework. This review critically evaluates pyrolysis, steam gasification, and light/electricity-driven H 2 technologies from lignocellulosic biomass, whose cellulose, hemicellulose, and lignin content governs hydrogen selectivity across process regimes. Among thermochemical routes, steam gasification outperforms pyrolysis in hydrogen selectivity and carbon utilization when coupled with CO 2 capture; pyrolysis remains attractive for feedstock flexibility despite tar-formation constraints. Emerging photothermal, photoelectrochemical, and electrocatalytic technologies exhibit low-temperature activity, integrating thermal, photonic, and electronic inputs to overcome kinetic barriers and enable simultaneous H 2 production with biomass valorization. Critical challenges such as catalyst deactivation, solar-to-hydrogen efficiency, and feedstock variability are analyzed for scalability. A conceptual integrated thermochemical–electrocatalytic framework is proposed, identifying biomass gasification with photo- and electro-assisted reforming as a scalable pathway toward renewable H 2 systems aligned with global decarbonization goals.