The light components generated during the hydrothermal liquefaction of lignin are characterized by high water content, complex composition, difficult separation, and limited resource utilization, which have become major constraints on the high-value utilization of all lignin-derived fractions. In this study, the light components derived from lignin hydrothermal liquefaction were employed as feedstock for hydrogen production via photothermal synergistic aqueous-phase reforming, providing a promising route for waste-liquid valorization while alleviating the energy supply–demand imbalance and environmental pressures. However, systematic studies on photothermal synergistic reforming systems and the corresponding reaction mechanisms for lignin hydrothermal liquefaction-derived light components remain relatively limited. During the reforming process, these components underg side-chain cleavage, and deep reforming reactions, ultimately producing gaseous products dominated by H₂ and CO₂. To regulate the catalyst structure and enhance catalytic performance, three catalyst systems were rationally designed and systematically optimized, including the biochar-modified Ti₍₅₎-Ni₍₂₎-HT₁₈₀ catalyst, the TiO₂/g-C₃N₄ heterostructured TiO₂/Ni-g-C₃N₄ catalyst, and the Ni–Co bimetallic synergistic Ni/Co_(3:1)-TiO₂ catalyst. The average hydrogen production rate increased from 7.60 to 14.04 mmol·g^-1·h^-1 and ultimately reached 74.48 mmol·g^-1·h^-1. These findings provide mechanistic insights and technical guidance for the comprehensive valorization of lignin-derived fractions.

Lignin Liquefaction, Aqueous-phase Products, Photothermal Catalysis, Hydrogen Production by Reforming