Photoconversion of Xylan to Glyceric Acid Coupled with Hydrogen Evolution Enabled by Coral-Like S-Scheme Heterojunction.

Photocatalytic biomass refining offers a promising strategy for the sustainable co-production of high-value chemicals and clean fuels. Herein, a coral-like bifunctional g-C3N4/Mn0.7Cd0.3S S-scheme heterojunction (CNMCS) was rationally constructed for simultaneous xylan photoreforming and hydrogen evolution. X-ray diffraction and transmission electron microscopy analyses confirm the formation of an interconnected hierarchical structure with intimate interfacial contact between g-C3N4 nanotubes and Mn0.7Cd0.3S nanoparticles, while x-ray photoelectron spectroscopy and density functional theory calculations reveal an S-scheme charge transfer pathway driven by the internal electric field. The optimized 6CNMCS photocatalyst achieves a glyceric acid yield of 77.6% and an H2 evolution rate of 2.89 mmol•gcat -1•h-1 without sacrificial agents. The enhanced performance is attributed to efficient charge separation and synergistic interfacial interactions that promote xylan adsorption and selective C-H bond activation. Mechanistic studies indicate that carbon-centered radicals and reactive oxygen species cooperatively drive selective C-C bond cleavage toward glyceric acid formation. This work provides a new strategy for integrating biomass valorization with clean hydrogen production.