Photothermal gas-solid design breaks tri-phase bottlenecks for solar H₂ production

Photocatalytic water splitting holds great promise for sustainable H₂ production, yet its practical efficiency in conventional gas-liquid-solid tri-phase systems remains fundamentally limited by three interrelated bottlenecks: inefficient utilization of the visible-to-infrared solar spectrum, substantial photothermal heat dissipation into the bulk solution, and severely retarded mass transfer exacerbated by bubble-induced active site blocking. Herein, we report a photothermally driven gas-solid reaction system that simultaneously overcomes these limitations through the synergistic integration of a metal-organic framework (MOF)-derived TiO₂/Co₃O₄ heterojunction photocatalyst with a TiN-modified aluminosilicate wool (TiN ASW) photothermal substrate. The heterojunction architecture promotes photogenerated charge separation while preserving strong redox capability, delivering a H₂ evolution rate of 93.3 μmol h^-1, a more than 130-fold enhancement over pristine TiO₂. Upon immobilization on the TiN ASW substrate, the integrated TiO₂/Co₃O₄-TiN ASW system achieves a markedly improved hydrogen evolution rate of 295.62 μmol h^-1, corresponding to a 3.17-fold improvement over the conventional tri-phase counterpart. Thermal imaging supports localized interfacial heating, while the floating architecture may alleviate transport limitations associated with H₂ release. This work demonstrates synergistic management of dynamic energy and mass transfer, unlocking new avenues toward high-efficiency solar-to-hydrogen conversion.