Coordinating Solar Capture and Mass Transport to Boost Photothermal-Assisted CO₂ Reduction with H₂O

Poor mass transfer of reactants at the catalytic interface seriously impedes solar-driven CO₂ conversion, particularly for photocatalysis in pure water without sacrificial reagents, which is detrimental to tackling energy shortages and achieving carbon neutrality. Herein, a hollow porous BiVO₄@O-TiN-TiO₂ nanoantenna arrays (NAs) heterojunction photocatalyst with a photothermal effect is developed for efficient photocatalytic CO₂ methanation. The hollow porous array structure formed after annealing in ammonia and air significantly increases the photocatalysts' specific surface area and surface temperature, enhancing light absorption, CO₂ molecule mass transfer, and activation on the catalyst surfaces. Benefiting from the collaborative matching of energy and reactants at the catalytic interface, the yields of CO and CH₄ over the hollow porous BiVO₄@O-TiN-TiO₂ NAs photocatalyst reached 175.8 and 373.8 µmol m^-2 h^-1 (89.5% selectivity) in pure water, which are 1.3 and 21.1 folds higher than that of the BiVO₄@TiO₂ NAs photocatalyst, respectively. Notably, the low-cost BiVO₄@O-TiN-TiO₂ NAs photocatalyst achieves a solar-to-fuels efficiency of 0.6‰, comparable to catalytic systems using noble metals or sacrificial agents. This work demonstrates the highly selective conversion of CO₂ to CH₄ via enhanced reactant mass transfer and multi-field (photo-electric-thermal) coupling, offering a potential approach for solar-driven low-cost synthesis of hydrocarbon fuels.