Coordinating Solar Capture and Mass Transport to Boost Photothermal‐Assisted CO ₂ Reduction with H ₂ O

Abstract Poor mass transfer of reactants at the catalytic interface seriously impedes solar‐driven CO ₂ 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 BiVO ₄ @O‐TiN‐TiO ₂ nanoantenna arrays (NAs) heterojunction photocatalyst with a photothermal effect is developed for efficient photocatalytic CO ₂ 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, CO ₂ 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 CH ₄ over the hollow porous BiVO ₄ @O‐TiN‐TiO ₂ 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 BiVO ₄ @TiO ₂ NAs photocatalyst, respectively. Notably, the low‐cost BiVO ₄ @O‐TiN‐TiO ₂ 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 CO ₂ to CH ₄ 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.