Noble-metal co-catalysis could increase the CH₄ product selectivity for photocatalytic CO₂ reduction by TiO₂. However, the high cost and scarcity of noble metals are key obstacles for their extensive use. Thus, it is necessary to explore cheap alternatives. Herein, Mo-doped TiO₂ with different Mo concentrations were successfully prepared via a one-pot hydrothermal method at 473 K. The activity measurements of the photocatalysts show that the CH₄ selectivity is increased with the Mo concentrations increasing and reaches 54.1 % at a Mo concentration of about 0.3 wt%. With further increasing the Mo concentrations, the CH₄ selectivity begins to decrease. Transient photocurrent and fluorescence emission spectroscopy measurements, IR spectra for adsorbed D₂O and ·OH trapping suggest that the promoted electron-hole separation and proton supply are together responsible for the enhanced CH₄ selectivity. Moreover, photocatalytic CO, formaldehyde, and methanol reductions with H₂O and ·CH₃ trapping show that the enhanced CH₄ selectivity is not directly related with the interaction of CO₂ with catalyst surfaces. These reaction results also imply that photocatalytic CO₂ reduction might follow the fast-deoxygenation pathway over TiO₂-based catalysts. The present work supplies a guide to explore cheap modifiers for selective photocatalytic CO₂ reduction to CH₄.

贵金属共催化可提高TiO ₂还原光催化CO ₂的CH ₄产物选择性。然而，贵金属的高成本和稀缺性是其广泛使用的主要障碍。因此，有必要探索廉价的替代品。在此，通过一锅水热法在473 K下成功制备了不同Mo浓度的Mo掺杂的TiO _2。光催化剂的活性测量表明，随着Mo浓度的增加，CH _4的选择性增加，并在₅ ℃时达到54.1％。 Mo浓度为约0.3重量％。随着Mo浓度的进一步增加，CH ₄选择性开始降低。瞬态光电流和荧光发射光谱测量，吸附的D ₂ O和·OH俘获的红外光谱表明，促进的电子-空穴分离和质子供应共同促进了CH ₄选择性的提高。此外，用H ₂ O和·CH ₃捕集光催化还原CO，甲醛和甲醇的过程表明，提高的CH ₄选择性与CO ₂与催化剂表面的相互作用并不直接相关。这些反应结果还暗示，光催化还原CO ₂可能遵循TiO _2上的快速脱氧途径。基催化剂。本工作提供了指导，以探索用于将光催化CO ₂选择性还原为CH _4的廉价改性剂。