Synergistic effect of Cu²⁺ and Cu⁺ in SrTiO₃ nanofibers promotes the photocatalytic reduction of CO₂ to methanol

Photocatalytic reduction of CO₂ to methanol over SrTiO₃ (ST) perovskite oxide is considered as a promising method to alleviate environment and energy problems at the same time. Meanwhile, the inducing of Cu plays an important role in photocatalytic activity and selectivity. Herein, a series of SrTi_1-xCu_xO₃-H₂ (STCu_x-H, x = 0.04, 0.06, 0.08, and 0.1) nanofiber catalysts were prepared by electrospinning combined with in-situ dissolution strategy. Cu_xO dissolved in situ on a one-dimensional nanofiber structure could realize more active sites exposed and convenient directional movement of electrons, simultaneously. The unique structure facilitates the enhancement of photocatalytic activity and the improvement of selectivity. The methanol yield of STCu_0.08-H nanofiber catalyst upped to 5.38 ± 0.19 μmol·g⁻¹·h⁻¹, which was twice that of ST. Moreover, the photocatalytic activity did not decrease significantly after four times of reuse. The characterization further demonstrated that STCu_0.08-H had stronger light response ability and faster electron transfer ability than ST under the synergistic action of Cu²⁺ and Cu⁺. STCu_0.08-H had superior CO₂ adsorption, activation ability, and electronic reduction capability by DFT calculation. This study provided a new idea about the design of perovskite oxide nanofiber for photocatalytic CO₂ reduction.