Hierarchical N-doped TiO₂@Bi₂W_xMo_1-xO₆ core-shell nanofibers for boosting visible–light–driven photocatalytic and photoelectrochemical activities

Heterogeneous photocatalysis has been proven to be a promising approach to overcome the great challenges encountered with conventional technologies for environmental remediation. Herein, for the first time, a novel hierarchical architecture of nitrogen-doped TiO₂@Bi₂W_xMo_1-xO₆ (N-T@BWMO-x, x = 0–1.0) was rationally designed and fabricated through an electrospinning route followed by a solvothermal process. The photocatalytic activity of the as–prepared samples was evaluated based on the degradation of tetracycline hydrochloride (TC) under visible–light irradiation. The results indicated that the molar fraction of W/Mo has a strong impact on the photocatalytic efficiency and photoelectrochemical performance of the N-T@BWMO composites. Compared to N-TiO₂ and the binary composites, [email protected] exhibited outstanding photocatalytic activity and significant cycling stability. The enhanced photocatalytic activity can be synergistically linked to the excellent native adsorption, extended light–harvesting region, hierarchical structure, and strong interfacial interaction between N-TiO₂ and BWMO, which can effectively prolong the lifetime of charge-carriers. Moreover, active species-trapping and electron paramagnetic resonance results confirmed that holes and superoxide radicals were the dominant active species responsible for TC removal. A possible photocatalytic mechanism underlying the degradation of TC by [email protected] is also proposed. We expect that our findings will provide new insights into the use of highly efficient core–shell heterostructure photocatalysts, with potential applications in environmental decontamination.