LAUSR

Achieving high selectivity and conversion efficiency simultaneously is a challenge for visible‐light‐driven photocatalytic CO2 reduction into CH4. Here, a facile nanofiber synthesis method and a new defect control strategy at room‐temperature are reported for the fabrication of flexible mesoporous black Nb2O5 nanofiber catalysts that contain abundant oxygen‐vacancies and unsaturated Nb dual‐sites, which are efficient towards photocatalytic production of CH4. The oxygen‐vacancy decreases the bandgap width of Nb2O5 from 3.01–2.25 eV, which broadens the light‐absorption range from ultraviolet to visible‐light, and the dual sites in the mesopores can easily adsorb CO2, so that the intermediate product of CO* can be spontaneously changed into *CHO. The formation of a highly stable NbCHO* intermediate at the dual sites is proposed to be the key feature determining selectivity. The preliminary results show that without using sacrificial agents and photosensitizers, the nanofiber catalyst achieves 64.8% selectivity for CH4 production with a high evolution rate of 19.5 µmol g−1 h−1 under visible‐light. Furthermore, the flexible catalyst film can be directly used in devices, showing appealing and broadly commercial applications.