Fabrication of Flexible Mesoporous Black Nb2O5 Nanofiber Films for Visible‐Light‐Driven Photocatalytic CO2 Reduction into CH4

Abstract Achieving high selectivity and conversion efficiency simultaneously is a challenge for visible‐light‐driven photocatalytic CO 2 reduction into CH 4 . Here, a facile nanofiber synthesis method and a new defect control strategy at room‐temperature are reported for the fabrication of flexible mesoporous black Nb 2 O 5 nanofiber catalysts that contain abundant oxygen‐vacancies and unsaturated Nb dual‐sites, which are efficient towards photocatalytic production of CH 4 . The oxygen‐vacancy decreases the bandgap width of Nb 2 O 5 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 CO 2 , 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 CH 4 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.