Facile fabrication of electrospun black titania nanofibers decorated with graphitic carbon nitride for the application of photocatalytic CO2 reduction

Abstract

Black titania nanofibers (NFs) were electrospun and subjected to a simplified two-step sintering process at low pressure. Disordered “black” titania structures developed; Ti-O exhibited a blue shift and electrons occupied oxygen vacancies. Black titania NFs were coated with graphitic carbon nitride (g-C3N4) via sintering in an Ar atmosphere; the facile fabrication of metal-free heterostructures using non-toxic H2O reaction medium was reported to participate in photocatalytic CO2 reduction under UV–vis light irradiation, showing CO and CH4 yields of 5.19 and 1.65 μmol/g, respectively. The heterostructured g-C3N4/black titania NFs indicated 1.8-fold higher production of CO2 conversion (CO and CH4) compared to that of g-C3N4 while the heterostructure showed 2.12 times higher production of CO2 conversion (CO and CH4) compared to that of black titania NFs. Finally, the reusability test of the heterostructure was conducted upto the fourth cycle. Throughout the entire electronic band, heterostructured g-C3N4/black titania NFs exhibited increased absorption at 470 nm, even at the lowest photoluminescence intensity compared to that of g-C3N4. The calculated Fermi level and conduction/valence bands showed that the heterostructured g-C3N4/ black titania NFs exhibited proper band position associated with a sufficient kinetic overpotential of (△Ea,CH4) 0.54 eV, for successful production of both CO and CH4. This confirms that g-C3N4 and black titania NFs were well-connected via their interfaces so that this metal-free heterostructured g-C3N4/black titania NFs has proven its possibility to yield its CO2 conversion products.