Intrinsic electric field assisted polymeric graphitic carbon nitride coupled with Bi4Ti3O12/Bi2Ti2O7 heterostructure nanofibers toward enhanced photocatalytic hydrogen evolution

Polymeric carbon nitride as a low-cost and robust photocatalyst has been limited by the rapid recombination of photo-generated electron-hole pairs and low visible light utilization efficiency. It is demonstrated a ternary heterostructured photocatalyst polymeric graphitic carbon nitride (for simplicity, g-C3N4) coupled with Bi4Ti3O12/Bi2Ti2O7 (BTO) by a simple route of electrospinning/calcination. This optimal photocatalyst shows efficient reproducible hydrogen evolution (638 mu molh(-1) g(-1)) under visible light, which is about 7.6 times higher than BTO and 1.55 times higher than g-C3N4. The optimal loading of BTO nanorods on g-C3N4 increases light absorption to generate more photoelectrons and simultaneously promotes separation and transfer of photoinduced electrons and holes, which arises from the intrinsic electric field formed between the (Bi2O2)(2+) slabs and the (Bim-1TiO3m+1) units in Bi2Ti2O7 and Bi4Ti3O12. On the basis of further obtained temperature dependent experimental results through the Arrhenius relationship, mechanism of temperature dependent spontaneous polarization is proposed. This study offers new insight into the design of efficient ternary heterostructured advanced materials for water treatment to resolve the energy crisis problem. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.