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 μmolh⁻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 (Bi_m−1TiO_3m+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.