Fast interfacial charge transfer in α-Fe₂O_3-δC_δ/FeVO_4-x+δC_x-δ@C bulk heterojunctions with controllable phase content

The novelties in this paper are embodied in the fast interfacial charge transfer in α-Fe₂O_3-δC_δ/FeVO_4-x+δC_x-δ@C bulk heterojunctions with controllable phase compositions. The carbon source-glucose plays an important role as the connecting bridge between the micelles in the solution, forming interfacial C-O, C-O-Fe and O-Fe-C bonds through dehydration and polymerization reactions. Then the extra VO₃^- around the FeVO₄ colloidal particles can react with unstable Fe(OH)₃, resulting the phase transformation from α-Fe₂O₃ (47.99-7.16%) into FeVO₄ (52.01-92.84%), promoting photocarriers' generation capacities. After final carbonization, a part of C atoms enter into lattices of α-Fe₂O₃ and FeVO₄, forming impurity levels and oxygen vacancies to increase effective light absorptions. Another part of C sources turn into interfacial carbon layers to bring fast charge transfer by decreasing the charge transition resistance (from 53.15 kΩ into 8.29 kΩ) and the surface recombination rate (from 64.07% into 7.59%). The results show that the bulk heterojunction with 90.29% FeVO₄ and 9.71% α-Fe₂O₃ shows ideal light absorption, carriers' transfer efficiency and available photocatalytic property. In general, the synergistic effect of optimized heterojunction structure, carbon replacing and the interface carbon layers are critical to develop great potential in stable and recoverable use.