Superior photocatalytic behaviour of novel 1D nanobraid and nanoporous α-Fe₂O₃ structures

We have produced novel nanostructures of pure and ceramic α-Fe ₂O₃ using electrospinning, followed by annealing at 500 °C for 5 h with ramp rate of 5 °C min^-1. Electron microscopy clearly reveals the novel morphologies, namely nanobraids and nanoporous α-Fe₂O₃, suggesting that the precursor, (iron(iii) acetylacetonate, (Fe(acac)₃)) to polyvinylpyrrolidone (PVP) ratio greatly influences structural transformations of Fe₂O₃. 4 wt% of Fe(acac)₃/PVP solution used for electrospinning at 15 kV a potential produced nanobraid-like ceramic α-Fe₂O₃, indicating that binodal phase separation is predominant at this ratio. On the other hand, the electrospinning of 6 wt% of Fe(acac)₃/PVP solution induces spinodal phase separation that results in the formation of nanoporous ceramic α-Fe₂O₃ fibers. The nanobraids and nanoporous ceramic α-Fe₂O₃ exhibit superior photocatalytic performances of up to 91.2% and 90.2% for the organic dye, Congo red (CR) in the shorter time of 140 min under photoirradiation. It is concluded that the presence of the porous surface and smaller crystallite size in the α-Fe₂O₃ nanostructures act as active catalytic centers and play a key role in allowing effective interaction between organic dye and α-Fe₂O₃, in turn enhance photocatalytic degradation performance.