Porous Fe₂O₃ nanotubes with Α-Γ phase junction for enhanced charge separation and photocatalytic property produced by molecular layer deposition

Constructing nanotubular morphologies and heterojunctions are two effective strategies to enhance the charge separation and transport of α-Fe₂O₃ for improved photocatalytic performance, while the fabrication of porous α-Fe₂O₃ nanotubes with precisely tailored wall thickness, pore structure, crystallinity, and junctions still remains a big challenge. Herein, two novel molecular layer deposition (MLD) procedures are designed to prepare porous Fe₂O₃ nanotubes with tunable pore structure and phase junction. The organic fractions of the obtained Fe-hybrid MLD films not only act as soft templates to generate nanopores in nanotube walls but also play a key role in the formation of phase-junction. The porous structure and phase-junction significantly improve the mass diffusion and charge separation efficiency of Fe₂O₃ nanotubes, leading to a drastically increased photocatalytic activity for photo-Fenton reaction. Especially, the porous α-γ Fe₂O₃ nanotubes produced by two-step AB MLD from iron tert-butoxide and ethylene glycol exhibit the highest photocatalytic activity, which is more than a 6.5-fold and 20-fold improvement compared with the nonporous pure α-Fe₂O₃ nanotubes and commercial α-Fe₂O₃ nanoparticles, respectively. The MLD method provides a new bottom-up approach to develop efficient Fe₂O₃ based heterostructure porous photocatalysts for waste-water cleaning and water splitting.