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

• Published in: Applied catalysis. B, Environmental Environmental, 2019-07, Vol.248, p.218-225
• Main Authors: Chen, Chaoqiu, Duan, Feifei, Zhao, Shichao, Wang, Weike, Yang, Fan, Nuansing, Wiwat, Zhang, Baiyan, Qin, Yong, Knez, Mato
• Format: Article
• Language: English
• Subjects: Catalytic activity; Charge efficiency; Charge separation; Charge transport; Deposition; Ethylene glycol; Fabrication; Gamma phase; Heterojunctions; Heterostructures; Iron oxides; Molecular layer deposition; Morphology; Nanoparticles; Nanoporous hematite nanotubes; Nanotechnology; Nanotubes; Phase junction; Photo-Fenton reaction; Photocatalysis; Porosity; Separation; Wall thickness; Wastewater; Water splitting
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2019.02.029

Porous Fe2O3 nanotubes with α-γ phase junctions synthesized by novel MLD procedure exhibit drastically boosted photocatalytic activity, which is more than a 6.5-fold and 20-fold improvement compared with the nonporous α-Fe2O3 nanotubes and commercial α-Fe2O3 nanoparticles, respectively. [Display omitted] •Two Fe-hybrid films with tunable organic fragments are synthesized by two novel MLD processes.•The porous and phase structure of Fe2O3 nanotubes are determined by the organic fractions of the MLD Fe-hybrid films.•The porous structure and phase-junction significantly improve the charge separation efficiency of Fe2O3 nanotubes.•The optimized porous α-γ Fe2O3 nanotubes exhibit outstanding photocatalytic activity, 6.5-fold higher than nonporous α-Fe2O3 nanotubes. 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.