Enhanced photocatalytic activity of octahedral anatase particles prepared by hydrothermal reaction

• Published in: Catalysis today Vol. 280; pp. 29 - 36
• Main Authors: Wei, Z., Kowalska, E., Wang, K., Colbeau-Justin, C., Ohtani, B.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2017
• Subjects: Anatase; Morphology; OAPs; Octahedral particles; Photocatalytic activity; Platinum nanoparticles; OAPs; Octahedral particles; Photocatalytic activity; Platinum nanoparticles; Anatase; Morphology
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2016.04.028

[Display omitted] •Significant influence of preparation conditions on morphology and photocatalytic activity.•Morphology-dependent photocatalytic activity of octahedral anatase particles.•Hindered recombination of electrons and holes in octahedral anatase particles proved by TRMC study.•Uniform deposition of Pt under aerobic conditions results in significant enhancement of photocatalytic activity. Octahedral anatase particles (OAPs) were prepared by hydrothermal reaction (HT) with various experimental conditions, including different amounts of titanate nanowires (TNWs), different water volumes and different pH values, to obtain products with high contents of OAPs. The properties of photocatalysts were investigated by XRD, SEM, TEM, XPS and time-resolved microwave conductivity (TRMC). Photocatalytic activities for oxidative decomposition of acetic acid (CO2 system) and anaerobic dehydrogenation of methanol (H2 system) were tested. It was found that a larger amount and concentration of TNWs, as well as higher pressure during HT, resulted in the formation of smaller crystallites with higher density of mobile electrons. Enhanced photocatalytic activity, achieved for samples with the best morphology (higher content of OAPs), correlated with slower TRMC signal decay, i.e., slower recombination of charge carriers (e−/h+) probably due to lower content of deep electron traps. It was found that properties of platinum nanoparticles, deposited in-situ in the H2 system in the absence or presence of pre-sparged oxygen, and their connection with OAPs were decisive factors for photocatalytic activity.