Bipyramidal anatase TiO2 nanoparticles, a highly efficient photocatalyst? Towards a better understanding of the reactivity

Abstract

Anatase nanoparticles with shape controlled bipyramidal morphology (TiO 2-A-bipy) exhibited mainly {101} facets were synthesized through the sol-gel method and then used for the photodegradation of three model pollutants-Rhodamine B, phenol and formic acidunder UV-A radiation exposure. These titania samples exhibit better photocatalytic efficiency than the commercial TiO 2-P25 reference for the dye degradation while this one demonstrates a higher activity for both phenol and formic acid. Moreover, supplementary washings of the particles significantly enhanced their photocatalytic efficiency in any case. To better understand these differences in term of photoactivity and the role of the TiO 2 surface according to the nature of the targeted organic pollutant, various characterization techniques such as XRD, TEM and N 2-sorption were used. Their surface properties were studied by FT-IR, TRMC and EPR. The presence of more acidic sites on TiO 2-A-bipy surface could explain the faster degradation of the dye molecule through surface-mediated reactions. On the other side, a better generation and separation dynamic of photogenerated charges for TiO 2-P25 could account for its higher photocatalytic efficiency for both formic acid and phenol degradation. This study shows that even if a quick test of dye degradation is mostly used in literature to confirm the efficiency of a photocatalyst, further investigation is often needed.

The Establishment of a Theoretical Model for the Estimation of Some Photo-Physical Processes in Laser Dyes

“…The appearance of strong diffraction peaks at 25º (101), 48º (200), and 37º (004) indicated the presence of TiO 2 in the anatase phase. This finding is consistent with those from other published results [13][14][15]. The peak maximum spectra of the fluorescein laser dye were e = 490 nm for the absorption and f =514 nm for the fluorescence.…”

Diethylene Glycol-Assisted Organized TiO2 Nanostructures for Photocatalytic Wastewater Treatment Ceramic Membranes

“…The TiO2 phase was a decisive factor for photocatalytic activity; the anatase phase was considered more effective in this regard than other phases such as the The effect of the amount of DEG used on the crystalline property of TiO 2 structures was also investigated by XRD, as shown in Figure 6. The TiO 2 phase was a decisive factor for photocatalytic activity; the anatase phase was considered more effective in this regard than other phases such as the rutile and brookite phases [37,38]. The higher photocatalytic activity was attributed to the larger surface area, lower recombination rate, and higher electron lifetime of the anatase phase.…”

“…rutile and brookite phases [37,38]. The higher photocatalytic activity was attributed to the larger surface area, lower recombination rate, and higher electron lifetime of the anatase phase.…”

Morphological control of TiO2 anatase nanoparticles: What is the good surface property to obtain efficient photocatalysts?

“…However, the good photocatalytic efficiency of the AGlu sample cannot be generalized and another publication describing in details the photocatalytic efficiency of the AGlu sample on different photodegradation reactions show for instance that the phenol degradation is correlated to HO• production. [66] Indeed, the proposed degradation mechanism of this pollutant [67] require the presence of reactive radicals for an indirect degradation at low concentrations. Overall, all the characterizations presented are supporting that the most acidic sample AGlu, exposing {101} faces is thus the best photocatalyst of our set of materials for a direct reduction of the RhB.…”