Low Temperature Synthesis of High Energy Facets Exposed Sheet–like Anatase TiO₂ Mesocrystals Show Reduced e⁻/h⁺ Pair Recombination Rates and Enhanced Photoactivity

Abstract

Herein, we report low temperature synthesis of anatase TiO2 mesocrystals with {001} facets exposed sheet‐like morphology via fluorine‐free synthesis by the synergistic effect of microwave and ultrasound treatments. The synthesized TiO2 powder showed higher surface area and enhanced photocatalytic degradation of a model dye under white light irradiation. The sheet‐like anatase TiO2 mesocrystals resulted long‐lived charge carriers and separation that was confirmed from photoluminescence and photocurrent measurements. A five‐fold enhancement in the photocurrent was obtained for the mesocrystals compared to reference sample, which revealed that the orientation of nanocrystallites in sheet‐like morphology play a pivotal role in electron transport. The effect of charge carriers on photocatalytic activity was studied in detail and it followed the order, hydroxyl radicals> holes>electrons. Additionally, the TiO2 sol showed excellent stability. Further, the photoinactivation of Escherichia coli and Candida albicans was evaluated using zone of inhibition test under indoor irradiation and synthesized anatase TiO2 showed a clear zone of inhibition with diameter 37.2 mm and 40.0 mm, respectively whereas commercial TiO2 shows meager inactivation. The results indicate that our approach of combined microwave and sonication can serve as a facile approach for the synthesis of {001} facets exposed anatase sheet‐like TiO2 mesocrystals under halide‐free and low temperature conditions.

Hydrophilic 3D Interconnected Network of Bacterial Nanocellulose/Black Titania Photothermal Foams as an Efficient Interfacial Solar Evaporator

“…The BT flakes were ground to a fine powder and used without further modifications. White titania (WT) was prepared by the method adopted by Sumina et al…”

“…23 The BT flakes were ground to a fine powder and used without further modifications. White titania (WT) was prepared by the method adopted by Sumina et al 49 Preparation of Bacterial Nanocellulose (BNC). BNC was produced using the K. rhaeticus PG2 strain isolated from a rotten pomegranate in a modified Hestrin−Schramm (HS) medium containing glycerol as a carbon source.…”

“…The diffraction peaks observed at 25.3, 37.8, 48.1, and 54.4°are assigned to (101), (004), (200), and (105) diffracting planes, respectively (JCPDS #21-1272; standard spectral data is marked as a blue line plot for comparison). Figure 1c shows the NIR absorption spectra recorded for BT powder and their comparison with those of white titania (WT) powder, 49 showing extended absorption of BT in the NIR range (see the red marked region in absorption spectra, Figure 1c). The corresponding diffused reflectance spectra (Figure 1d) show a negligible reflection loss for BT, making it an attractive photothermal material for the anticipated application.…”

Mesocrystals for photocatalysis: a comprehensive review on synthesis engineering and functional modifications

“…Among the existing mesocrystal photocatalysts, the development of TiO 2 mesocrystals has been attracting increased attention; therefore, the appearance and morphology details of TiO 2 mesocrystals are abundantly available as compared to others, including ellipsoidals, spheres, polyhedra, nanosheets, and nanorods. [35][36][37][38][39][40][41][42][43][46][47][48][49][52][53][54][55][56][57][58][59]61,65 In this subsection, we initially summarize the synthesis strategies of the different abovementioned species. Thereaer, versatile applications in photocatalytic hydrogen evolution and organics degradation, as well as the corresponding structure-related photocatalytic mechanisms, are discussed by using typical examples.…”

“…Pillai and coworkers have demonstrated anatase TiO 2 mesocrystals with exposed (001) facets and sheet-like morphologies by a facile halide-free low-temperature microwave-assisted sonochemical method, which exhibited good crystallinity, higher surface area, and excellent stability. 58 In particular, sheet-like mesostructures played a crucial role in electron transport, which enabled faster charge transfer as conrmed by the enhanced photocurrent of 131 nA at 0 V bias. Therefore, this environmentally friendly synthesis strategy enabled 2D anatase mesocrystals to exhibit high energy facets, crystallinity, and low recombination rate of the photogenerated charge carriers, and therefore, resulted in improved photocatalytic activity.…”