Abstract:TiO2-coated boron particles were prepared by a wet ball milling method, with the particle size distribution and average particle size being easily controlled by varying the milling operation time. Based on the results from X-ray photoelectron spectroscopy, transmission electron microscopy, energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy, it was confirmed that the initial oxide layer on the boron particles surface was removed by the wet milling process, and that a new B–O–Ti bond w… Show more
“…However, wet ball milling provides smaller particle size and narrower size distribution [23]. Jung et al [24] found that the size of TiO 2 particles was decreased and showed a uniform size distribution by using a wet ball milling process. Furthermore, phase, crystallite size, and crystallinity of TiO 2 play a critical role for high photocatalytic activity which they can be governed by calcination temperature in the sol-gel method.…”
In this work, TiO2 nanoparticles were successfully synthesized with narrow size distribution via a wet ball milling sol-gel method. The effect of calcination temperature on photocatalytic activity was observed from particle size, crystallite size, and phase transition of TiO2 nanoparticles. Increasing calcination temperature increased particle size, crystallite size, and the crystallinity of synthesized TiO2. Phase transition depended on variation in calcination temperatures. A two-phase mixture of anatase and brookite was obtained with lower calcination temperature whereas a three-phase mixture appeared when calcination temperature was 500–600 °C. With higher temperature, the rutile phase kept increasing until it was the only phase observed at 800 °C. Anatase strongly affected the photocatalytic activity from 300 °C to 600 °C while the particle size of TiO2 was found to have a dominant effect on the photocatalytic activity between 600 °C and 700 °C. A mixture of three phases of TiO2-600 exhibited the highest methylene blue degradation with the rate constant of 9.46 × 10−2 h−1 under ultraviolet (UV) irradiation.
“…However, wet ball milling provides smaller particle size and narrower size distribution [23]. Jung et al [24] found that the size of TiO 2 particles was decreased and showed a uniform size distribution by using a wet ball milling process. Furthermore, phase, crystallite size, and crystallinity of TiO 2 play a critical role for high photocatalytic activity which they can be governed by calcination temperature in the sol-gel method.…”
In this work, TiO2 nanoparticles were successfully synthesized with narrow size distribution via a wet ball milling sol-gel method. The effect of calcination temperature on photocatalytic activity was observed from particle size, crystallite size, and phase transition of TiO2 nanoparticles. Increasing calcination temperature increased particle size, crystallite size, and the crystallinity of synthesized TiO2. Phase transition depended on variation in calcination temperatures. A two-phase mixture of anatase and brookite was obtained with lower calcination temperature whereas a three-phase mixture appeared when calcination temperature was 500–600 °C. With higher temperature, the rutile phase kept increasing until it was the only phase observed at 800 °C. Anatase strongly affected the photocatalytic activity from 300 °C to 600 °C while the particle size of TiO2 was found to have a dominant effect on the photocatalytic activity between 600 °C and 700 °C. A mixture of three phases of TiO2-600 exhibited the highest methylene blue degradation with the rate constant of 9.46 × 10−2 h−1 under ultraviolet (UV) irradiation.
“…The literature suggests that a mass ratio of 3:7 (R to A) is the best for achieving high photocatalytic activities [ 31 ]. However, other reports detail that even a lesser proportion of R can also yield improved photoactivities, and the parameters like crystallite size, surface area, and optical absorption will determine the PCA in such cases [ 18 ]. Also, a mixture of A and brookite (B), as well as R and B, can result in fast photodegradation rates of organic molecules [ 32 ].…”
Section: Resultsmentioning
confidence: 99%
“…One must note that the smaller particle size of TiO 2 can result in larger surface area and higher photocatalytic activity. Towards this direction, the grinding process of the powder, like dry/wet ball milling (BM), was employed to obtain smaller particle size and narrower size distribution [ 18 , 19 ]. On the other hand, it is to be noted that phase, crystallite size, and crystallinity of TiO 2 play an important role in the enhancement of photocatalytic activity, and these modifications were attempted by the calcination process.…”
Titanium dioxide (TiO2), the golden standard among the photocatalysts, exhibits a varying level of photocatalytic activities (PCA) amongst the synthetically prepared and commercially available products. For commercial applications, superior photoactivity and cost-effectiveness are the two main factors to be reckoned with. This study presents the development of simple, cost-effective post-treatment processes for a less costly TiO2 to significantly enhance the PCA to the level of expensive commercial TiO2 having demonstrated superior photoactivities. We have utilized sequential calcination and ball milling (BM) post-treatment processes on a less-costlier KA100 TiO2 and demonstrated multi-fold (nearly 90 times) enhancement in PCA. The post-treated KA100 samples along with reference commercial samples (P25, NP400, and ST01) were well-characterized by appropriate instrumentation and evaluated for the PCA considering acetaldehyde photodegradation as the model reaction. Lattice parameters, phase composition, crystallite size, surface functionalities, titanium, and oxygen electronic environments were evaluated. Among post-treated KA100, the sample that is subjected to sequential 700 °C calcination and BM (KA7-BM) processes exhibited 90-fold PCA enhancement over pristine KA100 and the PCA-like commercial NP400 (pure anatase-based TiO2). Based on our results, we attribute the superior PCA for KA7-BM due to the smaller crystallite size, the co-existence of mixed anatase-srilankite-rutile phases, and the consequent multiphase heterojunction formation, higher surface area, lattice disorder/strain generation, and surface oxygen environment. The present work demonstrates a feasible potential for the developed post-treatment strategy towards commercial prospects.
“…Another interesting application of the wet ball-milling process was reported the same year by Jung et al [126] for the TiO 2 nano-coating of boron particles. Briefly, a tungsten carbide milling jar was filled with titanium(IV) isopropoxide, boron powder (average particles’ size ~ 800 nm), and hexane inside a glove box filled with nitrogen.…”
Section: Part Bmentioning
confidence: 99%
“…The ball-milling-derived TiO 2 -coated nanoparticles were promising for hydrogen and oxygen evolution reactions (HERs, OERs) in photoelectrochemical applications.Fig. 19TEM image ( a ) and EDX maps ( b – d ) of TiO 2 -coated boron particles wet-milled for 8 h.Reprinted with permission from [126]. Copyright (2016) MDPI…”
A new field where the utilization of mechanochemistry can create new opportunities is materials chemistry, and, more interestingly, the synthesis of novel nanomaterials. Ball-milling procedures and ultrasonic techniques can be regarded as the most important mechanochemical synthetic tools, since they can act as attractive alternatives to the conventional methods. It is also feasible for the utilization of mechanochemical forces to act synergistically with the conventional synthesis (as a pre-treatment step, or simultaneously during the synthesis) in order to improve the synthetic process and/or the material’s desired features. The usage of ultrasound irradiation or ball-milling treatment is found to play a crucial role in controlling and enhancing the structural, morphological, optical, and surface chemistry features that are important for heterogeneous photocatalytic practices. The focus of this article is to collect all the available examples in which the utilization of sonochemistry or ball milling had unique effects as a synthesis tool towards zero- or one-dimensional nanostructures of a semiconductor which is assumed as a benchmark in photocatalysis, titanium dioxide.Graphical Abstract
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