Titanium dioxide is a commonly used ingredient in cosmetics acting as a thickening agent and inorganic UV filter. However, TiOsub.2 is difficult to disperse, which causes problems in spreading the ...formulations. The solution to this problem is to modify the titanium dioxide surface to change its properties by creation of the new type of hybrid inorganic-organic UV filter. Therefore, this study aimed to functionalize titanium dioxide with organosilicon compounds and determine how this modification will affect the dispersibility of TiOsub.2 in the colloidal system and the stability of emulsions. First, the functionalized octaspherosilicates were obtained and characterized. Next, the synthesized compounds were applied as modifiers for titanium dioxide and were analyzed by FT-IR, UV-Vis, and laser diffraction. Furthermore, the hydrophilic-hydrophobic character was assessed by measuring the contact angle. The new materials were introduced into emulsions and the formulations were analyzed in terms of particle size distribution and stability by multiple light scattering. It was found that the modification of titanium dioxide with spherosilicates significantly improved both the stability of emulsion and the dispersibility of novel materials in the colloidal system compared to nonmodified TiOsub.2. The covalent binding of the modifier with the titanium dioxide had an impact on the stability of the emulsion.
Management of ubiquitous nitrate contamination in drinking water sources is a major engineering challenge due to its negative impacts from eutrophication to immediate risk to human health. Several ...water treatment technologies exist to manage nitrate pollution in water sources. However, the most widely used technologies are phase separation treatments. In this context, nanoscale photocatalysis emerges as a highly promising transformative technology capable of reducing nitrate to innocuous nitrogen with noticeable selectivity. This critical review describes the photocatalytic reduction mechanisms of nitrate towards undesirable products (nitrite, ammonium) and the more desirable product (dinitrogen). The mechanisms are based on the standard reduction potential of each individual species and highlight the contribution of reducing species (e.g. CO2−) radicals formed from different hole scavengers. The strategic use of different pure, doped, and composite nanoscale photocatalysts is discussed on the basis of reduction mechanisms' overall conversion, kinetic rates, and selectivity towards N2. The choice of light source affects pathways and influences by-product selectivity because direct photolysis of N-intermediates, which has been overlooked in the literature. In addition, the re-oxidation of nitrite and ammonia as drawback process is explained. Finally, an exhaustive analysis presents the photocatalytic reduction applications for treating real water matrices and the competing effect of other species. Overall, this critical review aims to contribute to the understanding of the potential application/constraints of photocatalysis in inorganic nitrogen management, and guide researchers towards future efforts required for widespread implementation.
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•Critical review on fundamentals and challenges of nitrate photocatalytic reduction•Photolytic and photocatalytic mechanism of nitrate targeting N2 in lieu of NH4+•Influence of photocatalysts and hole scavengers on selectivity and performance•Consideration of undermining re-oxidation mechanisms of nitrite and ammonia•Photocatalytic nitrate reduction in actual water matrices: towards real applications
This article compares the effectiveness of pure and modified TiO2 for photocatalytic degradation of different organic matters and clarifies the advantages of the modified TiO2 with photoactivity ...under visible light. Photocatalytic degradation technique with titanium dioxide is generally applied for treating wastewater containing refractory organic contaminants with the purpose of reuse due to its ability to achieve complete mineralization of the compounds under mild conditions such as ambient temperature and pressure. Performance of different types of photocatalytic reactors, effects of important parameters on the reactors performance, effect of various methods used to enhance the photocatalytic activity of TiO2 including doping, sensitization of TiO2 and surface modification are discussed in details. So far, a few review papers have been published and extensive information have been reported on the structure and electronic properties of TiO2, difference between TiO2 with other common semiconductors used for photocatalytic applications, various methods used to enhance the photocatalytic characteristics of TiO2 including dye sensitization, doping, coupling, the effects of various operating parameters on the photocatalytic degradation of phenols and dyes and types of reactors, comparison between effective modes of TiO2 application as immobilized on surface or as suspension, and photocatalytic hybrid membrane system are presented. However, in the published review papers, performance of the different modified photocatalysts is rarely compared quantitatively. Therefore, in order to provide an inclusive and effective comparison among the studies, specific removal rate (SRR) (mgcompoundremoved/gcat.h) was calculated as a response.
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•Atomistic Behler–Parrinello potentials based on artificial neural networks (ANNs).•Free and open source software (ænet) for construction and usage of ANN potentials.•ANN potential ...library for interfacing with MD and MC software, e.g., ASE.•Accurate and efficient ANN potential for TiO2 crystal phases.
Machine learning interpolation of atomic potential energy surfaces enables the nearly automatic construction of highly accurate atomic interaction potentials. Here we discuss the Behler–Parrinello approach that is based on artificial neural networks (ANNs) and detail the implementation of the method in the free and open-source atomic energy network (ænet) package. The construction and application of ANN potentials using ænet is demonstrated at the example of titanium dioxide (TiO2), an industrially relevant and well-studied material. We show that the accuracy of lattice parameters, energies, and bulk moduli predicted by the resulting TiO2 ANN potential is excellent for the reference phases that were used in its construction (rutile, anatase, and brookite) and examine the potential’s capabilities for the prediction of the high-pressure phases columbite (α-PbO2 structure) and baddeleyite (ZrO2 structure).
Ein kritischer Schritt bei der photokatalytischen Wasserdissoziation ist die lochvermittelte Oxidationsreaktion. Einblicke auf molekularer Ebene in den Mechanismus dieser komplexen Reaktion unter ...realistischen Bedingungen mit hoher zeitlicher Auflösung sind äußerst wünschenswert. Wir verwenden Femtosekunden zeitaufgelöste, oberflächenspezifische Summenfrequenzspektroskopie, um die photoinduzierte Reaktion direkt an der Grenzfläche des Photokatalysators TiO2 in Kontakt mit flüssigem Wasser bei Raumtemperatur zu untersuchen. Dank der inhärenten Oberflächenspezifität der spektroskopischen Methode können wir spezifisch die Reaktion von den Grenzflächenwassermolekülen direkt an der Grenzfläche auf Zeitskalen auf denen die Reaktion abläuft verfolgen. Nach der Erzeugung von Löchern an der Oberfläche des Katalysators, sofort nach der Photoanregung mit UV‐Licht, erfolgt die Wasserdissoziation auf einer Zeitskala von unter 20 ps. Der Reaktionsmechanismus ist bei pH 3 und 11 ähnlich. In beiden Fällen beobachten wir die Umwandlung von H2O in Ti−OH‐Gruppen und die Deprotonierung bereits vorhandener Ti−OH‐Gruppen. Diese Studie bietet einzigartige experimentelle Einblicke in die frühen Schritte der photoinduzierten Dissoziationsprozesse an der Photokatalysator‐Wasser Grenzfläche, die für die Entwicklung verbesserter Photokatalysatoren relevant sind.
The organic-inorganic composites F70-TiOsub.2, based on fullerene with carboxyl group derivatives and TiOsub.2 semiconductor, have been designed and constructed to become an optical-functional ...photocatalyst via the facile sol-gel method. The composite photocatalyst obtained shows excellent photocatalytic activity for the high-efficiency conversion of benzylamine (BA) to N-benzylidene benzylamine (NBBA) with air pressure at a normal temperature under visible light irradiation. By optimizing the composition, the composites with the 1:15 mass ratio of F70 and TiOsub.2, denoted as F70-TiOsub.2(1:15), demonstrated the highest reaction efficiency for benzylamine (>98% conversion) to N-benzylidene benzylamine (>93% selectivity) in this study. However, pure TiOsub.2 and fullerene derivatives (F70) exhibit decreased conversion (56.3% and 89.7%, respectively) and selectivity (83.8% and 86.0%, respectively). The UV-vis diffuse reflectance spectra (DRS) and Mott-Schottky experiment's results indicate that the introduction of fullerene derivatives into anatase TiOsub.2 would greatly broaden the visible light response range and adjust the energy band positions of the composites, enhancing the sunlight utilization and promoting the photogenerated charge (esup.−-hsup.+) separation and transfer. Specifically, a series of results on the in situ EPR tests and the photo-electrophysical experiment indicate that the separated charges from the hybrid could effectively activate benzylamine and Osub.2 to accelerate the formation of active intermediates, and then couple with free BA molecules to form the desired production of N-BBA. The effective combination, on a molecular scale, between fullerene and titanium dioxide has provided a profound understanding of the photocatalysis mechanism. This work elaborates and makes clear the relationship between the structure and the performance of functional photocatalysts.
Tuning the reaction parameters to maximize products yield is one of the major needs for any process. The goal of this research is to increase the reduction of CO.sub.2 with water by examining the ...operating parameters of a meso-scale continuous-flow type photochemical reactor over hydrothermally synthesized photocatalysts such as Pt/TiO.sub.2 and Pt/TiO.sub.2/RGO. Effects of catalyst type, weight of catalyst utilized, photochemical reactor temperature, retention time by variating the liquid water flow rate, and cocatalyst loading were investigated to increase the concentration of total organic carbon compounds including HCHO and CH.sub.3OH. The effect of titanium dioxide phase ratio (anatase: rutile) presence at the Pt/TiO.sub.2/RGO photocatalysts was also studied. The results revealed that the 0.3 wt.% Pt/TiO.sub.2/RGO.sub.5% photocatalyst which includes a phase ratio of 81:19 for anatase: rutile respectively has the superior photocatalytic activity to other studied photocatalysts. The physciochemical properties of different prepared photocatalytic samples were determined using various characterization techniques. Analyzing the liquid products on gas chromatography, it was found that CH.sub.3OH represents the major product whereas HCHO was the minor one. This reactor exhibits a great performance towards CO.sub.2 photocatalytic reduction under the optimized conditions.
Titanium dioxide of bronze phase (TiO2(B)) has attracted considerable attention as a promising alternative lithium/sodium‐ion battery anode due to its excellent operation safety, good reversible ...capacity, and environmental friendliness. However, several intrinsic critical drawbacks, including moderate electrochemical kinetics and unsatisfactory long cyclic stability, significantly limit its practical applications. It is crucial to develop reliable strategies to resolve these issues to advance the TiO2(B) based materials into practical applications in lithium/sodium‐ion batteries. In this review, both the theoretical and experimental investigations on the TiO2(B) based materials over the last few decades are chronically elaborated. Insights on the general and detailed evolution trends of the research on TiO2(B) anodes are provided. The review also points to future directions for the TiO2(B) anode research to advance the practical application of TiO2(B) anodes.
A comprehensive chronicle review of the TiO2(B) lithium/sodium‐ion battery anodes over the last few decades is performed. With the unique perspective, the evolution trends of the related studies are revealed, which are instructive and inspiring for the development of high‐performance rechargeable batteries.
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