Figure - available from: Research on Chemical Intermediates
This content is subject to copyright. Terms and conditions apply.
![a Applications of titanium oxide-based photocatalysts in reaction systems with H2O and O2. b Reaction systems with only H2O (O2-free). The inset shows the production of electrons in the conduction band and holes in the valence band under UV light irradiation of TiO2 semiconducting materials [13]](publication/326790021/figure/fig1/AS:962165213257728@1606409471198/a-Applications-of-titanium-oxide-based-photocatalysts-in-reaction-systems-with-H2O-and.png)
a Applications of titanium oxide-based photocatalysts in reaction systems with H2O and O2. b Reaction systems with only H2O (O2-free). The inset shows the production of electrons in the conduction band and holes in the valence band under UV light irradiation of TiO2 semiconducting materials [13]
Source publication
With the prevalence of green chemistry and the concept of a harmonious society, humans have much greater environmental awareness than ever before. Mesoporous TiO2 and its corresponding photocatalysts can assist the search for a better and more ideal life. In this review, we first briefly introduce the development of various mesoporous materials, af...
Citations
... In this study, we employed a low-thermal-budget microwave (MW)-assisted oxidation method to fabricate a titanium oxide (TiO x ) layer, which has high carrier mobility and inherent chemical stability [23]. Inspired by the unique characteristics of chitosan and TiO x , we fabricated solid polymer electrolyte (SPE)-chitosan memristors with TiO x and evaluated their endurance in RS behavior and resistance distribution, as well as their artificial synaptic behaviors. ...
This study proposes a high-performance organic-inorganic hybrid memristor for the development of neuromorphic devices in the memristor-based artificial synapse. The memristor consists of a solid polymer electrolyte (SPE) chitosan layer and a titanium oxide (TiOx) layer grown with a low-thermal-budget, microwave-assisted oxidation. The fabricated Ti/SPE-chitosan/TiOx/Pt-structured memristor exhibited steady bipolar resistive switching (BRS) characteristics and demonstrated excellent endurance in 100-cycle repetition tests. Compared to SPE-chitosan memristors without a TiOx layer, the proposed organic-inorganic hybrid memristor demonstrated a higher dynamic range and a higher response to pre-synaptic stimuli such as short-term plasticity via paired-pulse facilitation. The effect of adding the TiOx layer on the BRS properties was examined, and the results showed that the TiOx layer improved the chemical and electrical superiority of the proposed memristor synaptic device. The proposed SPE-chitosan organic-inorganic hybrid memristor also exhibited a stable spike-timing-dependent plasticity, which closely mimics long-term plasticity. The potentiation and depression behaviors that modulate synaptic weights operated stably via repeated spike cycle tests. Therefore, the proposed SPE-chitosan organic-inorganic hybrid memristor is a promising candidate for the development of neuromorphic devices in memristor-based artificial synapses owing to its excellent stability, high dynamic range, and superior response to pre-synaptic stimuli.
... Although mesoporous materials cannot match up with the high hydrothermal stability of zeolites, they have found their use in many applications including photocatalysis, batteries, solar and fuel cells . [9,58,237] The poor hydrothermal stability is due to the presence of a large number of silanol groups on the wall and the absence of crystallinity. The selection of a suitable template allows the synthesis of mesoporous materials with controlled pore size, composition and morphology, which can be targeted for a specific application. ...
Porous materials have attracted considerable attention in materials science, chemistry and multidisciplinary areas of research due to their diverse structures, tailorable functionalities, large surface areas, remarkable optical transparency, confinement and shape selectivity effects. The precise architecture of porous photocatalytic materials has been extensively reported by the hybridization of semiconducting nanoparticles (NPs), light-responsive metal complexes and plasmonic metal NPs with silica-based micro-, meso- and macro-porous nanostructures. This review targets to cover state-of-the-art accomplishments in the surface engineering chemistry of zeolites, mesoporous silica, and metal-organic frameworks (MOFs) as excellent host materials for solar to chemical energy conversion and environmental remediation. The specific advantages and disadvantages of representative porous materials in photocatalysis have also been elaborated and summarized. Finally, key advances and prospects are presented to overcome the current challenges in photocatalysis and to inspire further studies in this rapidly evolving research field.
... Loading POMs on TiO 2 is an effective method to improve photocatalytic performance due to the synergistic effect between POMs and TiO 2 (Dong et al. 2018). In recent years, some studies had used titanium dioxide-loaded POM composites as photocatalysts . ...
... The electron-hole pairs generated by ultraviolet light excitation of TiO 2 are very easily recombined, thereby affecting the photocatalytic effect (Yao et al. 2015). In TiO 2 -POM composites, the POMs, which are strong electron acceptors, accept photogenerated electrons formed by photoexcitation, thereby prolonging the recombination time of photogenerated electrons and holes so that more photogenerated electrons can participate in the reduction reaction (Dong et al. 2018;Zhao et al. 2013). ...
Nitrate nitrogen in water, especially in groundwater, is a major problem in the current drinking water environment. In this study, copper- and nickel-modified phosphotungstate catalysts supported on TiO2 were prepared by the sol-gel solvothermal method, and photocatalytic reduction by phosphotungstate was used to remove nitrate nitrogen in water under ultraviolet irradiation. The maximum removal rate was 59.60% with 0.8 g/L Cu-H3PW12O40/TiO2, 90 mg/L nitrate nitrogen, and 60 min reaction time. For Ni-H3PW12O40/TiO2, the maximum removal rate of nitrate nitrogen was 54.58%, achieved with a catalyst concentration of 0.8 g/L, nitrate nitrogen concentration of 120 mg/L, and reaction time of 30 min. Both catalysts could remove nitrate nitrogen from water under the condition of photocatalysis.
... Recently, photocatalytic wastewater treatments by means of semiconductors were deeply studied [1,2]. Among various semiconductors, TiO 2 and ZnO have been recently used as effective, inexpensive and nontoxic photocatalysts for the degradation of a wide range of different pollutants [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The biggest advantage of ZnO in comparison with TiO 2 is that it absorbs a larger fraction of UV spectrum [15]. ...
Zinc oxide-hydroxyapatite composites were prepared using wet impregnation method. Firstly, a natural phosphate ore rich in silica and calcium phosphate was sieved to separate silica phase from phosphate phase. Then, through a chemical precipitation method, a pure hydroxyapatite (HAP) was obtained, which was used as a support for ZnO immobilization and applied for the photodegradation of two toxic contaminants: a transparent molecule (caffeine) and dye molecule (rhodamine B). During the present work two weight ratio percentages of zinc oxide were used: 25 wt.% and 50 wt.% of ZnO relative to HAP. The samples were characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), X-ray Fluorescence (XRF), BET surface area (SBET), Scanning Electron Microscopy (SEM-EDS) and by Transmission Electron Microscopy (TEM-STEM). The immobilization of ZnO on HAP surface followed by thermal treatment at 400 °C for 2 h to get a homogenous dispersion of ZnO on the hydroxyapatite support. At high ZnO impregnation percentage, photodegradation performances of ZnO-HAP under UV illumination were fast and superior than the ZnO photocatalyst alone. The results showed that due to the presence of HAP, the conversion of both molecules became faster and greater, since it promotes the synergic phenomena of adsorption and photocatalysis. The toxicity of the treated substrate solutions obtained in the corn kernels germination test indicated a low toxicity after the photodegradation processes, probably due to a high mineralization degree.
... Heterogeneous photocatalysis has been considered an attractive and efficient technology for environmental application (Byrne et al., 2018) (Ahmed and Haider, 2018) (Paola et al., 2012). In the scenario of heterogeneous photocatalysis, two semiconductor oxides have attracted most attention in the investigations for their use in the elimination of pollutants from the environment: one is TiO 2 and the other ZnO (Paola et al., 2012) (Nasr et al., 2018) (Dong et al., 2018) (Fujishima et al., 2000) (Noman et al., 2018) (Ong et al., 2018) (Ani et al., 2018) (Lee et al., 2016) (Wetchakun et al., 2018). Both semiconductors have similar band gap (ranging from 3.0 to 3.2 eV), which limits their use in the UV part of the solar spectrum. ...
... However, since there is evidence of the formation of complexes (photoactive or not) of other substrates frequently studied, such as rhodamine B and caffeine, with Fe 3þ /Fe 2þ or Zn 2þ , also the role of those complexes, in photo-assisted degradation of the substrates in aqueous solution, should be investigated. In fact, many transition metal ions have been used as doping agents for TiO 2 or ZnO (Paola et al., 2012) (Nasr et al., 2018) (Dong et al., 2018) (Fujishima et al., 2000) (Noman et al., 2018) (Ong et al., 2018) (Ani et al., 2018) (Lee et al., 2016) (Wetchakun et al., 2018) (Khaki et al., 2017) (Etacheri et al., 2015) (Rauf et al., 2011) and, depending on the method of incorporating them into the semiconductor, they could play different roles. ...
Iron (III) was incorporated, to the surface of a synthesized ZnO, using two nominal molar percentages of Fe (III) relative to ZnO Samples dried and calcined . Photocatalytic activities of the catalysts were assessed based on the degradation of rhodamine B (RhB) and caffeine (CAF) in aqueous solution under two irradiation conditions: UV and visible light illumination. Prior to the photocatalytic tests, the interaction of each one of the substrates with either Fe(III) or Fe(II) was studied in homogeneous medium under UV-illumination and oxygenated environment. It was found that Fe (III) can play an important role in homogeneous media in the photoassisted degradation, both of rhodamine B and caffeine, while Fe (II) does not exert a relevant role in the photoassisted degradation of the referred substrates. FeZnO samples display similar or poorer performance than pure ZnO in the presence of UV light for both studied substrates. The phenomenon can be attributed to the formation of either goethite or ZnFe2O4 at the ZnO surface where the coupled Fe3+/Fe2+ can act as recombination centers for the photogenerated charges. On the contrary, all Fe-ZnO samples showed enhanced photocatalytic activity under visible illumination which seems to be independent of the iron content. In this context, the mechanisms for photoassisted degradation of both the substrates in homogeneous medium and photocatalytic degradation are discussed, as well as the role of Fe in the photodegradation processes.
The textile industry, a vital economic force in developing nations, faces significant challenges including the release of undesired dye effluents, posing potential health and environmental risks which need to be minimized with the aid of sustainable materials. This study focuses on the photocatalytic potential of hydroxyapatite together with different dopants like titanium-di-oxide (TiO2) and zinc oxide (ZnO). Here, we synthesized hydroxyapatite (HAp) using different calcium sources (calcium hydroxide, calcium carbonate) and phosphorous sources (phosphoric acid, diammonium hydrogen phosphate) precursors through a wet chemical precipitation technique. Pure and doped HAp were characterized via different technologies, which consist of X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), as well as UV-vis spectroscopy. The effectiveness of the synthesized photocatalyst was evaluated by its interactivity with synthetic azo dyes (Congo red). The photodegradation of Ca(OH)2_HAp, CaCO3_HAp, ZnO-doped HAp as well as TiO2-doped HAp, were obtained as 89%, 91%, 86%, and 91%, respectively. Furthermore, at neutral pH, TiO2-doped HAp shows the highest degradation (86%), whereas ZnO-doped HAp possesses the lowest degradation (73%). Additionally, various XRD models (Monshi–Scherrer's, Williamson–Hall, and Halder–Wagner methods) were employed to study crystallite dimension.
The present research work employed a hydrothermal technique to synthesize GO-based Pure Bi2O3 and GO-based Fe-doped Bi2O3 mesoporous nanocomposites. X-ray diffraction, Raman spectroscopy, FE-SEM, EDAX, UV–Vis, Photoluminescence, and BET were introduced to characterize the nanocomposites that were synthesized. The photocatalytic degradation of Congo red and Methylene Blue-Methyl Orange mixed dye under solar light irradiation was then scrutinized. The results showed that the photocatalytic efficiency of GO-based 0.5 % Fe doped Bi2O3 was significantly greater than all other synthesized samples, with 91.57 % in 90 min for Congo red and 91.47 % in 120 min for MO-MB dyes. The enhancement in the degradation of harmful dyes in GO/0.5 % Fe doped Bi2O3 nanocomposite was attributable to a larger surface area of about 102.571 m2/g, the development of defects, low band gap and the production of higher active sites. According to the regeneration investigation, GO-based 0.5 % Fe doped Bi2O3 nanocomposite can be effectively recycled up to three cycles while keeping high efficiency without a significant reduction in degradation rate and excellent stability.
In order to increase the photocatalytic performance of titanium dioxide mesocrystals (TMCs), in this study, Ag nanoparticles with different mass content were first photodeposited on the surface of as-prepared TMCs to form heterostructured Ag–TMCs catalysts, followed by loading them on g-C3N4 via one step “bottom-to-up” calcination method. The results of photocatalytic degradation toward RhB experiments showed that the prepared ternary photocatalyst of g-C3N4/Ag–TMCs exhibited excellent photocatalytic activity not only compared with the bare TMCs and Ag–TMCs, but also with all of those reported TiO2/Ag/g-C3N4 ternary photocatalysts. Such improved photocatalytic properties were attributed to the synergistic effect created by the LSPR effect and an important role as an electron-conduction bridge of Ag and the existence of heterojunction structure formed between Ag, TMCs and the further coupling g-C3N4, which added to the evidences that enabled the prepared g-C3N4/Ag–TMCs catalyst enhanced transfer efficiency of photogenerated carriers and suppressed recombination rate of electron-hole pairs. Moreover, the deposited Ag content had a positive effect on the photocatalytic degradation efficiency. On the basis of the results of this study, the specimen of g-C3N4/9% Ag–TMCs showed RhB degradation efficiency up to 100% under only 15 min visible-light irradiation. A possible degradation mechanism was also proposed based on several characterizations including photoluminescence spectrum and a serious of photoelectrochemical measurements. Overall, the prepared g-C3N4/Ag–TMCs ternary photocatalyst with good recyclability looked promising for future practical applications in the visible-light photodegradation of organic pollutants.
Photocatalytic technology is a “green”, environmentally friendly, energy-saving technology, which is considered to be an ideal method for removing volatile organic compounds (VOCs). At present, photocatalytic technology mostly uses powdered...
This paper investigates a new path to synthesis an ordered nanostructured mesoporous titanosilicate by the assembly of preformed titanosilicate (MTS-9) precursors with triblock copolymers. Silver nanoparticles (AgNPs) with different loadings are supported on MTS-9 composite by two different methods: Deposition Precipitation with Urea (DPU) and Impregnation Reduction with Citrate (IRC). The structure and active component of catalysts were confirmed trough N2 adsorption‐desorption, X‐ray diffraction (XRD), scanning electron microscopy (SEM), and high‐resolution transmission electron microscopy (HRTEM). The influence of catalytic activity of AgNPs supported on MTS-9 has been evaluated in the oxidation of Carbon monoxide (CO). The obtained results emphasize on the improvement of catalytic activity of MTS-9 by AgNPs. A total of CO-oxidation up to 100% was achieved at 240 °C for the catalyst prepared by impregnation reduction with citrate. Indeed, the 0.5% Ag/MTS-9 (IRC) catalyst exhibited a high stability after four continuous runs. Overall, this catalyst could be very suitable for oxidation of carbon monoxide industrial process.
