Commercial TiO2 Nanoparticles Research Articles

Copper oxide modification to improve the photocatalytic activity of titanium dioxide nanoparticles: P25 versus P90

Titanium dioxide (TiO2) has been recognized as one of the most active photocatalysts for organic pollutant degradation under ultraviolet (UV) light irradiation. In order to reduce the fast charge recombination in the TiO2, various methods have been investigated, including the addition of metal oxide co-catalysts. Owing to the characteristic of the nanoparticles, the modification of nanoparticles involving heat treatment is still a challenging task. In this work, two commercial TiO2 nanoparticles, namely P25 and P90 (Evonik), were modified by copper oxides (CuO) and the photocatalytic activity was evaluated for degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under UV light. The CuO/P25 and CuO/P90 samples with various loading amounts (0.1, 0.25, 0.5 and 1.0 wt %) were prepared by precipitation of copper(II) nitrate to the P25 or P90 nanoparticles at pH of 9, followed by calcination at 573 K. X-ray diffraction (XRD) patterns indicated that all samples have the characteristics of both anatase and rutile phases. While the addition of CuO did not much affect the structure, crystallite size, and anatase-rutile ratio of the P25 and P90 nanoparticles, the presence of the copper species was confirmed by the scanning electron microscopy (SEM) equipped with the energy-dispersive X-ray (EDX) spectroscopy. Moreover, fluorescence spectra also showed that the CuO quenched the emission intensity of both the P25 and P90 nanoparticles, suggesting the successful decrease of the charge recombination in the TiO2 nanoparticles. Photocatalytic activity tests showed that the P25 and P90 gave percentage degradation of 90 and 47 %, respectively, after a 1-hour reaction. Even though not much improvement was observed for P25 TiO2 nanoparticle after the CuO addition (92 %), the activity of P90 nanoparticle was enhanced from 47 % to 86–87 % with the CuO addition of 0.1–0.25 wt %. This study demonstrated that it is feasible to improve the photocatalytic activity of TiO2 commercial nanoparticles, in this case, the P90, by surface modification using the CuO.

Synthesis and Characterization of TEOS Coating Added With Innovative Antifouling Silica Nanocontainers and TiO2 Nanoparticles

We study the synthesis and characterisation of an innovative TEOS-based composite coating, which could improve previous formulations used in the field of monument conservation. The proposed coating is composed by a tetraethoxyorthosilicate matrix (TEOS), containing an elasticiser (hydroxyl-terminated polydimethylsiloxane (PDMS-OH)) and a non-ionic surfactant (n-octylamine). The specific self-cleaning and antifouling properties are obtained by the addition of different kinds of nanofillers: the commercial TiO2 nanoparticles, plus two different silica nanocontainers, loaded with the commercial biocide 2-mercaptobenzothiazole. Through a multi-analytical approach, we evaluate the effect of the nanoparticles concentration on the coatings drying rate, on the variation of their visual aspect and textural properties. Our results show that the addition of the silica nanocontainers at 0.05% (w/v) in sol does not change the colour of the coating and reduces the formation of cracks after drying. Moreover, the coating charged with nanocontainers undergoes slower drying, thus improving its penetration into the pores of the treated surface. Further tests of photocatalytic and biocidal properties of this new product on different lithotypes and their potential interactions are in progress.

Polyhedral TiO2 particle-based cathode for Li-S batteries with high volumetric capacity and high performance in lean electrolyte

Achieving high volumetric capacity in Li-S batteries featuring light weight opens up unique applications. To address this, we demonstrate a high tap-density cathode based on polyhedral TiO2 (poly-TiO2) particles. The poly-TiO2 particles are obtained by fracturing 3D ordered macroporous TiO2 structure. Poly-TiO2 particles achieve high packing densities by assembly of surface-to-surface contact. Compared to commercial TiO2 nanoparticles, poly-TiO2 exhibits an apparent tap-density of about 6 times higher. We prepare a Li-S battery with a poly-TiO2 particle-assembled film as the host of the sulfur. The poly-TiO2 particle cell exhibits a volumetric capacity of 1145 mAh/cm3, which is about 9 times higher than the TiO2 nanoparticle cathode cell. The poly-TiO2 cathode with high tap-density shows excellent performance in lean electrolyte condition. Under extremely lean electrolyte conditions with an E/S value of 2.8, the poly-TiO2 cell exhibits a high capacity of 607 mAh/g at 1C-rate.

Laser synthesis of TiO2–carbon nanomaterial layers with enhanced photodegradation efficiency towards antibiotics and dyes

Graphene-based photocatalytic layers were prepared by reactive matrix assisted pulsed laser evaporation technique. Binary, nitrogen doped reduced graphene oxide (RGO)/TiO2 and ternary RGO/TiO2/graphitic carbon nitride (g-C3N4) compounds were synthesized and simultaneously deposited onto solid substrates. Aqueous dispersions of commercial graphene oxide platelets and TiO2 nanoparticles were prepared. NH3 or melamine powder was added to the dispersions to achieve enhanced nitrogen doping and synthesis of g-C3N4 during laser irradiation. The photocatalytic efficiency of the layers towards degradation of antibiotic, chloramphenicol and organic dye molecules was systematically investigated and correlated with structural, compositional, and morphological features. This study provides new insights into the importance of TiO2 crystal facets and the synergistic effects between TiO2 nanocrystals and the other constituents, nitrogen doped RGO and g-C3N4 of the hybrid layers. As a result of combined effect of constituent materials, TiO2, RGO, and g-C3N4 as well as N doping of RGO, through the generation of quaternary and pyrrolic N functionalities, the composite layers showed high photocatalytic efficiency for degradation of organic molecules. Stability and reusability experiments indicated that the composite layers maintain their high photodegradation efficiency towards organic molecules during consecutive degradation cycles. Active radical scavenging experiments were also carried out in order to determine the role of the main active species involved in the photocatalytic degradation process.

The role of redox states and junctions in photocatalytic hydrogen generation of MoS2-TiO2-rGO and CeO2-Ce2Ti3O8.7-TiO2-rGO composites

Photocatalytic generation of hydrogen (H2) using semiconductor junctions is an effective and sustainable way to produce H2. One challenge in photocatalytic systems is to promote an effective separation of charges and reduce charge recombination to enhance overall performance of the photocatalytic system. In the present work, MoS2- TiO2-reduced graphene oxide (MTG) and CeO2-Ce2Ti3O8.7-TiO2-reduced graphene oxide (CTG) composites were synthesized through hydrothermal route using a KOH pretreatment on the TiO2 nanoparticles before Mo or Ce incorporation, in order to increase reactivity and defects such as oxygen vacancies. The structural analysis done by X-ray diffraction and Raman spectroscopy reveals the formation of KTi8O16.5 traces, TiO2 and rGO in MTG as well as rGO, CeO2, Ce2Ti3O8.7 and TiO2 phases in CTG. From high resolution transmission electron micrographs, the composite phases were identified. In MTG, well defined graphene, TiO2 and MoS2 phases were observed. In CTG, CeO2 nanoparticles nucleated onto Ce2Ti3O8.7. XPS analysis reveals the presence of oxygen vacancies and Ti3+ in TiO2 both in CTG and MTG, Mo2+ and Mo4+ in MTG, and Ce4+ and Ce3+ in CTG, respectively. From optical absorption, band gap of 3.3 eV and 3.4 eV was found for CTG and MTG respectively. CTG shows an extended absorption tail that would arise from Ce3+ induced defects within the band gap. Photoluminescence confirmed the presence of MoS2 and defect states both in MTG and CTG. From the structural, chemical and optical data, electronic band diagrams are proposed to explain the mechanisms of H2 evolution in the composites. The homojunction due to the presence of rutile and anatase in the commercial TiO2 nanoparticles improves charge separation in TiO2. The oxygen vacancies in Ce2Ti3O8.7 and Ti3+ in TiO2 as well as the sulphur vacancies in MoS2 create interband defect states below conduction bands of the respective semiconductors that trap the photoelectron, which leads to prolonging the lifetime of charge carriers, resulting in reduced charge recombination. The presence of defect states in the TiO2–Ce2Ti3O8.7-CeO2 interfaces create extended absorption below the TiO2 bandgap. The presence of the graphene boosted charge transport in composites and acted as a co-catalyst to photogenerate the H2, presumably because the work function value of rGO with respect to that of H2 evolution reaction as well as to its electron donor character. Observed H2 evolution rates in MTG and CTG were 363.83 μmolg−1h−1and 355.9 μmolg−1h−1 respectively, under 254 nm illumination. The photocatalytic activity of the CTG composite was reported for the first time. The KOH pretreatment on TiO2 nanoparticles effectively increased the H2-photogeneration with respect to previous reports.

Ultrasound and microwave technology for flake-TiO2 growth and immobilization on cotton fabrics in micro-dissolution process

Recent years have witnessed the explosive progress of functional nano materials in textile field, requires us to re-recognize and understand the potential hazards of nanoparticles. A harmless, cost-effective and facile approach of growing functional particles with special morphology and immobilizing onto cellulose fabric (CF) to prepare functional fabrics is highly desired. Here, commercial TiO2 nanoparticles (TiO2 NPs) grow under ultrasound-microwave and form a flake-like structure, which retain excellent photocatalytic degradation ability and prevented the potential harm to human body when nanoparticles fell off. The method was implemented based on 4-methylmorpholine-N-oxide (NMMO) aqueous system which was approved as a favorable solvent for dissolving cellulose, and grew flake-TiO2 on cotton fibers under the assistance of the ultrasound and microwave. The as-prepared TiO2-CF possessed satisfactory photocatalytic activity for Methylene blue (MB) and Rhodamine B (RhB) dyes under ultraviolet light with the low dye residue rate of about 5% and 1%, respectively. After 50 times rigorous washing procedures, the titania loading next to 18% was confirmed by thermogravimetric analysis, which proved that TiO2-CF had good wash fastness.

Using Soft Polymer Template Engineering of Mesoporous TiO2 Scaffolds to Increase Perovskite Grain Size and Solar Cell Efficiency.

The mesoporous (meso)-TiO2 layer is a key component of high-efficiency perovskite solar cells (PSCs). Herein, pore size controllable meso-TiO2 layers are prepared using spin coating of commercial TiO2 nanoparticle (NP) paste with added soft polymer templates (SPT) followed by removal of the SPT at 500 °C. The SPTs consist of swollen crosslinked polymer colloids (microgels, MGs) or a commercial linear polymer (denoted as LIN). The MGs and LIN were comprised of the same polymer, which was poly(N-isopropylacrylamide) (PNIPAm). Large (L-MG) and small (S-MG) MG SPTs were employed to study the effect of the template size. The SPT approach enabled pore size engineering in one deposition step. The SPT/TiO2 nanoparticle films had pore sizes > 100 nm, whereas the average pore size was 37 nm for the control meso-TiO2 scaffold. The largest pore sizes were obtained using L-MG. SPT engineering increased the perovskite grain size in the same order as the SPT sizes: LIN < S-MG < L-MG and these grain sizes were larger than those obtained using the control. The power conversion efficiencies (PCEs) of the SPT/TiO2 devices were ∼20% higher than that for the control meso-TiO2 device and the PCE of the champion S-MG device was 18.8%. The PCE improvement is due to the increased grain size and more effective light harvesting of the SPT devices. The increased grain size was also responsible for the improved stability of the SPT/TiO2 devices. The SPT method used here is simple, scalable, and versatile and should also apply to other PSCs.

Nitrogen-doped TiO2 fibers for visible-light-induced photocatalytic activities

Nitrogen-doped TiO2 fibers (N–TiO2 Fs) were successfully and efficiently fabricated using titanium diisopropoxide bis(acetylacetonate) and polyvinylpyrrolidone (PVP) as a carrier polymer and nitrogen source via centrifugal spinning and subsequent calcination methods. XRD analysis confirmed that N–TiO2 Fs contains only anatase and rutile phases. XPS analysis revealed that N-atoms (from PVP) were successfully incorporated into the lattice of TiO2 whereas DTA and FTIR analysis confirmed that calcination at 550 °C for 1 h is appropriate to remove all organic impurities from the N–TiO2 Fs. SEM images showed that the N–TiO2 Fs of diameter (0.65 μm–1.2 μm) were produced and controlled with the amount of Ti-precursor. BET analysis confirmed that the addition of commercial TiO2 nanoparticles increased the specific surface area of the N–TiO2 Fs. UV–Vis diffuse reflectance measurements showed that N–TiO2 Fs exhibited a stronger light absorption in the visible region and a red-shift which is responsible for narrow band gap energy owing to the presence of N-atoms in the TiO2 lattice. This results in enhanced photocatalytic activity of the synthesized N–TiO2 Fs for degradation of methylene blue under visible light irradiation.

One-step fabrication of highly self-hydroxylated TiO2 mesocrystals and photocatalytic behavior towards water splitting

TiO2 mesocrystals have been considered as an efficient photocatalyst due to the effective charge transport. Introducing hydroxyls in TiO2 is respected to reduce the energy barrier of hydrogen formation. Herein, a simple one-step fabrication of highly self-hydroxylated TiO2 mesocrystals (MCs) for enhancing photocatalytic hydrogen evolution is proposed. TiO2 single crystals (SCs), polycrystals (PCs) and MCs are obtained via regulating the pH of the precursor during hydrothermal treatment. Results indicate that the moderate alkaline condition is favorable for the synthesis of highly self-hydroxylated TiO2 MCs. Compared with SCs, PCs and commercial P25 TiO2 nanoparticles, MCs exhibit the best photocatalytic activity in H2 evolution. Specifically, the maximum hydrogen evolution rate under solar light illumination (22.8 mmol/h/g) is 10.5 times higher than that of P25. Moreover, the MCs exhibit excellent catalytic stability and the hydrogen evolution rate can be maintained at 20.8 mmol/h/g under solar illumination after five cycles of reactions. The highly self-hydroxylated TiO2 MCs are constructed from crystallographically oriented nanocrystals with abundant hydroxyls. The unique superstructure and large surface area of MCs enable the effective charge separation and transport. Moreover, the high density of hydroxyls can reduce the recombination rate of photo-generated free charges and energy barrier for hydrogen formation while facilitate light absorption. The synthesis of highly self-hydroxylated TiO2 MCs and the underlying mechanism offer interesting insights for modifying the structure and properties of TiO2 towards high-performance hydrogen evolution.

Effect of Biotitania and Titania Addition on Bioactivity and Antibacterial Properties of Calcium Silicate Cement.

Nanoparticles are gaining more interest in dentistry for their antimicrobial, physical as well as other properties. This study aimed to evaluate the effect of adding two types of nanoparticles (NPs) on calcium silicate hydraulic cement's (CSHC) unique bioactivity and antibacterial properties. Biotitania/AgCl NPs were synthetized and characterized for its morphology, types of formed functional groups and crystalline AgCl using field emission scanning electron microscope (FE-SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), Fourier transformation infrared spectroscopy (FT-IR) and thermo-gravimetric analysis (TGA). The former NPs and commercial titania (TiO2) NPs were added (0.5, 1.5 and 3-weight %) to commercial CSHS powder. A total of 140 disk-shaped specimens (10 mm×1 mm) were prepared (seven material groups per each test in addition to the eighth cell control group) to evaluate cell viability and alkaline phosphatase activity (ALP) after 3 and 12 days, respectively. All were incubated with mesenchymal stem cells. Antibacterial efficacy against Streptococcus mutans (S. mutans) was evaluated through the bacterial growth curve slopes while being in direct contact with the tested material groups for 18 h. One-way analysis of variance (ANOVA) and post hoc Tukey's tests were used to analyze the obtained data. Addition of all NPs percentages had no significant effect (P0.05) on cell viability in comparison to positive control CSHC. Commercial TiO2 NPs (0.5 weight %) had statistically significant lower values (P≤0.05) for bacterial growth curve slope. However, addition of all NPs percentages had significantly improved (P≤0.05) the ALP activity of CSHC with the most prominent effect to 3-weight% biotitania/AgCl NPs. Based on this in vitro study, addition of biotitania/AgCl NPs up to 3-weight% significantly improved the bioactivity of CSHC without having a significant negative impact on its antibacterial efficacy. Interestingly, the addition of commercial TiO2 even in small amounts can significantly improve CSHC antibacterial efficacy.

The SALSAC approach: comparing the reactivity of solvent-dispersed nanoparticles with nanoparticulate surfaces.

We demonstrate that the ‘surface-as-ligand, surface-as-complex’ (SALSAC) approach that we have established for annealed nanoparticulate TiO2 surfaces can be successfully applied to nanoparticles (NPs) dispersed in solution. Commercial TiO2 NPs have been activated by initial treatment with aqueous HNO3 followed by dispersion in water and heating under microwave conditions. We have functionalized the activated NPs with anchoring ligands 1–4; 1–3 contain one or two phosphonic acid anchoring groups and 4 has two carboxylic acid anchors; ligands 1, 2 and 4 contain 6,6′-dimethyl-2,2′-bipyridine (Me2bpy) metal binding domains and 3 contains a 2,2′:6′,2′′-terpyridine (tpy) unit. Ligand functionalization of the activated NPs has been validated using infrared and 1H NMR spectroscopies, and thermogravimetric analysis. NPs functionalized with 1, 2 and 4 react with [Cu(MeCN)4][PF6] and those with 3 react with FeCl2·4H2O; metal binding has been investigated using solid-state absorption spectroscopy and scanning electron microscopy (SEM). Competitive binding of ligands 1–4 to TiO2 NPs has been investigated and shows preferential binding of phosphonic acid over carboxylic acid anchors. For the phosphonic acids, the binding orders are 3 > 1 > 2 which is rationalized in terms of relative pKa values (phosphonic acid and [HMe2bpy]+ or [Htpy]+) and the number of anchoring groups in the ligands. Ligand exchange between ligand-functionalized NPs and homoleptic metal complexes gives NPs functionalized with heteroleptic copper(i) or iron(ii) complexes.

High‐Efficiency Photocatalysis of Self‐Hydroxylated TiO2 Nanocrystals for Water Splitting

AbstractHerein, a facile and controllable strategy to synthesize self‐hydroxylated TiO2 nanocrystals with promoted photocatalytic activity in hydrogen evolution is demonstrated. Various colors (yellow, light yellow, blueish gray and gray) in appearance are induced by controlling the molar ratio of titanium source to oxidant during the hydrothermal treatment. Compared with commercial P25 TiO2 nanoparticles, the as‐obtained self‐hydroxylated TiO2 nanocrystals exhibit better photocatalytic performance in H2 evolution. Specifically, the maximum hydrogen evolution rate under solar light illumination (10.0 mmol/h/g) is 4.6 times superior to that of P25. The characterization results confirm the presence of abundant hydroxyls resulting from the hydrothermal treatment, which decreases the recombination rate of carriers and the energy barrier of hydrogen formation while facilitates light absorption for promoting photocatalytic performance.

The effect of different nanocatalysts for photocatalytic degradation of methylene blue

The aim of this study was to investigate photodegradation of Methylene Blue (MB) in water by using ZnO and TiO2 nanoparticles. Adsorption and photocatalytic oxidation studies were carried out by using produced TiO2, commercial TiO2 and commercial ZnO nanoparticles. In order to evaluate performance tests, 5 mg/l of MB solution was used. The samples were mixed in the dark for 2 hours for establishing adsorption-desorption equilibrium. The photocatalytic tests of the samples were performed by assessing the decomposition rate of MB solutions under UV light. The results of the photocatalytic showed that the highest color removal efficiencies was obtained by TiO2 catalyst where Methylene blue solution was completely degraded.

Photocatalytic inactivation of Escherischia coli under UV light irradiation using large surface area anatase TiO2 quantum dots.

In this study, high specific surface areas (SSAs) of anatase titanium dioxide (TiO2) quantum dots (QDs) were successfully synthesized through a novel one-step microwave–hydrothermal method in rapid synthesis time (20 min) without further heat treatment. XRD analysis and HR-TEM images showed that the as-prepared TiO2 QDs of approximately 2 nm size have high crystallinity with anatase phase. Optical properties showed that the energy band gap (Eg) of as-prepared TiO2 QDs was 3.60 eV, which is higher than the standard TiO2 band gap, which might be due to the quantum size effect. Raman studies showed shifting and broadening of the peaks of TiO2 QDs due to the reduction of the crystallite size. The obtained Brunauer–Emmett–Teller specific surface area (381 m2 g−1) of TiO2 QDs is greater than the surface area (181 m2 g−1) of commercial TiO2 nanoparticles. The photocatalytic activities of TiO2 QDs were conducted by the inactivation of Escherischia coli under ultraviolet light irradiation and compared with commercially available anatase TiO2 nanoparticles. The photocatalytic inactivation ability of E. coli was estimated to be 91% at 60 µg ml−1 for TiO2 QDs, which is superior to the commercial TiO2 nanoparticles. Hence, the present study provides new insight into the rapid synthesis of TiO2 QDs without any annealing treatment to increase the absorbance of ultraviolet light for superior photocatalytic inactivation ability of E. coli.

Caffeine and irgasan removal from water using bamboo, laurel and moringa residues impregnated with commercial TiO2 nanoparticles

ABSTRACTThe adsorption/degradation of caffeine and irgasan from aqueous artificial solutions by using.Lignocellulosic residues (LR) impregnated with TiO2 nanoparticles was studied. Three different LR were used: bamboo (Guadua angustifolia), laurel (Cordia allidora) and moringa (Moringa oleifera Lam.), each one with three nominal particle size ranges: 75–149, 45–75, and ≤45 μm. Commercially available TiO2 nanoparticles were added to these residues using the wet impregnation technique. The chemical composition of the LR was determined according to ASTM standards. FTIR spectroscopy and scanning electron microscopy were used to determine the functional groups and morphology of the modified materials, respectively. Adsorption/degradation tests were carried out in batch systems as a function of adsorbent concentration, contact time, nanoparticle content on the impregnated residues and light type influence. The maximum adsorption capacity was (37.1 mg. g-1/55.3 mg.g-1), using 40 wt.% nanoparticle-impregnated ≤45 μm laurel residues during 180 minutes, for a (7.0/0.7 g.L-1) concentration of (caffeine/irgasan). The caffeine adsorption isotherms were well described by the Langmuir and Freundlich models, while the Freundlich model describes irgasan adsorption. The use of UV radiation accelerated threefold the removal process.

Novel hollow titanium dioxide nanospheres with antimicrobial activity against resistant bacteria.

The search for and synthesis of new antimicrobial nanostructures is important to reduce microbial incidence that induces infectious diseases and to aid in the antibiotic resistance crisis, which are two of the most pressing issues in global public health. In this work, novel, hollow, calcined titanium dioxide nanospheres (CSTiO2) were successfully synthesized for the first time through the combination of electrospinning and atomic layer deposition techniques. Poly(vinylpyrrolidone) (PVP) electrosprayed spherical particles were double-coated with alumina and titanium dioxide, and after a calcination process, hollow nanospheres were obtained with a radius of approximately 345 nm and shell thickness of 17 nm. The structural characterization was performed using electron microscopy, and X-ray diffraction and small-angle X-ray diffraction evidenced an anatase titanium dioxide crystalline structure. Thermogravimetric analysis and Fourier-transform infrared spectroscopy studies demonstrated the absence of polymer residue after the calcination process. The antimicrobial properties of the developed CSTiO2 hollow nanospheres were evaluated against different bacteria, including resistant E. coli and S. aureus strains, and when compared to commercial TiO2 nanoparticles, CSTiO2 nanospheres exhibited superior performance. In addition, the positive effect of UV irradiation on the antimicrobial activity was demonstrated.

Modelling and optimization of photocatalytic degradation of phenol via TiO2 nanoparticles: An insight into response surface methodology and artificial neural network

The epidemic growth of the pharmaceuticals industries over the years in order to meet the human demands had exerted substantial pressure on the global environment, particularly water pollutions crisis. Herein, the photocatalytic degradation of phenol was investigated via commercial TiO2 nanoparticles. The Artificial Neural Network (ANN) and Response Surface Methodology (RSM) was employed for scrutinizing the suitable modelling and optimized condition of the TiO2 nanoparticles in yielding a profound rate of phenol removal. The parameters of investigation involved pH, phenol concentration, catalyst doses and degradation time. The RSM data shows the profound rate of phenol removal ˜ 99.48% was achieved by TiO2 NPs in a designed photocatalytic system that set at 5.42 pH, 15.21 mg/L phenol concentration, 1.75 g/L TiO2 dosage and 540 min irradiation time. The designed system fits well with the Pseudo-First-Order and the Langmuir isotherm model with R2 > 0.999. On the other hand, the ANN study revealed that the predicated model was perfectly fitted with the experimental data giving the highest value of R2. This work provides an insight into two different statistical modelling and optimization which could provide exposure for developing an optimized nanomaterial towards the removal of hazardous pollutant.

Synergistic effects of C, N, S, Fe-multidoped TiO2 for photocatalytic degradation of methyl orange dye under UV and visible light irradiations

The aim of this work is the synthesis and characterization of C, N, S–Fe multidoped TiO2 photocatalysts. The nanoparticles were prepared by sol–gel method and investigated by X-ray diffraction (XRD), transmission electron microscopy, UV–visible diffuse reflectance spectroscopy (DRS) and N2 adsorption–desorption isotherm (BET). Photocatalytic activity of the photocatalysts was studied by degrading methyl orange (MO) under UV and visible light irradiations. XRD analysis illustrated that all synthesized samples present the anatase phase. CNS–0.3Fe-doped TiO2 exhibited the highest surface area of 891 m2/g. DRS showed that Fe doping had efficiently narrowed the band gap to 2.74 eV and broaden the visible-light response region. The synthesized nanomaterials exhibited high photodegradation ability in the decomposition of MO than commercial pure TiO2 nanoparticles Degussa P25.

A new strategy to obtain nano-scale particles of lithium titanate (Li4Ti5O12) by the oxidant peroxo method (OPM)

Lithium titanate with spinel structure (Li4Ti5O12) has attracted attention for its potential use as anode in lithium-ion batteries. Usually, this material is obtained by solid-state reaction using high temperatures and considerable time in the calcination. Lithium titanate was synthesized in this study using a new approach of the oxidant peroxo method (OPM). The pure spinel phase was obtained by solid-state reaction utilizing commercial LiOH and TiO2 nanoparticles with surface modified with peroxo-groups (TiO2-OPM). These nanoparticles were synthesized from the peroxo-complex of titanium, formed on the OPM route. The results show that the use of TiO2-OPM as precursor favored the production of Li4Ti5O12 at lower temperature and time when compared to commercial titanium dioxide (TiO2-COM). The greater reactivity of this powder is related to the peroxo-groups present on the surface of the TiO2, since their decomposition generates a great amount of energy that accelerates the reaction.

Facile surface modification of immobilized rutile nanoparticles by non-thermal glow discharge plasma: Effect of treatment gases on photocatalytic process

The aim of this study was to enhance the photocatalytic performance of commercial rutile TiO2 nanoparticles using non-thermal glow discharge plasma methodology. Due to the lower photocatalytic performance compared to the anatase phase, the rutile phase has seldom been explored by researchers, despite its significant advantages. Nanoparticles of rutile TiO2 were immobilized on glass plates using heat attachment method whose surface properties were modified by non-thermal glow discharge plasma using different gases. XRD, FE-SEM, UV-DRS, XPS, PL, and BET analyses were performed for physiochemical characterization of rutile nanoparticles. While the stable rutile crystalline phase remained intact, a variety of physiochemical modifications were observed. XPS analysis revealed diminished titanium to lattice oxygen ratio, suggesting the formation of surface oxygen vacancies. Pseudo-first-order reaction rate for photocatalytic degradation of malachite green was improved by 3.31, 2.22, and 1.83 times over unmodified photocatalysts using argon, oxygen, and nitrogen gases, respectively. The proposed surface modification method remarkably improved the photocatalytic performance of immobilized rutile nanoparticles without adding any impurities to its structure. Further, the reusability of plasma-treated photocatalysts was satisfying, where the relative decolorization efficiency dropped by 4.4% after four consecutive 60-minute cycles, suggesting a good potential for operation in wastewater treatment reactors.