Commercial P25 TiO2 Research Articles

Outstanding visible photocatalytic activity of a new mixed bismuth titanatate material

In this work, a new photocatalyst based on bismuth titanates with outstanding visible photocatalytic activity was prepared by a facile hydrothermal method. The synthesised material showed visible activity as high as UV activity of commercial TiO2 P25 under the same experimental conditions for phenol degradation. A wide characterisation of the photocatalyst was performed. The material was composed of three phases; majority of Bi20TiO32 closely interconnected to Bi4Ti3O12 and amorphous TiO2. The high visible activity showed by this material could be ascribed to a combination of several features; i.e. low band gap energy value (2.1eV), a structure allowing a good separation path for visible photogenerated electron-holes pairs and a relatively high surface area. This photocatalyst appeared as a promising material for solar and visible applications of photocatalysis.

Metal–Organic Framework-Templated Synthesis of Bifunctional N-Doped TiO2–Carbon Nanotablets via Solid-State Thermolysis

Porous nitrogen-doped TiO2–carbon hybrid nanotablets were prepared via one-step solid-state thermolysis of amino-functionalized titanium metal–organic framework NH2-MIL-125(Ti). Amorphous, anatase, rutile, or mixture phases of TiO2 were obtained controllably by manipulating pyrolysis temperature. The anionic N- in NH2-MIL-125(Ti)’s 3D structure formed as pyridinic nitrogen and pyrrolic nitrogen into the graphene layer. Meanwhile, a programmed evolution of the porous structure of the resultant composites, i.e., microporous, hierarchically micro/mesoporous, and mesoporous, was presented systematically. The morphology and specific nanoporous structure of the products are conferred by the metal–organic framework template. The resultant composites with hierarcical meso/miciroporous structures showed highly improved CO2 uptake ability compared with those of commercial P25 TiO2, g-C3N4, and 3D graphene. TiO2 nanoparticles are well dispersed in the porous nitrogen-doped carbon matrix, endowing the obtained compos...

Triton X-100 induced cuboid-like BiVO4 microsphere with high photocatalytic performance

A highly active visible light-induced BiVO4 photocatalyst was prepared by a simple co-precipitation method using ammonia solution as a pH adjustor and Triton X-100 (TX100) as a structure directing agent. The physical properties of the prepared BiVO4 photocatalyst were investigated by several techniques such as X-ray diffractometer (XRD), Brunauer–Emmett–Teller (BET) surface area measurement, scanning electron microscopy (SEM), energy dispersive analysis (EDS), Fourier-transformed infrared spectroscopy (FT-IR), photoluminescence (PL), and UV–Vis diffused reflectance spectroscopy (DRS). XRD results revealed the existence of a monoclinic scheelite structure in both the unmodified and the modified samples. The TX100 played a crucial role to control the cuboid-like shape morphology of BiVO4. The DRS results showed that the as-prepared cuboid BiVO4 possessed enhanced visible light absorption range compared with that of the unmodified BiVO4. The photocatalytic activity was evaluated via indigo carmine (IC) degradation under visible light irradiation. The modified BiVO4 showed higher photocatalytic efficiency than the unmodified BiVO4 and the commercial P25-TiO2 which could be ascribed to the better charge separation efficiency.

Magnetically recoverable TiO2-WO3 photocatalyst to oxidize bisphenol A from model wastewater under simulated solar light.

A novel magnetically recoverable, visible light active TiO2-WO3 composite (Fe3O4@SiO2@TiO2-WO3) was prepared to enable the photocatalyst recovery after the degradation of bisphenol A (BPA) under simulated solar light. For comparison, the photocatalytic activity of other materials such as non-magnetic TiO2-WO3, Fe3O4@SiO2@TiO2, TiO2, and the commercial TiO2 P25 was also evaluated under the studied experimental conditions. The structure and morphology of the synthesized materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and electron dispersion spectroscopy (EDS). Moreover, Brunauer-Emmett-Teller (BET) surface area and magnetic properties of the samples were determined. The Fe3O4@SiO2@TiO2-WO3 and TiO2-WO3 led to a BPA degradation of 17.50 and 27.92%, respectively, after 2h of the simulated solar light irradiation. Even though their activity was lower than that of P25, which degraded completely BPA after 1h, our catalysts were magnetically separable for their further reuse in the treatment. Furthermore, the influence of the water matrix in the photocatalytic activity of the samples was studied in municipal wastewater. Finally, the identification of reaction intermediates was performed and a possible BPA degradation pathway was proposed to provide a better understanding of the degradation process. Graphical abstract ᅟ.

The effect of silver nanoparticles/graphene-coupled TiO2 beads photocatalyst on the photoconversion efficiency of photoelectrochemical hydrogen production

In this work, a novel configuration of the photoelectrochemical hydrogen production device is demonstrated. It is based on TiO2 beads as the primary photoanode material with the addition of a heterostructure of silver nanoparticles/graphene. The heterostructure not only caters to a great improvement in light harvesting efficiency (LHE) but also enhances the charge collection efficiency. For LHE, the optimized cell based on TiO2 beads/Ag/graphene shows a 47% gain as compared to the cell having a photoanode of commercial P25 TiO2 powders. For the charge collection efficiency, there is a pronounced improvement of an impressive value of 856%. The reason for the improvement in light absorption is attributed to either the light scattering of TiO2 beads or the surface plasmonic resonance on the Ag nanoparticles/graphene. The photoconversion efficiency (PCE) of the resulting cells is also presented and discussed. The PCE of the TiO2 beads/Ag/graphene cell is approximately 2.5 times than that of pure P25 cell.

Photocatalytic Degradation of Phenolic Compounds in Presence Electrogenearated O3 and or H2O2

A Graphene oxide (GO) was prepared using modified Hummer`s method starting from graphite. GO was impregnated on commercial nanoparticles P25 TiO2 (GOTi) or WO3. After that, reduced GOTi or GOWO3 was obtained by hydrothermal reduction. The photocatalysis behavior of as-prepared catalysts were tested towards the phenolic compounds degradation and compared against commercial P25 TiO2 in presence and absence of in-situ electrochemically generated ozone. The SiO2/Ti300nm/Pt100nm/TiOx100nm/SnOx500nm electrode was used to produce ozone electrochemically. Table 1 showed that the photocatalytic degradation rate constant of phenol on RGOTi under Xe illumination in presence of H2O2 and electrochemically generated ozone is the better than TiO2. Table 1: Rate constant data in min-1 of phenol (20 mg L-1) on Ti and RGOTi under 150 Xe illuminations in absence and absence of 70 µL H2O2 and Ozone Xe Xe + H2O2 Xe + O3 Xe + H2O2 + O3 Ti RGOTi Ti RGOTi Ti RGOTi Ti RGOTi 0.0214 0.0226 0.0296 0.032 0.0257 0.0262 0.0375 0.0615

Immobilized TiO2 nanoparticles produced by flame spray for photocatalytic water remediation

Anatase/rutile mixed-phase titanium dioxide (TiO2) photocatalysts in the form of nanostructured powders with different primary particle size, specific surface area, and rutile content were produced from the gas-phase by flame spray pyrolysis (FSP) starting from an organic solution containing titanium (IV) isopropoxide as Ti precursor. Flame spray-produced TiO2 powders were characterized by means of X-ray diffraction, Raman spectroscopy, and BET measurements. As-prepared powders were mainly composed of anatase crystallites with size ranging from 7 to 15 nm according to the synthesis conditions. TiO2 powders were embedded in a multilayered fluoropolymeric matrix to immobilize the nanoparticles into freestanding photocatalytic membranes. The photocatalytic activity of the TiO2-embedded membranes toward the abatement of hydrosoluble organic pollutants was evaluated employing the photodegradation of rhodamine B in aqueous solution as test reaction. The photoabatement rate of best performing membranes significantly overcomes that of membranes produced by the same method and incorporating commercial P25-TiO2.

Study of the E. coli elimination from urban wastewater over photocatalysts based on metallized TiO2

In this study, a series of photocatalysts based on TiO2 was tested in the elimination of Escherichia coli (E. coli) from urban wastewater. Firstly, TiO2 obtained by sol-gel method was modified by sulfation, and then gold or platinum nanoparticles were photodeposited on sulfated titania surface. Platinized samples were also prepared with different Pt content of 0.5 and 2wt.%. The samples thus obtained were extensively characterized and it was found that sulfation considerably increases the SBET value of TiO2 and promotes the anatase phase formation; it was also found that 0.5wt.% Pt-TiO2 sample presents the lowest noble metal particle size and the best particle dispersion. All the photocatalysts synthesized have shown bactericidal effect and the results obtained by using bare and metalized TiO2 were considerably better than the results obtained with the commercial TiO2 P25 Evonic. Different light intensities were also evaluated in the photocatalytic tests and it was found that 120W/m2 leads to obtain the highest E. coli elimination from wastewater samples; however no total elimination of E. coli or other species of bacteria was achieved even after 5h of photocatalytic treatment without catalyst. Total elimination of the E. coli was achieved after 3h of photocatalytic reaction by using 120W/m2 of light intensity and 2wt.% Pt-TiO2 as photocatalyst; no bacterial regrowth was observed even after 72h.

Oxygen-deficient Zn2Ti3O8−x nanoparticle as anode material for lithium ion batteries

Zn2Ti3O8−x nanoparticles containing oxygen vacancies were prepared with nanotube titanium acid as the titanium source via molten salt method in air atmosphere in order to improve the electronic conductivity of zinc titanate as the anode of lithium-ion batteries. The effect of oxygen vacancies on the structure and electrochemical properties of the as-prepared Zn2Ti3O8−x nanoparticles as the electrode material of lithium ion batteries was studied with Zn2Ti3O8 prepared from commercial P25-TiO2 as a control. Findings indicate that the as-prepared Zn2Ti3O8−x nanoparticles contain a large amount of oxygen vacancies and Ti3+ in the bulk phase, and they exhibit markedly improved electrochemical properties than Zn2Ti3O8 without oxygen vacancy. Namely, the electrode made of the as-prepared Zn2Ti3O8−x nanoparticles exhibits a high capacity of 246, 222, 181, 156, 127 and 88 mA h/g at a current density of 0.1, 0.2, 0.5, 1, 2 and 5 A/g, and it does not undergo obvious capacity fading after 450 cycle of charge/discharge at a current density of 0.1 A/g, showing great potential as the anode material for high-rate and long-life lithium-ion batteries. This is because the oxygen vacancies and Ti3+ in the bulk phase can significantly enhance the electronic conductivity of the electrode material.

Preparation and freezing behavior of TiO2 nanoparticle suspensions

Freeze casting can prepare porous materials with high porosity, directional pores, and complex shapes. However, due to the difficulty of obtaining nanoparticle suspensions with high solids loading, the formed bodies usually experience large shrinkage and have low strength in the process of vacuum drying and heat treatment. To address these problems, we studied the zeta potential, agglomeration, and rheological property of commercial P25 TiO2 nanoparticle suspensions by adjusting the pH value and the sodium hexametaphosphate additive amount of the suspensions. Suspensions with up to 30vol% solids loading were prepared. The water freezing process and the directional arrangement of the pores are influenced by freezing temperature gradient, and porous TiO2 samples with directional laminar structures are obtained.

Enhanced photocatalytic activity of degrading short chain chlorinated paraffins over reduced graphene oxide/CoFe2O4/Ag nanocomposite

Short chain chlorinated paraffins have recently attracted great attention because of their environmental persistence and biological toxicity as an important organic pollutant. In this work, reduced graphene oxide/CoFe2O4/Ag (RGO/CoFe2O4/Ag) nanocomposite was prepared and employed for photocatalytic degradation of short chain chlorinated paraffins. The process of photocatalytic degradation of short chain chlorinated paraffins over RGO/CoFe2O4/Ag under visible light (λ>400nm) was investigated by in situ Fourier transform infrared spectroscopy and the related mechanisms were proposed. An apparent degradation ratio of 91.9% over RGO/CoFe2O4/Ag could be obtained under visible light illumination of 12h, while only about 21.7% was obtained with commercial P25 TiO2 under the same experimental conditions, which demonstrates that the RGO/CoFe2O4/Ag nanocomposite is a potential candidate for effective photocatalytic removal of short chain chlorinated paraffins.

Photocatalytic activity of TiO2, ZnO and Nb2O5 applied to degradation of textile wastewater

Abstract In this work, photocatalysis was employed in the treatment of textile effluent from industrial laundry jeans using the catalysts TiO2 P25 (commercial), TiO2, ZnO and Nb2O5, under artificial UV irradiation. The parameters investigated were: pH of the solution and catalyst concentration. The photocatalytic activity was evaluated by means of kinetic efficiency (rate constant and half life time), thermodynamic (absorbance reduction at 228, 254, 284, 310, 350, 500 and 660 nm), COD reduction, mineralization in terms of the formation of inorganic ions (NH4+, NO3−, NO2−, SO42− and Cl−) and toxicity reduction (bioassays using Artemia salina). The photocatalytic degradation of textile effluent at pH 3.0 and catalyst concentration of 0.250 g L−1 showed the best results, being found 95.91%; 87.35%; 86.95% and 59.18% of absorbance reduction at 660 nm (λmax) after 300 min of artificial irradiation with TiO2 P25, Nb2O5, TiO2 and ZnO, respectively. TiO2 and Nb2O5 were responsible for the reduction of approximately 70 and 66% of COD and the photocatalytic activity of TiO2 was very close to TiO2 P25. In this sense, Nb2O5 becomes a promising alternative to replace the commercial TiO2 P25. Bioassays with Artemia salina confirmed the efficacy of the treatment, indicating that after photodegradation there was an expressive decrease in effluent toxicity for up to 3 times.

Diclofenac removal by simulated solar assisted photocatalysis using TiO2-based zeolite catalyst; mechanisms, pathways and environmental aspects

The study explores the potential of immobilized TiO2-based zeolite composite photocatalyst (TiO2-FeZ) made of commercial AEROXIDE TiO2 P25 and iron-exchanged zeolite of ZSM5 type (FeZ), for solar assisted treatment of diclofenac (DCF), pharmaceutical included in the “watch list” during last prioritization in water legislation by EU.In this study the efficiency of applied photocatalytic treatment, solar/TiO2-FeZ/H2O2, of DCF water solution was evaluated on basis of DCF removal and conversion kinetics, as well as the changes of common parameters for assessing water quality. Hence, the changes in the removal and mineralization of overall organic content, biodegradability, toxicity to Vibrio fischeri, dechlorination of DCF and its formed by-products, were monitored during the treatment. The obtained data were correlated with the evolution of DCF by-products, identified and monitored during the treatment by HPLC/MSMS analysis. In order to estimate the influence of water matrix, all experiments were performed in the presence of chloride or sulphate as counter ions. The obtained data revealed that degradation mechanism of DCF by applied treatment process using immobilized TiO2-FeZ includes the adsorption onto photocatalyst surface and consequent degradation. The contribution of homogeneous Fenton reaction due to leached iron ions was found to be negligible. The adsorption and degradation pathway of DCF were influenced by the type of counter ions, which was reflected in the observed changes of water quality parameters.

Synthesis of spindle-shaped AgI/TiO2 nanoparticles with enhanced photocatalytic performance

A novel synthetic route has been developed to prepare silver iodide (AgI) loaded spindle-shaped TiO2 nanoparticles (NPs). The morphology and crystallinity characterization revealed that small AgI NPs, with an average diameter of 15nm were dispersed on the surface and interior of nanoporous anatase TiO2 support. High-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) surface area, Raman and X-ray photoelectron spectroscopy (XPS) were used to identify the nanoporous structure of TiO2 and the existence of AgI NPs. Diffuse reflectance spectra (DRS) showed that AgI/TiO2 composite exhibited a remarkable enhancement of visible light absorption, which is ascribed to the addition of AgI. For illustrating the superior property of this hybrid as photocatalyst, the degradation experiments were carried out for processing rhodamine B (RhB) solution under visible light irradiation and it was found that the photocatalytic activity was dramatically improved for AgI/TiO2 compared with nanoporous TiO2 and commercial P25 TiO2. The enhanced photocatalytic properties could be attributed to the large surface area of porous TiO2, good stability of AgI particles, and the effective charge separation due to the synergetic effect between AgI and TiO2 that can facilitate the separation of electron-hole pairs. Our novel composite based on nanoporous spindle-shaped TiO2 represents a promising new pathway for the design of high-performance photocatalysts for environmental applications.

Solar-driven photocatalytic treatment of diclofenac using immobilized TiO2-based zeolite composites.

The study is aimed at evaluating the potential of immobilized TiO2-based zeolite composite for solar-driven photocatalytic water treatment. In that purpose, TiO2-iron-exchanged zeolite (FeZ) composite was prepared using commercial Aeroxide TiO2 P25 and iron-exchanged zeolite of ZSM5 type, FeZ. The activity of TiO2-FeZ, immobilized on glass support, was evaluated under solar irradiation for removal of diclofenac (DCF) in water. TiO2-FeZ immobilized in a form of thin film was characterized for its morphology, structure, and composition using scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX). Diffuse reflectance spectroscopy (DRS) was used to determine potential changes in band gaps of prepared TiO2-FeZ in comparison to pure TiO2. The influence of pH, concentration of hydrogen peroxide, FeZ wt% within the composite, and photocatalyst dosage on DCF removal and conversion efficiency by solar/TiO2-FeZ/H2O2 process was investigated. TiO2-FeZ demonstrated higher photocatalytic activity than pure TiO2 under solar irradiation in acidic conditions and presence of H2O2.

Synergetic effects of lanthanum, nitrogen and phosphorus tri-doping on visible-light photoactivity of TiO2 fabricated by microwave-hydrothermal process

Effects of La, N, and P doping on the structural, electronic and optical properties of TiO2 synthesized from TiCl4 hydrolysis via a microwave-hydrothermal process were investigated by X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption isotherm, X-ray photoelectron spectroscopy, electron paramagnetic resonance, UV-vis absorbance spectroscopy, photoelectrochemical measurements, and photoluminescence spectroscopy. The results showed that the presence of La in the tri-doped TiO2 played a predominant role in inhibiting the recombination of the photogenerated electrons and holes. The existence of the substitutional N, interstitial N, and oxygen vacancies in TiO2 lattices led to the band gap narrowing. It was P-doping rather than La or N doping that played a key role in inhibiting both anatase-to-rutile phase transformation and crystal growth, in stabilizing the mesoporous textural properties, and in increasing the content of surface bridging hydroxyl. Moreover, the tri-doping significantly enhanced the surface Ti4+–O2––Ti4+–O−• species. All above-mentioned factors cooperated to result in the enhanced photoactivity of the tri-doped TiO2. As a result, it exhibited the highest photoactivity towards the degradation of 4-chlorophenol (4-CP) under visible-light irradiation among all samples, which was much superior to commercial P25 TiO2.

Geometry-enhanced ultra-long TiO2 nanobelts in an all-vanadium photoelectrochemical cell for efficient storage of solar energy

Direct capture and storage of abundant but intermittent solar energy using storage devices are of paramount importance in development of sustainable energy, yet the daunting challenge is to enhance the conversion efficiency. Here we report an all-vanadium (all-V) photoelectrochemical storage cell (PESC) using geometry-enhanced ultra-long TiO2 nanobelts (TNBs) to significantly improve solar energy storage efficiency. The TNBs are synthesized using a simple stirring-assisted hydrothermal method, where the stirring speed is adopted to effectively tune the geometry and structure of the TNBs. We demonstrate that highly efficient solar energy storage is realized by ultra-quick oxidization and reduction reaction of vanadium ions with, respectively, holes and electrons produced on the TNB surface. The obtained incident photon-to-current efficiency (IPCE) is ~22% at 350nm without any external bias, double that of commercial P25 TiO2 (~11%). The observed improved efficiency results from enhanced photoactivity and charge separation in the semiconductor, and mass transport of vanadium ions in the photoelectrode.

Fabrication of magnetic Fe3O4/C/TiO2 composites with nanotube structure and enhanced photocatalytic activity

Magnetic hybrid photocatalysts containing TiO2 nanotube as outer catalytic layer and Fe3O4 as the core, with an amorphous carbon intermediate layer, were synthesised, characterised and applied to degradation of phenol under Xenon lamp irradiation. For the composite, Fe3O4/C microspheres were surrounded by anatase TiO2 nanotubes with a diameter of ∼8–10 nm. Photocatalytic performance of the Fe3O4/C/TiO2 nanotube (FCT-NT) composites was also evaluated and showed enhanced activity superior to commercial P25 and homemade TiO2 particles. The outstanding photocatalytic performance of FCT-NT sample could be attributed to its improved surface area and enhanced capability of optical absorption. Notably, the novel photocatalyst showed excellent magnetic behaviour and could be efficiently separated and collected from the wastewater.

CO2 photoreduction with water vapor by Ti-embedded MgAl layered double hydroxides

Photocatalytic reduction of CO2 into value-added fuels (e.g., CO and CH4) is a promising approach of storing solar energy and mitigating greenhouse gas emissions simultaneously. In this work, a novel material of crystallized titanium-embedded magnesium-aluminum layered double hydroxides (MgAlTi-LDHs) is developed and tested for CO2 photoreduction with water. Three different materials synthesis methods were explored: (1) coprecipitation, (2) coprecipitation+hydrothermal, and (3) coprecipitation+calcination+reconstruction. The coprecipitation method alone only produced amorphous TiOx species in the LDHs, while the latter two methods resulted in the formation of crystalline anatase TiO2 when appropriate treatment temperatures were applied but the specific surface area was decreased due to the thermal treatment. Compared with commercial TiO2-P25 nanoparticles, all MgAlTi-LDHs prepared in this work demonstrated two to four times higher catalytic activities in CO2 photoreduction to CO. Among the MgAlTi-LDHs, the CO2 photoreduction activity was affected by both the crystallinity of TiO2 and the specific surface area. Consequently, the material hydrothermally treated at 150–200°C demonstrated the highest CO production due to a well-balanced TiO2 crystallinity and specific surface area. Findings in this work contribute to the development of efficient photocatalysts for CO2 reduction and advance the understanding of the catalyst property-activity relationships.

Insights into the removal of terbuthylazine from aqueous solution by several treatment methods

This paper reports the removal of the s-triazine herbicide terbuthylazine (TBA) from aqueous solution by various treatment methods including adsorption onto activated carbon (AC) and multiwalled carbon nanotubes (MWCNT), UV254 photolysis, UV254/H2O2, single ozonation, O3/H2O2, catalytic ozonation (AC, MWCNT and TiO2 as catalysts) and some solar driven processes such as TiO2 photocatalytic oxidation and photo-ozonation. TBA was adsorbed onto AC and MWCNT following a pseudo-second order kinetics and Freundlich isotherm. Rapid small scale column tests showed that TBA could be removed from solution by adsorption onto AC better than atrazine. The UV254/H2O2 treatment resulted in excellent removal of TBA primarily due to the oxidation capability of hydroxyl radicals (kHO = 3.3109 M−1 s−1) generated from H2O2 photolysis. As the H2O2 initial concentration was increased from 5 to 50 mg L−1 the HO exposure per UV fluence (RHO,UV) increased, making the process more efficient. Single ozonation also allowed complete removal of the herbicide though the process was slow (kO3=15.4 M−1 s−1 at pH > 4). The ozonation process could be greatly accelerated by the enhanced generation of HO through O3/H2O2 and O3/AC processes, which also led to more efficient processes in terms of ozone utilization. Commercial TiO2 (TiO2-P25) and lab prepared anatase TiO2 (TiO2-cat) nanoparticles catalyzed the removal of TBA by solar photocatalysis. In contrast, a lab prepared MWCNT-TiO2 composite was not useful as catalyst in solar photo-oxidation processes because of the HO scavenging nature of the MWCNT used as support. A mechanism for TBA degradation by O3 and HO has been suggested after TBA degradation intermediates identification.