Commercial TiO2 Research Articles

Tuning oxygen vacancies via photoinduced defect engineering in plasma pre-treated TiO2 for efficient solar-light-driven oxidation of trace methane

Photocatalysis employing cost-effective commercial titanium dioxide offers an ideal solution for eliminating trace methane emissions from livestock and poultry farming. However, significant challenges such as the rapid recombination of photogenerated carriers, a limited light absorption spectrum, and weak adsorption capabilities considerably hinder the effectiveness of titanium dioxide in the photocatalytic treatment of trace methane. This study proposes a novel approach to activate plasma pre-treated N-doped commercial anatase TiO2 into dual-defect TiO2 (N-doped TiO2-x) featuring stable and controllable oxygen vacancies (OV) through photoinduced defect engineering. Characterizations of the photocatalyst confirm the successful creation of surface defects, further evaluated through solar-light-driven CH4 (ppm level) removal investigations. The yield of this N-doped TiO2-x in converting CH4 is 4.84 μmol h−1, 44 times greater than that of unmodified TiO2, significantly outperforming previous studies. UV–Vis diffuse reflection spectra, and photoluminescence indicate that the modified commercial anatase TiO2 possesses a narrower band gap, efficient photogenerated carrier separation, and enhanced charge transfer. Furthermore, density functional theory (DFT) calculations demonstrate that the synergistic effects of oxygen vacancies and N doping enhance the adsorption and activation of both O2 and CH4 in the rate-determining step of the reaction. This innovative strategy holds considerable promise for modifying various materials for more efficient photocatalytic applications.

Comparative study on solar photocatalytic degradation of naproxen using nitrogen doped ZnO and nitrogen doped TiO2: Kinetics and Intermediates analysis

Solar photocatalytic degradation of Naproxen (NPX) in a synthetic wastewater was evaluated with synthesized nitrogen doped TiO2 and nitrogen doped ZnO and compared with commercial TiO2 and ZnO. The effect of operating parameters such as initial NPX concentration (1–3.5 mg/l), catalyst dosage (0.15–0.5 g/l), pH (4.5–9.0), and contact time (0–330 min) on NPX degradation was investigated in detail. The batch study showed 93 %, 90 %, 71 % and 85 % NPX degradation on average solar intensities (1200–1420 W/m2) with ZnO, N-ZnO, TiO2 and N-TiO2 respectively for optimised conditions (initial NPX concentration-2 mg/l, (ZnO & N-ZnO)−0.35 g/l, (TiO2 & N-TiO2)−0.15 g/l, pH-4.5 and contact time-180 min). Kinetic investigations on photocatalytic degradation of NPX were carried out for the initial 1 h duration and it complied with pseudo-first order kinetics with the four catalysts, whereas ZnO showed the highest rate constant (k = 0.0331/minutes). Depth of reactor solution had no significant impact on NPX degradation. Continuous process was conducted along with TOC analysis for HRT of 60 min, which showed mineralization efficiencies of 36 %, 26 % and 16 % for N-TiO2, ZnO and N-ZnO respectively. The 90th percentile solar light intensity corresponding to the maximum NPX degradation was found to be 1100 W/m2. Quantum yield were calculated for NPX degradation with and without catalyst, it showed 35 % for ZnO and 3.5 % for photolysis. The intermediates and mineralization efficiency was analysed using LC-MS and TOC analyzer respectively. This study concluded that N-TiO2 had better NPX removal and mineralization efficiency along with formation of simpler compounds and organic acids as the end products.

Investigation of the influencing factors and optimization study for the removal of levofloxacin in water using commercial TiO2 photocatalyst under UV-LED irradiation

Abstract Photocatalysis holds significant promise for effectively eliminating toxins, hard-to-biodegrade, and persistent organic pollutants in water. In this study, we used commercial TiO2 as a photocatalyst under UVA-LED irradiation to remove levofloxacin from water. In the photocatalytic tests, levofloxacin removal efficiency in water reached 68.21% after 120 minutes at pH 4 with an antibiotic/catalyst concentration ratio of 1:20. ANOVA revealed that the model achieved significance, as indicated by a p-value of 0.009. LEVO degradation under UVA-LED is three times higher than that under natural light. Optimal conditions for LEVO removal include pH 4, LEVO/TiO2 ratio of 1:20, and UVA-LED irradiation. The regression model predicts LEVO removal with high accuracy (R2 = 0.8469). This study highlights the use of photocatalysis with TiO2 as a promising approach for pharmaceutical pollutant removal, emphasizing the need for further research in sustainable water treatment technologies.

NiO/vermiculite composites prepared for photocatalytic degradation of methanol-water solution and hydrogen generation

A novel eco-friendly NiO/Vm clay based photocatalysts were synthesized from two vermiculites (Vm1 and Vm2) and nickel(II) nitrate hexahydrate (Ni(NO3)2·6H2O salt precursor by the chemical precipitation without and with the sodium hydroxide (NaOH) or ammonium hydroxide (NH4OH, 28% NH3 in H2O) as precipitation agents (Synthesis A) in comparison with the solid-state thermal decomposition (Synthesis B) at 600 °C. Structural properties of all specimens were characterized by X-ray fluorescence, scanning electron microscopy, X-ray diffraction, infrared (IR) and Raman spectroscopy. The photocatalytic performance of NiO/Vm composites was evaluated under UV radiation (λ = 254 nm) for decomposition of methanol-water to hydrogen over 4-h and the stable yield of hydrogen over the 24-h periods. The NaOH and NH4OH affected the NiO crystallite size and therefore the photocatalytic activity during 4 h. Different 2:1 layer charge of Vm1 (0.82 e−) and Vm2 (0.40 e−) and the specific surface area of Vm1 (about 43 m2/g) and Vm2 (about 34 m2/g) supported H2 yield of 628.2 μmol/gcat. and 596.8 μmol/gcat., close to 657.0 μmol/gcat. produced in the presence of commercial photocatalyst TiO2 Evonik P25. Crystalline NiO precipitated and anchored in NiO/Vm composites contained smaller crystallites than those in free NiO. Vermiculite silica surface supports coverage of NiO by hydrogen bonding to Si-OH groups influencing the geometry of the NiO crystal structure (disorder NiO(X)). The heterojunction with Si-O-Ni bonding, at which electrons transfer from Vm to NiO cause enriching electron density in NiO and favoring its photocatalytic activity. Photocatalytic hydrogen generation from methanol–water mixture at the presence of all specimens indicated the main product H2 and minimum by-products CH4 and CO. The stable hydrogen production for 24 h was confirmed only in the presence NiO/Vm1–24 while maintaining the NiO(X) in small crystallites. The thermal solid-state procedure provided the gradual dehydration of vermiculites and Ni(NO3)2·6H2O to the same amount and crystallinity of NiO in NiO/Vm1 and NiO/Vm2 composites. The results of this work confirm that vermiculites mixed layer structures with different negative layer charge play a dominant role as semiconductors for anchored NiO. The photocatalytic activity of NiO/vermiculite composites can be harnessed to treat wastewater containing organic contaminants.

In-situ synthesis of SnO/CuSnO3 nanostructures to catalyze azo dye degradation, CO2 reduction, and amines direct alkylation reactions under visible light

The extensive use of photocatalysis to address environmental concerns, energy production, and organic transformations has attracted attention in recent decades. The SnO/CSO photocatalytic materials were fabricated through a single-step hydrothermal method and comprehensively characterized using a muti-technique approach to demonstrate the physicochemical, morphological, and electronic features. According to the photocatalytic experiments, the SnO/CSO could remove >96 % of acid blue 92 (AB92) azo dye under optimum conditions, with rate constant 2.37 × 10−2 min−1. Furthermore, the photocatalyst significantly outperformed commercial TiO2 (P25), in reducing CO2 to CO and CH4 with a production rate of 10.8 and 1.18 μmol g−1 h−1, respectively, under visible light irradiation. The successful direct alkylation of amines to valuable organic compounds within 10 min of the reaction time with a conversion selectivity of >90 % was another capability of the materials, making it a good candidate for pharmaceutical synthesis purposes.

In situ synthesis of mesoporous TiO2 doped with bismuth single atoms for tunable photocatalytic degradation of formaldehyde

Modification of a photocatalyst with single-atom metals to maximize atomic utilization and suppress charge carrier recombination is an effective strategy to dramatically improve the photocatalytic performance. Here we report the first successful development of the mesoporous TiO2 doped with Bi single-atom catalyst. The resulting single-atom photocatalyst possesses a narrower band gap structure, enhanced conductivity and outstanding photocatalytic activity driven by full spectrum light, which is 20 times higher than that of the commercial TiO2. As evidenced by photo-electrochemical characterizations and density functional theory (DFT) calculations, the Bi single atoms are confirmed to exhibit strong capacity to trap photo-generated electrons and probably act as the active sites in photocatalytic formaldehyde (CH2O) degradation. Additionally, reactive oxygen species (O2−, OH, and 1O2) were identified as key ingredients in promoting CH2O decomposition to CO2 and H2O. This innovative approach provides a promising method for fabricating mesoporous single-atom catalysts with tunable catalytic property.

Theoretical prediction of SbP3 monolayer as anode material for lithium-ion battery applications

Herein, we have carried out a systematic investigation using first-principles calculations on the properties of Li atoms adsorbed on SbP3 monolayer in order to evaluate its pertinence as an anode material for (LIBs). The diffusion barrier value of Li atom on the SbP3 monolayer is around 0.44 eV, which is quite low. The value of OCV of the SbP3 monolayer is moderate and comparable to the commercial anode materials TiO2. Also, the theoretical storage capacity of Li-ion in SbP3 monolayer is 499.36 mAhg−1. Therefore, these findings render the SbP3 monolayer a potential candidate as an efficient anode material for LIBs.

Fluorogenic Reaction Probes Defect Sites on Titanium Dioxide Nanoparticles

AbstractTitanium dioxide nanoparticles (TiO2 NPs) have traditionally been utilized as industrial catalysts, finding widespread application in various chemical processes due to their exceptional stability and minimal toxicity. However, quantitatively assessing the reactive sites on TiO2 NPs remains a challenge. In this study, we employed a fluorogenic reaction to probe the apparent reactivity of TiO2 NPs. By manipulating the number of defect sites through control of hydrolysis speed and annealing temperature, we determined that the Ti(III) content is positively correlated with the reactivity of TiO2 NPs. Additionally, these Ti(III) sites could be introduced by reducing commercial TiO2 NPs using NaBH4. Our findings suggest that fluorogenic oxidation of Amplex Red is an effective method for probing defect site densities on TiO2 NPs. Utilizing single‐molecule fluorescence imaging, we demonstrated the ability to map defect site density within TiO2 nanowires. Achieving sub‐nanoparticle spatial resolution, we observed significant intraparticle and interparticle variations in the defect site distribution, leading to substantial reactivity heterogeneity.

Nitrogen assisted one-step hydrothermal synthesis of commercial TiO2 for methylene blue degradation under visible light irradiation

Strategies to make more efficient use of sunlight have been developed. Different synthesis parameters have been studied for the production of multiphase photocatalysts. In this work, for the first time, the performance of a one-step nitrogen-assisted hydrothermal synthesis of TiO2 using TiO2–P25 as a Ti precursor was investigated for the degradation of methylene blue under visible light irradiation. Urea and ethylenediamine (EDA) were evaluated as nitrogen sources. The produced photocatalysts had a rod-like nanostructure with the formation of mesopores. The resulting phase was a heterojunction of anatase, TiO2(B), and rutile, which enhanced charge separation. The presence of nitrogen during the hydrothermal reaction altered the morphology of TiO2, impacting the crystallite size. The U photocatalyst (urea source) achieved the best result for visible light with prior adsorption, degrading around 11 % of methylene blue in 5 h. This shows that it is possible to obtain a photocatalyst with superior performance to TiO2–P25 under both ultraviolet and visible light. This study presents an efficient strategy for improving the optical response of TiO2 by using nitrogen during a hydrothermal reaction, which has potential for industrial applications.

Enhanced acetaminophen photodegradation under UV using anatase–rutile TiO2 phase heterojunction – Z-scheme mechanism and factors affecting efficiency

In this work, the commercial Hombikat UV-100 anatase (AH) was calcined at 1000 °C for 4 h to obtain a rutile phase grown on anatase (AR), proven by X-ray diffraction pattern. The dry powder of AH and AR were physically mixed to form AH + AR samples in different ratios. Although the characterization of AR revealed that it had microstructure bigger than AH, lower surface area, lower water-molecule absorption, higher surface states and lower charge separation, all mixed AH + AR samples, which had physically-induced tuning in phase heterojunction, outperformed the commercial TiO2 P25 in acetaminophen (ATM) photodegradation efficiency. This could be due to effective charge separation and more active sites involved in AH + AR samples as seen in the depicted Z-scheme mechanism based on their band-edge positions obtained from Mott-Schottky analysis, scavenger tests and ATM photodegradation efficiency. In addition, this work also showed that band-edge positions, band-gap energy and heterojunction were correlated in determining the ATM photodegradation efficiency.

An S-scheme artificial photosynthetic system with H-TiO2/g-C3N4 heterojunction coupled with MXene boosts solar H2 evolution

Solar hydrogen production via water splitting is pivotal for solar energy harnessing, addressing key challenges in energy and environmental sustainability. However, two critical issues persist with single-component photocatalysts: suboptimal carrier transport and inadequate light absorption. While heterojunction-based artificial photosynthetic systems like Z-scheme photocatalysts have been explored, their charge recombination and light harvesting efficiency are still unsatisfactory. S-scheme heterojunctions have gained attention in photocatalysis, owing to their pronounced built-in electric field and superior redox capabilities. In this study, we introduce a MXene-based S-scheme H-TiO2/g-C3N4/Ti3C2 heterojunction (TCMX), synthesized through electrostatic self-assembly. The as-prepared TCMX exhibited an excellent photocatalytic hydrogen evolution rate of 53.67 mmol g−1 h−1 surpassing the performance of commercial Rutile TiO2, H-TiO2, g-C3N4, and HTCN. The effectiveness of TCMX is largely due to the built-in electric field in the S-scheme heterojunction and the cocatalytic activity of MXene promoting rapid separation of photogenerated charges and resulting in well-separated electron and hole enriched sites. This study offers a new approach to enhance photocatalytic hydrogen evolution efficiency and paves the way for the future design of S-scheme heterojunctions.

Boosting Supercapacitor Efficiency with Amorphous Biomass-Derived C@TiO2 Composites.

Carbon materials are readily available and are essential in energy storage. One of the routes used to enhance their surface area and activity is the decoration of carbons with semiconductors, such as amorphous TiO2, for application in energy storage devices.

Boosting the sonodynamic performance of CoBiMn-layered double hydroxide nanoparticles via tumor microenvironment regulation for ultrasound imaging-guided sonodynamic therapy

Sonodynamic therapy (SDT), a promising strategy for cancer treatment with the ability for deep tissue penetration, has received widespread attention in recent years. Sonosensitizers with intrinsic characteristics for tumor-specific curative effects, tumor microenvironment (TME) regulation and tumor diagnosis are in high demand. Herein, amorphous CoBiMn-layered double hydroxide (a-CoBiMn-LDH) nanoparticles are presented as multifunctional sonosensitizers to trigger reactive oxygen species (ROS) generation for ultrasound (US) imaging-guided SDT. Hydrothermal-synthesized CoBiMn-LDH nanoparticles are etched via a simple acid treatment to obtain a-CoBiMn-LDH nanoparticles with abundant defects. The a-CoBiMn-LDH nanoparticles give greater ROS generation upon US irradiation, reaching levels ~ 3.3 times and ~ 8.2 times those of the crystalline CoBiMn-LDH nanoparticles and commercial TiO2 sonosensitizer, respectively. This excellent US-triggered ROS generation performance can be attributed to the defect-induced narrow band gap and promoted electrons and holes (e−/h+) separation. More importantly, the presence of Mn4+ enables the a-CoBiMn-LDH nanoparticles to regulate the TME by decomposing H2O2 into O2 for hypoxia relief and US imaging, and consuming glutathione (GSH) for protection against ROS clearance. Biological mechanism analysis shows that a-CoBiMn-LDH nanoparticles modified with polyethylene glycol can serve as a multifunctional sonosensitizer to effectively kill cancer cells in vitro and eliminate tumors in vivo under US irradiation by activating p53, apoptosis, and oxidative phosphorylation-related signaling pathways.

Boosting Li-ion storage kinetics via constructing layered TiO2 anode

Due to the typical intercalation-deintercalation mechanism, TiO2 holds great promise as a sustainable anode for next-generation lithium-ion batteries (LIBs). However, commercial TiO2 (C–TiO2) is granular and shows slow ionic conductivity, which greatly hinders its development due to sluggish kinetics, leading to low reversible capacity and inferior rate capability. In this study, a two-dimensional layered TiO2 (L-TiO2) anode is prepared via a one-step calcination process, which can effectively shorten the lithium ions diffusion path and improve its lithium ions conductivity. We elucidated the enhanced electrochemical performance of L-TiO2 as an anode in LIBs through pseudocapacitive acceleration of lithium ions intercalation and deintercalation using various characterization techniques, including different scan rate cyclic voltammetry tests, in situ electrochemical impedance spectroscopy, in situ Raman spectroscopy, and in situ X-ray diffraction. In comparison to C–TiO2 material, L-TiO2 material showcases remarkable electrochemical performance, achieving a capacity of 166 mAh/g after 100 cycles at 0.1 C. Additionally, the lithium-ion diffusion coefficient calculated for the L-TiO2 is two orders of magnitude greater, underscoring its potential as a negative electrode material for LIBs.

Interaction of phenolic compounds with functionalized TiO2: Enhanced catechol adsorption and cooperative phenol adsorption

A commercial TiO2 sample functionalized with 3-aminopropyltrimethoxysilane (APTMS) and 4-carboxyphenylboronic acid (CPBA), has been previously proposed as a suitable photocatalyst to perform selective photocatalytic degradation of pollutants in aqueous streams, while avoiding the oxidation of valuable catechol simultaneously present in the reacting medium. In the present study, we highlight the adsorption mechanisms underlying the higher affinity of catechol, compared to phenol, with the surface of modified TiO2, quantitatively justifying the photocatalytic selective degradation results previously obtained. Moreover, a cooperative adsorption mechanism of phenol onto the TiO2 sample modified with APTMS has been for the first time observed. The resulting sigmoidal adsorption isotherms, satisfactorily fitted with the Hill model, could be attributed to the enhanced surface hydrophobicity and, more importantly, to alterations of the folding of APTMS molecules on the TiO2 surface occurring upon increasing the concentration of the phenolic compounds.Photocatalytic tests revealed that the existence of boronate groups on the surface of TiO2 hinders the photocatalytic degradation of catechol and facilitates a swifter oxidation of phenol. These findings confirm the potential for selective photocatalytic degradation, in line with modern conceptions of innovative and environmentally sustainable wastewater treatments.

Photocatalytic Degradation of Naproxen: Intermediates and Total Reaction Mechanism.

Photochemical and photocatalytic oxidation of naproxen (NPX) with UV-A light and commercial TiO2 under constant flow of oxygen have been investigated. Adsorption experiments indicated that 90% of the solute remained in the solution. Combined chemical analysis of samples on the photochemical degradation indicated that NPX in an aqueous solution (20 ppm) is efficiently transformed into other species but only 18% of the reactant is mineralized into CO2 and water after three hours of reaction. Performing the photocatalytic oxidation in the presence of TiO2, more than 80% of the organic compounds are mineralized by reactive oxidation species (ROS) within four hours of reaction. Analysis of reaction mixtures by a combination of analytical techniques indicated that naproxen is transformed into several aromatic naphthalene derivatives. These latter compounds are eventually transformed into polyhydroxylated aromatic compounds that are strongly adsorbed onto the TiO2 surface and are quickly oxidized into low-molecular-weight acids by an electron transfer mechanism. Based on this and previous studies on NPX photocatalytic oxidation, a unified and complete degradation mechanism is presented.

Facile Synthesis to Porous TiO2 Nanostructures at Low Temperature for Efficient Visible-Light Degradation of Tetracycline.

In this study, nanoporous TiO2 with hierarchical micro/nanostructures was synthesized on a large scale by a facile one-step solvothermal method at a low temperature. A series of characterizations was performed and carried out on the as-prepared photocatalysts, which were applied to the degradation of the antibiotic tetracycline (TC). The results demonstrated that nanoporous TiO2 obtained at a solvothermal temperature of 100 °C had a spherical morphology with high crystallinity and a relatively large specific surface area, composed of a large number of nanospheres. The nanoporous TiO2 with hierarchical micro/nanostructures exhibited excellent photocatalytic degradation activity for TC under simulated sunlight. The degradation rate was close to 100% after 30 min of UV light irradiation, and reached 79% only after 60 min of visible light irradiation, which was much better than the photodegradation performance of commercial TiO2 (only 29%). Moreover, the possible intermediates formed during the photocatalytic degradation of TC were explored by the density functional theory calculations and HPLC-MS spectra. Furthermore, two possible degradation routes were proposed, which provided experimental and theoretical support for the photocatalytic degradation of TC. In this study, we provide a new approach for the hierarchical micro/nanostructure of nanoporous TiO2, which can be applied in industrial manufacturing fields.

Performance evaluation of Bi/Zn‐impregnated commercial TiO2 nanoparticles for photocatalytic nitrobenzene decomposition

AbstractBACKGROUNDCommercial TiO2 nanoparticles were subjected to modification through Bi and Zn metal doping. The resulting catalysts were comprehensively characterized, and their performance was then reviewed for removal of model pollutant nitrobenzene in water.RESULTSAmidst the synthesized catalysts, the co‐doping of Bi/Zn (0.25:0.75 wt%) demonstrated the best photocatalytic degradation activity, achieving 95% degradation within 90 min of reaction time, with 2.99 × 10−2 min−1 rate constant value. The involvement of different radicals during the degradation process was elucidated by employing appropriate radical scavengers. Furthermore, the degradation results were investigated applying the first‐order kinetic model, leading to the determination of reaction rate constants and initial rates of the degradation process.CONCLUSIONAn improved photocatalytic activity was observed with metal doping due to the synergistic effect of doped metals with commercial TiO2 and profound charge transfer among them. It was observed that performance was increased with temperature rise in the practical range of application, that is, 5–20 °C. This behavior was due to high rate of movement of charge carriers. Further, involvement and functioning of various radical species such as h+, OH− and O2− in nitrobenzene degradation were successfully established using appropriate radical scavengers. © 2024 Society of Chemical Industry (SCI).

Synthesis of TiO2 nanoparticles using red spinach leaf extract (Amaranthus Tricolor L.) for photocatalytic of methylene blue degradation

ABSTRACT Textile industry waste such as methylene blue can pose a serious threat to health and ecosystems. One solution to overcome this problem is to utilize photocatalytic technology using TiO2 semiconductors. This research aims to make green synthetic TiO2 nanoparticles (NPs) using red spinach (Amaranthus Tricolor L.) leaf extract and used for photodegradation of methylene blue. Extraction of red spinach leaves showed that 30 min and a temperature of 95°C showed the highest phenolic content. In this research, several phenolic compounds were also identified in red spinach extract. For TiO2 NPs, the X-ray diffraction results show that TiO2 has a pure anatase phase. Electron microscope results show that TiO2 has the shape of agglomerated spherical clusters. The particle size distribution shows that TiO2 has an average size range of 77–90 nm. The methylene blue photodegradation showed that TiO2 had an efficiency of 90.36% for 180 min, higher than commercial TiO2 Evonic. This result can be attributed to the small particle size and broadband spectra so that photocatalysis is more effective.

CQDs-based nanocomposites for the 5-(hydroxymethyl)furfural photooxidation

Carbon quantum dots (CQDs) are widely investigated as an enhancing photocatalytic component of various nanocomposites. With this aim hetero-structures containing CQDs associated to metal oxides were prepared following a hydrothermal approach in which commercial ZnO and TiO2 P-25 Degussa were used as carriers. CQDs were synthesized in advance by a low-temperature hydrothermal (LHT) treatment of useless humins wastes produced by the glucose dehydration in an acidic medium. Their photocatalytic behavior was investigated in the HMF selective oxidation. The obtained results revealed electronic interactions between CQDs and MOx (i.e., ZnO and TiO2) which have as effect the enhancement of the charge separation and diminution of the charge recombination. The influence of CQDs and buffer addition on the products distribution was evaluated. The highest photocatalytic efficiency corresponded to the TiO2/CQD180-12 heterostructure: under UV irradiation FDCA was produced in 360 min with a selectivity of 35.5% for a conversion of 93.4% of HMF.