Photocatalytic Activity Of TiO2 Research Articles

Solar Light Elimination of Bacteria, Yeast and Organic Pollutants by Effective Photocatalysts Based on Ag/Cr-TiO2 and Pd/Cr-TiO2.

This study focused on searching for more effective nanomaterials for environmental remediation and health protection; thus, coliform bacteria, yeast and the organic food dye sunset yellow were selected as target pollutants to be eliminated under solar light by Ag/Cr-TiO2 and Pd/Cr-TiO2. Firstly, Cr3+ was in situ incorporated into the anatase crystalline lattice by the sol-gel method; then, Ag or Pd nanoparticles were deposited on Cr-TiO2 by chemical photoreduction. The scientific challenge addressed by the development of these composites was to analyse the recovery of Cr, to be employed in photocatalyst formulation and the enhancement of the TiO2 photocatalytic activity by addition of other noble metals. By extensive characterization, it was found that after TiO2 doping with chromium, the parameters of the crystal lattice slightly increased, due to the incorporation of Cr ions into the lattice. The TiO2 band gap decreased after Cr addition, but an increase in the optical absorptions towards the visible region after noble metals deposition was also observed, which was dependent of the Ag or Pd loading. Generally, it was observed that the noble metals type is a factor that strongly influenced the effectiveness of the photocatalysts concerning each substrate studied. Thus, by using Ag(0.1%)/Cr-TiO2, the complete elimination of E. coli from samples of water coming from a highly polluted river was achieved. Pd(0.5%)/Cr-TiO2 showed the highest efficiency in the elimination of S. cerevisiae from a lab prepared strain. On the other hand, the Pd(0.1%)/Cr-TiO2 sample shows the highest dye degradation rate, achieving 92% of TOC removal after 180 min.

Interstitial N-Doped TiO2 for Photocatalytic Methylene Blue Degradation under Visible Light Irradiation

Photocatalysis is a promising method for methylene blue (MB) degradation due to its effectiveness and environmental compatibility. Among the photocatalysts, titanium dioxide (TiO2) has been widely used for MB degradation due to its exceptional photocatalytic activity. However, the wide bandgap limits the degradation efficiency of TiO2 under visible light. Here, an interstitial nitrogen-doped TiO2 (5%NT/TiO2) used thiourea as the N source was fabricated for visible light-derived MB degradation. The 5%NT/TiO2 exhibited an extended absorption range of visible light. Moreover, photoelectrochemical measurements showed an improvement in the photocurrent response and charge transfer behavior on N/TiO2. Thus, 5%NT/TiO2 had enhanced photocatalytic activity compared with pristine TiO2 and substitutive N-doped TiO2 (5%NAB/TiO2). The accelerated photocatalytic MB degradation process on N/TiO2 could be mainly attributed to the interstitial N doping, which caused the appearance of new energy states and extended optical properties. Through comparing the impact of interstitial and substitutive in TiO2 activity, our work proposes a suitable form of element doping to enhance the optical properties and photocatalytic activity of TiO2 and even other semiconductors, providing guidance for future work.

Study Effect of rGO Addition on Photocatalytic Activity of TiO2 in Reducing Carbon Dioxide Using Electrochemical Method

Abstract Increasing the carbon dioxide (CO2) concentration every year can cause various environmental problems. One of the technologies to reduce CO2 is carbon capture. The semiconductor of TiO2 is widely used as a photocatalyst to reduce CO2. However, TiO2 has limitations in absorbing light in the visible region because it has a large band gap value. Besides, TiO2 has a fast recombination of electron-hole pairs so it can reduce photocatalytic activity. An addition of rGO is expected to cover the shortcomings of TiO2 because rGO has good conductivity and a small band gap. We synthesized rGO-TiO2 photocatalyst and measured its activity in capturing and converting CO2 using an electrochemical method. By using voltage difference as an electron driver in reacting with CO2 we observe the reaction between electrons and CO2. The measurements were carried out under irradiated and unirradiated conditions. The CV measurements show that the rGO-TiO2 electrode with 60% rGO content has reduction and oxidation peaks. Based on the electrochemical half-reaction table, the reduction peaks in unirradiated conditions indicate the conversion of CO2 to CH4 and (COOH)2, while under irradiated the reduction peak indicates the formation of HCOO− and CH2CH2. The results show that by using the rGO-TiO2 composite as an electrode not only reduces CO2 but also converts the CO2 into hydrocarbon.

Photocatalytic activity of TiO2:TiN nanocomposite films prepared by DC reactive sputtering technique for air purification

This study concerns the production of advanced materials and a novel technique for enhancing photocatalytic efficiency, focusing specifically on the purification of air contaminated with methane gas. Titanium dioxide:Titanium nitride (TiO2/TiN) nanocomposite films were prepared by dc reactive magnetron sputtering of highly-pure titanium sheet in presence of oxygen and nitrogen as reactive gases with optimized mixing ratios to produce the composite structures. The structural, morphological, and optical characteristics of the prepared nanocomposites were determined and analyzed. The primary goal of this study was to enhance the photocatalytic activity of such nanocomposites against methane gas pollution. It is observed that increasing the nitrogen content in the TiO2:TiN nanocomposite structure led to notable improvements in photocatalytic efficiency. Specifically, when these nanocomposites were subjected to a UV light, they exhibited enhanced photocatalytic activity in the removal of methane gas from the surrounding air, which demonstrates a direct correlation with increased nitrogen (N) content in the composite structure. These nanocomposites are reasonably promising in removing harmful gases and pollutants present in indoor and outdoor environments. This exploration not only sheds light on the remarkable potential of TiO2:TiN nanocomposites for air purification but also highlights the importance of innovative techniques, such as dc reactive magnetron sputtering in the field of materials science and engineering as well as in environmental remediation.

Structural analysis of green synthesized Fe doped TiO2 nanocomposites and their application to wastewater remediation

Pure and Fe-doped TiO2 nanoparticles were synthesized through green synthesis route for wastewater remediation application. Pure and Fe-doped TiO2 nanoparticles were further characterised through various techniques like XRD, SEM, and EDS. The XRD patterns indicate pure anatase phase with space group I 41/a m d through the Rietveld refinement. The average crystalline size of Fe-doped TiO2 nanoparticles decreases with the increment in the concentration of doping. The high agglomeration of pure and Fe-doped TiO2 nanoparticles is observed through SEM. EDS analysis conforms the presence of Fe, Ti, and O elements in the nanoparticles. The photo catalytic activities of pure and Fe-doped TiO2 under ultraviolet (UV) light with different concentration were investigated. The dissolved oxygen in the water increases with the increment of Fe doping and time of exposer of UV light.

Green Preparation of Stachys Eudenia-Derived Carbon Quantum Dots and Their Photocatalytic Applications

In this present work, the composites were obtained from carbon quantum dots and TiOf via green synthesis and the photoactivities of these composite structures were investigated under ultraviolet light. Carbon quantum dot was obtained from Stachys euadenia which is an endemic plant found only in southern Türkiye. Carbon quantum dot-TiO2 nanocomposites were fabricated via facile hydrothermal approach which is an easy and effectual method to obtaining of environmentally friendly, low cost and well crystallized nanoparticles. The structural and morphological characteristics of these nanocomposites were investigated by X-ray diffraction, tunneling electron microscopy and scanning electron microscopy. Also, optical analyses of carbon quantum dots were carried out by absorbance and fluorescence spectroscopy. Photocatalytic activity of TiO2 and carbon quantum dot-TiO2 nanocomposites were investigated under ultraviolet light illumination with the decomposition of methylene blue dye. Carbon quantum dot-TiO2 nanocomposites show a better activity than TiO2.

Coupling interface, electronic and conjugation effects in C-COFs/TiO2 composite structure toward boosting photocatalytic hydrogen evolution

Hydrogen energy, recognized as a pivotal clean energy source, has attracted considerable attention in the realm of photocatalytic hydrogen production. Nevertheless, inorganic materials were difficult to regulate band gaps, resulting in limited photogenerated carrier rates. Additionally, organic materials frequently suffer from insufficient stability and a propensity for electron recombination. Therefore, fully utilizing the interface effect will become an important breakthrough for novel and efficient catalysts. Herein, hydroxylate covalent organic frameworks (H-COFs) were formed by direct synthesis method, in addition, titanium dioxide (TiO2) was used as an inorganic substrate, and TiO2 was transformed titanium acid under weakly acidic conditions, meanwhile, chloride covalent organic frameworks (C-COFs) growth on TiO2 surface by interface effect when H-COFs were formed into C-COFs under titanium acid. The structure characteristics, photoelectric performance, bandgap width and stability of C-COFs/TiO2 were confirmed through characterization analysis. C-COFs/TiO2 exhibit strong stability, conjugation effects, electron deficiency effects, and catalytic efficiency. Hydrogen production rate up to 5598 μmol g−1 h−1 by C-COFs/TiO2 as photocatalyst. C-COFs/TiO2 lead to 161 times improvement in photocatalytic activity for TiO2 and 3.6 times improvement in photocatalytic activity for H-COFs. The catalytic reaction mechanism was obtained by utilizing experimental data and DFT calculation. This synergistic integration of organic inorganic combined catalyst provides a foundational framework for advancing research into novel photocatalysts.

Effect of Mg and Cu co-doping on nanostructured TiO2 photocatalytic activity

Effect of Mg and Cu co-doping on nanostructured TiO2 photocatalytic activity

Remediation of methylene blue water solution with iodine doped TiO2 nanoparticles and their regeneration: For reuse and check phytotoxicity level of treated water

Titanium dioxide (TiO2) is an essential metal-oxide semiconductor with unique features, such as low cost, photostability, nontoxicity, and abundance used as a photocatalyst. However, TiO2's photocatalytic activity is limited because it exclusively absorbs incoming light in the ultraviolet (UV) range. In present work, Iodine-doped TiO2 (IDT) photocatalysts were prepared employing solution-combustion process in various mol % of iodine (I), i.e., Ti1-xIxO2 (x = 0.00–0.05). Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and UV–Vis Diffuse Reflectance spectroscopic (DRS) were used to characterise the synthesised IDT. DRS indicated that iodine doping increased the absorbance range while diminishing its bandgap energy. As the I doping concentration in TiO2 increased, there was a constant shift in absorbance towards the visible light area. The XRD demonstrated that the prepared photocatalysts were solely with the anatase phase of TiO2. The FTIR identified the functional groups in the prepared photocatalysts and numerous Ti–O lattice stretching and bending vibrational bands. Photocatalytic degradation of methylene blue (MB) dye was tested in a UV photochemical reactor. The 3 % IDT photocatalyst has the highest photodegradation efficiency amid all the prepared pristine and IDT photocatalysts. Regarding dye photodegradation, the synthesised TiO2 photocatalyst doped with 3 % Iodine outperformed the commercially available Aeroxide P-25 photocatalyst. Furthermore, the nanoparticles demonstrated excellent reusability in regeneration trials. A study on the germination of "Vigna Radiata" was done to determine phytotoxicity as part of the investigation into the potential use of photocatalytically treated water in irrigation. The phytotoxicity evaluation results show that the treated water has potential for use in irrigation.

Investigating for Photocatalytic Activity of Hybrid TiO2/Reduced Graphene Oxide and Application in Reducing VOCs

In this study, rGO/TiO2 hybrid nanostructures (rGO : reduced Graphene Oxide) have been successfully fabricated for the purpose of application in the treatment of volatile organic compound (VOCs) that harmful for the environment through the method of directly measuring the change in concentration of decomposed VOCs in real time under UV-excited conditions using a home-made measuring system. the results showed that hybrids TiO2 : rGONFs (reduced Graphene Oxide nano flake) samples with the weight ratio between two kind of material are 99%:1% and 98%:2% which reduced VOCs faster than 2 time intrinsic TiO2. The phenomenon of 2D materials involved in the hybrids lead to the fact that the photocatalytic activity of TiO2 had been significantly improved, this can be explained as follows: When heterogeneous hybrid was formed, because of the difference in energy levels of conduction band between two materials was negligible, heterojunction barrier is not too high this made the photogenerated electrons from TiO2 easily move through rGONFs under UV stimulation. This thing has significantly reduced the recombination of the generated carrier in TiO2 during irradiation, which lead to an increase in the lifetime of the carrier and make photocatalytic reaction of the assembly become more effective. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Structural Properties and Photocatalytic Activity of TiO2/Au Nanocomposites Synthesized with Glucose

AbstractA one‐pot synthesis of plasmonic gold‐modified TiO2 nanocomposites is reported by using glucose reduction of HAuCl4 in presence of titanium tetraisopropoxide. The resulting nanocomposites are characterized by thermal‐gravimetric analyses, X‐ray diffraction combined with X‐ray fluorescence and photoelectron spectroscopies. A binary system of β‐TiO2 and anatase phases is obtained for low Au content while only anatase form is favored when the initial Au rate rises. This investigation also suggests the inclusion of gold in the TiO2 structure. Although the optical bandgap of the different nanocomposites remains around 3 eV, the increase of Au content induces a shift of both valence and conduction edge bands to lower energy levels. The photocatalytic activity of TiO2/Au nanocomposites is assessed through the decolorization of different cationic and anionic dyes as model compounds. Regarding rhodamine and methylene blue dyes, the sample TiO2 modified with 3.5 wt% of Au presents the best performance. The relation between the structure of the nanocomposites and their capacity to degrade pollutants is discussed.

Bimetallic CuCo nanoparticles optimized hydrogen generation active centers thereby significantly enhancing TiO2 photocatalytic activity

Bimetallic nanostructures are currently a hot pot material among many hydrogen generation co-catalysts. In this study, CuCo bimetallic nanostructures were formed by introducing Co into Cu as the co-catalyst for TiO2. Characterization results from XRD, XPS, and TEM indicated the successful preparation of the high-crystallinity, impurity-free CuCo/TiO2 photocatalyst, with CuCo bimetallic nanoparticles uniformly dispersed on TiO2. After the addition of Co, density functional theory (DFT) calculations showed that the free energy of H adsorption on the Cu site was optimized from 0.27 eV to −0.56 eV, which was beneficial for hydrogen production from TiO2. Electrochemical characterization, photoluminescence (PL) spectroscopy, infrared (IR) thermography, and finite difference in time domain (FDTD) results showed that the bimetallic CuCo acted as the co-catalyst, which increased the temperature of the reaction system, facilitated the separation of light-generated electron-hole pairs, and accelerated the charge transfer, thus promoting the photocatalytic hydrogen generation. The findings of the photocatalytic performance demonstrate that the photocatalyst exhibits the H2 generation rate of 1933.8 μmol/g/h, which is approximately 9 times greater than that of pure TiO2 (213.4 μmol/g/h), when the bimetallic CuCo is loaded in the molar ratio of 5:5 and at the loading amount of 2 wt%. Additionally, the photocatalyst demonstrated excellent catalytic stability, reaching 87.1% of the initial after 16 h of cycling tests. It is foreseen that further study and optimization of various metal couplings may enable the larger widespread application of bimetals as co-catalysts for hydrogen generation.

Efficient photocatalytic hydrogen generation by CeCO3OH/TiO2 composites

Due to its low photogenerated carrier separation efficiency and wide band gap, the photocatalytic activity of TiO2 is not ideal. In this work, CeCO3OH/TiO2 composites were successfully prepared by a simple hydrothermal method. A series of characterisations shows that the CeCO3OH/TiO2 composites improves the photogenerated carrier separation efficiency, narrowes the band gap width and increases the visible light absorption capacity compared with the monomer, enhancing the photocatalytic hydrogen evolution performance. Under visible light irradiation, 20% CeCO3OH/TiO2 exhibites the highest photocatalytic hydrogen production performance of 2386.16 μmol g−1 h−1, which is 18.7 times higher than that of pure TiO2 and 25.8 times higher than that of pure CeCO3OH. It provides ideas for the development of more efficient photocatalytic materials and technologies.

Crystal surfaces cooperate with F ion migration to improve the photocatalytic performance of Z-type Ag-Ag2S/F-TiO2 composites

The TiO2 has the problems of low utilization of visible light and high photogenerated carrier recombination rate. The photocatalytic activity of TiO2 can be significantly improved by introducing F ion and narrow band gap material Ag2S. When F ions are present on the {001} surface of TiO2, surface F ions drive positively charged holes across the {001} surface, creating a synergistic effect that promotes the separation of electron-hole pairs. During the sample composite process, a certain amount of Ag will be precipitated to form an all-solid Z-type heterojunction structure of Ag2S, Ag and F-TiO2, which can improve the electron-hole separation efficiency. The results of XPS characterization confirmed the migration of F ion and the precipitation of Ag. The Ag2S/F-TiO2 composite sample was referred to as AT for short, and the corresponding ratio was 1:10,1:20,1:30,1:40, the optimal sample AT 1:20 degraded 95.6% tetracycline hydrochloride within 2 hours. This work simultaneously realizes TiO2 self-modification (synergistic effect of F ion migration and TiO2{001} crystal surface) and composite modification (formation of all-solid Z-type heterojunction), a new idea of studying TiO2 self-modified cooperative heterostructures is proposed, and the good application potential of AT nanocomposites in photocatalytic water treatment technology is demonstrated.

Microwave-assisted Synthesis and Photocatalytic Activities of TiO2Nanoparticles

Microwave-assisted Synthesis and Photocatalytic Activities of TiO₂Nanoparticles

Gas-Phase Fabrication and Photocatalytic Activity of TiO2 and TiO2-CuO Nanoparticulate Thin Films.

CuO-loaded TiO2 nanomaterials have applications in pollutant degradation via photocatalysis. However, the existing methods of fabricating these nanomaterials involve liquid-phase processes, which require several steps and typically generate liquid waste. In this study, TiO2 and TiO2-CuO nanoparticulate thin films were successfully fabricated through a one-step gas-phase approach involving a combination of plasma-enhanced chemical vapor deposition and physical vapor deposition. The resulting films consisted of small, spherical TiO2 nanoparticles with observable CuO on the TiO2 surface. Upon annealing in air, the TiO2 nanoparticles were crystallized, and CuO was completely oxidized. The photocatalytic activity of TiO2-CuO/H2O2, when introduced into the rhodamine 6G degradation system, was substantially enhanced under both ultraviolet and visible light irradiation. Moreover, this study highlights the influence of pH on the photocatalytic activity; TiO2-CuO/H2O2 exhibited the highest photocatalytic activity at pH 13, with a reaction rate constant of 0.99 h-1 cm-2 after 180 min of visible light irradiation. These findings could facilitate the development of nanoparticulate thin films for enhanced pollutant degradation in wastewater treatment.

Preparation and photocatalytic activity of TiO2 photonic crystals modified by bimetallic Ag–Pt nanostructures

To better understand the interactions between TiO2 photonic crystals (PC) and metallic nanostructures (MNSs), we studied the slow photon effects in PC and electron trapping taking place in MNSs on the photocatalytic decomposition of rhodamine B.

Harnessing the synergistic potential of TiO2-CuSe composites for enhanced photocatalytic and antibacterial activities.

With growing environmental concerns, the removal of toxic industrial dyes from wastewater has become a critical global issue. In this study, TiO2-CuSe composites were synthesized using a cost-effective and simple chemical method to determine the optimal concentration of CuSe for the efficient degradation of methylene blue (MB) under visible light. The TiO2 samples exhibited a mix of rutile and anatase phases, while CuSe formed in a hexagonal phase. Both TiO2 and CuSe were observed to have agglomerated particles with indistinct boundaries. The optical bandgap shifted towards the visible region from 3.25 eV (pure TiO2) to 2.91 eV with increasing the amount of CuSe in the composites. The photocatalytic activity of TiO2, CuSe, and TiO2-CuSe composites was evaluated by monitoring MB degradation, with the composites outperforming the individual components under visible light. Notably, the TiO2-20% CuSe composite (AK-4) demonstrated superior efficiency, removing 98% of MB in just 70 minutes. The photocatalysts also exhibited enhanced antibacterial properties, effectively reducing E. coli colonies from 1.71 × 1012 CFU mL-1 (pure TiO2) to 1 × 1010 CFU mL-1 for the AK-4 composite. This study suggests that visible light-activated TiO2-CuSe composites could be effective for both water purification and bacterial infection control.

The effects of water, substrate, and intermediate adsorption on the photocatalytic decomposition of air pollutants over nano-TiO2 photocatalysts.

The photocatalytic performance of nano-TiO2 photocatalysts in air pollutant degradation greatly depends on the adsorption of water, substrates, and intermediates. Especially under excessive humidity, substrate concentration, and intermediate concentration, the competitive adsorption of water, substrates, and intermediates can seriously inhibit the photocatalytic performance. In the past few years, extensive studies have been performed to investigate the influence of humidity, substrate concentration, and intermediates on the photocatalytic performance of TiO2, and significant advances have been made in the area. However, to the best of our knowledge, there is no review focusing on the effects of water, substrate, and intermediate adsorption to date. A comprehensive understanding of their mechanisms is key to overcoming the limited application of nano-TiO2 photocatalysts in the photocatalytic decomposition of air pollutants. In this review, the progress in experimental and theoretical fields, including a recent combination of photocatalytic experiments and adsorption and photocatalytic simulations by density functional theory (DFT), to explore the impact of adsorption of various reaction components on nano-TiO2 photocatalysts is comprehensively summarized. Additionally, the mechanism and broad perspective of the impact of their adsorption on the photocatalytic activity of TiO2 in air treatment are also critically discussed. Finally, several solutions are proposed to resolve the current problems related to environmental factors. In general, this review contributes a comprehensive perspective of water, substrate, and intermediate adsorption toward boosting the photocatalytic application of TiO2 nanomaterials.

Controlling TiO2 photocatalytic behaviour via perhydropolysilazane-derived SiO2 ultrathin shell.

This study addresses the inherent photocatalytic activity of pure titanium dioxide (TiO2), which limits its application as an industrial pigment. To mitigate this issue, a core-shell structure was employed, where TiO2 cores were encapsulated within SiO2 shells. Perhydropolysilazane (PHPS) was introduced as a superior SiO2 precursor over tetraethylorthosilicate (TEOS), resulting in thinner and more uniform SiO2 shells. Utilizing TiO2's photocatalytic properties, hydroxyl radicals facilitated the conversion of PHPS into SiO2via native Si-H bonds, eliminating the need for additional reducing agents. The formation of PHPS-derived TiO2@SiO2 core-shell nanoparticles demonstrated inherent self-limiting behaviour, ensuring uniform shell thickness regardless of PHPS concentration, simplifying the process for large-scale industrial applications compared to TEOS, which demands precise parameter control. Photocatalytic evaluations highlighted significant passivation of TiO2 photocatalytic activity by PHPS-derived TiO2@SiO2 core-shell particles and TiO2/SiO2 thin films. Specifically, TiO2@PHPS nanoparticles achieved 89-96% passivation compared to 30% with TiO2@TEOS, while TiO2/PHPS films degraded only 12% of Eosin B versus 80% with TiO2 films. Moreover, both PHPS-derived nanoparticles and films maintained TiO2's inherent high whiteness and high-refractive-index optical properties, underscoring their suitability for applications in white paint production, cosmetics, and high-refractive-index coatings.