Titania Photocatalysts Research Articles

Influence of Ag-concentration on TiO2-supported catalysts for photocatalytic degradation of microplastics PA66 in marine

Over the past few years, microplastics pollution in marine environments has become a global concern. In this study, a series of silver-doped titanium dioxide (Ag/TiO2) photocatalysts were prepared by the photo-assisted deposition method as an alternative approach for the rapid removal of microplastics particles from aqueous media, specifically polyamide 66 (PA66), the major type of microplastics in marine. The physicochemical and optical properties of photocatalysts were analyzed by Scanning Electron Microscopy (SEM), X-ray Energy Dispersion Spectrum (EDS), X-ray Diffraction (XRD), Photoluminescence Spectroscopy (PL), and Ultraviolet-visible Diffuse Reflectance Spectroscopy (UV–vis DRS). The characterization results of the photocatalysts indicated that the appropriate loading of Ag on TiO2 significantly enhanced the optical properties of the catalysts. Specifically, 1.5 % Ag/TiO2 (AT1.5) exhibited the best light absorption performance and the lowest bandgap value, effectively suppressing the recombination of photogenerated electron-hole pairs. Furthermore, a series of photocatalytic degradation experiments confirmed that AT1.5 exhibited optimal performance in degrading PA66. Under UVA irradiation for 4 hours, the photocatalytic degradation of PA66 by AT1.5 resulted in a mass loss of 58.9 %. The degradation rate of PA66 increased with the amount of catalyst. When the mass ratio of AT1.5 to PA66 was 3:1, PA66 experienced 100 % mass loss after 4 hours of UVA exposure. Finally, through qualitative analysis, this study proposed the possible pathways and mechanisms for the photocatalytic degradation of PA66 by Ag/TiO2. Despite the challenges posed by microplastics pollution to marine ecosystems, this research provides a rapid and effective degradation method.

Choose Your Dopant─Ultrananotitania Directing Photocatalytic Electron Destination.

Anatase titania photocatalysts are the subject of thousands of papers annually. Since the photoefficiency is low, doping TiO2 photocatalysts with various elements is a widely employed technique to enhance performance. However, studies involving different catalyst sizes, morphologies, or dopants often yield varied or even contradictory conclusions. Herein, we report a versatile platform based on ultranano, <2 nm, particles, that minimizes defects, produces uniform morphology, and enables systematic investigation of dopant control of product formation. Charge-carrier destination is determined by the redox couple in the oxide matrix; a couple that is measured by diffuse reflectance spectroscopy. Versatility is demonstrated via doping with all fourth-period transition elements (except Sc). For oxidation reactions, two distinct reaction pathways are identified; the balance between the pathways is regulated by the reduction potential of the dopant in the matrix. The prospect for directing charge transfer significantly expands potential applications for titania.

Amorphous titanium dioxide with synergistic effect of nitrogen doping and oxygen vacancies by photoexcited sol-gel preparation for enhanced photodegradation of tetracycline

In this paper, a novel N-doped amorphous titanium dioxide (N20AT-hν) photocatalyst was prepared by the sol–gel route in which the sol added with salicylaldehyde hydrazone undergoes gel after photoexcitation. Based on a systematic exploration of as-prepared catalysts, it is known that N20AT-hν sample has a particle size of 50–60 nm, a specific surface area of 294.699 m2 g−1, and which is doped with nitrogen elements and forms abundant oxygen vacancies (OVs). The photocatalytic degradation rate of N20AT-hν for 20 mg L−1 tetracycline solution reached 92.23 % after 60 min, and the rate exhibited a slight decrease of 8.68 % after five cycles. Reactive species trapping experiments and electron spin resonance techniques indicate that superoxide radicals and holes are instrumental in photocatalytic degradation. Possible mechanism of forming the active species through OVs mediated traps and electron transfer pathways has been proposed. Furthermore, the predictive evaluations suggest that the degradation of tetracycline solutions by N20AT-hν sample results in less harmful decomposition product.Benefiting from the environmental friendliness of preparation method and the superiority of elemental doping, N20AT-hν material with synergistic effects has great potential for environmental applications.

The Influence of Dye Stimulation on Etched TiO2/ENR/PVC for Elevating Photocatalytic Activity and Photoelectrochemical Properties

AbstractThe application of polymer blends such as epoxidized natural rubber (ENR) and polyvinyl chloride (PVC) in immobilizing titanium dioxide (TiO2) photocatalysts has enticed many researchers. However, the presence of polymer limits the photocatalytic activity by hindering the surface‐active site of the immobilized TiO2. In this study, photoetching treatment with the presence of dye was successfully applied on the immobilized TiO2/ENR/PVC (TEP) to enhance the photocatalytic and photoelectrochemical (PEC) performance. Priorly, a dip coating technique was used to immobilize the TEP. The dye photoetching treatment was performed for several cycles to determine the reusability of the immobilized TEP. Furthermore, it demonstrated a significant enhancement of photocatalytic activity at which the best performance with the pseudo‐first‐order rate constant, k value of 0.1483 min−1 at the 13th cycle. The nonetched, photoetched TEP without dye and dye photoetched TEP have been characterized by scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), X‐ray diffraction (XRD), thermal gravimetric analysis (TGA), and PEC. It is believed that the dye photoetched TEP will produce a good photocatalytic activity and PEC performance due to the presence of dye stimulant during the photoetching treatment.

New strategy for photocatalytic antibacterial concrete: in situ fluoride-modified negatively charged interfaces

Sponge cities embody a green and sustainable urban development approach, with permeable concrete structures crucial for collecting natural precipitation. Over time, however, microbes from rainwater can adhere to and proliferate on these concrete surfaces, potentially accelerating material corrosion and posing health risks. To combat this, our study introduces a straightforward and effective antimicrobial surface strategy. We applied a fluorine-modified titanium dioxide photocatalyst coating to permeable foam concrete surfaces. The fluorine regulation enhances electron transfer to the titanium dioxide, creating a negatively charged interface. This charge repels negatively charged microbes electrostatically and curbs microbial growth through the oxidative properties of photogenerated radicals. Tested under 50 mW/cm2 of simulated sunlight, the bacterial count at the negatively charged interface was just 35.7% of that at a positively charged interface, with the coating retaining about 90% of its antibacterial efficacy even in highly contaminated conditions. This research offers a cost-effective and efficient method for developing antimicrobial coatings for building materials.

Estimation and Optimization of the Radiant Field in Flat Plate Heterogeneous Photoreactors with the P1-approximation of the Radiative Transfer Equation (RTE).

In this work, the P1-approximation of the radiative transfer equation (RTE) was used for the description and optimization of the radiant field in a flat plate photoreactor under solar radiation with three commercial brands of titanium dioxide photocatalysts. The boundary layer of photon absorption (δ_abs), the average volumetric rate of photon absorption (VRPA), and a new apparent optical thickness (ζ_app1) were used as design parameters for optimization. A simple mathematical expression for the calculation of δ_abs also called the best reactor thickness was formulated. For the three catalysts, varying the reactor height (L), it was found a decrease in the local volumetric rate of photon absorption (LVRPA) from the top side until the bottom of the reactor for any value of the catalyst loading (Ccat). It was also observed that when Ccat increases the VRPA increases exponentially until a fixed value where it remains almost constant. With L= 1 cm, the optimum Ccat (Ccatop) was 0.2 g/l in 0.85 cm of thickness, 0.3 g/l in 0.82 cm of thickness, and 0.4 g/l in 0.89 cm of thickness for the photocatalysts Degussa P-25, Aldrich, and Hombitak respectively. The optimum apparent optical thickness (ζ_(app1,op)) was 4.03, 4.62, and 3.7 for the photocatalysts Degussa P-25, Aldrich, and Hombitak respectively. These results are in good agreement with the literature. Results found in this work give predictions on radiation absorption in flat plate photocatalytic reactors with different heights.

Photocatalytic Hydrogen Production Using TiO2-based Catalysts: A Review.

Photocatalytic water splitting is an environmentally friendly hydrogen production method that uses abundant renewable resources such as water and sunlight. While Titanium dioxide (TiO2) photocatalyst exhibits excellent properties, its high band gap limits absorption to ultraviolet (UV) irradiation, resulting in low photo conversion efficiency. This review explores various modification techniques aimed at enhancing the efficiency of TiO2 under visible light irradiation. Factors influencing the photocatalytic water splitting reaction, such as catalyst structure, morphology, band gap, sacrificial reagents, light intensity, temperature, and potential of Hydrogen (pH)are examined. This review also summarizes different catalyst synthesis methods, and types of photocatalytic reactors, and provides insights into quantum yield. Finally, the review addresses the challenges and future outlook of photocatalytic water splitting.

Optimizing Titanium-dioxide Photocatalysts for Efficient Degradation of Methylene Blue: The Influence of Hydrothermal Reaction Time

Optimizing Titanium-dioxide Photocatalysts for Efficient Degradation of Methylene Blue: The Influence of Hydrothermal Reaction Time

Photocatalytic inactivation of bio-aerosol using surface-active iron-titanium thin film immobilized on sustainable cementitious composite

The current research introduces a novel in-situ and visibly-active heterojunction formation concept to fabricate a sustainable antimicrobial cementitious material. To achieve this, cement mortar incorporating iron-rich industrial waste products (FWPs) was outer-coated with photocatalyst Titanium dioxide (TiO2). The proposed technique forms a novel surface-active Fe2TiO5 heterojunction oxide layer, which considerably improves the photocatalytic and antimicrobial properties of TiO2 under the visible spectrum of light. Primarily, the study evaluated the structural suitability of the developed iron-rich cementitious material in terms of its durability and strength properties. The findings indicate that the iron-rich cementitious material performed better than conventional cementitious material. After this, the effectiveness and novelty of the proposed research were examined, such that the Fe2TiO5 photocomposite was subjected to detailed microscopic investigations such as XRD, HRTEM, UV-DRS, XPS, FESEM, etc. The results verified the production of the inherent Fe2TiO5 heterojunction through the presence of Fe in the photocatalyst TiO2 lattice via the formation of ITO complex bonds. It also revealed that the Fe2TiO5 photocomposite functions effectively under visible light with an energy band gap of 2.57 eV. The antimicrobial activity of the Fe2TiO5 photocomposite was also assessed by neutralizing E.coli bioaerosols. The disinfection results indicated that the Fe2TiO5 photocomposite exhibits excellent antimicrobial properties. It achieved 69.33 % and 95–98 % antibacterial efficiency under dark and visible light, respectively. Thus, the study establishes a Fe2TiO5 photocomposite material that combines photocatalytic and antimicrobial properties, making it suitable for use as a sustainable building material. Also, it contributes to environmental sustainability by promoting a circular economy and green building practices.

Efficient photodegradation of methylene blue dye using cerium-doped titanium dioxide (Ce@TiO2) photocatalyst under visible light irradiation

Water pollution is one of the important threats nowadays, to meet the difficulties several studies are being processed. This work aims to improve water quality by breaking dye components from the waste effluents of textile industries. Methylene blue (MB) widely used textile colorant brings several health issues to all living categories aquatic and terrestrial, including humans. All new syntheses of Cerium-doped Titanium dioxide (Ce@TiO2) nanoparticles have been achieved and proven to be a super-efficient photocatalyst for the photodegradation of MB in wastewater samples. This photocatalyst was prepared using the sol-gel technique without any hazardous chemicals in moderate conditions. The formation of Ce@TiO2 is confirmed by different characterization using XRD, FTIR, SEM-EDS, and HR-TEM analysis. The photocatalytic efficiency of Ce@TiO2 photocatalyst is carried out with varying parameters such as pH, contact time, photocatalyst dose, and MB concentration. Ce@TiO2 is an effective photocatalyst for MB degradation from wastewater at optimized conditions with 92 % removal within 90 min of reaction time. The degradation kinetics follow a pseudo-first-order model, with a rate constant (K) of 0.027min−1, while achieving a remarkable total organic carbon elimination of over 90.0 %. Furthermore, the reusability test showcased the remarkable stability of Ce@TiO2 over four cycles, with only a minor decline (<8 %) observed in MB degradation efficiency.

Photocatalytic β-O-4 bond cleavage in lignin models and native lignin through CdS integration on titanium oxide photocatalyst under visible light irradiation

Converting lignin, a key sustainable biopolymer, into valuable oxygen-containing compounds is a significant challenge. To address such a challenge, photocatalytic self-transfer hydrogenolysis strategy is employed utilizing a CdS(x%)/TiO2 heterojunction photocatalyst, with minimal CdS loading on TiO2. The CdS(3 %)/TiO2 catalyst, under blue light, dehydrogenates HCα–OH groups, transferring hydrogen to Cβ–O bonds, cleaving β-O-4 ether bonds in lignin model compounds yielding over 95 % phenols and acetophenones. It utilizes glyceryl moieties as a hydrogen source, yielding ∼ 24 % of diverse lignin monomer derivatives from teak lignin. Improved charge separation in the CdS(3 %)/TiO2 catalyst is revealed by electrochemical and spectral analyses and exhibits delayed charge carrier recombination. Scavenging studies confirm a type II charge transfer mechanism and support visible-light-driven lignin fragmentation. The present photocatalytic process offers a promising, cost-effective approach for converting lignin into valuable aromatic compounds, advancing renewable biomass-derived chemicals.

Metal organic framework-assisted copper-modified titania (Cu/TiO2) with abundant exposed active sites and highly accessible pore channels for an enhanced photo-generation of hydrogen

Metal-doping is a common strategy for establishing active sites on photocatalyst, but appropriately exposing them for maximized atomic utilization remains a great challenge in photocatalytic research. Herein, we propose a metal organic framework (MOF)-assisted approach to synthesis copper-modified titania (Cu-TiO2/Cu) photocatalyst with homogenously distributed and highly accessible active sites in its matrix. Significantly, an MOF precursor, namely NH2-MIL-125, with co-chelation of titania (Ti) and copper (Cu) was subjected to mild calcination, subsequently results in Cu-modified TiO2 with highly accessible channels to its inner surface. These channels provide not only a large reactive surface (>400 m2 g-1); they also enable facile modifying route for the pre-deposited Cu in prior to photoreaction. Specifically, NH3 treatment was applied to partially reduce deposited Cu ions (Cu+ and Cu2+) into Cu nanoparticles, where their interplays realize improved optical properties and charge separation during photoreactions. Furthermore, the NH3-induced Cu nanoparticles could also serve as the adsorptive site for H+, thereby enabling 5629 μmol h-1 g-1 H2 generation over the optimum photocatalyst of Cu20/TiO2/Cu500. Such performance is associated to 35.44 and 1.71-fold improvements compared to pure TiO2 (Cu0/TiO2) and untreated Cu-ion modified TiO2 (Cu20/TiO2), respectively. This work offers a new synthetic strategy for obtaining photocatalyst with evenly distributed and highly accessible active sites, thus improving the commensurability of photocatalytic H2 generation from the industrial perspective.

Photocatalytic performance of TiO2 modified with graphene derivatives and Fe (Ⅲ) at different thermal reduction temperatures

ABSTRACT To further investigate the synergistic effects of Fe (Ⅲ) and graphene derivatives with varying degrees of oxidation for photocatalysis, commercial titanium dioxide nanoparticles and graphene oxide were employed as precursors to synthesize the catalyst in this study. Graphene oxygenated derivatives and Fe (Ⅲ)-modified titanium dioxide photocatalysts with different oxidation degrees were prepared using a simple one-step solvothermal method. The results demonstrated that the photocatalytic performance in degrading rhodamine B and sulfamethoxazole was enhanced with an increase in the oxidation degrees of graphene materials. Through the combined action of delocalized conjugated π electrons as electron transfer mediators, Fe (Ⅲ) as an electron trap, and photosensitization reactions, titanium dioxide exhibited exceptional photocatalytic properties with the assistance of graphene derivatives and Fe (Ⅲ) co-catalysts in the degradation of organic compounds.

Selective conversion of furfural to furfuryl alcohol by heterogeneous TiO2 photocatalysis

Selective synthesis of furfuryl alcohol from furfural conversion via semiconductor photocatalytic route has appeared as a promising solution for transforming biomass into high‐value‐added products under mild temperature and pressure conditions. Titanium dioxide (TiO2) photocatalysts were prepared by a simple sol‐gel method followed by a calcination treatment of 500 – 1000 ºC, resulting in materials with distinct physicochemical properties. The photocatalytic efficiency of the TiO2 samples was examined in the selective production of furfuryl alcohol from furfural under UV‐LED irradiation. The influence of various organic solvents, including ethanol, methanol, 2‐propanol, and acetonitrile, was evaluated to optimise the selectivity towards furfuryl alcohol production. Photocatalysts with larger anatase to rutile ratio and increased density of oxygen vacancies (defects) exhibited superior performance for furfuryl alcohol production. The presence of these defects on the catalyst surface leads to a significant enhancement in the photocatalytic efficiency by acting as crucial active sites. Among the TiO2 samples, the highest conversion of furfural into furfuryl alcohol was observed with the TiO2 sample calcined under an air atmosphere at 600 ºC (TiO2‐600), achieving 85% yield and 100% selectivity for furfural after 30 min reaction using ethanol as solvent.

Visible light photocatalytic degradation of HDPE microplastics using vanadium-doped titania

Efficient strategies are necessary to effectively remove microplastics (MPs), which are widely present in the environment. Among various techniques, photocatalysis using visible light has emerged as a promising ap-proach to tackle the growing concerns surrounding microplastic waste. This research explored the potential of vanadium-doped titanium oxide as a photocatalyst for degrading high-density polyethylene (HDPE) micro-plastics under visible light irradiation. Vanadium-doped titanium oxide photocatalyst was synthesized using the sol-gel method, and then characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-visible spectroscopy. The XRD analysis confirmed the formation of the anatase phase, while the SEM imaging provided valuable information on the catalyst’s morphology and elemental composition. The successful incorporation of vanadium ions into the structure was demonstrated by UV-visible spectrosco-py that revealed a redshift in the absorption edge. The vanadium-doped titanium oxide photocatalyst was em-ployed in the degradation of HDPE under visible light. The experimental results exhibited a significant reduc-tion in the mass of the plastic after 350 hours of illumination. V-TiO₂ achieved a maximum reduction of 5.7%, while TiO₂ nanoparticles showed only the 2% decrease. This study demonstrates the potential of V-TiO₂ as an efficient visible-light-driven photocatalyst for HDPE degradation, contributing to the mitigation of microplastics pollution in a sustainable manner.

Effect of TiO2/Fe2O3 nanopowder synthesis method on visible light photocatalytic degradation of reactive blue dye

Water pollution and scarcity of clean water are major issues of concern globally. In this study, titanium dioxide (TiO2) photocatalyst doped with ferric oxide (Fe2O3) was used to degrade reactive blue dye (171) using sunlight irradiation. Two approaches were employed to synthesize the photocatalyst: synthesis of ferric oxide and titanium precursor through ultrasonic-assisted sol-gel method and using iron (III) nitrate nonahydrate with commercial titanium dioxide. The photocatalysts were characterized using FTIR Spectroscopy, SEM, XRD analyses, and UVDRS to determine their chemical composition, morphology, crystallinity, and light absorption, respectively. The effect of contaminant concentration (1–3 ppm), solution pH and photocatalyst type on the degradation efficiency was studied. Doping enabled visible light absorption as confirmed by the UVDRS analysis. Solar photocatalytic degradation resulted in complete (100 % removal) of the dye within 2 h under solar irradiation for all concentrations of the dye studied. Furthermore, the photocatalysts exhibited superior performance in both neutral and acidic solutions compared to basic ones. After four cycles, the dye removal efficiency has decreased by less than 15 % for all the photocatalysts confirming the significant activity and high stability of the nanocomposite. The increased dye photodegradation efficacy of Fe2O3 doped TiO2 under sunlight irradiation is attributed to the narrowing of the photocatalyst's bandgap from 3.76 eV (in pure TiO2) to 2.83 eV. This narrowing of the bandgap enhances the absorption of visible light from sunlight, thus making this photocatalyst effective under sunlight and eliminating the use of electricity which is a requirement for ultraviolet photocatalysis.

A facile strategy for the construction of visible light responsive P25 heterojunction via the annealing treatment with PEG

As the most widely used titanium dioxide (TiO2) photocatalysts, P25 is not able to absorb the visible light due to its limited light response range. In this work, visible light responsive P25 was prepared via the annealing treatment at 300 ℃ under anaerobic conditions with polyethylene glycol (PEG) as the additive. The annealing treatment with PEG not only endows P25 the visible light responsive property but also creates oxygen vacancy (Vo) favoring the separation of charge carriers, which both contributes to its efficient photocatalytic activity. Our work offers a facile approach for the construction of visible light responsive heterojunction via the annealing treatment with organic additive.

Facile preparation of environmental benign LED white light active humic acid nanolayer coated titanium dioxide photocatalyst for bisphenol A degradation

Natural organic matter is a mixture of microbial decomposition products widely found in surface and groundwater. These organic materials have great potential as carbon-based precursors for chemical synthesis. This work demonstrated the development of a green photocatalyst via a facile adsorption process that combined colloidal titanium dioxide (TiO2) with humic acid. The resulting photocatalyst was visible light active and able to completely degrade 5 mg/L of BPA within 6 h under the irradiation of energy-efficient LED white light. The first-order kinetic rate constant of the reaction was determined to be 1.7 × 10−2 min−1. The enhanced photocatalytic activity was attributed to the decreased band gap energy and effective charge separation that limits the photogenerated electron-hole recombination. The outcome of this research opened an opportunity for the development of sustainable functional materials using natural organic matter.

Preparation, characterization of co-Ni co-doped titania photocatalyst and its application for the photocatalytic degradation of textile and PPCPs industrial wastewater under sunlight

The undoped TiO2 (T), 1% Ni-doped TiO2 (N1T), and 1% Co–1% Ni co-doped TiO2 (C1N1T) photocatalysts were prepared by the sol–gel technique. The characterization of prepared materials was carried out by X-ray diffraction, Diffused Reflectance Spectroscopy, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Brunauer–Emmett–Teller and Thermogravimetric Analysis to analyze composition, phase, morphology, and optical properties. These results revealed that C1N1T exhibited higher surface area, better pore volume and enhanced optical properties as compared to undoped and Ni-doped TiO2. Furthermore, the photoactivity of C1N1T nanoparticles was manifested toward Acetaminophen, Phenol and reactive dyes i.e., Remazol Black B and Yellow 2 G. Moreover, C1N1T nanoparticles showed remarkable degradation efficiency of 53%, 56%, 98% and 89% for Acetaminophen, Phenol and anionic dyes, i.e. Remazol Black B and Yellow 2 G under optimized conditions (pollutant concentration = 20 ppm; time = 120 min; C1N1T loading = 20 mg; irradiation source = solar light; pH = 4 for each dye, pH = 7 for phenol and pH = 9 for acetaminophen). The significant degradation values suggested that the C1N1T photocatalyst can be effectively employed to degrade the textile dyes and PPCPs from industrial wastewater.

Facet-Dependent Photocatalytic Behavior of Rutile TiO2 for the Degradation of Volatile Organic Compounds: In Situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy and Density Functional Theory Investigations.

In this study, a custom rutile titanium dioxide (TiO2) photocatalyst with a single exposed surface was utilized to investigate the facet-dependent photocatalytic mechanism of toluene. The degradation of toluene was dynamically monitored using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) technology coupled with theoretical calculations. The findings demonstrated that the photocatalytic degradation rate on the TiO2 (001) surface was nearly double that observed on the TiO2 (110) surface. This remarkable enhancement can be attributed to the heightened stability in the adsorption of toluene molecules and the concurrent reduction in the energy requirement for the ring-opening process of benzoic acid on the TiO2 (001) surface. Moreover, the TiO2 (001) surface generated a greater number of reactive oxygen species (ROS), thereby promoting the separation of photogenerated charge carriers and concurrently diminishing their recombination rates, amplifying the efficiency of photocatalysis. This research provides an innovative perspective for a more comprehensive understanding of the photocatalytic degradation mechanism of TiO2 and presents promising prospects for significant applications in environmental purification and energy fields.