Modification Of TiO2 Research Articles

Mesoscopic TiO2/Nb2O5 Electron Transfer Layer for Efficient and Stable Perovskite Solar Cells

AbstractThere has been tremendous advancement in the field of perovskite photovoltaics by means of interfacial engineering, compositional engineering and optimization of charge collection efficiency. The large bandgap oxides deposited using atomic layer deposition (ALD) technique have proven to be successfully passivating the interfacial defects owing to the advantages offered by this technique. Here, the effect of surface modification of mesoporous TiO2 (ms‐TiO2) layer with a transition metal oxide named niobium pentoxide (Nb2O5) deposited by ALD technique on the performance and stability of perovskite solar cells (PSCs) is investigated. The results reveal that functionalization with ultrathin Nb2O5 layer improve the optoelectronic properties and morphology of the deposited perovskite films. Moreover, the charge transfer is improved and hence the interfacial recombination is reduced. This results in improved power conversion efficiency (PCE) from 19.11% to 21.04% and open‐circuit voltage (VOC) from 1.118 to 1.147 V for the modified champion device. Additionally, the device shows negligible hysteresis with enhanced shelf life thermal and UV stabilities.

Insoluble matrix proteins from shell waste for synthesis of visible-light response photocatalyst to mineralize indoor gaseous formaldehyde

HCHO is the most concerned indoor air pollutant that photocatalytic degradation is a feasible approach. To achieve efficient and complete degradation of HCHO under visible light irradiation, heteroatoms are usually doped in TiO2. But using natural materials as a dopant instead of expensive and toxic chemicals to fertilize TiO2 remains challenging. This paper proposes a sustainable and green approach to synthesize an efficient N, Ca co-doped TiO2 photocatalyst (TIMP) by using the insoluble matrix proteins (IMPs) extracted from abalone shell. TIMP-0.8 achieves near completely degradation HCHO within 45 min under visible light at ambient temperature and exhibits superior stability after 7 cycles. TIMP-0.8 has monodispersity with smaller diameter, high porosity, abundant defects and high adsorption affinity for surface hydroxyls compared with pure TiO2. With the assistance of IMPs, the rate-determining step of HCHO degradation changes from −COOH oxidation to spontaneous decomposition of HCO3−, significantly facilitating the elimination and mineralization of HCHO. Overall, IMPs from abalone shell are natural surfactant, bio-templet, and dopant for TiO2 modification, contributing to desirable visible-light photocatalytic performance for HCHO degradation. This paper provides new insight for high-value utilization of waste shell and photocatalytic indoor purification.

OXIDATIVE AMMONOLYSIS OF 4-METHYLPYRIDINEON OXIDE VANADIUM-TITANIUM-ZIRCONIUM CATALYST MODIFIED BY TIN AND TUNGSTEN OXIDES

Catalysts based on vanadium pentoxide modified by Ti, Sn, Zr and W oxides were tested in the oxidative ammonolysis of 4-methylpyridine. The role of the main process parameters such as temperature, the ratio of the initial components in the conversion of the methyl group to the nitrile one, and the optimal conditions for the oxidative ammonolysis of 4-methylpyridine were determined. It is determined that the V-Ti-Zr-O-catalyst and the sample containing 9% of tungsten oxide are superior in catalytic activity to the V-Ti-Zr-Sn-O contact. Conditions that ensure a high selectivity for the formation of 4-cyanopyridine were found. The highest yield of the target product (85-86%) was obtained on V-Ti-Zr-W-O at 270 °C, and the yield of 4-cyanopyridine was 87.5% at 310° C on the V-Ti-Zr-Sn-O catalyst. The phase composition and structural changes occurring in modified vanadium oxide catalysts have been studied. It is determined that mixed V-Ti-Zr-Sn-O and V-Ti-Zr-W-O catalysts contain ZrV2O7, the monoclinic modification of ZrO2 (baddeleyite), TiO2 (anatase), SnO2, WO3, and V2O5. In catalysts, it can exist in small amounts as a separate VO2 phase. The V-Ti-Zr-W-O catalyst showed the best catalytic properties. It has highactivity and selectivity towards 4-cyanopyridine.

Simultaneous desulfurization and denitrogenation of diesel over Er/W-N-TiO2 photocatalyst

Designing an efficient photocatalyst for desulfurization with simultaneous denitrogenation is essential for producing clean diesel fuel. In this paper, we prepared a photocatalyst with high desulfurization and denitrogenation activities by Er, W, and N co-doping modification of TiO2. Some influences of metal content, reaction time and temperature, basic nitride content and species, catalyst amount, and stability of the catalyst on desulfurization and denitrogenation were considered. Experimental results showed the desulfurization ratio was 100%, and the denitrogenation ratio was also 100% under the suitable conditions. The TOF of thiophene, benzonthiophene, and 4, 6- DMDBT reached 33.1, 34.2, and 36.2, respectively. The results of PL, UV–vis, and EPR showed that the co-doping of Er, W, and N extended the photo-absorption range and improved the hole-electron separation of TiO2 when the content of Er and W was 1.6% and 1.0%, respectively. This might be because the co-doping of Er, W, and N increased oxygen vacancies and defects on the catalytic surface, formed lower gap energy, and transfered and reserved electrons more quickly under visible light. Also, the photocatalytic mechanism of Er/W-N-TiO2 was proposed in the present work.

Modification of TiO2 with metal chalcogenide nanoclusters for hydrogen evolution

Using density functional theory, corrected for on-site Coulomb interactions (DFT + U), we have investigated surface modification of TiO2 with metal chalcogenide nanoclusters for hydrogen evolution. The nanoclusters have composition M4X4 (M = Sn, Zn; X = S, Se) and are adsorbed at the rutile (110) surface. The nanoclusters adsorb exothermically, with adsorption energies in the range −2.8 eV to −2.5 eV. Computed density of states (DOS) plots show that cluster-derived states extend into the band-gap of the rutile support, which indicates that modification produces a redshift in light absorption. After modification, photoexcited electrons and holes are separated onto surface and cluster sites, respectively. The free energy of H adsorption is used to assess the performance of metal chalcogenide modified TiO2 as a catalyst for the hydrogen evolution reaction (HER). Adsorption of H at nanocluster (S, Se) and surface (O) sites is considered, together with the effect of H coverage. Adsorption free energies at cluster sites in the range −0.15 eV to 0.15 eV are considered to be favourable for HER. The results of this analysis indicate that the sulphide modifiers are more active towards HER than the selenide modifiers and exhibit hydrogen adsorption free energies in the active range, for most coverages. Conversely, the adsorption free energies at the selenide nanoclusters are only in the active range at low H coverages. Our results indicate that surface modification with small, dispersed nanoclusters of appropriately selected materials can enhance the photocatalytic activity of TiO2 for HER applications.

Solar light assisted photocatalytic degradation of 1,4-dioxane using high temperature stable anatase W-TiO2 nanocomposites

This work outlines a systematic and detailed study of the modification of anatase TiO2 with tungsten (W). The impact this coupling has on the temperature of the anatase to rutile phase transition and the photocatalytic degradation of 1,4-dioxane, a highly toxic compound that is increasingly present in water bodies is also studied. TiO2 composite photocatalysts with 2, 4, 8 and 16 mol. % W, respectively, were produced using a sol-gel process and then calcined between 500−1000 °C. The crystallinity and phase composition of pure and W-TiO2 photocatalysts were examined using X-ray Diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). All W-TiO2 composite photocatalysts demonstrated 100 % anatase crystalline phase at calcination temperatures as high as 800 °C. Due to the retention of 26 % anatase after calcination at 950 °C, 8 mol. % W was established as the optimum W loading for the development of high temperature stable anatase W-TiO2 composite photocatalysts. The % anatase content also significantly impacts the photocatalytic activity of the W-TiO2 composite photocatalysts. In the presence of solar light, 100 % of 1,4-dioxane was successfully degraded by 2-W-TiO2, 4-W-TiO2 and 8-W-TiO2 composite photocatalysts, respectively, calcined at 800 °C. However, as the calcination temperature increases and the % anatase content decreases, only 70 % of 1,4-dioxane was degraded when using 4-W-TiO2 and 8-W-TiO2 calcined at 900 °C. The highest % removal of 1,4-dioxane was also achieved using 8-W-TiO2 calcined at both 800 and 900 °C. 8-W-TiO2 is therefore considered the optimum sample for both photocatalysis and phase transition temperature.

A Facile Synthesis of Anatase Ni2+ Doped TiO2 Nanorods with Highly Improved Visible-Light Photocatalytic Performance

Objective: Herein, we reported a simple and effective approach to synthesis of pure and Ni2+ doped TiO2 nanorods by a photon-induced method (PIM) followed by calcination at 850 ºC in air atmosphere. Methods: Basically, the PIM was used to tuning the properties of as-prepared TiO2 photocatalyst. These obtained samples were further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and UV-visible diffuse reflectance spectroscopy (UV-vis DRS) analysis. XRD results reveals that the both pure TiO2 and Ni doped TiO2 nanorods has anatase phase up to 850°C. Results: The HR-TEM analysis indicates that doping Ni is favourable to the formation of rod-like TiO2 sample. Also, the observed photocatalytic results demonstrates that the Ni doped TiO2 can be achieved a complete degradation of methylene blue (MB) within 30 min under direct sunlight irradiation as compared to pure TiO2. Conclusion: Therefore, this work revealing the doped Ni has a good potential to modification of TiO2 with an excellent photocatalytic activity for water treatment applications.

Modification of morphology and optic properties of TiO2 as photoreforming catalyst for H2 production from biomass derivatives: a review

Hydrogen is one of the solutions to overcome the problems facing the world today, the energy crisis and a decrease in environmental quality. Its has high chemical energy per mass and its combustion only results water and does not emit greenhouse gas. Nevertheless, hydrogen doesn’t exist in nature as H2 form. Hence, it requires a sustainable production methods. Biomass (lignocellulose) and its derivatives can be renewable feedstock for producing biohydrogen via clean process i.e photoreforming. One of the keys to the success of this technology is the development of suitable photocatalysts that are able to maximize light harvesting from solar and hydrogen production. TiO2 is the establish material because of its high photocatalytic activity, not toxic, biologically and chemically inert. Its main drawback are its band gap value (ca. 3.2 eV) and fast recombination of electron–hole that detrimental to the photocatalytic activity. The alternative to overcome these problems are modification of TiO2 by nanotubes structure and doping of metals. In this paper, we will review about TiO2 nanotubes and its preparation strategies. Then, we will describe role of metal to enhance photocatalytic performance of TiO2 nanotubes. The Impact of both modification to morphology and optic properties and enhancement of H2 production from biomass and its derivatives will be study. The future direction for photoreforming of biomass and its derivatives were also suggested. Modification of Titania by nanotube structure and doping it with bi-metal consist of transition metal like Ni-Cu opens up opportunities and challenges for other researchers.

Adsorptive and Photocatalytic Properties of Tungsten-Modified Titanium Dioxide

We have synthesized oxide composites based on tungsten-modified titanium dioxide and investigated specific features of their formation and their physicochemical, adsorptive, and photocatalytic properties. The results demonstrate that tungsten modification of TiO2 makes it possible to obtain nanopowders (7.2 to 96.7 nm in particle size) with a free specific surface area from 6.4 to 215 m2/g. The synthesized composites have been shown to have considerably higher adsorption capacity and photocatalytic activity (PCA) in comparison to unmodified TiO2 with the same thermal history and Degussa P-25 commercially available titanium dioxide. The materials in which tungsten is incorporated into the crystal lattice of anatase, without tungsten in the form of an individual phase, offer the highest PCA. The electrical conductivity of the composites has been shown to correlate with their PCA.

Effect of TiO2 modification with fluorine on the physicochemical properties and activity in the photocatalytic oxidation of pollutants in air under UV irradiation

Effect of TiO2 modification with fluorine on the physicochemical properties and activity in the photocatalytic oxidation of pollutants in air under UV irradiation

The Role of Adsorption in the Photocatalytic Decomposition of Dyes on APTES-Modified TiO2 Nanomaterials

This work investigated for the first time the role of adsorption in the photocatalytic degradation of methylene blue and Orange II dyes in the presence of 3-aminopropyltriethoxysilane (APTES)-modified TiO2 nanomaterials. It has been demonstrated that the decrease in adsorption has a detrimental effect on photocatalytic activity. APTES/TiO2 photocatalysts were successfully prepared by solvothermal modification of TiO2 in a pressure autoclave, followed by heat treatment in an inert gas atmosphere at the temperature range from 300 °C to 900 °C. It was observed that functionalization of TiO2 via APTES effectively suppressed the anatase-to-rutile phase transformation, as well as the growth of crystallites size during calcination, and reduction of specific surface area (APTES modification inhibits sintering of crystallites). The noted alterations in the adsorption properties, observed after the calcination, were generally related to changes in the surface characteristics, mainly surface charges expressed by the zeta potential. Positively charged surface enhances adsorption of anionic dye (Orange II), while negatively charged surface was better for adsorption of cationic dye (methylene blue). The adsorption process substantially affects the efficiency of the photocatalytic oxidation of both dyes. The methylene blue decomposition proceeded according to the pseudo-first and pseudo-second-order kinetic models, while the degradation of Orange II followed the zero, pseudo-first, and pseudo-second order kinetic models.

Suppressed Microcracking and F Penetration of Ni-Rich Layered Cathode via the Combined Effects of Titanium Dioxide Doping and Coating

To understand the effect of heat treatment of TiO2 modification for Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode, the TiO2 coating layer is formed on the surface of LiNi0.8Co0.1Mn0.1O2 cathode by heat treat...

Electrospun-based TiO2 nanofibers for organic pollutant photodegradation: a comprehensive review

Abstract Titanium dioxide (TiO2) is commonly used as a photocatalyst in the removal of organic pollutants. However, weaknesses of TiO2 such as fast charge recombination and low visible light usage limit its industrial application. Furthermore, photocatalysts that are lost during the treatment of pollutants create the problem of secondary pollutants. Electrospun-based TiO2 fiber is a promising alternative to immobilize TiO2 and to improve its performance in photodegradation. Some strategies have been employed in fabricating the photocatalytic fibers by producing hollow fibers, porous fibers, composite TiO2 with magnetic materials, graphene oxide, as well as doping TiO2 with metal. The modification of TiO2 can improve the absorption of TiO2 to the visible light area, act as an electron acceptor, provide large surface area, and promote the phase transformation of TiO2. The improvement of TiO2 properties can enhance carrier transfer rate which reduces the recombination and promotes the generation of radicals that potentially degrade organic pollutants. The recyclability of fibers, calcination effect, photocatalytic reactors used, operation parameters involved in photodegradation as well as the commercialization potential of TiO2 fibers are also discussed in this review.

Blending of Dielectric Perovskite with Electron Transport Materials: A Case Study towards Improving Bio-Molecular Devices for Energy Harvest

In the present work, the photovoltaic performance changes of organic dye anchored anatase TiO2 based photo-anode after incorporating dielectric material PLT15 (Pb0.85La0.15TiO3) in the TiO2 matrix were studied for DSSC application. The TiO2 and PLT15 modified TiO2 were prepared through a wet chemical process and the crystalline nature, morphological features, and optical properties were studied via XRD, SEM, and Uv–vis analysis, respectively. A few notable changes in the morphology and UV–vis absorption characteristics were observed when TiO2 was modified with PLT15. The hypsochromic shift in the UV–vis absorption spectrum was identified after the modification of TiO2 with PLT15. The estimated bandgap for the PLT15 modified TiO2 was found lower than the primitive TiO2, which shows the lowering of density of states after modification. DSSCs were prepared by anchoring two different natural biomolecule-based organic dyes originating from chlorophyll and carotene were used as a sensitizer for TiO2 and PLT15 modified TiO2 photoanodes. It was observed that extracted chlorophyll dye shows comparatively broader absorption than carotene under visible light and exhibits higher photo-conversion efficiency of DSSC. Furthermore, the modification of TiO2 with dielectric material (PLT15) improves the photoconversion efficiency than the primitive one. This present work provides a comprehensive insight to the researchers regarding the use of dielectric modified semiconducting metal oxide-based photoanodes for bio-molecular devices for energy harvest.

Improved Performance of DSSC Photoanodes After the Modification of TiO2 with Reduced Graphene Oxide

Improved Performance of DSSC Photoanodes After the Modification of TiO2 with Reduced Graphene Oxide

Biological Effect of Silver-modified Nanostructured Titanium Dioxide in Cancer.

Nanomedicine is a promising scientific field that exploits the unique properties of innovative nanomaterials, providing alternative solutions in diagnostics, prevention and therapeutics. Titanium dioxide nanoparticles (TiO2 NPs) have a great spectrum of photocatalytic antibacterial and anticancer applications. The chemical modification of TiO2 optimizes its bioactive performance. The aim of this study was the development of silver modified NPs (Ag/TiO2 NPs) with anticancer potential. Ag/TiO2 NPs were prepared through the sol-gel method, were fully characterized and were tested on cultured breast cancer epithelial cells (MCF-7 and MDA-MB-231). The MTT colorimetric assay was used to estimate cellular viability. Western blot analysis of protein expression along with a DNA-laddering assay were employed for apoptosis detection. We show that photo-activated Ag/TiO2 NPs exhibited significant cytotoxicity on the highly malignant MDA-MB-231 cancer cells, inducing apoptosis, while MCF-7 cells that are characterized by low invasive properties were unaffected under the same conditions.

Surpassing the 1 Li/Ti capacity limit in chlorine modified TiO[formula omitted]Cl[formula omitted

TiO2 is a Li-ion electrode material based on abundant materials which exhibits high cycle life and requires no stringent high temperature processing. Amorphous TiO2 is known to reach the theoretical capacity of 1280 mAh/cm3. This theoretical limit can only be achieved through nano-scaling of the system or through chlorine modification. In both cases, all the available Ti+IV atoms are reduced to Ti+III, with insertion of Li+ ions upon the reductive step. The energy density of batteries containing a TiO2 anode remains limited by the high oxidation potential (1.8V vs. Li+/Li) and suffer from poor rate performance.Two routes can be followed to improve the performance and applicability of TiO2 as Li-ion battery electrode. The first approach focuses on increasing the reversible insertion capacity of LixTiO2 beyond x = 1, alternatively lowering the insertion potential increases the energy density of the anode.High level chlorine modification of TiO2 is observed to significantly enhance the Li-ion storage capability of Lix TiO2, exceeding x = 1, beyond the current theoretical limit of 1280 mAh/cm3 or 330 mAh/g.This work focuses on elucidating the reaction mechanism which increases the insertion capacity. A combination of electrochemical techniques, RBS and TOF-SIMS is used on thin-film electrodes. The lithium insertion beyond x > 1, is associated to the conversion of TiO2 to metallic Ti, similar to the conversion reactions observed in other binary oxides.Through chlorine modification the energy density of the anode is enhanced, both by increasing the capacity of TiO2 and by introducing a low potential insertion reaction.

Photocatalytic Decomposition of Acetaldehyde on Different TiO2-Based Materials: A Review

Purification of air from the organic contaminants by the photocatalytic process has been confirmed to be very perspective. Although many various photocatalysts have been prepared and studied so far, TiO2 is still the most commonly used, because of its advantageous properties such as non-toxicity, relatively low cost and high stability. Surface modifications of TiO2 were extensively proceeded in order to increase photocatalytic activity of the photocatalyst under both UV and visible light activations. The intention of this review paper was to summarize the scientific achievements devoted to developing of TiO2-based materials considered as photocatalysts for the photocatalytic degradation of acetaldehyde in air. Influence of the preparation and modification methods on the parameters of the resultant photocatalyst is reviewed and discussed in this work. Affinity of the photocatalyst surfaces towards adsorption of acetaldehyde will be described by taking into account its physicochemical parameters. Impact of the contact time of a pollutant with the photocatalyst surface is analyzed and discussed with respect to both the degradation rate and mineralization degree of the contaminant. Influence of the photocatalyst properties on the mechanism and yield of the photocatalytic reactions is discussed. New data related to the acetaldehyde decomposition on commercial TiO2 were added, which indicated the different mechanisms occurring on the anatase and rutile structures. Finally, possible applications of the materials revealing photocatalytic activity are presented with a special attention paid to the photocatalytic purification of air from Volatile Organic Compounds (VOCs).

Surface modification of TiO2 with Pd nanoparticles for enhanced photocatalytic oxidation of benzene micropollutants

This paper describes a simple method for the modification of TiO2 surface with palladium to prepare a highly active photocatalyst for oxidation of benzene micropollutants in air. The method consists of the impregnation of anatase TiO2 with a solution of palladium (II) acetate (Pd(OAc)2) in acetone followed by photodecomposition of Pd(OAc)2 under UV irradiation. No additional electron donor is required for Pd photodeposition because acetate ligands play this role. Photodecomposition of Pd(OAc)2 can be efficiently performed either before the target photocatalytic reaction or in situ during the reaction. Pd-loaded photocatalysts were characterized using UV–vis DRS, XPS, TEM, EDX, and CO chemisorption techniques. The formation of metallic (Pd0) and oxidized (PdOx) palladium on the TiO2 surface was shown. An increased amount of metallic Pd was observed during photodecomposition of Pd(OAc)2 compared to its thermal decomposition at low temperature. The modification of TiO2 with Pd nanoparticles substantially increased its photocatalytic activity in the oxidation of benzene vapor under UV light. A Pd content of 1 wt.% was found to be optimum, which provided a three-fold increase in activity compared to pristine TiO2. In addition to increasing the oxidation rate, Pd nanoparticles suppressed the formation of CO as a byproduct during the process that increased the efficiency of air purification by the photocatalytic oxidation method. The proposed preparation techniques can be employed for easy modification of powdered photocatalysts or fabric filters used in photocatalytic air purifiers.

Modification of TiO2/AC catalyst for visible light degradation of ionic liquid contaminated wastewater: Effect of Cu loading on the characterization and efficiency

The emergence of ionic liquids (ILs) as a green substitute for the conventional volatile organic compound has attracted many researchers to keep synthesizing and improving ILs formula for enhanced performance in various industrial application. Due to the various possible combinations of cations and anions, the properties of the formulated ILs varies which directly affecting its toxicity and degradability. One of the major concerns over the use of ILs is the potential water pollution caused by cross contamination during the industrial processes. The present study reports on the photodegradation of 1-butyl-3-methylimidazolium chloride ([C 4 mim][Cl]), which is a common IL used in industry. The effect of Cu 2+ loading on the performance of TiO 2 /Activated carbon composite photocatalyst was studied. The modification of TiO 2 with Cu 2+ managed to shift the absorption edge of TiO 2 towards visible light region, with enhanced performance as compared to the pristine TiO 2 . Less agglomeration rate of the Cu-TiO 2 /AC in comparison to TiO 2 and TiO 2 /AC revealed the important role of metal dopant in suppressing the growth rate during the calcination process. The presence of activated carbon (AC) as support for the powdered TiO 2 has improved the diffusion rate of [C 4 mim][Cl]. The Cu-TiO 2 /AC composite photocatalyst containing 0.1 wt% of Cu showed the highest total degradation compared to other photocatalysts which is in agreement with the characterization analysis of the composite photocatalyst.