TiO2 Nanocatalysts Research Articles

Synthesis, Spectroscopic Characterization of Cobalt ComplexfromC16H19N3O3S and photodegradation using prepared Nano TiO2catalyst

Coblatcomplex has been prepared by reaction between C16H19N3O3S (L) as ligand and metal salt (II). The prepared complex were characterized by infrared spectra, electromic spectra, magnetic susceptibility, molar conductivity measurement and metal analysis by atomic absorption and (C.H.N) analysis. From these studies tetrahedral geometry structure for the complex was suggested. The photodegredation of complex were study using photoreaction cell and preparednanoTiO2 catalyst in different conditions (concentration, temperatures, pH).The results show that the recation is of a first order with activation energy equal to (6.6512 kJ /mol).

TiO2-PDMS composite sponge for adsorption and solar mediated photodegradation of dye pollutants

A hydrophobic composite sponge with photocatalytic property is fabricated combining porous polydimethylsiloxane (PDMS) structure and semiconductor TiO2 nanocatalyst. The porous PDMS structures are prepared using sugar as a sacrificial template. The typical size of the pores in the sponge varies from 10 μm to 100 μm. The surface and the pore wall of the PDMS sponge are decorated with TiO2 nanoparticles which are mostly present as an aggregate. These PDMS composite sponges were shown to remove organic pollutants such as the toxic dye Rhodamine B from water efficiently and selectively, via synergistic effects of adsorption and photocatalytic degradation. These sponges first remove a significant amount of the dye from solution by adsorption (∼50% removal) even in the absence of light. Upon exposure to solar light, the dye adsorbed on the surface of the TiO2-PDMS sponge was photocatalytically degraded, resulting in the further removal of the dye from solution (total 80% removal). The overall dye removal efficiency TiO2-PDMS composite sponge is comparable with that of a similar amount of the TiO2 in solution. However, the application of composites eliminates the need for complicated separation of the powder catalyst from the solution. Most importantly these composite sponges could be easily regenerated by exposing them to solar light. The excellent performance and the recyclability of these cost-effective TiO2-PDMS sponges suggest their promising applications in textile wastewater treatment.

Environmentally benign chemical recycling of polycarbonate wastes: comparison of micro- and nano-TiO2 solid support efficiencies

Abstract Polycarbonate (PC) wastes, including optical discs (CDs) and digital optical discs (DVDs), were chemically recycled into valuable materials such as 4,4′-(propane-2,2-diyl)diphenol (BPA) and etherified derivatives of BPA using sodium hydroxide (NaOH) as the alkali metal catalyst and nanostructured titanium dioxide (nano-TiO2) and microstructured titanium dioxide (micro-TiO2) as the solid supports in the binary green system consisting of water and 2,2′-oxydi(ethan-1-ol) (DEG) under conventional heating method, and data were compared. In this study, the effects of various parameters, such as solvent composition, concentration of NaOH, and solid support, were studied on the reaction progress. In these reactions, the importance of water as the green solvent was investigated in achieving pure BPA as the valuable material. When used with 20% aqueous DEG (pbw), a pure BPA can be obtained at 70% yield in the presence of nano-TiO2 and micro-TiO2 as the solid supports. According to the results, the use of nano-TiO2 in comparison with micro-TiO2 accelerates the chemical recycling of PC wastes. The nano-TiO2 catalyst recovery shows that the recovered solid support is applicable for four cycles. The obtained products were characterized using spectroscopic methods, namely, 1H NMR, 13C NMR, and Fourier transform infrared spectroscopy as well as gas chromatography-mass spectrometry.

Visible light driven photocatalytic decomposition of penicillin G by Ti 3+ self-doped TiO 2 nano-catalyst through response surface methodology

Abstract In present study, Ti3+ self-doped TiO2 (r-TiO2) nano-catalyst was successfully fabricated by one-step solution reduction treatment in the presence of potassium borohydride. The self-doping process can induce the generation of Ti3+ and oxygen vacancy (Ov) to form a new energy level in the forbidden band of TiO2. Moreover, physicochemical properties of the resulting samples were studied by series of techniques. Results suggest that r-TiO2 nano-catalyst exhibits remarkable enhancement of visible light harvesting and higher charge separation efficiency. In order to investigate the influence factors on degradation of penicillin G (PENG), the experimental design was made using central composite method (CCD) of response surface methodology (RSM). For this purpose, the r-TiO2 dosage, PENG concentration and initial pH value were selected as critical parameters. Results indicate the r-TiO2 dosage and initial pH possess higher influences. Besides, the highest photocatalytic efficiency of PENG (98.3%) can be obtained under the optimal conditions of r-TiO2 dosage 50 mg, PENG concentration 100 mg/L and initial pH 5.5, respectively.

Catalytic decomposition of PCDD/Fs on a V2O5-WO3/nano-TiO2 catalyst: effect of NaCl.

The effect of NaCl addition on the properties, activity, and deactivation of a V2O5-WO3/nano-TiO2 catalyst was investigated during catalytic decomposition of gas-phase polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). The extent of deactivation relates directly to the NaCl loading of the catalyst. Poisoning by sodium neutralizes acid sites, interacts strongly with active VOx species, and reduces the redox capacity of catalysts. In addition, NaCl is also a chlorine source and may actually accelerate the synthesis of new PCDD/Fs. Washing a catalyst with dilute sulfuric acid largely restores catalytic activity, breaking the interaction of Na+ ions and dispersed vanadia and removing Na from the catalyst surface. Consequently, catalyst acidity and redox capacity almost recover. Furthermore, sulfate residues react with surface adsorbed water to generate Brønsted acid sites, ensuing a surge of strong acidity of the catalysts.

Photocatalytic activity of Nitrogen and Silica doping on TiO2 nanocatalyst and grafted onto PMMA film

In this paper, N-doped and Si-doped TiO2 nanocatalyst as powder and grafted onto PMMA film have been prepared and tested for the photocatalysis toward methylene blue dye under UV and visible light irradiation. The samples were characterized by using X-ray diffraction (XRD), N2-physisorption, UV-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), scanning electron microscope with energy dispersive X-ray (SEM-EDX) and photoluminescence (PL). The kinetic were used to investigate the performance of grafted film of modified materials compared with pristine TiO2 grafted onto PMMA film. The results showed that, kinetic constant parameter of modified TiO2 were improved both as powder and grafted film.

Tailoring performance of La-modified TiO2 nanocatalyst for continuous photocatalytic CO2 reforming of CH4 to fuels in the presence of H2O

Photo-induced CO2 reforming of CH4 in the presence of H2O over La-modified TiO2 nanoparticles in a continuous flow photoreactor has been investigated. The structure and properties of the catalyst samples, synthesized by a sol-gel method, were systematically characterized by XRD, Raman, SEM, TEM, CO2-TPD, TGA, N2-sorption, XPS, UV–Vis DRS and PL spectroscopy. The crystallite size was reduced while, BET surface area and basicity were increased due to the presence of La2O3. The La-modified TiO2 nanocatalysts were tested under different catalyst loading, irradiation time, reaction temperature and type of reductants. The main products detected over La/TiO2 catalysts during photo-induced CO2-CH4 reaction system were CO, H2 and C2H6. The amount of CO produced over 5 wt.% La/TiO2 was 9.6 fold more the amount of CO produced by pure TiO2. When H2O was added to the CO2-CH4 reaction system, the yield of CO increased 37 fold higher over 5 wt.% La/TiO2 compared to TiO2. The enhanced photocatalytic performances can be attributed to the synergistic effect of La2O3 for CO2 adsorption with hindered charge recombination rate by La3+ and appropriate redox potentials. The photocatalytic turnover productivity (PTOP), calculated for the first time, presented amounts of products evolved with the photon energy consumption. The highest PTOP number achieved for CO production using the CO2-CH4-H2O reaction system was 3.83 fold higher than PTOP achieved in CO2-CH4 reaction system. However, PTOP for the production of H2 and C2H6 in CO2-CH4 system was 1.2 and 2.1 fold higher than the CO2-CH4-H2O reaction system, respectively. The stability test revealed prolonged life time of La/TiO2 in cyclic runs for dynamic CO2-CH4 conversion to fuels in the presence of H2O than using only CO2-CH4 reaction system. Therefore, CO2-CH4 could efficiently be converted to fuels over a La/TiO2 catalyst while the addition of H2O could promote both photoactivity and stability.

Paramagnetic and Photocatalytic Properties of C-S co-Doped TiO2 Nanocatalysts

Paramagnetic and Photocatalytic Properties of C-S co-Doped TiO2 Nanocatalysts

Synthesis of TiO2 Nanoparticles and Good Dispersion on SBA-15 Mesoporous Materials for High Photocatalytic Activity

This paper reports the preparation of TiO2 based photocatalysts from two different types of silica materials, silica gel and SBA-15. This study examines the factors that affect the photocatalytic activity of catalyst composite, such as types of silica support, TiO2 loading, and pH value of dye solution. The samples were characterized by XRD, UV-vis, FTIR, FE-SEM, TEM, TGA, and surface area analyzer. Experimental results show that TiO2 supported on silica gel or SBA-15 materials can effectively enhance photocatalytic reaction than unsupported catalysts. The TiO2/SBA-15 materials have larger pore volume and pore size compared to TiO2/silica-gel materials, which exhibited a much higher adsorption and photodegradation activity. The resulting mesoporous TiO2/SBA-15 had a high surface area of 574 m2/g, pore volume of 1.30 cm3/g, pore size of about 8.0 nm, and mesopore content as high as 100%. The results of this study will be useful in enhancing photocatalytic efficiency of TiO2 nanocatalyst materials.

Synthesis, Spectroscopic Characterization of Cobalt ComplexfromC16H19N3O3S and photodegradation using prepared Nano TiO2catalyst

Coblatcomplex has been prepared by reaction between C16H19N3O3S (L) as ligand and metal salt (II). The prepared complex were characterized by infrared spectra, electromic spectra, magnetic susceptibility, molar conductivity measurement and metal analysis by atomic absorption and (C.H.N) analysis. From these studies tetrahedral geometry structure for the complex was suggested. The photodegredation of complex were study using photoreaction cell and preparednanoTiO2 catalyst in different conditions (concentration, temperatures, pH).The results show that the recation is of a first order with activation energy equal to (6.6512 kJ /mol).

Ni/MMT-promoted TiO2 nanocatalyst for dynamic photocatalytic H2 and hydrocarbons production from ethanol-water mixture under UV-light

Photocatalytic H2 evolution from ethanol-water mixture over Ni and montmorillonite (MMT)-loaded TiO2 nanocomposite has been investigated. The samples, prepared by a single step sol-gel method, were characterized by XRD, SEM, TEM, FTIR, XPS, UV–Vis and PL spectroscopy. The TiO2 crystal growth was controlled by Ni/MMT, thus produced anatase phase TiO2. The nickel presented over the TiO2 as Ni2+, thus promoted charges separation. The photocatalytic H2 production activity was conducted in a gas phase continuous flow photoreactor system under UV-light. A significant enhancement in photoactivity of Ni-promoted MMT/TiO2 catalyst was detected for selective H2 production with appreciable amounts of C1-C3 hydrocarbons. The highest amount of H2 evolved over 3 wt% Ni-10 wt% MMT/TiO2 composite was 3470 μmole g-cat. −1 h−1 at selectivity 99%, 2.62 order of magnitude higher than pure Ni/TiO2, 6.48 fold more than MMT/TiO2 and 6.45 times the amount of H2 produced the over the pure TiO2 catalyst. Among the hydrocarbons, MMT promoted CH4/C2H6 production, while Ni/MMT was favorable for CH4/C3H6 production. The activity and selectivity of Ni-MMT/TiO2 was reduced at higher catalyst loading due to mass transfer limitations. In addition, significantly improved and stable cyclic performance was detected over the irradiation time for dynamic and selective H2 evolution. The enhanced performance of the Ni-MMT/TiO2 composite for H2 production is mainly associated with efficient charges separation due to synergistic effect of Ni/MMT and appropriate redox potentials. The reaction mechanism to understand the production of H2 and hydrocarbons in a gas phase system is critically deliberated.

Non-light-driven reduced graphene oxide anchored TiO2 nanocatalysts with enhanced catalytic oxidation performance

As a single-atom-thick carbon material with high surface and good conductivity, graphene provides an ideal platform for designing composite nanomaterials for high-performance catalytic system. Herein, we obtained a TiO2-reduced graphene oxide nanocomposite (TiO2-RGO) with graphene oxide and tetrabutyl titanate using a facile in situ hydrothermal method. The merit of this method is that the nanocomposites could be produced directly from graphene oxide in the hydrothermal reaction, where the reduction of graphene oxide and the decoration of TiO2 occurred simultaneously. TiO2 nanoparticles anchored on graphene sheets as spacers to keep the neighboring sheets separated. The in situ growth route provides a desirable platform for constructing graphene-supported nanocomposites with improved properties. As one of the major applications of the nanocomposites, we investigate the performance of as-prepared TiO2-RGO as effective non-light-driven catalysts for activating H2O2 in oxidative degradation of the dye. The system was employed in oxidation degradation not only to reach high degradation efficiency but also to avoid any energy consumption. Meanwhile, the proposed catalytic system processes broad-spectrum oxidative degradation activity for different model organic pollutants. Overall, this work could provide new insights into the fabrication of a TiO2-RGO as high performance catalysts and facilitate their application in the environmental protection issues.

Sonophotocatalytic degradation of diazinon in aqueous solution using iron-doped TiO2 nanoparticles

Abstract Diazinon is a moderately persistent organophosphorus pesticide used to control a variety of insects in both household and agricultural because of its inhibition ability of acetylcholinesterase in the vast majority of insects .So far, diazinon residues have been found in many agricultural products and affecting a wide range of non-target organisms proving harmful to human and aquatic environments. The aim of this study was to evaluate the sonophotocatalytic degradation of diazinon, in aqueous solution, using iron doped TiO2 nanoparticles .Iron-doped TiO2 nanoparticles were synthesized under mild hydrothermal conditions (T = 110 °C, p = autogenous, t = 12 h). The systematic characterization of nanoparticles was determined using Powder X-ray Diffraction, Fourier transform infrared and Scanning electron microscopy techniques. Moreover, the effects of different parameters such as pH, nanocatalyst dosage, initial diazinon concentration, and Fe doping concentration on the degradation efficiency of diazinon were investigated. The degradation efficiency of diazinon in each sample was measured using a UV–Vis spectrophotometer (λmax = 247 nm) at different time intervals. The results demonstrated that nanoparticles were successfully synthesized and the forms of the nanoparticles synthesized are quite similar to each other and approximately pseudo-spherical. The optimum conditions for sonophotocatalytic degradation of the diazinon obtained were: pH 5.5, nanocatalyst dosage = 0.4 g/l, initial diazinon concentration = 30 mg/l, dopant percentage = 1.5% and contact time = 100 min. Under optimal conditions, the sonophotocatalytic degradation efficiency of diazinon was 85%. In addition, the results showed that the iron-doped TiO2 nanocatalyst, UV irradiation and US irradiation had a positive effect on the sonophotocatalytic degradation of diazinon. The maximum degradation values of diazinon achieved for separate applications, namely, iron-doped TiO2, UV irradiation, and US irradiation was 30, 36, and 19% respectively.

Photocatalytic Oxidation of Glucose into Formate on Nano TiO2 Catalyst

Formic acid, as an excellent hydrogen-storage material, has recently become increasingly important. Previous conversion of biomass into formic acid suffers from problems of strict operation conditions such as the use of a high concentration of H2O2 oxidant and alkali at higher temperatures or the precious metal catalysts. Here, a straightforward photocatalytic method to selectively convert glucose into formate is first reported. Using a nano TiO2 catalyst, we show that glucose can be efficiently converted into formic acid with a high yield of 35% at ambient condition with 0.03 M NaOH concentration, and the proposed method also worked on xylose for formate production. The conversion of glucose into formic acid is mainly attributed to the accelerated formation of active oxidative radicals (O2•–, •OH) in the presence of hydroxyl ions, and also, hydroxyl ions adjust the charge of the TiO2 surface and control the adsorption of glucose and the desorption of formic acid. These results open up a new approach towa...

Combined experimental and theoretical study of visible light active P doped TiO2 photocatalyst

Using the hydrothermal method, a P-doped TiO2 nano-catalyst is prepared for widening the application spectrum of TiO2. The synthesized samples are investigated using XRD, TEM, and UV–visible absorption spectra. A P-doped TiO2 system is simulated and calculations for geometrical structure, electronic and optical properties are performed based on density functional theory. Comparison of the electronic band structure of anatase TiO2 before and after doping verified that doping tuned the band structure. XRD patterns revealed that pure anatase phase is the only phase in case of pure and doped samples. TEM observations reveal spherical morphology. The P doped TiO2 experimentally as well as theoretically responded to visible light confirming the band structure findings. Photocatalytic activity of the doped samples drastically improved compared to bare TiO2.

Photo-induced CO2 reduction by hydrogen for selective CO evolution in a dynamic monolith photoreactor loaded with Ag-modified TiO2 nanocatalyst

Ag-promoted TiO2 nanoparticles immobilized over the cordierite monolithic support for dynamic and selective photo-reduction of CO2 to CO by the use of hydrogen has been investigated. Ag-loaded TiO2 NPs synthesized by a facile sol–gel method were coated over the monolith channels by dip-coating method. The samples were characterized by XRD, Raman, FTIR, SEM, TEM, XPS, N2 adsorption–desorption, UV–Vis and PL spectroscopy. The photo-activity test of Ag-modified TiO2 NPs was conducted for dynamic photocatalytic CO2 reduction with H2 as a reductant via a reverse water gas shift (RWGS) reaction in a cell type and monolith photo-reactors. Using 5 wt. % Ag/TO2 NPs, CO2 was energetically converted to CO with a yield rate 1335 μmole g-catal.−1 h−1, a 111 fold-higher than the amount of CO produced over the pure TiO2 catalyst. More importantly, photo-activity of Ag/TiO2 catalyst for CO evolution can be improved by 209 fold using monolith photo-reactor than the cell type reactor under the same operating conditions. This enactment was evidently due to the efficient light harvesting with larger illuminated surface area inside monolith micro-channels and efficient charges separation in the presence of Ag-metal. The reusability of Ag/TiO2 NPs loaded over the monolithic support showed favorable recycling capability than the catalyst dispersed in a cell reactor. A possible reaction mechanism for this observation has been discussed in detail.

Influence of lanthanum precursors on the heterogeneous La/SnO2–TiO2 nanocatalyst with enhanced catalytic activity under visible light

Surfactant controlled synthesis of La/SnO2–TiO2 nanocomposite was studied by using anionic surfactant dioctyl sulfosuccinate sodium salt (DOSS) synthesized via sol–gel method followed by hydrothermal method by using different lanthanum precursors. The structural investigation, thermal degradation, kinetics, thermodynamics properties, crystallite size, morphology, surface and photocatalytic properties of synthesized samples were studied by using different characterization techniques i.e. Thermogravimetric analysis (TGA), Fourier transform-infrared spectroscopy (FTIR), Particle Size Analyzer (PSA), Powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and Ultraviolet–Visible spectrophotometer (UV–VIS). Band gap calculations and optical properties of both SnO2–TiO2 and La/SnO2–TiO2 were studied by using UV–Visible spectroscopy. The performance of both SnO2–TiO2 and La/SnO2–TiO2 nanocomposites as a photocatalytic agent was also investigated for the degradation of methylene blue (MB) under the illumination of sunlight.

Optimization of Photodegradation of Acid Blue 113 Dye on Anatase TiO2 Nanocatalyst Using Response Surface Methodology

Optimization of Photodegradation of Acid Blue 113 Dye on Anatase TiO2 Nanocatalyst Using Response Surface Methodology

Biodiesel production from used cooking oil using a novel surface functionalised TiO2 nano-catalyst

A novel, efficient and recyclable mesoporous TiO2/PrSO3H solid acid nano-catalyst was synthesised by the post-synthetic grafting of propyl sulfonic acid groups onto a mixed phase of a TiO2 support. The synthesised nano-catalyst was characterised using FTIR, SEM, TEM, XPS, N2 adsorption–desorption isotherms, XRD, DSC, TGA, and CHNS analysis. The loading percentage of propyl sulfonic acid on the TiO2 support was calculated using CHNS analysis and TGA. The catalytic performance of TiO2/PrSO3H on the production of the fatty acid methyl esters (FAME) via simultaneous esterification and transesterification reactions from used cooking oil (UCO) has been studied. The effects of different process parameters showed that 98.3% of FAME can be obtained after 9h of reaction time with 1:15 molar ratio of oil to methanol, 60°C reaction temperature and 4.5wt% catalyst loading. It was also found that the one-pot post-surface functionalisation strategy with hydrophilic functional groups (–SO3H) enhanced the acid strengths of the nano-catalyst providing more acid sites for the reactants, and improving the accessibility of methanol to the triglycerides (TG)/free fatty acids (FFAs) by increasing the pore volumes/sizes of the nano-catalyst. The solid acid nano-catalyst was re-used in four consecutive runs without significant loss of catalytic efficiency. Finally, the synthesised biodiesel fuel satisfied ASTM and EN standards.

Photocatalytic Degradation of Methylene Blue by Plasmonic Metal-TiO₂ Nanocatalysts Under Visible Light Irradiation.

This study demonstrates photocatalytic activity of 1 wt% plasmonic metal (Au, Ag and Cu)–TiO₂ nanocatalysts prepared via photodeposition method for the photo oxidative decomposition of methylene blue (MB 0.01 mM) under visible light (50 mWcm−2) irradiation. Plasmonic metal loaded-TiO₂ photocatalysts absorb with an absorption maximum at localized surface plasmon resonance wavelengths (500–785 nm). It has been observed that pH altered the surface charge (ζ) of TiO₂ (ζ = –4.98, –4.0 and +9.16 at pH = 10, 7 and 3, respectively). The point of zero charge (PZC) at pH 6.3 has been determined from a correlation plot between pH and ζ. Higher rate of degradation was observed at pH = 10 because of electrostatic interaction of cationic MB with anionic TiO₂. Higher photocatalytic activity was shown by Cu–TiO₂ followed by Au–TiO₂ and Ag–TiO₂ photocatalysts in comparison to TiO₂-P25. This enhancement in photocatalytic efficiency is attributed to the plasmonic effect and effective charge separation at the interface between nano size metal deposits and TiO₂ particles. The overall photocatalytic reaction followed pseudo first order kinetics as per Langmuir Hinshelwood kinetic equation. GC and GC-MS studies suggested the formation of thionin after demethylation and derivatives of benzene sulphonic acid which are subsequently degraded to CO₂ after prolonged irradiation time.