Co-doped TiO2 Nanoparticles Research Articles

Chemical warfare agents’ degradation on Fe–Cu codoped TiO2 nanoparticles

Metal ion-doped titanium dioxide (TiO2) nanoparticles have been proved to be one of the most efficient decontaminating catalysts towards chemical warfare agents (CWAs). Nowadays, most of the researchers are paying their attention to the study of single metal ion-doped TiO2 nanoparticles, while a few reports are focused on the photocatalytic degradation performance of two or more kinds of metal ions codoped TiO2 nanoparticles. In this work, Fe–Cu codoped TiO2 nanoparticles have been prepared by the homogeneous precipitation method. 2-Chloroethyl ethyl sulfide (2-CEES), as a model, has been used to investigate its photocatalytic degradation efficiency on the prepared catalysts. The results showed that 10 wt% Fe2–Cu1 codoped TiO2 nanoparticles have an obvious improved photocatalytic activity compared with the single Fe/Cu-doped TiO2 nanoparticles, which are majorly attributed to its physical structure properties through HRTEM, XRD, UV–Vis, BET and BJH characteristics. An appropriate amount of Fe–Cu dopant does not change the crystal structure of TiO2 nanoparticles, but improves the dispersion, reduces the grain size, increases the surface area and improves the light utilization. 10% Fe2–Cu1 codoped TiO2 nanoparticles were dispersed into HFE-458 (HCF2CF2CH2OCF2CF2H), and the disinfection efficiency of 2-chloroethyl ethyl sulfide (HD simulation, 2-CEES), dimethyl methanephosphonate (GD simulation, DMMP) and malathion (VX simulation) were studied under the simulated sunlight irradiation. After reacting for 60 min, the degradation efficiency of 2-CEES, DMMP and malathion is 99.73%, 99.20% and 94.27%, respectively.

Facial fabrication of carbon quantum dots (CDs)-modified N-TiO2-x nanocomposite for the efficient photoreduction of Cr(VI) under visible light

In this study, for the first time, a novel CDs-N-TiO2-x nanocomposite was successfully fabricated by decorating the carbon quantum dots (CDs) on the nitrogen (N) and Ti3+ codoped TiO2 nanoparticles using a facile hydrothermal-calcination method. X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS), electron paramagnetic resonance (EPR) spectra, and X-ray photoelectron spectroscopy (XPS), etc., were utilized to investigate the physicochemical properties of the catalyst and to confirm the successful introduction of CDs and the formation of N/Ti3+ codoping levels in the nanocomposite. Owing to the synergy between the modification of CDs and codoping of N and Ti3+, the as-prepared CDs-N-TiO2-x nanocomposite exhibited enhanced visible light absorption and more efficient charge separation compared with its counterparts, such as the pristine TiO2, N-doped TiO2 (N-TiO2), N and Ti3+ codoped TiO2 (N-TiO2-x), and carbon quantum dots-TiO2 (CDs-TiO2), etc. As a result, the CDs-N-TiO2-x nanocomposite displayed a remarkable performance for Cr(VI) reduction under visible light irradiation. Moreover, adding the appropriate amount of citric acid as the hole scavenger significantly increased the reduction rate of Cr(VI). In addition, the reduction efficiency was better under acidic conditions and considerably affected by the initial Cr(VI) concentration and catalyst dosage. Thermogravimetric analysis and cyclic runs demonstrated a unique thermal and chemical stability of the CDs-N-TiO2-x nanocomposite. The mechanism of the enhanced photoreduction of Cr(VI) by the CDs-N-TiO2-x nanocomposite was discussed based on all the characterization and experimental results. Moreover, the developed CDs-N-TiO2-x nanocomposite also exhibited efficient photocatalytic performance to reduce the Cr(VI) contained in real laboratory wastewater.

Hydrothermal synthesis of photoactive nitrogen- and boron- codoped TiO2 nanoparticles for the treatment of bisphenol A in wastewater: Synthesis, photocatalytic activity, degradation byproducts and reaction pathways

Hydrothermal technique was employed for the synthesis of N- and B-codoped TiO2 at different atomic percentages and calcination temperatures (350 and 400 °C). Borane tert-butylamine complex was used as a novel precursor for the dopant atoms. The photocatalytic activities of catalysts were evaluated for destruction of bisphenol A (BPA) spiked in clean water and in secondary treated wastewater influent (SWI) collected from the Groundwater Replenishment System GWRS (Orange County, CA, USA), the world's largest water purification system for indirect potable reuse. Results of X-ray photoelectron spectroscopy (XPS) revealed the incorporation of N and B atoms onto TiO2 lattice via substitution of O and/or Ti, and interstitial incorporation mechanisms. Carbon doping (graphite-like carbon; O-C = O) was also evidenced from XPS spectra. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) revealed pristine TiO2 and all doped TiO2 existed in anatase structure. The anatase phase of catalysts was further confirmed by simulation of selected area electron diffraction (SAED) of the catalysts and reported anatase TiO2 using the simulation software CrysTBox (v 1.10). Among all prepared catalysts, 2.0NBT-350 (N + B = 2.0%, calcination = 350 °C) possessed the smallest particle size (12.9 nm), largest BET surface area (108.5 m2/g) and highest visible-light absorption (i.e., λ > 400 nm). Simulated solar light/2.0NBT-350 system exhibited the maximum removal of BPA (0.1 μM) at the optimum catalyst dose of 0.8 g/L in clean water, over three consecutive degradation reuse cycles without any noticeable decrease in its photocatalytic activity. BPA was also successfully removed in SWI water, however with slower kinetics due to hydroxyl radical quenching effect of dissolved organic and inorganic species present in the SWI matrix. Degradation byproducts were identified by LC/Q-TOF-ESI-MS analysis. Six byproducts were found in the reaction mixture, with two compounds were newly identified in the current study. BPA oxidation routes comprised successive BPA hydroxylation, elimination of aromatic ring, ring opening, and cyclization of aliphatic compounds. This study is a promising demonstration for controlled design and synthesis of photocatalysts useful for environmental applications, especially for the treatment of BPA in wastewater effluents.

Facile synthesis of Cu/N co-doped TiO2 nanoparticles and their optical and electrical properties

In the present work, pure and copper/nitrogen (Cu/N) co-doped TiO2 nanoparticles (NPs) with various Cu concentrations have been synthesized via sol–gel route. The optical and electrical properties of the prepared pure and Cu/N-doped TiO2 NPs have been assessed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope, Brunauer, Emmett and Teller method and UV–Vis spectroscopy. The results show that the addition of suitable amounts of Cu and N content in TiO2 can alter its optical and electrical properties by extending absorption in the visible region and band gap reduction. XPS and XRD measurements suggest that some of the Ti sites are replaced by Cu atoms, while O sites are occupied by N atoms. An adequate addition of Cu/N in TiO2 could lead to smaller particle size, higher specific surface area, increased dye adsorption and retarded charge carrier recombination. An optimized 0.3 mol% Cu/N-doped sample shows a significant change in band gap value of TiO2 from 3.2 to 2.78 eV, enabling it to respond in the visible region. Hence, it can be used as a suitable alternative nanomaterial for dye-sensitized solar cell photoanode application and for photocatalysis operation as well.

Novel sol–gel synthesis of Al/N co-doped TiO2 nanoparticles and their structural, optical and photocatalytic properties

In the present investigation novel Aluminium/Nitrogen (Al/N)-codoped TiO2 nanoparticles (NPs) have been prepared via sol–gel route under mild conditions. The structural, optical, morphological and compositional properties of all the prepared samples have been characterized by X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope, Transmission Electron Microscopy, UV–Vis spectroscopy (UV–Vis) and Photoluminescence Spectroscopy (PL). XRD results reveal that the doping of Al in TiO2 nanostructure hinders its crystal growth and stabilizes the crystal structure. XPS result confirms the successful incorporation of Al and N in TiO2 structure. UV–Vis measurement shows a distinct alteration in the optical properties of TiO2 resulting in red shift i.e. lower band gap values relative to undoped TiO2 NPs. Moreover, PL spectra reveal prolonged electron–hole pair lifetime for efficient photocatalytic performance. Thus, Al/N co-doped samples exhibit enhanced absorption, retarded charge carrier recombination and hence excellent photocatalytic activity for degradation of methylene blue (MB) solution under visible light irradiation. A sample doped with 2 wt% Al/N-doped TiO2 NPs shows best photocatalytic activity among all other samples.

Synthesis of silver and sulphur codoped TiO2 nanoparticles for photocatalytic degradation of methylene blue

In the present work, silver and sulphur codoped TiO2 (Ag–S/TiO2) photocatalysts were effectively prepared by sol–gel technique. The prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray analysis (EDX), Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance UV–Vis spectroscopy (UV-DRS) and photoluminescence (PL). The XRD patterns consisted of anatase crystalline phases and the particle size and shape of the prepared samples were observed by SEM and HR-TEM. The presence of doping ions was confirmed by EDX analysis, the decreased band-gap energy of Ag–S codoped TiO2 nanoparticles was investigated by UV-DRS. The decreased in the intensity of Ag–S codoped TiO2 was absorbed due to the lower separation of electron–hole pairs were confirmed by PL spectrum. The Ag–S codoped TiO2 showed higher photocatalytic activity than pure and single-doped TiO2 in the photodegradation of methylene blue (MB) aqueous solution under visible light irradiation. The given work was a good model to associate the considering of the synergistic effect of metal and non-metal codoped TiO2 in the photocatalysis and photo electrochemistry.

Novel synergistic combination of Al/N Co-doped TiO2 nanoparticles for highly efficient dye-sensitized solar cells

The present investigation reports the sol-gel synthesis of novel Aluminium/Nitrogen (Al/N)-codoped TiO2 nanoparticles (NPs) and their successful incorporation in dye-sensitized solar cells (DSSCs). The impact of Al doping on the operation of Al/N-doped TiO2 DSSCs has been systematically investigated by varying Al content, while keeping N content constant. The prepared samples have been examined for their crystallite size, surface morphology, chemical state, surface area, optical response and electrical response using various characterization techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–Visible spectroscopy (UV–Vis), Scanning electron microscopy (SEM), Tunnelling electron microscopy (TEM) and Electrochemical impedance spectroscopy (EIS). The photovoltaic measurement of all the prepared cells has been performed using solar simulator under 100 mW cm−2 light intensity. A DSSC with 2 wt% Al/N-doped TiO2 NPs shows the best power conversion efficiency (PCE) of 11.08% about 40.78% enhancement in the PCE relative to Degussa P25 based DSSC. The experimental results show that an adequate inclusion of Al and N in TiO2 nanostructure lead to smaller particle size, stabilized structure, increased specific surface area, elevated dye loading, smooth charge carrier separation, enhanced short circuit current density (Jsc) and hence improved PCE of DSSC.

Visible light photocatalytic activity of tungsten and fluorine codoped TiO2 nanoparticle for an efficient dye degradation

Tungsten and fluorine codoped TiO2 (W, F-TiO2) nanoparticles were synthesis by sol-gel method. The XRD analysis shows that all the samples existed as anatase phase of TiO2. Also, the crystalline size of codoped TiO2 is decreasing than the pure and monodoped TiO2. TEM images indicate that grain size of pure and codoped TiO2 nanoparticles are in the range of 15–22 and 6–14 nm, respectively. Band gap of codoped TiO2 nanoparticles showed narrowing (2.85 eV) when compared to monodoped TiO2 (3.02 and 2.97 eV) and pure (3.16 eV) nanoparticles. The observed lower intensity from PL study in the codoped TiO2 sample than that in other TiO2 samples indicated that the recombination of photoinduced electrons and holes in TiO2 could be effectively inhibited in the W and F ions. The codoped TiO2 exhibited the highest photocatalytic activity under visible light compared with other TiO2. The codoped TiO2, great visible light absorption is produced by the formation of impurity energy states near both the band edges which also act as both the photogenerated charges to diminish the recombination process.

Enhancement of Ce/Cr Codopant Solubility and Chemical Homogeneity in TiO2 Nanoparticles through Sol-Gel versus Pechini Syntheses.

Ce/Cr codoped TiO2 nanoparticles were synthesized using sol-gel and Pechini methods with heat treatment at 400 °C for 4 h. A conventional sol-gel process produced well-crystallized anatase, while Pechini synthesis yielded less-ordered mixed-phase anatase + rutile; this suggests that the latter method enhances Ce solubility and increases chemical homogeneity but destabilizes the TiO2 lattice. Greater structural disruption from the decomposition of the Pechini precursor formed more open agglomerated morphologies, while the lower levels of structural disruption from pyrolysis of the dried sol-gel precursor resulted in denser agglomerates of lower surface areas. Codoping and associated destabilization of the lattice reduced the binding energies in both powders. Cr4+ formation in sol-gel powders and Cr6+ formation in Pechini powders suggest that these valence changes derive from synergistic electron exchange from intervalence and/or multivalence charge transfer. Since Ce is too large to allow either substitutional or interstitial solid solubility, the concept of integrated solubility is introduced, in which the Ti site and an adjacent interstice are occupied by the large Ce ion. The photocatalytic performance data show that codoping was detrimental owing to the effects of reduced crystallinity from lattice destabilization and surface area. Two regimes of mechanistic behavior are seen, which are attributed to the unsaturated solid solutions at lower codopant levels and supersaturated solid solutions at higher levels. The present work demonstrates that the Pechini method offers a processing technique that is superior to sol-gel because the former facilitates solid solubility and consequent chemical homogeneity.

Sol–gel synthesis of Sn/Fe co-doped TiO2 nanoparticles: study of structural, optical and photocatalytic properties

Titanium dioxide (TiO2) nanoparticles co-doped with tin and iron cations were synthesized using a simple sol–gel method with titanium(IV) tetra isopropoxide, tin(II) chloride dihydrate and iron(III) chloride hexahydrate as precursor materials. Different samples of Sn and Fe co-doped TiO2 nanoparticles (3, 5, 7 wt% Sn and 3, 5, 7 wt% Fe) were prepared. The effect of co-dopant on structural, optical, photocatalytic, and morphological properties of doped TiO2 nanoparticles were studied by X-ray diffraction (XRD), UV–Vis absorption spectroscopy, scanning electron microscopy, and transmission electron microscopy. Surface chemical state of nanoparticle was thoroughly examined by atomic X-ray photoelectron spectroscopy. XRD results showed the formation of TiO2 anatase phase in all samples. UV–Vis spectra showed that Sn/Fe co-doped TiO2 nanoparticles showed a decrease in the band gap energy (Eg) relative to undoped TiO2 sample. Thus, co-doped samples showed enhanced absorption at visible region and exhibited excellent photocatalytic activity for degradation of methylene blue solution under visible irradiation. 5 wt% Sn + 5 wt% Fe sample showed better photocatalytic activity than others samples.

Mg-La Co-Doped TiO<sub>2</sub> as Compact Layer for High Efficient Dye-Sensitized Solar Cells

A compact layer of TiO2, between FTO and mesoporous TiO2 layer of DSSC anode, has the ability to reduce the electron recombination while mesoporous TiO2 layer functions to collect and transport electrons injected by the photoexcited dye. In enhancing the desired functions of compact and mesoporous TiO2, we study the effects of co-doping it with Mg, Eu, and La. MgLa co-doped TiO2 as compact layer has demonstrated higher efficiency due to its increased oxygen vacancies and smaller particle size which results reduced recombination. The combination of pure and co-doped TiO2 nanoparticles to be selected as either compact or mesoporous layer of DSSC anode depends on their respective properties, as demonstrated in this paper.

DFT, Experimental and Photocatalytic Efficiency of CoCl2 and CoCl2-Thiourea Codoped TiO2 Nanoparticles

Density Functional Theory (DFT) gives greater idea about the electronic behaviour of molecules. In this work TiO 2 (TTDO) nano particles doped with CoCl 2 (CCT) and CoCl 2 -thiourea codoped (CCTT) were studied by DFT, synthesis, characterisation and photo degrading efficiency for Acid Orange 7 dye. The computations were performed using B3LYP/631G** in gas phase at 25 °C. Important parameters like bond length, bond order, bond angle, dihedral angle, charge density, dipole moment and molecular orbitals were studied using computation. It was found that the photo degrading ability of CCT and CCTT were increased over TTDO due to doping. This may be due to the enhanced electron density on the Ti atom of CCT and CCTT over TTDO. Further the higher dipole moment and narrow band gap of CCT and CCTT were responsible for their higher photo catalytic activity. As a whole the electronic effect governs the higher photocatalytic activity of the CCT and CCTT over TTDO.

Enhanced photovoltaic performance of a dye sensitized solar cell with Cu/N Co-doped TiO2 nanoparticles

Pure and Copper/Nitrogen (Cu/N)-codoped TiO2 photoanodes with various Cu concentrations are prepared via sol–gel route for the photoanode application in dye-sensitized solar cells (DSSCs). All the prepared samples are characterized by X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), UV–Vis spectroscopy (UV–VIS) and Electrochemical Impedance Spectroscopy (EIS). Addition of suitable amount of Cu and N content in TiO2 can alter its optical and electrical properties by extending absorption in the visible region and band gap reduction. The results show that some of the Ti sites are replaced by Cu atoms while O sites are occupied by N atoms. Upon adequate addition of Cu/N could lead to smaller particle size, higher specific surface area, increased dye adsorption and retarded charge carrier recombination. A significant improvement in the power conversion efficiency is observed in case of optimized 0.3 mol% Cu/N-doped TiO2 nanoparticles (NPs) based DSSC. This optimized 0.3 mol% Cu/N-doped photoanode accomplished a best power conversion efficiency of 11.70% with a short circuit current density of 23.41 mA cm−2 which is 41% higher than that of the pure TiO2 photoanode based DSSC (6.82%).

Structural and magnetic study of undoped and cobalt doped TiO2 nanoparticles.

The present study investigates the influence of cobalt doping on the structural and magnetic properties of TiO2 nanoparticles prepared by a simple wet chemical method. The single phase anatase structure of Co-doped TiO2 nanoparticles was confirmed by X-ray powder diffraction. A morphological study using scanning electron microscopy and transmission electron microscopy indicates the formation of TiO2 nanoparticles of sizes 6–10 nm. The high resolution TEM image shows clear lattice fringes indicating the highly crystalline nature of the nanoparticles which was further analysed by selected area electron diffraction pattern which indicates a polycrystalline nature of anatase TiO2. The shifting and broadening of the most intense Eg (1) mode in micro-Raman study of Co-doped TiO2 nanoparticles and XPS spectra indicate the incorporation of Co in TiO2. Magnetic measurement shows ferromagnetic behavior at room temperature in undoped TiO2 which has originated due to the presence of oxygen vacancies which are intrinsic in nature. But the M–H curve of Co-doped TiO2 shows the coexistence of ferromagnetic and paramagnetic phases with enhanced magnetization. The enhancement in magnetization has arisen due to Co doping and the paramagnetism may be due to the presence of some undetected clusters of oxides of cobalt.

Nitrogen and Fluorine Codoped, Colloidal TiO2 Nanoparticle: Tunable Doping, Large Red-Shifted Band Edge, Visible Light Induced Photocatalysis, and Cell Death.

Visible light photocatalysis by TiO2 requires efficient doping of other elements with red-shifted band edge to the visible region. However, preparation of such TiO2 with tunable doping is challenging. Here we report a method of making nitrogen (N) and fluorine (F) codoped TiO2 nanoparticle with tunable doping between 1 and 7 at. %. The preparation of N, F codoped TiO2 nanoparticle involves reaction of colloidal TiO2 nanorods with an ammonium fluoride-urea mixture at 300 °C, and the extent of N/F doping is tuned by varying the amount of ammonium fluoride-urea and the reaction time. Resultant colloidal N, F codoped TiO2 nanoparticles show doping dependent shifting of the band edge from the UV to near-IR region, visible light induced generation of reactive oxygen species (ROS), and visible light photodegradation of bisphenol A. A colloidal form of doped TiO2 nanoparticle offers labeling of cells, visible light induced ROS generation inside a cell, and successive cell death. This work shows the potential advantage of anisotropic nanoparticle precursor for tunable doping and colloidal form of N, F codoped TiO2 nanoparticle as a visible light photocatalyst.

Structural, optical and weak magnetic properties of Co and Mn codoped TiO2 nanoparticles

The present investigation focuses on the structural properties and magnetic response of Co, Mn and Co-Mn doped TiO2 nanoparticles (within 3% dilute doping) along with their optical and electrical studies. X-ray diffraction (XRD) patterns for all these samples show the formation of tetragonal TiO2 anatase phase with no extra impurity phases. Further, Raman bands at 143 cm−1, 396 cm−1, 516 cm−1 and 639 cm−1 also confirm the anatase phase in these samples. Diamagnetic response has been observed in pure TiO2 nanoparticles. However, room temperature (RT) ferromagnetism has been observed with Co and/or Mn doping which gets enhanced further with codoping of Co ions. The observed ferromagnetism has been attributed to the formation of shallow levels with doping/codoping. The Co and/or Mn-doped TiO2 nanoparticles are referred as diluted magnetic semiconductors due to their combined semiconducting and ferromagnetic response. UV-Vis spectra show the band gap of these samples are in the range of 3.03 eV–3.24 eV and a reduction in band gap is observed after codoping. The temperature dependent electrical conductivity measurements also show an enhancement in conductivity after codoping at RT.

Preparation of cerium and sulfur codoped TiO2 nanoparticles based photocatalytic activity with enhanced visible light

Abstract In this work, the preparation and characterization of Titanium dioxide (TiO 2 ) codoped with Cerium (Ce) and Sulfur (S) elements was prepared by a hydrothermal method and their photocatalytic activities have been examined. The attained catalysts were characterized by TEM, XRD, BET, FT-IR and UV–vis DRS measurements for investigating nanostructure, crystal phase, band gap and light-harvesting properties of these samples, respectively. The codoping strategy was approved to decrease together the band gap of TiO 2 and the recombination rate of the photo-generated electron-hole pairs. Low concentration doping and codoping with Ce and S with anatase phase in TiO 2 nanoparticle from the XRD studies. UV-DRS indicate that the band gap of TiO 2 (3.2 eV) reduced to 3.02 eV, 2.89 eV and 2.82 eV, by Ce-doping, S-doping and Ce-S codoping, respectively. The Photocatalytic performance of the samples was tested using the degradation of Methyl Orange (MO) as a function of time. It was observed that the codoped TiO 2 provided the highest photocatalytic activity in comparison to the mono-doped and pure TiO 2 since of high visible light absorption and likely reduction in the recombination of photo-generated charges. It is decided that for the codoped TiO 2 , great visible light absorption is produced by the formation of impurity energy states near both the band edges which also act as the trapping sites for both the photo-generated charges to diminish the recombination process.

Polysulfone/N,Pd co-doped TiO2 composite membranes for photocatalytic dye degradation

Hybrid multifunctional membranes capable of simultaneously performing photocatalysis and filtration can lead to improved water treatment processes. Transparent polymeric membranes exhibiting two surfaces that can come directly into contact with the polluted water can be desirable candidates for photocatalyst deposition. Different proportions of N,Pd co-doped TiO2 were embedded in a PSf polymeric membrane through the phase inversion method and the membrane evaluated for the degradation of a dye (eosin yellow) under visible light irradiation. The synthesised hybrid membranes were characterised by FTIR, Raman Spectroscopy, DRUV-Vis, SEM, EDS, XRD, AFM, SAXSpace and Contact angle measurements. Anatase type N,Pd co-doped TiO2 nanoparticles were successfully entrapped in the PSf membrane through a simple phase inversion method. Addition of TiO2 to the PSf membrane led to improved membrane porosity, wettability and visible light activity while membrane integrity was maintained. Higher TiO2 loadings resulted in increased membrane roughness and particle aggregation of the embedded TiO2. Up to 92% dye degradation was realised with the 7% N,Pd TiO2/PSf nanocomposite membrane after 180 min of visible light irradiation. Degradation kinetics followed a pseudo first order model, evidence of possible changes in the membrane properties upon irradiation with simulated solar radiation. Solar active photocatalytic membranes fabricated through embedding doped TiO2 nanoparticles are promising candidates for low energy water purification in marginalised rural communities.

Titanium mesh supported TiO2 nanowire arrays/upconversion luminescence Er3+-Yb3+ codoped TiO2 nanoparticles novel composites for flexible dye-sensitized solar cells

Ti-mesh supported TiO2 nanowire arrays (NWAs)/upconversion luminescence Er3+-Yb3+ codoped TiO2 nanoparticles (UC-EY-TiO2 NPs) composite structured photoanodes for fully flexible dye sensitized solar cells (DSSCs) were firstly constructed via a hydrothermal and spin coating process. UV–vis-NIR absorption spectra of the TiO2 NWAs/UC-EY-TiO2 NPs composites exhibited strong absorption around near infrared (NIR) 980nm. The composites excited by 980nm NIR laser could emit upconversion fluorescence at 489, 526, 549 and 658nm, which expanded the spectral response range and sunlight capturing capability of formed flexible DSSCs. Moreover, the TiO2 NWAs/UC-EY-TiO2 NPs was coated with an Nb2O5 thin layer to further suppress electron recombination losses. The complete flexible DSSCs based on Nb2O5 coated TiO2 NWAs/2.0mol% Er3+-1.0mol% Yb3+ codoped TiO2 NPs photoanode and Pt/ITO-PEN counter electrode exhibited an enhanced photon to current conversion efficiency of 8.10%, a 68% improvement compared to TiO2 NWAs/undoped TiO2 NPs based DSSCs (4.82%).

Photocatalytic degradation of 2,4-dichlorophenol by Co-doped TiO2 (Co/TiO2) nanoparticles and Co/TiO2 containing mixed matrix membranes

Chlorophenols are special groups of organic pollutants which are widespread in water and soil sources. Advanced oxidation processes (AOPs) appear to be well-established techniques for degradation of chlorophenols. In this research, TiO2 nanoparticles containing different amounts of cobalt, Co/TiO2, (as AOP photocatalysts) were synthesized by sol-gel method and characterized by FTIR, XRD, SEM and DRS analysis. According to the XRD patterns, pure TiO2 and Co/TiO2 samples are in anatase phase. According to DRS results, the presence of cobalt in TiO2 lattice shifted the absorption edge to higher wavelengths (red shift) and Co/TiO2 exhibited the higher photocatalytic activity under visible light. The best degradation performance was achieved when TiO2 nanoparticles containing 1.34mol% −Co (Co/TiO2 (1.34)) was used as photocatalyst for 2,4-dichlorophenol (2,4-DCP) degradation under visible light irradiation. Photocatalytic mixed matrix membranes (MMMs) containing Co/TiO2 (1.34) were fabricated by phase inversion technique and the effect of these nanoparticles on separation, thermal and morphological properties of polymeric (here polyethersulfone (PES)) membranes was investigated by using FESEM, DSC and photocatalytic permeation experiments respectively. Permeation test results showed that addition of Co/TiO2 (1.34) to PES matrix can improve both flux and rejection percent of the resulting membrane. It was found that addition of 1wt.% Co/TiO2 (1.34) to PES matrix can increase membrane flux and 2,4-DCP rejection percent (under visible light) by 53% and 25.3% respectively in which a nearly 2,4-DCP free solution is achievable in permeate site. Therefore fabricated photocatalytic mixed matrix membranes containing Co/TiO2 nanoparticles are suitable for photocatalytic separation of 2,4-DCP.