Treatment of textile wastewaters by solar-driven advanced oxidation processes

Heterogeneous (TiO₂/UV, TiO₂/H₂O₂/UV) and homogenous (H₂O₂/UV, Fe²⁺/H₂O₂/UV) solar advanced oxidation processes (AOPs) are proposed for the treatment of recalcitrant textile wastewater at pilot-plant scale with compound parabolic collectors (CPCs). The textile wastewater presents a lilac colour, with a maximum absorbance peak at 516 nm, high pH (pH = 11), moderate organic content (DOC = 382 mg C L⁻¹, COD = 1020 mg O₂ L⁻¹) and high conductivity (13.6 mS cm⁻¹), associated with a high concentration of chloride (4.7 g Cl⁻ L⁻¹). The DOC abatement is similar for the H₂O₂/UV and TiO₂/UV processes, corresponding only to 30% and 36% mineralization after 190 kJ_UV L⁻¹. The addition of H₂O₂ to TiO₂/UV system increased the initial degradation rate more than seven times, leading to 90% mineralization after exposure to 100 kJ_UV L⁻¹. All the processes using H₂O₂ contributed to an effective decolourisation, but the most efficient process for decolourisation and mineralization was the solar-photo-Fenton with an optimum catalyst concentration of 100 mg Fe²⁺ L⁻¹, leading to 98% decolourisation and 89% mineralization after 7.2 and 49.1 kJ_UV L⁻¹, respectively. According to the Zahn-Wellens test, the energy dose necessary to achieve a biodegradable effluent after the solar-photo-Fenton process with 100 mg Fe²⁺ L⁻¹ is 12 kJ_UV L⁻¹.     

Highly efficient Zr-substituted catalysts CuZnAl1−xZrxO used for hydrogen production via dimethyl ether steam reforming

A series of CuZnAl_1−xZr_xO catalysts with different weight ratios of ZrO₂/(Al₂O₃ + ZrO₂) were prepared by co-precipitation and used for catalytic production of hydrogen via the route of dimethyl ether steam reforming (DME SR). Multiple techniques such as N₂ physisorption, X-ray diffraction (XRD), temperature-programmed reduction by hydrogen (H₂-TPR), N₂O chemisorption and X-ray absorption fine structure (XAFS, including XANES and EXAFS) were employed for catalyst characterization. It is found that the relative contents of Al and Zr greatly influence the catalytic performance of the catalysts including DME conversion, H₂ yield and CO/CO₂ selectivity. The catalyst CuZnAl_0.8Zr_0.2O shows not only the highest DME conversion but also the highest H₂ yield in the whole reaction temperature region of 300–425 °C. Poorly crystallized CuO and ZnO phases were identified by XRD for CuZnAl_1−xZr_xO catalysts. The crystallinity of them increases with the decrease of Al content. The partial substitution of Al by Zr improves both the reducibility and the dispersion of copper species as revealed by H₂-TPR results. The N₂O chemisorption and Cu K-edge XAFS results conformably indicate that the Cu species in CuZnAl_0.8Zr_0.2O possesses the highest dispersion. In addition, after used in DME SR reaction, the catalyst CuZnAl_0.8Zr_0.2O possesses the highest Cu⁺/Cu⁰ ratio, as calculated by Cu K-edge XANES fitting. The lowest CO selectivity during DME SR over this catalyst is highly related to the highest Cu⁺/Cu⁰ ratio.     

Kinetic study of formic acid oxidation on carbon supported Pd electrocatalyst

The oxidation of formic acid at the Pd/C catalyst electrode is a completely irreversible kinetic process with the reaction order of 1.0. The oxidation rate of formic acid is increased with increasing the concentration of formic acid and is decreased with increasing H⁺ concentration. The apparent negative reaction order with respect to H⁺ is about −0.18 or −0.04 in H₂SO₄ or HClO₄ solution respectively, because bisulfate anions would inhibit formic acid oxidation at some extent. The kinetic parameters, charge transfer coefficient and the diffusion coefficient of formic acid were obtained under the quasi steady-state conditions.     

A study on lithium/air secondary batteries—Stability of NASICON-type glass ceramics in acid solutions

The stability of a NASICON-type lithium ion conducting solid electrolyte, Li_1+x+yTi_2−xAl_xP_3−ySi_yO₁₂ (LTAP), in acetic acid and formic acid solutions was examined. XRD patterns of the LTAP powders immersed in 100% acetic acid and formic acid at 50 °C for 4 months showed no change as compared to the pristine LTAP. However, the electrical conductivity of LTAP drastically decreased. On the other hand, no significant electrical conductivity change of LTAP immersed in lithium formate saturated formic acid-water solution was observed, and the electrical conductivity of LTAP immersed in lithium acetate saturated acetic acid-water increased. Cyclic voltammogram tests suggested that acetic acid was stable up to a high potential, but formic acid decomposed under the decomposition potential of water. The acetic acid solution was considered to be a candidate for the active material in the air electrode of lithium-air rechargeable batteries. The cell reaction was considered as 2Li + 2 CH₃COOH + 1/2O₂ = 2CH₃COOLi + H₂O. The energy density of this lithium-air system is calculated to be 1477 Wh kg⁻¹ from the weights of Li and CH₃COOH, and an observed open-circuit voltage of 3.69 V.     

Significant improvement of photocatalytic hydrogen generation rate over TiO2 with deposited CuO

TiO₂ photocatalyst with deposited CuO (CuO-TiO₂) was synthesized by the impregnation method using P25 (Degussa) as support, and exhibited high photocatalytic hydrogen generation activity from methanol/water solution. A substantial hydrogen evolution rate of 10.2 ml min⁻¹ (18,500 μmol h⁻¹ g⁻¹_catalyst) was observed over this efficient CuO-TiO₂ with optimal Cu content of 9.1 mol% from an aqueous solution containing 10 vol% methanol; this improved hydrogen generation rate is significantly higher than the reported Cu-containing TiO₂, including some Pt and Pd loaded TiO₂. Optimal Cu content of 9.1 mol% provided maximum active sites and allowed good light penetration in TiO₂. Over this efficient CuO-TiO₂, the hydrogen generation rate was accelerated by increasing the methanol concentration according to Freundlich adsorption isotherm. However, the photocatalytic hydrogen generation rate was suppressed under long time irradiation mainly due to accumulation of by-products, reduction of CuO and copper leaching, which requires further investigation.     

Synthesis of reduced graphene oxide–TiO2 nanoparticle composite systems and its application in hydrogen production

The utilization of solar energy for the conversion of water to hydrogen and oxygen has been considered to be an efficient strategy to solve crisis of energy and environment. Here, we report the synthesis of reduced graphene oxide–TiO₂ nanoparticle composite system through the photocatalytic reduction of graphite oxide using TiO₂ nanoparticles. Photoelectrochemical characterizations and hydrogen evolution measurements of these nanocomposites reveal that the presence of graphene enhances the photocurrent density and hydrogen generation rate. The optimum photocurrent density and hydrogen generation rate has been found to be 3.4 mA cm⁻² and 127.5 μmole cm⁻²h⁻¹ in 0.5 M Na₂SO₄ electrolyte solution under 1.5AM solar irradiance of white light with illumination intensity of 100 mW cm⁻². In graphene–TiO₂ nanocomposite, photogenerated electrons in TiO₂ are scavenged by graphene sheets and percolate to counter electrode to reduce H⁺ to molecular hydrogen thus increasing the performance of water-splitting reaction.     

Decontamination of cork wastewaters by solar-photo-Fenton process using cork bleaching wastewater as H2O2 source

This paper reports on a treatment strategy of cork wastewaters through the design of a solar-photo-Fenton process using cork bleaching wastewater as hydrogen peroxide (H₂O₂) source, as a pre-oxidation step, before a conventional biological oxidation process. This method proved to be efficient, achieving mineralization rates higher than 90% for different iron concentrations (20-80 mg Fe L⁻¹). Higher iron concentrations resulted in the lower energy consumption and 60 mg Fe L⁻¹ was selected as the optimum dose for 91% mineralization and used for biodegradability studies. According to the Zahn-Wellens test, the optimum phototreatment energy to achieve a biodegradable effluent is 13.6 kJ_UV L⁻¹ (65% mineralization), which corresponds to H₂O₂ consumption of 76.1 mM (approximately 8.5 L of cork bleaching wastewater (at 7.7 g H₂O₂ L⁻¹) for 15 L of cork boiling wastewater).     

Synthesis of highly-ordered TiO2 nanotubes for a hydrogen sensor

Highly-ordered, vertically oriented TiO₂ nanotubes are synthesized, and their hydrogen sensing properties are investigated. Self-organized TiO₂ nanotube arrays are grown by anodic oxidation of a titanium foil in an aqueous solution that contains 1 wt% hydrofluoric acid at 20 °C. We use a potential ramp at a rate of 100 mV s⁻¹, increasing from the initial open-circuit potential (OCP) to 20 V, and this final potential of 20 V is then held constant during the anodization process. The fabricated TiO₂ nanotubes are approximately 1 μm in length and 90 nm in diameter. For the sensor measurements, two platinum pads are used as electrodes on the TiO₂ nanotube arrays. The hydrogen sensing characteristics of the sensor are analyzed by measuring the sensor responses ((I − I₀)/I₀) in the temperature interval of 20–150 °C. We find that the sensitivity of the sensor is approximately 20 for 1000 ppm H₂ exposure at room temperature, and increases with increasing temperature. The sensing mechanism of the TiO₂ nanotube sensor could be explained with chemisorption of H₂ on the highly active nanotube surface.     

Visible light photocatalytic water splitting for hydrogen production from N-TiO2 rice grain shaped electrospun nanostructures

We report on the visible light-driven hydrogen production from splitting of water molecules by nitrogen-doped TiO₂ (N-TiO₂) with a rice grain-like nanostructure morphology. The N-TiO₂ nanostructures are prepared using sol-gel and electrospinning methods followed by post-annealing of the composite nanofibers. The nanostructures are characterized by microscopy and spectroscopy. First order rate constants for the visible light-assisted photocatalysis in the degradation of methylene blue (MB) dye are found to be 0.2 × 10⁻³ and 1.8 × 10⁻³ min⁻¹ for TiO₂ and N-TiO₂ (5 wt% of nitrogen), respectively. The N-TiO₂ utilized in water splitting experiments and evaluated hydrogen (H₂) of 28 and 2 μmol/h for N-TiO₂ and TiO₂, respectively. The improvement may be attributed due to the N-doping and higher surface area as ∼70 m²/g.     

Electrolytic Sn/Li2O coatings for thin-film lithium ion battery anodes

Sn/Li₂O composite coatings on stainless steel substrate, as anodes of thin-film lithium battery are carried out in SnCl₂ and LiNO₃ mixed solutions by using cathodic electrochemical synthesis and subsequently annealed at 200 °C. Through cathodic polarization tests, three major regions are verified: (I) O₂ + 4H⁺ + 4e⁻ → 2H₂O (∼0.25 to −0.5 V), (II) 2H⁺ + 2e⁻ → H₂, Sn²⁺ + 2e⁻ → Sn, and NO₃⁻ + H₂O + 2e⁻ → NO₂⁻ + 2OH⁻ (−0.5 to −1.34 V), and (III) 2H₂O + 2e⁻ → H₂ + 2OH⁻ (−1.34 to −2 V vs. Ag/AgCl). The coated specimens are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and charge/discharge tests. The nano-sized Sn particles embedded in Li₂O matrix are obtained at the lower part of region II such as −1.2 V, while the micro-sized Sn with little Li₂O at the upper part, such as −0.7 V. Charge/discharge cycle tests elucidated that Sn/Li₂O composite film showed better cycle performance than Sn or SnO₂ film, due to the retarding effects of amorphous Li₂O on the further aggregation of Sn particles. On the other hand, the one tested for cut-off voltage at 0.9 V (vs. Li/Li⁺) is better than those at 1.2 and 1.5 V since the incomplete de-alloy at lower cut-off voltage may inhibit the coarsening of Sn particles, revealing capacity 587 mAh g⁻¹ after 50 cycle, and capacity retention ratio C50/C2 81.6%, higher than 63.5% and 49.1% at 1.2 and 1.5 V (vs. Li/Li⁺), respectively.     

CuCr2O4/TiO2 heterojunction for photocatalytic H2 evolution under simulated sunlight irradiation

CuCr₂O₄/TiO₂ heterojunction has been successfully synthesized via a facile citric acid (CA)-assisted sol-gel method. Techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis diffuse reflectance spectrum (UV-vis DRS) have been employed to characterize the as-synthesized nanocomposites. Furthermore, photocatalytic activities of the as-obtained nanocomposites have been evaluated based on the H₂ evolution from oxalic acid solution under simulated sunlight irradiation. Factors such as CuCr₂O₄ to TiO₂ molar ratio in the composites, calcination temperature, photocatalyst mass concentration, and initial oxalic acid concentration affecting the photocatalytic hydrogen producing have been studied in detail. The results showed that the nanocomposite of CuCr₂O₄/TiO₂ is more efficient than their single part of CuCr₂O₄ or TiO₂ in producing hydrogen. The optimized composition of the nanocomposites has been found to be CuCr₂O₄·0.7TiO₂. And the optimized calcination temperature and photocatalyst mass concentration are 500 °C and 0.8 g l⁻¹, respectively. The influence of initial oxalic acid concentration is consistent with the Langmuir model.     

Inactivation of Clostridium perfringens spores and vegetative cells by photolysis and TiO2 photocatalysis with H2O2

Due to public health concerns related to the generation of dangerous by-products from conventional systems of water disinfection, innovative technologies based on the generation of oxidant radicals are being developed. The aim of this work is to evaluate the bactericidal activity of different treatments with light (λ: 320-800 nm), TiO₂ (1 g L⁻¹) and H₂O₂ (0.04 mM) on the viability of vegetative cells and spores of Clostridium perfringens. After spiking a natural water sample (from the Ebro River, Zaragoza (Spain)), the population of vegetative cells was of 10⁸ CFU·100 mL⁻¹ and of spores about 10³ CFU·100 mL⁻¹. Treatments without radiation source (TiO₂, H₂O₂, TiO₂/H₂O₂) show a poor level of inactivation (<0.5 log) on both bacterial forms. The light treatment achieves a vegetative cell inactivation of 1.2 log after 5 min of treatment and <0.5 log on spores after 30 min. The combined light/TiO₂ system increases the level of disinfection with a vegetative cell removal in the order of 6 log after 5 min and 0.6 log of spores after 5 min. Light/H₂O₂ and light/TiO₂/H₂O₂ treatments also significantly increase the disinfection of vegetative cells of C. perfringens (>6 log). Regarding spores, light/H₂O₂ and light/TiO₂/H₂O₂ treatments achieve constant inactivation of 1 log after 5 min of treatment. The application of a light/TiO₂/H₂O₂ treatment does not increase the level of inactivation with regard to the level reached by the light/TiO₂ and light/H₂O₂ systems. This fact shows there is no a significant interaction between TiO₂ and H₂O₂ under the conditions studied.     

Cobalt sulfide quantum dots modified TiO2 nanoparticles for efficient photocatalytic hydrogen evolution

Cobalt sulfide quantum dots (CoSx QDs) modified TiO₂ nanoparticles are prepared with a precipitation-deposition method using TiO₂, cobalt acetate and sodium sulfide as the precursors. CoSx QD acts as an effective cocatalyst, which accelerates the transfer of the photo-generated electrons and serves as the active site for the reaction between electrons and H₂O, thus enhancing the separation of the e⁻/h⁺ pairs and the photocatalytic H₂ production activity of TiO₂. The amount of CoSx exhibits an optimum value at about 5% (mole ratio to TiO₂), at which the H₂ production rate achieves 838 μmol h⁻¹ g⁻¹ using ethanol as the sacrificial reagent. This exceeds that of the pure TiO₂ by more than 35 times.     

Effective water splitting using N-doped TiO2 films: Role of preferred orientation on hydrogen production

N-doped TiO₂ film with preferred (211) orientation, deposited by RF magnetron sputtering, was investigated for the water-splitting hydrogen production. It is found that the preferred crystal growth orientation of the films can be controlled by N₂ flow rate during the deposition. The results reveal that not only the N-doping, but also the preferred orientation (i.e., large percentage of exposed (211) facet), can effectively enhance the activity of TiO₂-based photocatalyst. With the increase of exposed (211) facets, the hydrogen production rates of N-doped TiO₂ films rise from 760 μmol H₂ h⁻¹ m⁻² to 4500 μmol H₂ h⁻¹ m⁻², indicating that high performance of TiO₂-based photocatalyst can be achieved by controlling the preferred orientation of the films.     

Light fermentation of dark fermentation effluent for bio-hydrogen production by different Rhodobacter species at different initial volatile fatty acid (VFA) concentrations

Three different Rhodobacter sphaeroides (RS) strains (RS–NRRL, RS–DSMZ and RS–RV) and their combinations were used for light fermentation of dark fermentation effluent of ground wheat containing volatile fatty acids (VFA). In terms of cumulative hydrogen formation, RS–NRRL performed better than the other two strains producing 48 ml H₂ in 180 h. However, RS–RV resulted in the highest hydrogen yield of 250 ml H₂ g⁻¹ TVFA. Specific hydrogen production rate (SHPR) with the RS–NRRL was also better in comparison to the others (13.8 ml H₂ g⁻¹ biomass h⁻¹). When combinations of those three strains were used, RS–RV + RS–DSMZ resulted in the highest cumulative hydrogen formation (90 ml H₂ in 330 h). However, hydrogen yield (693 ml H₂ g⁻¹ TVFA) and SHPR (12.1 ml H₂ g⁻¹ biomass h⁻¹) were higher with the combination of the three different strains. On the basis of Gompertz equation coefficients mixed culture of the three different strains gave the highest cumulative hydrogen and formation rate probably due to synergistic interaction among the strains. The effects of initial TVFA and NH₄–N concentrations on hydrogen formation were investigated for the mixed culture of the three strains. The optimum TVFA and NH₄–N concentrations maximizing the hydrogen formation were determined as 2350 and 47 mg L⁻¹, respectively.     

H2 production by γ and He ions water radiolysis, effect of presence TiO2 nanoparticles

The effect of TiO₂ particles on the yield of H₂ formation under water radiolysis is measured. Irradiations were performed using a ⁶⁰Co γ−ray source as well as with He ions particles (4He2⁺) generated by a cyclotron with an external beam energy of 6 MeV. The resulting hydrogen as a stable product of radiolysis was measured by mass spectrometry. G(H₂) obtained for water radiolysis by He ions−irradiation in aerated and argon water are found to be 1.91 × 10⁻⁷ and 1.35 × 10⁻⁷ mol J⁻¹, respectively. In the presence of titanium oxide anatase−type dispersed in water, under He ions−irradiation, G(H₂) is found to increase slightly from 1.04 × 10⁻⁷ to 1.35 × 10⁻⁷ mol J⁻¹ by increasing the specific surface from 8 to 253 m²/g, respectively. Under γ-irradiation, G(H₂) is found to be 0.41 × 10⁻⁷ mol J⁻¹ close to primary yield of hydrogen in presence of OH. Radical scavenger. In addition, radiolysis of water adsorbed in the titanium oxide with low water content, which corresponds to a few layers of water sorbed onto the solid surface gives a huge values of the G(H₂). For the same amount of water, with using the dose absorbed by TiO₂ particles, for He ions-irradiation, G(H₂) increases from 14.5 × 10⁻⁷ to 35 × 10⁻⁷ mol J^-1 by increasing the surface area of TiO₂ nanoparticles from 4 to 52 m²/g, respectively. For γ−irradiation G(H₂) is found to be 5.25 × 10⁻⁷ mol J^-1 for the sample with 8 m²/g specific surface area.     

Structural properties of CuO/TiO2 nanorod in relation to their catalytic activity for simultaneous hydrogen production under solar light

CuO was introduced into porous TiO₂ nanorod through impregnation method. Before the impregnation step, TiO₂ nanorod was hydrothermally synthesized from TiO₂ powder in aqueous NaOH solution and followed by thermal treatment at 450 °C. The structures and properties of impregnated samples were characterized using various techniques, including XRD, BET, XAS, TEM, and UV-DRS. Their photocatalytic performance on simultaneous hydrogen production from pure water and aqueous methanol solution was also investigated under solar light. It was found that CuO/TiO₂ nanorod possessed a high surface area, good photocatalytic property and excellent hydrogen generation activity. Incorporation of Cu ions into the lattice framework of anatase TiO₂ nanorod enhanced the efficiency in visible region at 438–730 nm. Moreover, the XAS results showed that some Cu ions formed solid solution in the TiO₂ nanorod (Cu_xT_1−xO₂). However, the excessive incorporation of Cu ions did not improve any ability of anatase TiO₂ nanorod for production of hydrogen from pure water splitting. This could be due to the excessive CuO agglomeration at outside-pores which blocked the sensitization of TiO₂ nanorod. Only 1% Cu/TiO₂ nanorod was found to be a remarkable and an efficient photocatalyst for hydrogen production under solar light from both pure water and sacrificial methanol splitting. The highest rate of hydrogen production of 139.03 μmol h⁻¹ g_catalyst⁻¹ was found in sacrificial methanol which was 3.24% higher than in pure water.     

Pt nanoparticles deposited on TiO2 based nanofibers: Electrochemical stability and oxygen reduction activity

The electrochemical stability of Pt deposited on TiO₂ based nanofibers was compared with commercially available carbon supported Pt. Prior to the Pt deposition the TiO₂ material, which was either undoped or Nb doped, was air calcined. In one case the undoped TiO₂ was also reduced in a hydrogen atmosphere. XRD analysis revealed that the unreduced TiO₂ was present in the anatase phase, irrespective of whether the Nb dopant was present, whereas the rutile phase was formed due to reduction with H₂. The diameter of the TiO₂ fibers varied from 50 to 100 nm, and the average Pt particle diameter was approximately 5 nm. Pt supported on TiO₂ was more stable than Pt supported on C when subjected to 1000 voltammetric cycles in the range of 0.05-1.3 V vs. RHE. Nb doped TiO₂ showed the highest stability, retaining 60% of the electrochemically active surface area after 1000 cycles compared to the state after 100 cycles, whereas the carbon supported catalyst retained 20% of the active surface area. The commercial catalyst had the highest oxygen reduction activity due to its larger specific area (17.1 m² g⁻¹ vs. 5.0 m² g⁻¹ for Pt/TiO₂-Nb, measured after 100 cycles) and the higher support conductivity. The Pt supported on Nb doped or on H₂ reduced TiO₂ was more active than Pt supported on air calcined and otherwise unmodified TiO₂.     

Photo-electro-chemical chlorination of cuprous chloride with hydrochloric acid for hydrogen production

In this paper, a new photochemical cell is developed and analyzed for copper disproportionation within the Cu–Cl water splitting cycle. In the disproportionation step, cuprous chloride reacts with hydrochloric acid to generate cupric chloride and hydrogen gas. In past literature, it has been demonstrated that this reaction can be conducted electrochemically at 24 bars and 100 °C. This reaction is attractive because it generates compressed hydrogen. Consequently, the work required to compress hydrogen from standard pressure – to 350 bars for example – reduces approximately by 95%. To conduct this reaction electrochemically, the process requires electricity input. Rather than using an external supply, the method proposed in this paper drives the reaction 2CuCl(aq) + 2HCl(aq) → 2CuCl₂(aq) + H₂(g) with photonic energy derived from solar radiation. The photochemical cell comprises one photochemical and one electrochemical reactor separated by a proton conducting membrane. The electrochemical reactor is a half electrolysis cell where CuCl liquid is disproportionated with hydrochloric acid by releasing protons, according to 2CuCl(aq) + 2HCl(g) → 2CuCl₂(aq) + 2H⁺ + 2e⁻. The electrons are transferred to the second reactor by an electron-conducting media, consisting of electrodes and an external circuit. In the photochemical reactor, there are supramolecular complexes dissolved in dimethylformamide that generate multi-electrons at active sites under the influence of solar radiation and catalyze water reduction according to 2H₂O + 2e⁻ → H₂(g) + 2OH⁻. Gaseous hydrogen is collected from above the second reactor, while hydroxyl ions combine with the protons that cross the PEM to supply water according to 2OH⁻ + 2H⁺ → 2H₂O. The overall process is assisted electrically by a dye sensitized solar cell. An optical system including solar concentration, spectral splitting and an optical fibre is developed for enhanced solar energy absorption to supply thermally and electrically the Cu–Cl cycle with energy input. This paper examines the feasibility and expected efficiency of the photochemical disproportionation cell and describes the potential benefits of the thermo-photochemical water splitting process, in contrast to conventional thermochemical water splitting.     

Preparation and photocatalytic properties of HLaNb2O7/(Pt,TiO2) perovskite intercalated nanomaterial

A novel perovskite intercalated nanomaterial HLaNb₂O₇/(Pt, TiO₂) is fabricated by successive intercalated reaction of HLaNb₂O₇ with [Pt(NH₃)₄]Cl₂ aqueous solution, n-C₆H₁₃NH₂/C₂H₅OH organic solution and acidic TiO₂ colloid solution, followed by ultraviolet light irradiation. The gallery height and the band gap energy of HLaNb₂O₇/(Pt, TiO₂) is less than 0.6 nm and 3.14 eV, respectively. The photocatalytic activity of HLaNb₂O₇/TiO₂ is superior to that of unsupported TiO₂ and is enhanced by the co-incorporation of Pt. The photocatalytic hydrogen evolution based on HLaNb₂O₇/(Pt, TiO₂) is 240 cm³ h⁻¹ g⁻¹ using methanol as a sacrificial agent under irradiation with wavelength more than 290 nm from a 100-W mercury lamp. High photocatalytic activity of HLaNb₂O₇/(Pt, TiO₂) may be due to the host with rare earth La element and perovskite structure, the quantum size effect of intercalated semiconductor and the coupling effect between host and guest.