Isopropoxide Solution Research Articles

Flame synthesized tetragonal TiO2 nanoparticles for Methylene Blue and Congo Red dye removal applications

Commercially affordable titanium dioxide nanoparticles (TiO2 NPs) catalyst with low toxicity and high efficiency, were prepared by scalable Flame pyrolysis method. For this, titanium iso-propoxide solution was directly burned in air, the product in the form of white soot was collected over water cooled conical flask. The prepared nanoparticles were characterized by various sophisticated techniques viz. UV–Visible, FTIR, XRD, SEM, EDS and TEM. The SEM, TEM and Zeta Potential Analyzer illustrated spherical morphology of the synthesized TiO2 NPs with an average size of about 150 nm. The XRD confirmed formation of prominently dominated anatase phase co-existed with traces of rutile phase. The combination of anatase and rutile phase exhibited increased catalytic activity for removal of dyes. The flame synthesized TiO2 nanoparticles exhibited strong dye removal efficiency of 97.64 % for Methylene Blue and 92.39 % for Congo Red dyes respectively, making it vitally important for the waste water treatment and industrial dyes removal applications. Probable dye degradations mechanism on the surface of TiO2 NPs also proposed based on the LCMS results.

Characterization and photocatalytic activity of TiO2 nanoparticles on cotton fabrics, for antibacterial masks.

The in-situ impregnation of two commercial cotton fabrics (lab coat and Indiolino) with TiO2 nanoparticles (TiO2-NPs) was carried out. For this, two commercial cotton fabrics were dipped in titanium isopropoxide, titanium butoxide and titanium tetrachloride solutions to the TiO2-NPs formation and in-situ TiO2-NPs impregnation on the cotton fabric surface by the sonochemical, hydrothermal and solvothermal methods, respectively. The impregnated fabrics were characterized by ATR-FTIR, SEM–EDS, Raman, UV–Vis, DRS and tension tests. The results showed the successful formation and impregnation of TiO2-NPs on both cotton fabrics. The leaching of TiO2-NPs from cotton fabrics was negligible after several washing cycles. The self-cleaning properties and antibacterial activity of TiO2-NPs functionalized cotton fabrics were assessed by photocatalytic and antibacterial tests. The photocatalytic activity was determined by the degradation of methylene blue dye under UV and solar irradiation. The materials showed good photoactivity, since MB was degraded up to 99% under solar and UV irradiations in 60 min. The bactericidal capacity of the TiO2-NPs on fabrics, evaluated in-situ by SEM, showed that Indiolino presented the best antibacterial properties against Escherichia coli and Bacillus pumilus.

Growth of out-of-plane standing MoTe2(1-x)Se2x/MoSe2 composite flake films by sol–gel nucleation of MoOy and isothermal closed space telluro-selenization

This study describes the sol–gel processing of MoOy on Si (100) to subsequently achieve out-of-plane MoTe2/MoSe2 flake composite films by an isothermal closed space vapor transformation. The oxide precursor films have been prepared from a Mo isopropoxide solution in isopropanol and acid catalysis induced by HCl. Thermal annealing at 200, 400 and 600 °C enhanced the condensation after xerogel formation. An x-ray absorption analysis demonstrates that films condensed at 200 °C are at an intermediate chemical state between MoO3 and MoO2. To achieve MoTe2/MoSe2 composite films, the precursor oxide films were reduced in H2 and exposed to the chalcogenides by isothermal closed space vapor transport at 600 °C. The multilayered nanocomposite films grow with an out-of-plane flake-like structure and an evident integration of Se in the MoTe2 phase according to a MoTe2(1-x)Se2x alloy, with an estimation of x of 0.25. The alloy and the orientation of the flakes are consistent with the bands present in the Raman spectrum. These films are attractive for applications requiring high surface area interfaces favoring gas or ion exchange reactions with transition metal dichalcogenides.

TiO2/Activated Biochar Hybrid Material Prepared By Ultrasonication and Heat Treatment for Capacitive Deionization

TiO2-doped activated biochar was successfully prepared as a hybrid electrode material for capacitive deionization. The introduction of TiO2 has the advantages of low cost, high chemical stability, hydrophilicity, and eco-friendliness. Activated biochar was treated with titanium isopropoxide (TTIP) and isopropyl alcohol solution by an ultrasound assisted process followed by calcination at 400 °C. The physical and chemical properties of the resulting material was characterized by XPS, XRD, SEM, and TEM. Cyclic voltammetry was performed to analyze the electrochemical properties of the prepared electrodes. Furthermore, the performance of TiO2-biochar electrode was evaluated in a 3D-printed CDI cell and the salt removal capacity was examined using a chloride ion-selective electrode. It was shown that the removal capacity was enhanced from 5.1 mg/g NaCl (activated biochar) to 8.6 mg/g NaCl. The increase in capacity is associated with a better wettability of the electrode, which increases the number of surface-active sites and promotes a more efficient ion diffusion inside the biochar pores. This result is beneficial to improve biochar application as an inexpensive alternative electrode material with metal oxide modification.

Titanium Dioxide Nanorods as An Effective Blocking Layer in Solar Cells

Blocking layer holds a crucial function in dye-sensitized solar cells (DSSC). It essentially prevents recombination from occurring between electrons in the photoanode and the oxidized dye molecules within the electrolyte. Furthermore, this layer could strengthen the connection between the conductive substrate and the photoanode layer. Herein, titanium dioxide (TiO2) nanorods were applied as a blocking layer in DSSC, and the solar cell performance was subsequently compared with the cells containing conventional TiO2 nanoparticles blocking layer. The TiO2 nanorods were grown from titanium isopropoxide (TTIP) solution via the hydrothermal method for various durations, i.e., 30, 60, and 120 min. Meanwhile, the TiO2 nanoparticles blocking layer was deposited via the wet chemistry method by hydrolyzing titanium (IV) chloride (TiCl4). The morphology and structure of both types of blocking layers were compared, whereas the electrical properties of the solar cells were analyzed using incident photon-to-current conversion efficiency (IPCE) and current-voltage (I-V) characterization. It was found that different hydrothermal time resulted in TiO2 nanorods with different morphologies. The application of TiO2 nanorods blocking layer that was grown for 120 min led to a photoconversion efficiency of 3.29%, which was 8.2% and 4.4% higher than the photoconversion efficiency of cells without the blocking layer and with TiO2 nanoparticles blocking layer, respectively. Our results indicated that the blocking layer with a TiO2 nanorods structure could facilitate better electrons transfer than that of nanoparticles.

Enhanced methylene blue removal efficiency of TiO2 embedded porous glass

A porous glass (PG) embedded with titanium dioxide (TiO2) was produced via impregnation of the PG with Titanium (IV) Isopropoxide solution followed by crystallization. N2 sorption analyses revealed that the specific surface area (SSA) and total pore volume of the PG reached to 358 m2/g and 0.370 cm3/g, respectively. The adsorption capacity of methylene blue (MB) for the glasses was measured in the dark, instead the photocatalytic MB removal efficiency was evaluated by the degradation of MB under UV light illumination using a UV–vis spectrometer. The MB removal efficiency of the TiO2 synthesized anatase powder was only 32.3 % whereas, for TiO2 embedded PG (TiPG) it was 91.6 %, and nearly complete (> 99 %) efficacy was achieved for TiO2 embedded alkaline leached PG (TiPG-AL) under UV illumination 3 h period. Better MB removal efficiency was attributed to high SSA and dispersion of nano size anatase TiO2 crystallites within the porous structure.

Bottom-up synthesis of titanophosphate nanosheets by the aqueous solution process.

The synthesis of titanophosphate nanosheets in aqueous sols was examined by the bottom-up process. The nanosheets were formed by mixing titanium iso-propoxide, phosphoric acid, and tetraalkylammonium hydroxide (NR4OH) aqueous solutions, followed by diluting with water and heating at 80 °C, forming translucent aqueous sols of titanophosphate nanosheets with the same crystal structure as layered titanium phosphate Ti2O3(H2PO4)2·2H2O. Whether the nanosheets were crystallized depended on the reactions during the mixing of reagents before the water dilution. By controlling the acid–base reactions between the Ti species, phosphoric acid, and the hydroxides of bulky cations in the aqueous sols, the one-pot process yielded highly water-dispersible, flake-like titanophosphate nanosheets. Under some synthetic conditions, nanosheets formed even in weakly basic aqueous sols. These nanosheets can be coated on a substrate with low alkali-resistance, or used for the removal of metal ions from neutral aqueous solutions.

Lily (Iris Persica) pigments as new sensitizer and TiO2 nanofibers as photoanode electrode in dye sensitized solar cells

In this study, lily (Iris Persica) dyes as sensitizer were examined by UV–vis and FTIR analyses. Corresponding results showed that lily pigments effectively absorb incident light. This was mainly due to the presence of functional groups such as CO and OH in the pigment structure appeared on the FTIR analysis. This shows the appropriateness of lily pigment as sensitizer. On the other hand, anatase TiO2 nanofibers with different diameters were synthesized by Electrospinning method, using Titanium isopropoxide (TIPP) and polyvinylpyrrolidone (PVP) solution. The Electrospinning feed rate was altered from 0.1 to 0.5 mL/h to control the diameter of the TiO2 nanofibers. Other effective parameters including voltage, needle tip distance to collector and speed of collector were 25 kV, 15 cm and 500 rpm, respectively and were kept constant during synthesizing of nanofibers. The Synthesized nanofibers were analyzed and characterized by means of SEM, FESEM, XRD and TEM techniques. The FESEM and XRD analyses indicated that the nanofiber's diameter and crystallinity increase with increase in feed rate. The fabricated DSSC with 430 nm TiO2 nanofibers (obtained from flow rate of 0.3 mL/h) provided 1.72 % energy conversion efficiency (ղ), 50.78 % conversion efficiency of photon to electron (IPCE), short-circuit current density (JSC) of 2.716 mA/cm2 and open circuit voltage (VOC) of 0.738 V. The efficiency of the developed DSSCs, in comparison with the previously fabricated similar cells, were found higher, due to more effective absorption of light by the dyes and adsorption of pigment by nanofibers.

Study on Photo-Catalytic and Antimicrobial Activity of Green Synthesized TiO2 Nanoparticles Coated Vitrified Tiles

In the current study, a facile and eco-friendly method has been developed for the synthesis of titanium dioxide nanoparticles from titanium isopropoxide solution using <i>Datura metel</i> (Vellai Umathai) leaves and orange peel extract. Silver nanoparticles (60 nm) and silver nanoplates (130 nm) have been synthesized and characterized using UV-visible spectroscopy, X-ray diffractometer (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The silver nanoparticles are doped with TiO₂ nanoparticles. The photocatalytic activity of Ag nanoparticles and nanoplates doped TiO₂ nanoparticles coated on vitrified tiles was investigated, wherein, degradation of methylene blue, rapidly on exposure to sunlight was observed. Analysis of the antimicrobial activity measured using colony forming units showed a 4-log reduction in the growth of the Gram-negative bacteria and a 5-log reduction in the growth of the Gram-positive bacteria.<div><br></div>

Preparation, characterization of titanate nanosheet–pozzolan nanocomposite and its use as an adsorbent for removal of diclofenac from simulated hospital effluents

Abstract The nanocomposite titanate nanosheet–pozzolan (TNS–PZ) was prepared by the alkaline hydrothermal process using titanium (IV) isopropoxide solution as titanium precursors at different concentrations. The characterization of the material was obtained by, Diffuse Reflectance UV–vis analysis (DRUV), X-ray diffraction (XRD), Energy-dispersive X-Ray spectroscopy, Fourier transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption/desorption isotherms. The adsorbent material was used for successful removal of the anti-inflammatory diclofenac (DFC) from aqueous solutions. The kinetic data were better fitted to nonlinear general order kinetic model, based on the Bayesian Information Criterion (BIC). The equilibrium isotherms also were obtained employing the nonlinear method and based on the BIC; the best isotherm model was the Liu. Based on the Liu isotherm model, the maximum sorption capacity (Qmax) of DCF onto the TNS–PZ adsorbent was 90.52 mg g−1 at 10 °C. The thermodynamic parameters of adsorption were calculated, and the adsorption process was spontaneous, exothermic, and the magnitude of changes in enthalpy, are consistent with physical adsorption of DCF onto TNS–PZ. Also, the adsorbent was tested for simulated hospital effluents, and it was able to remove up to 96.50% of the effluents.

Defect Chemistry of Er3+-Doped TiO2 and Its Photocatalytic Activity for the Degradation of Flowing Gas-Phase VOCs

A series of Er-doped TiO2 photocatalysts, using Er(NO3)3·6H2O precursor ranging from 0.5 to 2 mol %, were synthesized via sol–gel method with titanium(IV) isopropoxide solution as reactant. The str...

Hollow rice grain-shaped TiO2 nanostructures for high-efficiency and large-area perovskite solar cells

Hollow rice grain-shaped titanium dioxide (TiO2) nanostructures (NSs) with the radius of 200–300 nm are fabricated by electrospinning titanium isopropoxide solution and further calcination. The resulting hollow rice grain-shaped TiO2 NSs are highly porous, which are beneficial to the infiltration of perovskites and provide a large contact area, as the building blocks to construct the mesoporous TiO2 layer for the large-area (the active area is 1 cm2) CH3NH3PbI3 based perovskite solar cells (PSCs). By varying the spin coating speed (2000 rpm, 4000 rpm, and 8000 rpm, respectively), the performance of PSCs changes with different TiO2 NSs distribution densities. The optimized PSC employing the 4000 rpm spin coating speed exhibits a photovoltaic conversion efficiency (PCE) of 14.2% with the short circuit current density (JSC) of 21.6 mA cm−2, open circuit voltage (VOC) of 1.07 V and fill factor (FF) of 0.61, which is superior to the plain structure based control group with the PCE of 9.6%. Furthermore, the PSC possesses a reproducible PCE value with weak hysteresis in its current density-voltage (J-V) curves. Moreover, photoluminescence (PL) measurements and finite-difference time-domain (FDTD) optical simulations reveal the enhanced fast charge carrier extraction/transport and light absorption in the proposed system, which makes electrospun hollow rice grain-shaped TiO2 NSs a promising electron transportation material for high-efficiency and large-area photovoltaic devices.

Processing parameters for electrospinning poly(methyl methacrylate) (PMMA)/titanium isopropoxide composite in a pump-free setup

Background: Electrospinning is a technique for producing nanofibers, useful in many fields of nanotechnology. The size and morphology of the nanofibers obtained depends on the polymer solution properties, the parameters of the equipment and the conditions of the surrounding. In almost all reported electrospinning set ups, a pump ,which regulates the flow of the polymer solution, has been included as one of the requirements. In this study, the effects of solution concentration, viscosity, voltage and the distance from the tip of the syringe to the aluminum collector on the morphology and diameters of poly(methyl methacrylate)(PMMA) fibers were investigated, using a pump-free electrospinning set up. Methods: Varied PMMA concentration (50 -120 mg/mL), voltage (10-18 kV) and distance (5 – 18 cm) of electrospinning were studied and the optimum electrospinning conditions identified. PMMA/ titanium isopropoxide solution of ratio 1:2 was prepared, electrospun at optimized conditions (15 kV, 18 cm, Dichloromethane/Dimethylformamide 60:40) and the fibers obtained analyzed using a scanning electron microscope. Results: Solutions of PMMA whose concentrations were less than 50 mg/mL, produced beads on fibers, whereas those at ~ 100 mg/mL formed the best bead-free fibers of diameter 350±50 nm. The results showed a direct dependence of fiber diameter on the solution viscosity. Fibers of larger diameters were obtained when the distance from the tip of the syringe to the aluminum collector and voltage were increased but at higher distances (&gt;18 kV) fewer fibers were collected. When the voltage was steadily increased, the fibers broadened and the diameters were non-uniform due to splaying and splitting. Increasing the distance between the pipette-tip and the collector from 10 to 18 cm resulted in reduced electric field which in turn yielded fewer fibers. Conclusions: The results obtained in a pump free set-up were comparable to those eletrospun in the presence of a pump.

Nb-Doping TiO2 Electron Transporting Layer for Efficient Perovskite Solar Cells

For improvement of the electron transporting and charge separation in the interface of TiO2 and perovskite, the smooth and compact Nb-doping TiO2 electron transporting layer was successfully prepared by a hydrolysis–pyrolysis method using an acidic titanium isopropoxide solution in isopropanol and niobium chloride (NbCl5) as the niobium source. The planar perovskite solar cells with the undoped TiO2 electron transporting layer gave a photoelectric conversion efficiency (PCE) of 14.56%, while the planar perovskite solar cells with the 2.5% Nb-doping TiO2 electron transporting layer obtained a PCE of 15.97%. When the TiO2 nanorod array was introduced between the 2.5% Nb-doping TiO2 electron transporting layer and the perovskite thin film, the corresponding perovskite solar cells achieved a PCE of 18.88% under illumination of simulated AM 1.5 sunlight (100 mA cm–2).

Surfactant Effect on the Synthesis of Mesoporous TiO&lt;sub&gt;2&lt;/sub&gt;-SiO&lt;sub&gt;2&lt;/sub&gt; Coatings Using Sol-Gel Technology

The aim of the research was to develop the area of mesoporous thin films of a binary TiO2–SiO2 system. Sol was synthesized from tetraethylorthosilicate as the silica source and titanium isopropoxide solution as the TiO2 source, while triblock copolymer surfactant (Pluronic F 127 (10% solution in water, (P))) was used as the mesostructure-directing agent. In this paper we present sol-gel obtained TiO2–SiO2 with a mesoporous structure. The effects of added titanium on the mesostructure and on the porosity are presented and discussed. Four different molar percentage ratios of Ti: Si were used for the synthesis of mixed TiO2–SiO2 mesoporous thin films on glass substrate. The mesoporous structure of thin films was characterized by X-ray diffraction (XRD) patterns, atomic force microscopy (AFM), scanning electron microscopy (SEM) and the water contact angle. These mesoporous TiO2–SiO2 thin films could have many potential applications in many areas such as separation membranes, catalysis, optics, and self-cleaning surfaces.

Synthesis and Photocatalytic Activity of Modified TiO&lt;sub&gt;2&lt;/sub&gt; Thin Films Prepared by Spray Pyrolysis

TiO2 and silver doped TiO2 thin films were prepared by spray pyrolysis technique and their photocatalytic activity were determined. Titanium(IV) isopropoxide solution or its mixture with silver nitrate were used as precursors. As-prepared at 300 °C films were X-ray amorphous. Calcination of the films at 500 °C for 5 – 6 hours allowed to obtain partially crystalline anatase films with uniform grain size in the range of 80 – 150 nm. Degradation degree of MB water solution by using TiO2 and TiO2/Ag photocatalysts under UV irradiation reached 60 and 70 % respectively.

Free-Standing, Binder-Free Titanium Suboxide Nanofiber Based Sulfur Cathodes for Li-S Batteries

Lithium sulfur batteries, with a high theoretical specific energy of ~2680 Wh/kg, have attracted great attention in the recent years owing to the direct use of sulfur as a cathode, which is cost-effective, environmentally friendly and naturally abundant. However, shuttling of intermediate polysulfides between cathode and anode is one of the major practical limitations for the realization of Li-S batteries. Others include large volume expansion during lithium insertion, low sulfur utilization, and insulating nature of sulfur and lithium disulfide. Over the years, various carbon and inorganic materials (metal oxides, metal-organic frameworks) have been employed as hosts or polysulfide reservoirs to minimize the shuttling effect and improve the conductivity of cathodes in Li-S batteries. Recently, titanium suboxides (TinO2n-1; n>1), with two Ti3+ and (n-2)Ti4+ (3d0) ions, have been utilized as bifunctional sulphur hosts that not only provide good electrical conductivity, but also chemically bind with the intermediate lithium polysulfide preventing their escape. However, formation of titanium suboxides generally requires high temperature processing, which results in highly dense low surface area material reducing the potential polysulfide-host interaction surface. Here, we report the use of free-standing, binder-free titanium suboxide nanofibers as host material in sulfur cathodes. Titanium suboxide nanofibers are produced by electrospinning titanium isopropoxide solution in presence of polyvinylpyrrolidone and subsequently, heating at 850˚C to create oxygen vacancies through carbothermal reaction. Sulfur impregnation was carried out by rapid melt-diffusion technique to form final sulfur/titanium suboxide cathodes. Lithium-sulfur coin cell batteries were assembled using as-prepared free-standing cathodes (without any current collector and binder) with ~50 wt% sulfur loading (~1.5 mg cm-2) and cycled at C/5 rate (1C = 1675 mAh g-1) after conditioning at C/10 rate. The initial discharge capacity was ~976 mAh g-1 at C/5 rate, which stabilized to an average capacity of ~738 mAh g-1 after three cycles with coulombic efficiency >97%. The conducting titanium suboxide nanofibers allow the effective utilization of sulfur/Li2S during discharging/charging of cells and help to maintain high discharge capacity (~700 mAh g-1) over 100 cycles. The chemical interaction between these inorganic hosts and lithium polysulfide is under investigation and will be discussed in detail. The electrochemical results presented here show the potential of titanium suboxide family (different n values) as foreseeable solution to the shuttling effect for developing high performance Li-S batteries. Figure 1

Preparation and Characterization of Pd Modified TiO2 Nanofiber Catalyst for Carbon–Carbon Coupling Heck Reaction

TiO2 fibers were prepared through electrospinning of poly methyl methacrylate (PMMA) and titanium isopropoxide (TIP) solution followed by calcination of fibers in air at 500°C. Cetyltrimethylammonium bromide (CTAB) protected palladium nanoparticles (Pd NPs) prepared through reduction method were successfully adsorbed on the TiO2 nanofibers (NF). Combined studies of X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) indicated that the synthesized Pd/TiO2 had anatase. BET indicated that the synthesized TiO2 and Pd/TiO2 had a surface area of 53.4 and 43.4 m2/g, respectively. The activity and selectivity of 1 mol% Pd/TiO2 in the Heck reaction have been investigated towards the Mizoroki-Heck carbon–carbon cross-coupling of bromobenzene (ArBr) and styrene. Temperature, time, solvent, and base were optimized and catalyst was recycled thrice. 1H NMR and 13C NMR indicated that stilbene, a known compound from literature, was obtained in various Heck reactions at temperatures between 100°C and 140°C but the recyclability was limited due to some palladium leaching and catalyst poisoning which probably arose from some residual carbon from the polymer. The catalyst was found to be highly active under air atmosphere with reaction temperatures up to 140°C. Optimized reaction condition resulted in 89.7% conversions with a TON of 1993.4 and TOF value of 332.2 hr−1.

Analysis of optical properties of TiO2 nanoparticles and PAN/TiO2 composite nanofibers

ABSTRACTThe aim of the study was the production of thin composite nanofibrous mats PAN/TiO2 nanoparticles using the electrospinning method from solution of PAN/TiO2/DMF. TiO2 nanoparticles were obtained using sol-gel method. To prepare sol mixture, organic alkoxides precursor of titanium isopropoxide and water solution were used. Calcination of TiO-gel and following milling were carried out to obtain nanoparticles of TiO2 rutile phase. In order to analyze the structure of the obtained particles, we used X-ray diffraction analysis (XRD) and energy dispersive spectrometer (EDS). Analysis of the morphology and chemical composition of the resulting composite nanofibers were carried out using a scanning electron microscope (SEM) with EDS. The analysis of the optical properties and the energy band structure prepared nanoparticles and thin composite nanofibrous mats were determined by spectral analysis of the absorbance as a function of the energy of radiation obtained using a UV–Vis spectrophotometer.

Photoanode-Driven Photoelectrochemical CO2 Reduction By Using the TiO2 Photoanodes and Different Metal Counter Electrodes(Pt, Ti, Cu, Sn, Zn)

Introduction Recently, global warming has become a serious problem all over the world. Being a greenhouse gas, the high levels of CO2 are a major contributor toward global warming. For address this problem, the photoelectrochemical CO2 reduction by using semiconductor photoelectrodes has attracted much attention as a potential means of converting solar energy into chemical energy in the form of usable organic fuels (CO, HCOOH, CH3OH, CH4, etc.). Titanium oxide (TiO2) has been a sustainable photocatalyst for environmental remediation because of its nontoxicity, availability, high oxidative potential and chemical stability. It is well-known that the TiO2 has three polymorphs: rutile, anatase, and brookite. In previous work, we have successfully synthesized the rutile and brookite TiO2 nanorods, which showed high levels of activity for degradation of 2-propanol and acetaldehyde under UV irradiation compared to the activity levels of anatase fine particles (ST-01). Therefore, in this study, we fabricated the TiO2 photoelectrodes by using the rutile and brookite nanorods, and investigated their photoelectrochemical properties under UV light irradiation. Moreover, we performed photoanode-driven photoelectrochemical CO2 reduction by using the TiO2 photoanodes and different metal counter electrodes (Pt, Ti, Cu, Sn, Zn) under UV light irradiation. Experimental Two polymorphs of TiO2 nanorods (rutile and brookite) were prepared by hydrothermal synthesis method, which described in our previously reports [1],[2]. Their photoelectrodes were fabricated by electrophoresis deposition method on the FTO conducting glasses. To improve photocurrent response, the necking treatment of the TiO2 photoelectrode was demonstrated: 0.01M titanium(IV) isopropoxide solution was dropped on the TiO2 electrode and then annealed in air at 400 ℃. The photoelectrochemical properties were investigated a three−electrode configuration using a silver−silver chloride (Ag/AgCl) reference electrode and different metal counter electrodes (Pt, Ti, Cu, Sn, Zn). The electrolyte was 0.1M KHCO3 aqueous solution. The electrolyte was stirred and purged with CO2 gas for 30 min before measurement. The photoelectrochemical CO2 reduction was carried out by using Xe lamp irradiation (100 mW/cm2, λ<800 nm). After photo-irradiation for 1h, the CO2 reduction products were evaluated by using gas-chromatography and ion chromatography. Results and discussion We investigated the photoelectrochemical CO2 reduction by using TiO2 photoanode and various metal counter electrodes (Pt, Ti, Cu, Sn, Zn). The CO2 reduction products were strongly dependent on the metal counter electrodes. In the case of Pt counter electrode, H2 was main product, and no CO2 reduction products such as CO, HCOOH, and CH3OH, were detected. This is because Pt has low overpotential for H2 generation compared to the other four metals (Ti, Cu, Sn, Zn). On the other hand, CO and/or HCOOH generation was generated when other four metals (Ti, Cu, Sn, Zn) was used as counter electrode. This is due to a relatively high overpotential for H2 generation. Among them (Ti, Cu, Sn, Zn), the Sn counter electrode showed the highest CO and HCOOH generation, which mechanism will be discussed in poster section. As described above, the photoelectrochemical CO2 reduction was demonstrated by using TiO2 photoanode combined with various metal counter electrodes under UV light irradiation. However, one fault of TiO2 is that it is inactive in the absence of ultraviolet (UV) light because of its large band gap (~3.0 eV for rutile and 3.2 eV for brookite). As nearly 50% of the incident solar energy on the earth’s surface falls within the visible light energy range, visible light-responsive photoanodes are strongly demanded. Therefore, we also introduced the photoelectrochemical properties of black TiO2 which could be synthesized by thermal annealing in reducing atmosphere. The detail information will be discussed in poster section.