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1.
The photoelectrochemical (PEC) properties of heterostructured CdS/BiVO4 and BiVO4/CdS film electrodes on conducting glass for hydrogen production under visible light were investigated. These two types heterostructured film electrodes were prepared using spin coating method and ultrasonic spray pyrolysis method. The structural analyses of the prepared films were determined by using XRD, SEM, EDX and UV–vis. Photoelectrochemical measurements were carried out in a convenient three electrodes cell with 0.5 M Na2SO3 aqueous solution. In order to investigate band gap influence of electrode PEC property, a series ITO/Cd1−xZnxS/BiVO4 and ITO/BiVO4/Cd1−xZnxS (x = 0 ∼ 1) film electrodes were also synthesized. After PEC test, a maximum photocurrent density from ITO/CdS/BiVO4 film electrode was confirmed. The maximum photocurrent density, 3 times and 113 times as that of single CdS film electrode and single BiVO4 film electrode, respectively. Incident photon to current conversion (IPCE) of as prepared film electrodes were measured and the value were 65% (ITO/CdS/BiVO4), 22% (single CdS film) and 10% (ITO/BiVO4/CdS) at 480 nm with 0.3 V external bias. Comparison with ITO/BiVO4/CdS electrode and single Cd1−xZnxS electrodes, the heterostructured ITO/CdS/BiVO4 electrode can effectively suppress photogenerated electron-hole recombination and enhance light harvesting. Therefore, the ITO/CdS/BiVO4 electrode gave the maximum photocurrent density and IPCE value. 相似文献
2.
《International Journal of Hydrogen Energy》2019,44(59):30899-30909
CdS has been widely used to modify TiO2-based photoanodes for photoelectrochemical (PEC) water splitting. Due to the poor interface contact between chalcogenides and oxides, however, such CdS modified TiO2 materials usually exhibit inefficient separation and transport of charges, leading to an unsatisfactory efficiency during the PEC water splitting process. Addressing this issue, we herein report a CdS/TiO2 nanotube array (CdS/TNA) photoanode that was fabricated through a successive ion layer absorption and reaction (SILAR) method with an additional subsequent annealing. This post-annealing process is essential to enhance the interface contact between the CdS and the TNAs, resulting in an accelerated transfer of photogenerated electrons from the CdS to the TNAs. In addition, the post-annealing also improves the light absorption capability of the CdS/TNA photoanode. The simultaneous enhancement of charge transport and light absorption provided by the post-annealing is essential for improving the PEC performance of the CdS/TNA photoanode. The CdS/TNA photoanode obtained by this strategy exhibits a much enhanced PEC performance in water splitting, and its photocurrent density and solar-to-hydrogen conversion efficiency could reach 4.56 mA cm−2 at 1.23 V vs. reversible hydrogen electrode and 5.61%, respectively. This simple but effective route can provide a general strategy for obtaining high-performance oxide-based photoelectrodes. 相似文献
3.
A densely packed TiO2 thin film onto an indium doped–tin oxide (ITO) substrate was synthesized at room temperature by chemical deposition and a CdS thin film was deposited onto the pre-deposited TiO2 film by a doctor blade route (powder of CdS was obtained from chemical deposition). TiO2/CdS film was annealed at 300 °C for 1 h in air for crystallinity improvement. The first grown TiO2 film was nanocrystalline, whereas the CdS film was polycrystalline as evidenced by X-ray diffraction (XRD) and selected area electron diffraction (SAED). Scanning electron microscopy (SEM) images show formation of mono-dispersed CdS spherical grains onto compact, densely packed spherical nanocrystalline grains of TiO2. The TiO2/CdS bilayer film was used in a photo-electrochemical cell as a working electrode, and a platinum electrode as a counter electrode (0.1 M lithium iodide electrolyte) under 80 mW/cm2 light illumination intensity. 相似文献
4.
The fabrication and characterization of CdSe/CdS/TiO2 nanotube-array coaxial heterogeneous structure that has potential applications in photocatalytic water splitting and toxic pollutants degradation are investigated. CdSe(top)/CdS(under) double-layer is conformally deposited onto TiO2 nanotubes by successive ionic layer adsorption and reaction (SILAR) and electrochemical atomic layer deposition (ECALD), respectively, for the CdS under layer and the CdSe top layer. Such double sensitized TiO2 nanotubular photoelectrode exhibits significant enhancements in photoconversion efficiency, visible light response, and efficient hydrogen generation. The detailed synthesis process and the surface morphology, phase structure, elemental analysis, and photoelectrochemical properties of the resulting films with the CdSe/CdS/TiO2 nanotube-array coaxial heterogeneous structure are discussed. The photoconversion efficiency of 9.47% and hydrogen generation rate of 10.24 ml h−1 cm−2 were observed. Both values are a 7-fold enhancement compared with that of the pure TiO2 nanotube. The as-prepared photoelectrode presents potential application for industrialized photocatalytic hydrogen generation in the future. 相似文献
5.
A novel photoelectrochemical cell with self-organized TiO2 nanotubes as photoanodes for hydrogen generation 总被引:1,自引:0,他引:1
Yongkun Li Hongmei Yu Wei SongGuangfu Li Baolian YiZhigang Shao 《International Journal of Hydrogen Energy》2011,36(22):14374-14380
A photoelectrochemical (PEC) cell with an innovative design for hydrogen generation via photoelectrocatalytic water splitting is proposed and investigated. It consisted of a TiO2 nanotube photoanode, a Pt/C cathode and a commercial asbestos diaphragm. The PEC could generate hydrogen under ultraviolet (UV) light-excitation with applied bias in KOH solution. The Ti mesh was used as the substrate to synthesize the self-organized TiO2 nanotubular array layers. The effect of the morphology of the nanotubular array layers on the photovoltaic performances was investigated. When TiO2 photocatalyst was irradiated with UV-excitation, it prompted the water splitting under applied bias (0.6 V vs. Normal Hydrogen Electrode, NHE.). Photocurrent generation of 0.58 mA/cm2 under UV-light irradiation showed good performance on hydrogen production. 相似文献
6.
Mesoporous ZrO2-modified coupled ZnO/TiO2 nanocomposites were prepared by a surfactant assisted sol–gel method. The photocatalytic performance of these materials was investigated for H2 evolution without noble metal co-catalyst using aqueous methanol media under AM1.5 simulated light. The H2 evolution was compared with coupled ZnO/TiO2, TiO2, ZnO and Degussa P25. The ZrO2-modified nanocomposites exhibited higher H2 generation, specifically 0.5 wt.% ZrO2 loading produced 30.78 mmol H2 g−1 compared to 3.55 mmol H2 g−1 obtained with coupled ZnO/TiO2. A multiple absorbance thresholds at 435 nm and 417 nm were observed with 0.5 wt.% ZrO2 loading, corresponding to 2.85 eV and 2.97 eV band gap energies. The high surface area, large pore volume, uniform crystallite sizes and enhanced light harvesting observed in ZrO2-modified nanocomposites were contributing factors for effective charge separation and higher H2 production. The possible mechanism of H2 generation from aqueous methanol solution over ZrO2-modified nanocomposite is presented. 相似文献
7.
Cr-doped-TiO2 thin films, with three different Cr concentrations (2, 5.5, and 9 at.%), have been synthesized by radio-frequency magnetron sputtering in order to sensitize TiO2 in visible light. UV–visible spectra showed that maximum narrowing (2.1 eV) of the TiO2 band gap is obtained for the highest Cr concentration. However, negligible photocurrent was measured with Indium Tin Oxide (ITO)/Cr-doped-TiO2 (9 at.%) single bilayer sample due to the increased recombination rate of the photo-generated charges on the defects associated to the Cr3+ ions. To lower the charge recombination rate in the Cr-doped-TiO2, multilayer films with different numbers of ITO/Cr-doped-TiO2 (9 at.%) bilayers (namely, 3-, 4-, 5-, 6- and 7-bilayers) were deposited by keeping the total thickness of TiO2 constant in each multilayer film. When the multilayer films were exposed to visible light, we observed that the photocurrent increases as function of the number of bilayers by reaching the maximum with 6-bilayers of ITO/Cr-doped-TiO2. The enhanced photocurrent is attributed to: 1) higher absorption of visible light by Cr-doped-TiO2, 2) number of space charge layers in form of ITO/TiO2 interfaces in multilayer films, and 3) generation of photoelectrons just in/or near to the space charge layer by decreasing the Cr-doped-TiO2 layer thickness. The reduced charge recombination rate in multilayer films was also confirmed by studying the photocurrent kinetic curve. The superior photocatalytic efficiency of the 6-bilayers film implies higher hydrogen production rate through water-splitting: we obtained indeed 24.4 μmol/h of H2 production rate, a value about two times higher than that of pure TiO2 (12.5 μmol/h). 相似文献
8.
Yanbiao LiuHaibin Zhou Baoxue Zhou Jinhua LiHongchong Chen Jingjing WangJing Bai Wenfeng ShangguanWeimin Cai 《International Journal of Hydrogen Energy》2011,36(1):167-174
A highly stable photoelectrocatalytic electrode made of CdS-modified short, robust, and highly-ordered TiO2 nanotube array for efficient visible-light hydrogen generation was prepared via sonoelectrochemical anodization and sonoelectrochemical deposition method. The short nanotube electrode possesses excellent charge separation and transfer properties, while the sonoelectrochemical deposition method improves the combination between CdS and TiO2 nanotubes, as well as the dispersion of CdS nanoparticles. Different characterization techniques were used to study the nanocomposite electrode. UV-vis absorption and photoelectrochemical measurements proved that the CdS coating extends the visible spectrum absorption and the solar spectrum-induced photocurrent response. Comparing the photoactivity of the CdS/TiO2 electrode obtained using sonoelectrochemical deposition method with others that synthesized using plain electrochemical deposition, the current density of the former electrode is ∼1.2 times higher that of the latter when biased at 0.5 V. A ∼7-fold enhancement in photocurrent response is obtained using the sonoelectrochemically fabricated CdS/TiO2 electrode in comparison with the pure TiO2 nanotube electrode. Under AM1.5 illumination the composite photoelectrode generate hydrogen at a rate of 30.3 μmol h−1 cm−2, nearly 13 times higher than that of pure titania nanotube electrode. Recycle experiments demonstrated the excellent stability and reliability of CdS/TiO2 electrode prepared by sonoelectrochemical deposition. This composite electrode, with its strong mechanical stability and excellent combination of CdS and TiO2 nanotubes, offers promising applications in visible-light-driven renewable energy generation. 相似文献
9.
Kan Li Jinlei Xu Xiaohu Zhang Tianyou Peng Xingguo Li 《International Journal of Hydrogen Energy》2013
AgIn5S8 and AgIn5S8/TiO2 heterojunction nanocomposite with efficient photoactivity for H2 production were prepared by a low-temperature water bath deposition process. The resultant AgIn5S8 shows an absorption edge at ∼720 nm, corresponding to a bandgap of ∼1.72 eV, and its visible-light-driven photoactivity (100.1 μmol h−1) for H2 evolution is 9 times higher than that (11 μmol h−1) of the product derived from a hydrothermal process, while the obtained AgIn5S8/TiO2 heterojunction nanocomposites prepared by using commercially available TiO2 nanoparticles (P25) as TiO2 source exhibit remarkably improved photoactivity as compared to the pristine AgIn5S8, and the AgIn5S8/TiO2 nanocomposite with molar ratio of 1:10 shows a maximum photocatalytic H2 evolution rate (371.1 μmol h−1), which is 4.3 times higher than that (85 μmol h−1) of the corresponding AgIn5S8/TiO2 nanocomposite derived from a hydrothermal method. This significant enhancement in the photocatativity of the present AgIn5S8/TiO2 nanocomposite can be ascribed to the better dispersion of the AgIn5S8 formed on TiO2 nanoparticle surfaces and the more intimate AgIn5S8/TiO2 heterojunction structure during the water bath deposition process under continuously stirring as compared to the corresponding nanocomposite derived from a hydrothermal method. This configuration of nanocomposite results in fast diffusion of the photogenerated carriers in AgIn5S8 towards TiO2, which is beneficial for separating spatially the photogenerated carriers and improving the photoactivity. The present findings shed light on the tuning strategy of spectral responsive region and photoactivity of photocatalysts for efficient light-to-energy conversion. 相似文献
10.
Won Jae Lee Pravin S. ShindeGuen Ho Go Easwaramoorthi Ramasamy 《International Journal of Hydrogen Energy》2011,36(9):5262-5270
The hydrogen generation from photoelectrochemical (PEC) water splitting under visible light was investigated using large area tungsten oxide (WO3) photoanodes. The photoanodes for PEC hydrogen generation were prepared by screen printing WO3 films having typical active areas of 0.36, 4.8 and 130 cm2 onto the conducting fluorine-doped tin oxide (FTO) substrates with and without embedded inter-connected Ag grid lines. TiO2 based dye-sensitized solar cell was also fabricated to provide the required external bias to the photoanodes for water splitting. The structural and morphological properties of the WO3 films were studied before scaling up the area of photoanodes. The screen printed WO3 film sintered at 500 °C for 30 min crystallized in a monoclinic crystal structure, which is the most useful phase for water splitting. Such WO3 film revealed nanocrystalline and porous morphology with grain size of ∼70-90 nm. WO3 photoanode coated on Ag grid embedded FTO substrate exhibited almost two-fold degree of photocurrent density enhancement than that on bare FTO substrate under 1 SUN illumination in 0.5 M H2SO4 electrolyte. With such enhancement, the calculated solar-to-hydrogen conversion efficiencies under 1 SUN were 3.24% and ∼2% at 1.23 V for small (0.36 cm2) and large (4.8 cm2) area WO3 photoanodes, respectively. The rate of hydrogen generation for large area photoanode (130.56 cm2) was 3 mL/min. 相似文献
11.
Highly ordered TiO2 nanotube arrays for hydrogen production have been synthesized by electrochemical anodization of titanium sheets. Under solar light irradiation, hydrogen generation by photocatalytic water splitting was carried out in the two-compartment photoelectrochemical cell without any external applied voltage. The hydrogen gas and oxygen generated on Pt side and on TiO2 nanotubes side respectively were efficiently separated. The effect of anodization time on the morphology structures, photoelectrochemical properties and hydrogen production was systematically investigated. Due to more charge carrier generation and faster charge transfer, a maximum photoconversion efficiency of 4.13% and highest hydrogen production rate of 97 μmol h−1cm−2 (2.32 mL h−1cm−2) were obtained from TiO2 nanotubes anodized for 60 min. 相似文献
12.
Lizhen Yao Wenzhong Wang Lijuan Wang Yujie Liang Junli Fu Honglong Shi 《International Journal of Hydrogen Energy》2018,43(33):15907-15917
In this study, we have developed a facile chemical bath deposition (CBD) method to grow p-type Cu2O nanoparticles on n-type TiO2 nanowire arrays (TiO2 NWAs) to fabricate TiO2/Cu2O core/shell heterojunction nanowire arrays (TiO2/Cu2O core/shell NWAs). When used as photoelectrode, the fabricated TiO2/Cu2O core/shell NWAs show improved photoelectrochemical (PEC) water splitting activity to pure TiO2 NWAs. The effects of the CBD cycle times on the PEC activities have been studied. The TiO2/Cu2O core/shell heterojunction nanowire array photoelectrode prepared by cycling 5 times in the CBD process achieves the highest photocurrent of 2.5 mA cm?2, which is 2.5 times higher than that of pure TiO2 NWAs. In addition, the H2 generation rate of this photoelectrode reaches to 32 μmol h?1 cm?2, 1.7 times higher than that of pure TiO2 NWAs. Furthermore, the TiO2/Cu2O core/shell heterojunction nanowire array photoelectrode shows excellent photostability and achieves a stable photocurrent of over 2.3 mA cm?2 during long light illumination time of 5 h. The enhanced photocatalytic activity of TiO2/Cu2O core/shell heterojunction nanowire array photoelectrode is attributed to the synergistic actions of TiO2 and Cu2O for improving visible light harvesting, and efficient transfer and separation of photogenerated electrons and holes. 相似文献
13.
Yongkun Li Hongmei Yu Changkun Zhang Li Fu Guangfu Li Zhigang Shao Baolian Yi 《International Journal of Hydrogen Energy》2013
We report on the design and synthesis of a novel Au/TiO2/Au heterostructure and its implementation as a photoanode for photoelectrochemical (PEC) application. The Au/TiO2/Au heterostructure was produced by assembling Au nanoparticles and TiO2 nanorods (NRs) onto FTO substrate, followed by electrodepositing Au nanoparticles on the TiO2NRs. Field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electrochemical methods were adopted to characterize the prepared photoanodes. Compared to the system involving Au nanoparticles directly linked to TiO2, this Au/TiO2/Au heterostructure exhibits significant improved photoresponse as a photoanode, as demonstrated good performance in PECs. This study illustrates the importance of pre-deposited Au underlayers in influencing PEC properties of hybrid assembled nanostructures. As the Au/TiO2NRs/Au photoanodes are easily fabricated and highly stable, Au/TiO2NRs/Au can serve as a good substitution for TiO2 in a variety of solar energy driven applications including PEC water splitting, photocatalysis, and solar cells. 相似文献
14.
Zhenyi Zhang Bin Dong Mingyi Zhang Jindou Huang Feng Lin Changlu Shao 《International Journal of Hydrogen Energy》2014
One-dimensional (1D) Pt/TiO2 hybrid nanofibers (HNFs) with different concentrations of Pt were fabricated by a facile two-step synthesis route combining an electrospinning technique and calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) results showed that the Pt nanoparticles (NPs) with the size of 5–10 nm were well dispersed in the TiO2 nanofibers (NFs). Further investigations from the UV–Vis diffuse reflectance (DR) and X-ray photoelectron spectroscopy (XPS) analysis revealed that some Pt ions were incorporated into the TiO2 lattice as Pt4+ state, which contributed to the visible light absorption of TiO2 NFs. Meanwhile, the Pt2+ ions existing on the surface of Pt NPs resulted in the formation of Pt–O–Ti bond at Pt NPs/TiO2 NFs interfaces that might serve as an effective channel for improving the charge transfer. The as-electrospun Pt/TiO2 HNFs exhibited remarkable activities for photocatalytic H2 evolution under visible light irradiation in the presence of l-ascorbic acid as the sacrificial agent. In particular, the optimal HNFs containing 1.0 at% Pt showed the H2 evolution rate of 2.91 μmol h−1 and apparent quantum efficiency of 0.04% at 420 nm by using only 5 mg of photocatalysts. The higher photocatalytic activity could be ascribed to the appropriate amount of Pt ions doping and excellent electron-sink effect of Pt NPs co-catalysts. 相似文献
15.
In order to sensitize TiO2 in visible light and to reduce photo-induced charge recombination, the multilayer films of Indium-Tin Oxide (ITO)/V-doped TiO2 were synthesized by radio-frequency magnetron sputtering. V-doped TiO2 thin films showed red shift in TiO2 absorption edge with increasing dopant concentration and, most importantly, the dopant energy levels are formed in the TiO2 band gap due to V5+/V4+ ions as confirmed by UV-Visible and XPS spectra. Multilayer films with different numbers of ITO/V-doped TiO2 (6 at.%) bilayers (namely, 2-, 3-, 4-, 5-, 6- and 7-bilayers) were deposited, in order to reduce the charge recombination rate, by keeping the total thickness of TiO2 constant in each multilayer film. In multilayer films, when exposed to visible light the photocurrent increases as function of the number of bilayers by reaching the maximum with 6-bilayers of ITO/V-doped TiO2. The measured enhanced photocurrent is attributed to: 1) ability of V-doped TiO2 to absorb visible light, 2) number of space-charge layers in form of ITO/TiO2 interfaces in multilayer films, and 3) generation of photoelectrons just in/or near to the space-charge layer by decreasing the V-doped TiO2 layer thickness. The reduced charge recombination rate in multilayer films was also confirmed by the photocurrent kinetic curves. The superior photocatalytic efficiency of the 6-bilayers film is also reflected in hydrogen production rate through water-splitting: we obtained indeed 31.2 μmol/h of H2 production rate. 相似文献
16.
Cheap and efficient photocatalysts were fabricated by simply mixing TiO2 nanoparticles (NPs) and CuO NPs. The two NPs combined with each other to form TiO2/CuO mixture in an aqueous solution due to the opposite surface charge. The TiO2/CuO mixture exhibited photocatalytic hydrogen production rate of up to 8.23 mmol h−1 g−1 under Xe lamp irradiation when the weight ratio of P25 to CuO was optimized to 10. Although the conduction band edge position of CuO NPs is more positive than normal hydrogen electrode, the TiO2/CuO mixture exhibited good photocatalytic hydrogen production performance because of the inter-particle charge transfer between the two NPs. The detailed mechanism of the photocatalytic hydrogen production is discussed. This mixing method does not require a complicated chemical process and allows mass production of the photocatalysts. 相似文献
17.
The hydrogen photo-evolution was successfully achieved in aqueous (Fe1−xCrx)2O3 suspensions (0 ≤ x ≤ 1). The solid solution has been prepared by incipient wetness impregnation and characterized by X-ray diffraction, BET, transport properties and photo-electrochemistry. The oxides crystallize in the corundum structure, they exhibit n-type conductivity with activation energy of ∼0.1 eV and the conduction occurs via adiabatic polaron hops. The characterization of the band edges has been studied by the Mott Schottky plots. The onset potential of the photo-current is ∼0.2 V cathodic with respect to the flat band potential, implying a small existence of surface states within the gap region. The absorption of visible light promotes electrons into (Fe1−xCrx)2O3-CB with a potential (∼−0.5 VSCE) sufficient to reduce water into hydrogen. As expected, the quantum yield increases with decreasing the electro affinity through the substitution of iron by the more electropositive chromium which increases the band bending at the interface and favours the charge separation. The generated photo-voltage was sufficient to promote simultaneously H2O reduction and SO32− oxidation in the energetically downhill reaction (H2O + SO32− → H2 + SO42−, ΔG = −17.68 kJ mol−1). The best activity occurs over Fe1.2Cr0.8O3 in SO32− (0.1 M) solution with H2 liberation rate of 21.7 μmol g−1 min−1 and a quantum yield 0.06% under polychromatic light. Over time, a pronounced deceleration occurs, due to the competitive reduction of the end product S2O62−. 相似文献
18.
《International Journal of Hydrogen Energy》2023,48(77):30018-30026
Hydrogen production by solar energy is an efficient and clean approach to fulfill the future energy demand. Herein, a novel multi-shelled porous heterostructure CoOx/CdS/TiO2 photoanode was fabricated by the hydrothermal and chemical method. There were more active sites, suitable surface defects and heterojunction structures in the homogeneous-porous-multi-shelled CoOx/CdS/TiO2 photoanode. It showed a photocurrent density of 2.89 mA/cm2 at 1.23V vs. RHE, which is 2.22 fold of the original TiO2 photoanode. The heterostructure fabrication of the CdS/TiO2 could broaden the visible light absorption and enhance the charge separation efficiency. The multi-shelled homogeneous porous structure of the CoOx/CdS/TiO2 further enhanced the charge separation efficiency and accelerated the interfacial oxygen evolution kinetics. The mechanism for the enhanced photoelectrochemical water splitting of favorable CoOx/CdS/TiO2 photoanode is proposed. 相似文献
19.
Chuangli Zhang Quanping Wu Xuebin Ke Juan Wang Xin Jin Song Xue 《International Journal of Hydrogen Energy》2014
Ultrathin hematite (α-Fe2O3) film deposited on a TiO2 underlayer as a photoanode for photoelectrochemical water splitting was described. The TiO2 underlayer was coated on conductive fluorine-doped tin oxide (FTO) glass by spin coating. The hematite films were formed layer-by-layer by repeating the separated two-phase hydrolysis-solvothermal reaction of iron(III) acetylacetonate and aqueous ammonia. A photocurrent density of 0.683 mA cm−2 at +1.5 V vs. RHE (reversible hydrogen electrode) was obtained under visible light (>420 nm, 100 mW cm−2) illumination. The TiO2 underlayer plays an important role in the formation of hematite film, acting as an intermediary to alleviate the dead layer effect and as a support of large surface areas to coat greater amounts of Fe2O3. The as-prepared photoanodes are notably stable and highly efficient for photoelectrochemical water splitting under visible light. This study provides a facile synthesis process for the controlled production of highly active ultrathin hematite film and a simple route for photocurrent enhancement using several photoanodes in tandem. 相似文献
20.
Chinmay Khare Kirill Sliozberg Robert Meyer Alan Savan Wolfgang Schuhmann Alfred Ludwig 《International Journal of Hydrogen Energy》2013
Layered WO3/TiO2 nanostructures, fabricated by magnetron sputtering, demonstrate significantly enhanced photocurrent densities compared to individual TiO2 and WO3 layers. First, a large quantity of compositions having different microstructures and thicknesses were fabricated by a combinatorial approach: diverse WO3 microstructures were obtained by adjusting sputtering pressures and depositing the films in form of wedges; later layers of TiO2 nanocolumns were fabricated thereon by the oblique angle deposition. The obtained photocurrent densities of individual WO3 and TiO2 films show thickness and microstructure dependence. Among individual WO3 layers, porous films exhibit increased photocurrent densities as compared to the dense layer. TiO2 nanocolumns show length-dependent characteristics, where the photocurrent increases with increasing film thickness. However, by combining a WO3-wedge type layer with a layer of TiO2 nanocolumns, PEC properties strikingly improve, by about two orders of magnitude as compared to individual WO3 layers. The highest photocurrent that is measured in the combinatorial library of porous WO3/TiO2 films is as high as 0.11 mA/cm2. Efficient charge-separation and charge carrier transfer processes increase the photoconversion efficiency for such films. 相似文献