共查询到20条相似文献,搜索用时 31 毫秒
1.
Zhenhao Xi Changjiang Li Lu Zhang Mingyang Xing Jinlong Zhang 《International Journal of Hydrogen Energy》2014
Cu2O/TiO2 nanoparticles were prepared by solvothermal method, which formed the heterostructure of Cu2O/TiO2. Due to the heterostructure, the H2 evolution rate under simulated solar irradiation was increasingly promoted. Meanwhile a certain amount of Cu particles which were confirmed by Transmission Electro Microscopy (TEM) and X-Ray Photoelectron Spectroscopy (XPS), formed on the surface of Cu2O/TiO2, and the photoactivity was accordingly further enhanced. The stabilized activity was maintained after many times irradiation. It is interesting that after a few hours irradiation the amount of Cu particles on the surface kept unchanged in the presence of Cu2O and TiO2. The Cu particles that formed during hydrogen generation reaction play a key role in the further enhancement of the hydrogen production activity. In this study, it is the first time to study the details on the formation of the stable ternary structure under simulated solar irradiation and their synergistic effect on the photoactivity of the water splitting. 相似文献
2.
Zhonghua Li Jiawen Liu Dongjun Wang Yuan Gao Jun Shen 《International Journal of Hydrogen Energy》2012
Cu2O/Cu/TiO2 nanotube heterojunction arrays were prepared by assembling Cu@Cu2O core-shell nanoparticles on TiO2 nanotube arrays (NTAs) using a facile impregnation-reduction method. SEM and TEM results show that Cu@Cu2O plate-like nanoparticles with tens of nanometers in size are confined inside TiO2 NTAs. Only the outmost several nanometers of the nanoparticles are Cu2O and the predominant inner of the nanoparticles are Cu metals. Cu L3VV Auger spectra of Cu2O/Cu/TiO2 NTAs suggest that Cu metals are enveloped by at least several nanometers Cu2O on the surface, which further confirms the Cu@Cu2O core shell structure of Cu nanoparticles. The ability of light absorption of Cu2O/Cu/TiO2 NTAs is enhanced. The range of absorption wavelengths changes from 400 to 700 nm due to the surface plasmon response of Cu metals core and Cu2O nanoparticles shell. The photocatalytic hydrogen production rate of Cu2O/Cu/TiO2 heterojunction arrays is enhanced when compared with those of Cu2O/TiO2 NTAs and TiO2 NTAs under UV light. Moreover, a stable H2 generation property was obtained under visible light (λ gt; 400 nm). The Cu metal core is believed to play a key role in the enhancement of photocatalytic properties of Cu2O/Cu/TiO2 nanotube heterojunction arrays. 相似文献
3.
Simultaneous photocatalytic reduction of water to H2 and CO2 to CO was observed over Cu2O photocatalyst under both full arc and visible light irradiation (>420 nm). It was found that the photocatalytic reduction preference shifts from H2 (water splitting) to CO (CO2 reduction) by controlling the exposed facets of Cu2O. More interestingly, the low index facets of Cu2O exhibit higher activity for CO2 photoreduction than high index facets, which is different from the widely-reported in which the facets with high Miller indices would show higher photoactivity. Improved CO conversion yield could be further achieved by coupling the Cu2O with RuOx to form a heterojunction which slows down fast charge recombination and relatively stabilises the Cu2O photocatalyst. The RuOx amount was also optimised to maximise the junction's photoactivity. 相似文献
4.
Shengsen Zhang Biyu Peng Siyuan Yang Yueping Fang Feng Peng 《International Journal of Hydrogen Energy》2013
The influence of the electrodeposition potential on the morphology of Cu2O/TiO2 nanotube arrays (Cu2O/TNA) and their visible-light-driven photocatalytic activity for hydrogen evolution have been investigated for the first time in this work. The photocatalytic hydrogen evolution rate of the as-prepared Cu2O/TNA at the deposition potential of −0.8 V was about 42.4 times that of the pure TNA under visible light irradiation. This work demonstrated a feasible and simple electrodeposition method to fabricate an effective and recyclable visible-light-driven photocatalyst for hydrogen evolution. 相似文献
5.
Simultaneous photocatalytic hydrogen production and CO2 reduction (to form CO and CH4) from water using methanol as a hole scavenger were investigated using silver-modified TiO2 (Ag/TiO2) nanocomposite catalysts. A simple ultrasonic spray pyrolysis (SP) method was used to prepare mesoporous Ag/TiO2 composite particles using TiO2 (P25) and AgNO3 as the precursors. The material properties and photocatalytic activities were compared with those prepared by a conventional wet-impregnation (WI) method. It was found that the samples prepared by the SP method had a larger specific surface area and a better dispersion of Ag nanoparticles on TiO2 than those prepared by the WI method, and as a result, the SP samples showed much higher photocatalytic activities toward H2 production and CO2 reduction. The optimal Ag concentration on TiO2 was found to be 2 wt%. The H2 production rate of the 2% Ag/TiO2–SP sample exhibited a six-fold enhancement compared with the 2% Ag/TiO2–WI sample and a sixty-fold enhancement compared with bare TiO2. The molar ratio of H2 and CO in the final products can be tuned in the range from 2 to 10 by varying the reaction gas composition, suggesting a viable way of producing syngas (a mixture of H2 and CO) from CO2 and water using the prepared Ag/TiO2 catalysts with energy input from the sun. 相似文献
6.
Shiping Xu Jiawei Ng Alan Jianhong Du Jincheng Liu Darren Delai Sun 《International Journal of Hydrogen Energy》2011,36(11):6538-6545
1-D mesoporous TiO2 nanotube (TNT) with large BET surface area was successfully synthesized by a hydrothermal-calcination process, and employed for simultaneous photocatalytic H2 production and Cu2+ removal from water. Cu2+, across a wide concentration range of 8-800 ppm, was removed rapidly from water under irradiation. The removed Cu2+ then combined with TNT to produce efficient Cu incorporated TNT (Cu-TNT) photocatalyst for H2 production. Average H2 generation rate recorded across a 4 h reaction was between 15.7 and 40.2 mmol h−1 g−1catalyst, depending on initial Cu2+/Ti ratio in solution, which was optimized at 10 atom%. In addition, reduction process of Cu2+ was also a critical factor in governing H2 evolution. In comparison with P25, its large surface area and 1-D tubular structure endowed TNT with higher photocatalytic activity in both Cu2+ removal and H2 production. 相似文献
7.
Ju Seong Kim Hyun Soo Han Sun Shin Gill Sang Han Hyun Suk Jung Kug Sun Hong Jun Hong Noh 《International Journal of Hydrogen Energy》2014
The design of photoanode with highly efficient light harvesting and charge collection properties is important in photoelectrochemical (PEC) cell performance for hydrogen production. Here, we report the hierarchical In2O3:Sn/TiO2/CdS heterojunction nanowire array photoanode (ITO/TiO2/CdS-nanowire array photoanode) as it provides a short travel distance for charge carrier and long light absorption pathway by scattering effect. In addition, optical properties and device performance of the ITO/TiO2/CdS-nanowire array photoanode were compared with the TiO2 nanoparticle/CdS photoanode. The photocatalytic properties for water splitting were measured in the presence of sacrificial agent such as SO32− and S2− ions. Under illumination (AM 1.5G, 100 mW/cm2), ITO/TiO2/CdS-nanowire array photoanode exhibits a photocurrent density of 8.36 mA/cm2 at 0 V versus Ag/AgCl, which is four times higher than the TiO2 nanoparticle/CdS photoanode. The maximum applied bias photon-to-current efficiency for the ITO/TiO2/CdS-nanowire array and the TiO2 nanoparticle/CdS photoanode were 3.33% and 2.09%, respectively. The improved light harvesting and the charge collection properties due to the increased light absorption pathway and reduced electron travel distance by ITO nanowire lead to enhancement of PEC performance. 相似文献
8.
Jhin-Wei ChenDung-Ching Perng Jia-Feng Fang 《Solar Energy Materials & Solar Cells》2011,95(8):2471-2477
Nano-structured Cu2O/ZnO nanorod (NR) heterojunction solar cells fabricated on indium tin oxide (ITO)-coated glass are studied. Substrate film and NR density have a strong influence on the preferred growth of the Cu2O film. The X-ray diffractometer (XRD) analysis results show that highly (2 0 0)-preferred Cu2O film was formed when plating on plain ITO substrate. However, a highly (1 1 1)-preferred Cu2O film was obtained when plating on sparse ZnO NRs. SEM, TEM and XRD studies on sparse NR samples indicate that the Cu2O nano-crystallites mostly initiate its nucleation on the peripheral surfaces of the ZnO NRs, and are also highly (1 1 1)-oriented. Solar cells with ZnO NRs yielded much higher efficiency than those without. In addition, ZnO NRs plated on a ZnO-coated ITO glass significantly improve the shunt resistance and open-circuit voltage (Voc) of the devices, with consistently much higher efficiency obtained than when ZnO NRs are directly plated on ITO film. However, longer NRs do not improve the efficiency due to low short-circuit current (Jsc) and slightly higher series resistance. The best conversion efficiency of 0.56% was obtained from a Cu2O/ZnO NRs heterojunction solar cell fabricated on a 80 nm ZnO-coated ITO glass with Voc=0.514 V, Jsc=2.64 mA/cm2 and 41.5% fill factor. 相似文献
9.
Preparation and photocatalytic properties of HLaNb2O7/(Pt,TiO2) perovskite intercalated nanomaterial
Leqing Fan Yuelin WeiYinghan Cheng Yunfang HuangSancun Hao Jihuai Wu 《International Journal of Hydrogen Energy》2014
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. 相似文献
10.
C. A. N. Fernando T. M. W. J. Bandara S. K. Wethasingha 《Solar Energy Materials & Solar Cells》2001,70(2)
H2 evolution was observed for the first time from a photoelectrochemical cell using an n-type Cu2O photoelectrode under visible light irradiation. Three-electrode configuration was used in the photoelectrochemical cell to observe H2 evolution. AgCl/Ag calomel electrode and a platinum plate were used as the reference and counter electrodes, respectively. Fe2+/Fe3+ redox couple was used as the electrolyte. H2 evolution was visible on the platinum electrode in the photoelectrochemical cell. 相似文献
11.
Takuya Miwa Satoshi Kaneco Hideyuki Katsumata Tohru Suzuki Kiyohisa Ohta Suresh Chand Verma Kunihiro Sugihara 《International Journal of Hydrogen Energy》2010
The photocatalytic hydrogen production from aqueous methanol solution was investigated with ZnO/TiO2, SnO/TiO2, CuO/TiO2, Al2O3/TiO2 and CuO/Al2O3/TiO2 nanocomposites. A mechanical mixing method, followed by the solid-state reaction at elevated temperature, was used for the preparation of nanocomposite photocatalyst. Among these nanocomposite photocatalysts, the maximal photocatalytic hydrogen production was observed with CuO/Al2O3/TiO2 nanocomposites. A variety of components of CuO/Al2O3/TiO2 photocatalysts were tested for the enhancement of H2 formation. The optimal component was 0.2 wt% CuO/0.3 wt% Al2O3/TiO2. The activity exhibited approximately tenfold enhancement at the optimum loading, compared with that with pure P-25 TiO2. Nano-sized TiO2 photocatalytic hydrogen technology has great potential for low-cost, environmentally friendly solar-hydrogen production to support the future hydrogen economy. 相似文献
12.
A new system using Bi2S3-loaded TiO2 photocatalysts (Bi2S3/TiO2) was developed to enhance the production of hydrogen. The Bi2S3 (5, 10, 15 wt%) particles in an urchin-like morphology with a length of about 2∼3 μm and a diameter of 15–20 nm, which can absorb all wavelengths in UV–visible radiation, were prepared by solvothermal method and loaded onto nano-sized TiO2 (10∼15 nm) for photocatalysis on hydrogen production. The evolution of H2 from methanol/water (1:1) photo splitting over the Bi2S3/TiO2 composite in the liquid system was enhanced, compared with that over pure TiO2 and Bi2S3. In particular, 14.2 ml of H2 gas was produced after 12 h when 0.5 g of a 10 wt% Bi2S3/TiO2 composite was used. On the basis of cyclic voltammetry (CV) results, the high photoactivity was attributed to the increase of band gap in the Bi2S3/TiO2 composite, due to the decreased recombination between the excited electrons and holes. 相似文献
13.
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
14.
The influence of redox-treated Pt/TiO2 photocatalysts on H2 production is investigated. Catalyst characterizations are performed by TEM, XPS, XRD, BET, and UV–vis/DR spectroscopy techniques. In terms of production rate, the oxidation treatment shows higher reactivity than the reduction treatment. The reduction treatment allows the formation of metallic Pt(0), which more easily catalyzes the transition of TiO2 from the anatase to the rutile phases. Reduction-treated Pt/TiO2 photocatalysts have lower SBET values than oxidation-treated Pt/TiO2 photocatalysts due to the higher percentage of TiO2 in the rutile phase. Combining the results of XPS and optical analyses, PtO/TiO2 shows a higher energy band gap than metallic Pt(0)/TiO2, indicating that oxidation-treated Pt/TiO2 is more capable of achieving water splitting for H2 production. According to the results of this study, the oxidation treatment of Pt/TiO2 photocatalysts can significantly enhance the reactivity of photocatalytic H2 production because of their homogenous distribution, lower phase transition, higher SBET, and higher energy band gap. 相似文献
15.
Wan-Ting Chen Vedran Jovic Dongxiao Sun-Waterhouse Hicham Idriss Geoffrey I.N. Waterhouse 《International Journal of Hydrogen Energy》2013
Low cost semiconductor photocatalysts that can efficiently harvest solar energy to generate H2 from water or biofuels will be critical to future hydrogen economies. In this study, low cost CuO/TiO2 photocatalysts (CuO loadings 0–15 wt.%) were prepared, characterized and evaluated for H2 production from ethanol–water mixtures (80 vol.% ethanol, 20 vol.% H2O) under UV excitation. TEM, XRF, EDAX, EPR, Raman, TGA, XPS and Cu L-edge NEXAFS data showed that at CuO loadings <5 wt.%, Cu(II) was highly dispersed over the TiO2 support, possibly as a sub-monolayer CuO species. At higher loadings, CuO crystallites of diameter 1–2 nm were identified. The photocatalytic activity of CuO/TiO2 photocatalysts was highly dependent on the CuO loading, with 1.25 wt.% CuO being optimal (H2 production rate = 20.3 mmol g−1 h−1). Results suggest that sub-monolayer coverages of Cu(II) or CuO on TiO2 are highly beneficial for H2 generation from ethanol–water mixtures and support the development of a sustainable H2 economy. 相似文献
16.
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
17.
Shengsen Zhang Hongjuan Wang Mingsang Yeung Yueping Fang Hao Yu Feng Peng 《International Journal of Hydrogen Energy》2013
Cu(OH)2/TNAs photocatalyst was prepared by loading Cu(OH)2 nanoparticles on TiO2 nanotube arrays (TNAs) using a chemical bath deposition method. The amount of Cu(OH)2 loaded on the arrays was controlled by the repeated deposition times. The prepared catalyst was used to generate hydrogen under simulated solar light irradiation, and the results demonstrated that the hydrogen yield of Cu(OH)2/TNAs was 20.3 times that of the pure TNAs. Furthermore, the photocatalytic efficiency for hydrogen production decreased only 5.8% after five cycles, indicating that Cu(OH)2/TNAs photocatalyst showed excellent stability and reusability. This work presents an applicable and facile method to fabricate a highly active and stable photocatalyst for hydrogen production. 相似文献
18.
Degussa TiO2 powder (P25) with Cu2O nanocrystals of different sizes deposited on the surface were prepared by a facile ethanol-induced deposition followed with a calcination process at 350 °C and characterized by XRD, XPS, HRTEM and UV–Vis diffuse reflectance spectra, respectively. In our protocol, Cu2O nanocrystals is formed by reducing Cu(II) with the ethanol adsorbed on the surface of P25. The absorption edge as well as photocatalytic activity for H2 evolution are closely related to the size of the Cu2O nanocrystals depending on the Cu content in the as-prepared composites. The 0.9 mol% Cu2O/TiO2 composite with ca. 4 nm Cu2O nanocrystals exhibits the highest photocatalytic H2 evolution rate of 318 μmol h−1 under the illumination of simulant solar light and an apparent quantum efficiency of 28.6% at 365 nm, 397 times higher than that of P25. This enhancement is mainly attributed to the quantum confinement effect of quantum-sized Cu2O nanocrystals (q-Cu2O), which can upgrade the conduction band bottom of q-Cu2O, and thus facilitates the effective separation of photogenerated charge carriers to enhance the photocatalytic activity. The results provided here not only offers a green and simple way for depositing q-Cu2O on the surfaces of P25 to get the photocatalyst with an excellent photocatalytic activity for H2 evolution, but also sheds a new insight for the fabrication of efficient p–n heterojunctions for the separation of electron-hole pairs by quantum confinement effect. 相似文献
19.
Photocatalytic hydrogen evolution over CuCrO2 总被引:1,自引:0,他引:1
We have been studying the technical feasibility of a photochemical H2 evolution based on a dispersion of CuCrO2 powder in aqueous electrolytes containing various reducing agents (S2−, and ). The title oxide combines a fair resistance to corrosion with an optimal band gap Eg of 1.32 eV. The intercalation of a small amount of oxygen should be accompanied by a partial oxidation of Cu+ into Cu2+ implying a p-type semiconductivity. The S2− oxidation inhibits the photocorrosion and the H2 evolution increases parallel to polysulfides formation. Most of H2 is produced when p-CuCrO2 is connected to n-Cu2O formed in situ. H2 liberation proceeds mostly on CuCrO2 while the oxidation of S2− takes place over Cu2O surface and the hetero system Cu2O/CuCrO2 is optimized with respect to some physical parameters. The photoactivity is dependent on preparation conditions and lowering the synthesis temperature through nitrate route leads to an increase in specific surface area Ssp. The photoelectrochemical H2 production is a multistep process where the rate determining step is the arrival of electrons at the interface because of their low mobility. Prolonged irradiation (>80 min) leads to a pronounced decrease of the photoactivity; the tendency toward saturation is due to the undesired back reduction of polysulfides in a closed system and to their strong absorption in the visible region (λmax = 520 nm). 相似文献
20.
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