共查询到20条相似文献,搜索用时 15 毫秒
1.
Thammanoon Sreethawong Chompoonuch Junbua Sumaeth Chavadej 《Journal of power sources》2009,190(2):513-524
Sensitized photocatalytic production of hydrogen from water splitting is investigated under visible light irradiation over mesoporous-assembled titanium dioxide (TiO2) nanocrystal photocatalysts, without and with Pt loading. The photocatalysts are synthesized by a sol–gel process with the aid of a structure-directing surfactant and are characterized by N2 adsorption–desorption analysis, X-ray diffraction, UV–vis spectroscopy, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray analysis. The dependence of hydrogen production on the type of TiO2 photocatalyst (synthesized mesoporous-assembled and commercial non-mesoporous-assembled TiO2 without and with Pt loading), the calcination temperature of the synthesized photocatalyst, the sensitizer (Eosin Y) concentration, the electron donor (diethanolamine) concentration, the photocatalyst dosage and the initial solution pH is systematically studied. The results show that in the presence of the Eosin Y sensitizer, the Pt-loaded mesoporous-assembled TiO2 synthesized by a single-step sol–gel process and calcined at 500 °C exhibits the highest photocatalytic activity for hydrogen production from a 30 vol.% diethanolamine aqueous solution with dissolved 2 mM Eosin Y. Moreover, the optimum photocatalyst dosage and initial solution pH for the maximum photocatalytic activity for hydrogen production are 3.33 g dm−3 and 11.5, respectively. 相似文献
2.
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
3.
The use of products from CO2 photoreduction for improvement of hydrogen evolution in water splitting
Xiaoyi Yang Tiancun Xiao Peter P. Edwards 《International Journal of Hydrogen Energy》2011,36(11):6546-6552
CuO/TiO2 photocatalysts were prepared and shown to enhance the rate of CO2 photoreduction and the production of total organic carbon (TOC), including HCOOH, HCHO and CH3OH. Resulting TOC could act as electron donors for enhancing visible light hydrogen evolution from Pt/TiO2 photocatalysts. The impacts on CO2 photoreduction were investigated including the effect of Cu dopant, pH, irradiation time and using Na2SO3 as a sacrificial agent, and those on hydrogen evolution was also studied including TOC concentration and Pt doping. The CO2 photoreduction mechanisms with respect to pH and CO2 reduction potentials were discussed. CuO/TiO2 and Pt/TiO2 photocatalysts were characterized by X-ray diffraction, Raman spectroscopy and diffuse reflection UV-vis spectrophotometry. Both photocatalysts showed a visible light response in comparison with pure TiO2. The photocatalytic experiments and FT-IR spectra indicated that photoproduct desorption was the rate-limiting step in the CO2 photoreduction. 相似文献
4.
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
5.
《International Journal of Hydrogen Energy》2023,48(14):5529-5540
In terms of improving photocatalytic hydrogen production performance, inexpensive and earth-rich cocatalysts have become promising alternatives to precious metals. Herein, a novel CoNi–TiO2 photocatalyst composed of TiO2 nanoflowers and CoNi alloy was prepared by hydrothermal and chemical reduction methods. Various characterizations and test results have confirmed that the further improvement of the photocatalytic performance of the CoNi–TiO2 photocatalyst is mainly due to the fact that the bimetallic CoNi alloy can accelerate charge transfer and inhibit the recombination of photo-induced carriers. The hydrogen production rate of the prepared CoNi–TiO2 is about 24 times higher than that of the pristine TiO2, and its hydrogen production rate value can reach 6580.9 μmol g?1 h?1, and showing comparable photocatalytic performance to 0.5 wt% Pt–TiO2. In addition, combined with the characterization results, a probable mechanism for enhanced photocatalytic performance was proposed. This study provides favorable enlightenment for the design of a series of highly efficient non-precious metal TiO2-based photocatalysts. 相似文献
6.
《International Journal of Hydrogen Energy》2022,47(56):23570-23582
A series of Au/TiO2 photocatalysts was synthesized via the light assistance through the photo-deposition for H2 production by photocatalytic water splitting using ethanol as the hole scavenger. Effect of solution pH in the range of 3.2–10.0 on the morphology and photocatalytic activity for H2 production of the obtained Au/TiO2 photocatalysts was explored. It was found that all Au/TiO2 photocatalysts prepared in different solution pH exhibited comparable anatase fraction (~0.84–0.85) and crystallite size of TiO2 (21–22 nm), but showed different quantity of deposited Au nanoparticles (NPs) and other properties, particularly the particle size of the Au NPs. Among all prepared Au/TiO2 photocatalysts, the Au/TiO2 (10.0) photocatalyst exhibited the highest photocatalytic activity for H2 production, owning to its high metallic state and small size of Au NPs. Via this photocatalyst, the maximum H2 production of 296 μmol (~360 μmol/g?h) was gained at 240 min using the 30 vol% ethanol as the hole scavenger at the photocatalyst loading of 1.33 g/L under the UV light intensity of 0.24 mW/cm2 with the quantum efficiency of 61.2% at 254 nm. The loss of the photocatalytic activity of around 20% was observed after the 5th use. 相似文献
7.
In this study, ternary P25/GO/Pt hybrid photocatalysts are prepared in different orders, using Degussa's TiO2 (P25), graphene oxide (GO), chloroplatinic acid as precursor. The prepared catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). This work is first time to compare the hydrogen production of the ternary P25/GO/Pt hybrid photocatalysts prepared in different orders. We focus on studying the introduction of GO and find that the quantity of introduced GO and electronic transfer path play an important role in photocatalytic activity on ternary P25/GO/Pt hybrid catalysts. When the proper Pt particle loaded on the flat surface of GO which was 0.5wt% of P25, the highest H2 evolution was obtained. 相似文献
8.
E. Pulido Melián Cristina R. López A. Ortega Méndez O. González Díaz M. Nereida Suárez J.M. Doña Rodríguez J.A. Navío D. Fernández Hevia 《International Journal of Hydrogen Energy》2013
A series of synthesised TiO2-based and commercial photocatalysts were modified by Pt photodeposition and a study made of their photocatalytic activity in hydrogen production. The modified commercial photocatalysts were Evonik P25, Kronos vlp7000 and Hombikat UV-100, and the other modified photocatalysts were synthesised by our group using sol–gel and sol–gel hydrothermal processes (SG400, SG750 and HT). Pt weight percentages used in the study were 0.5, 1.0 and 2.1 wt.% (Pt/TiO2). The photocatalysts were extensively characterised by X-ray diffraction (XRD), UV–vis diffuse reflectance, Brunauer–Emmett–Teller (BET) surface area measurement, transmission electron microscopy (TEM), scanning electron microscopy (SEM–EDX), Fourier transform infrared spectroscopy (FTIR) and laser light dispersion. Methanol (25% vol.) was used as sacrificial agent over the 8 h of the hydrogen production tests and measurements were taken of the final concentrations of formaldehyde and formic acid as well as initial and final TOC. Photoactivity of all photocatalysts increased in the presence of Pt. The most efficient of the synthesised photocatalysts was SG750 and of the commercial photocatalysts P25. Maximum production of SG750 was 1846 μmol h−1 at 1.0 wt.% Pt and its production per surface unit was notably higher than that of P25. 相似文献
9.
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
10.
Mariana P. Languer Francine R. Scheffer Adriano F. Feil Daniel L. Baptista Pedro Migowski Guilherme J. Machado Diogo P. de Moraes Jairton Dupont Sérgio R. Teixeira Daniel E. Weibel 《International Journal of Hydrogen Energy》2013
Photo-induced reforming of methanol, ethanol, glycerol and phenol at room temperature for hydrogen production was investigated with the use of ultra-small Pt nanoparticles (NPs) loaded on TiO2 nanotubes (NTs). The Pt NPs with diameters between 1.1 and 1.3 nm were deposited on TiO2 NTs by DC-magnetron sputtering (DC-MS) technique. The photocatalytic hydrogen rate achieved an optimum value for a loading of about 1 wt% of Pt. Apparent quantum yield for hydrogen generation was measured for methanol and ethanol water solutions reaching a maximum of 16% under irradiation with a wavelength of 313 nm in methanol/water solution (1/8 v/v). Pt NPs loaded on TiO2 NTs represented also a true water splitting catalyst under UV irradiation and pure distilled water. DC-MS method appears to be a technologically simple, ecologically benign and potentially low-cost process for production of an efficient photocatalyst loaded with ultra-small NPs with precise size control. 相似文献
11.
《International Journal of Hydrogen Energy》2023,48(59):22366-22378
A new straightforward protocol for the deposition of the platinum oxide (PtO–PtO2) particles onto the TiO2 semiconductor via controllable hydrolysis of the sulfuric acid solution of Pt(IV) hydroxide was developed. The developed approach represents a simple and “green” way to prepare the supported Adams-type catalysts. In the constructed composites (PtO2·xH2O/TiO2) the Pt ionic species (hydrated PtO and PtO2 nanoparticles) weakly interact with the titania surface, but under heating the Pt–O–Ti bonds are established, resulting in the stabilization of the Pt(II) ionic state. This state dominates in the obtained catalysts PtOx/TiO2 with a low platinum loading, while at a higher Pt content the metallic Pt particles also appear. The prepared PtOx/TiO2 photocatalysts have been successfully tested in the production of hydrogen under UV light from aqueous solutions of ethanol and glucose, the products of starch biomass processing. Appreciable activity in the production of hydrogen from water/ethanol mixtures was achieved, even at a Pt content of up to 0.05%. PtOx/TiO2 photocatalysts with Pt content of 0.2–0.4 wt% have been successfully used to produce hydrogen from aqueous glucose solutions, and PtOx(0.29)/TiO2 photocatalyst has demonstrated an exceptionally high rate of H2 production per gram of platinum introduced and the quantum efficiency comparable to the highest published values. 相似文献
12.
The photocatalytic activity in hydrogen production from methanol reforming can be significantly enhanced by Pt/MoO3/TiO2 photocatalysts. Compared with Pt/P25, the photocatalytic activity of optimized Pt/MoO3/TiO2 shows an evolution rate of 169 μmol/h/g of hydrogen, which is almost two times higher than that of Pt/P25. XRD and Raman spectra show that MoO3 are formed on the surface of TiO2. It is found that with the bulk MoO3 just formed, the catalyst shows the highest activity due to a large amount of heterojunctions and the high crystallinity of MoO3. The HRTEM image showed a close contact between MoO3 and TiO2. It is proposed that the Z-scheme type of heterojunction between MoO3 and TiO2 is responsible for the improved photocatalytic activity. The heterojunction structure of MoO3/TiO2 does not only promote the charge separation, but also separates the reaction sites, where the oxidation (mainly on MoO3) and reduction (on TiO2) reactions occurred. 相似文献
13.
In this study, photocatalytic hydrogen production over metal-incorporated CdS and ZnO (M/CdS/ZnO) nanocomposites under simulated solar light illumination was investigated. M/CdS/ZnO samples were synthesized by photodepositing a metal into CdS/ZnO powders. All photocatalysts showed increased hydrogen production with an increase in the light exposure time. The M/CdS/ZnO samples exhibited better hydrogen production yields than the CdS/ZnO nanocomposites, which in turn showed higher hydrogen production yields than pure ZnO did. The hydrogen production yields of the CdS/ZnO samples increased as the CdS/ZnO weight ratio increased from 0.01 to 0.10. However, they decreased with further increases in CdS loading, although the light absorption edges of the CdS/ZnO samples were further extended to the visible region. Pt/CdS/ZnO and Pd/CdS/ZnO exhibited similar hydrogen production yields, which were higher than the Ni/CdS/ZnO yield. The hydrogen production yield of Pt (0.5%)/CdS/ZnO was higher than that of Pt (0.1%)/CdS/ZnO. Notably, the hydrogen production yield of CdS/Pt/ZnO was lower than that of Pt/CdS/ZnO. Among three different electron donors (Na2S + Na2SO3, methanol, and lactic acid solutions), the Na2S + Na2SO3 solution led to the highest hydrogen production yield. A tentative mechanism for photocatalytic hydrogen production over M/CdS/ZnO nanocomposites under solar light irradiation, using a Na2S + Na2SO3 solution as an electron donor, was proposed. In summary, M/CdS/ZnO photocatalysts can be utilized efficiently for photocatalytic hydrogen production with solar light exposure through proper control of operating parameters. 相似文献
14.
《International Journal of Hydrogen Energy》2021,46(78):38678-38691
In this study, platinized mixed oxides (TiO2–Nb2O5) were tested on photocatalytic hydrogen production from a glycerol solution under UV light. Different samples with different Ti:Nb ratios were prepared by using a simple method that simultaneously combined a physical mixture and a platinum photochemical reduction. This method led to improved physicochemical properties such as low band gap, better Pt nanoparticle distribution on the surface, and the formation of different Pt species. Niobia content was also found to be an important factor in determining the overall efficiency of the Pt–TiO2–Nb2O5 photocatalyst in the glycerol reforming reaction. The photocatalytic results showed that Pt on TiO2–Nb2O5 enhanced hydrogen production from the aqueous glycerol solution at a 5 wt% initial glycerol concentration. The influence of different operating conditions such as the catalyst dosage and initial glycerol concentration was also evaluated. The results indicated that the best hydrogen and methane production was equal to 6657 μmol/L and 194 μmol/L, respectively after 4 h of UV radiation using Pt/Ti:Nb (1:2) sample and with 3 g/L of catalyst dosage. Moreover, the role of water in photocatalytic hydrogen production was studied through photocatalytic activity tests in the presence of D2O. The obtained results confirmed the role of water molecules on the photocatalytic production of hydrogen in an aqueous glycerol solution. 相似文献
15.
《International Journal of Hydrogen Energy》2022,47(19):10628-10637
Solar-to-hydrogen production has attracted increasing attention since it possesses great potential in alleviating energy and environmental crises to some extent. The key issue is to develop efficient photocatalysts exhibiting superior hydrogen production capability. In this work, Cu@TiO2 hybrid (Cu nanoparticles encapsulated in TiO2) has been successfully prepared by Cu2O self-template reduction through solvothermal treatment in ethylene glycol-water mixed solvent. When octahedral Cu2O is involved in the reaction system, the Cu2O@Ti-precursor octahedral structure is first formed and subsequently the Cu@TiO2 hybrid is prepared with the reduction of ethylene glycol (EG). The Cu@TiO2 hybrid derived with different mass of Cu exhibits improved photocatalytic hydrogen production performance compare to pure TiO2 and P25. Among those photocatalysts, the Cu@TiO2-10% (the copper content is 10 wt%) shows the highest hydrogen evolution rate of 4336.7 μmol g?1 h?1, and it is twice as much as the pure TiO2 and 1.9 times as much as P25, respectively. Based on the photo/electrochemical results, an efficient photo-generated electron-hole separation contributes to the enhancement of photocatalytic H2 evolution upon the Cu@TiO2 hybrid. When replacing octahedral Cu2O with cubic and truncated octahedrons ones, the Cu@TiO2 hybrid photocatalysts are also obtained and they also display superior solar-to-hydrogen evolution than pure TiO2 and P25. It is expected this work could develop an approach to design Cu-encapsulated hybrid photocatalysts for hydrogen generation. 相似文献
16.
《International Journal of Hydrogen Energy》2023,48(37):13780-13790
The photocatalytic performance has remained challenging due to the rapid recombination of photoexcited electron-hole (e-h) pairs. To overcome this problem, creating oxygen vacancies on the surface of semiconductors has been an effective strategy. Herein, we report the effects of oxygen vacancies (Ov) on photocatalytic HER performance of Pt nanoparticles (NPs) anchored on UiO-66-NH2. In contrast, under the same amount of Pt NPs, UiO-66-NH2 with high oxygen vacancies (denoted as Pt/UN-Ovh) exhibit superior photocatalytic H2 generation than the catalyst with low oxygen vacancies (denoted as Pt/UN-Ovl) under visible-light irradiation. Based on the experimental characterization and theoretical calculations, the high oxygen vacancies not only stabilize the Pt NPs on the substrate (UiO-66-NH2), but also develop the strong interaction between Pt NPs and support thereby Pt NPs traps more electrons from substrate and provides protons for H2 production inhibiting the electron-hole recombination. This work provides novel strategy for enhancing the photocatalysts performance of MOF based materials. 相似文献
17.
《International Journal of Hydrogen Energy》2020,45(40):20558-20567
The effect of tungsten carbide as co-catalyst in the photocatalytic H2 production from ethanol aqueous solutions (25% v/v) is reported. The photocatalytic H2 production using WC/TiO2 systems, in which tungsten carbide NPs are dispersed onto TiO2, is compared with that of TiO2800 with morphological and structural characteristics similar to WC/TiO2 and with the hydrogen produced using commercial TiO2 P25 as reference. To this end, WxCy/TiO2, WC1-x/TiO2_US and WO3/TiO2 photocatalysts were prepared, characterized and tested. The preparation of WxCy/TiO2 was accomplished by using a sol-gel based method which was useful for preparing bulk tungsten carbides. The preparation of WC1-x/TiO2_US is reported by the first time using a sonication method from WC1-x and TiO2800. Materials were characterized using N2 physisorption, XRD, SEM-EDX, TEM-HRTEM, UV–vis RDS, XP and Raman spectroscopy. The presence of 2–3 nm NPs with different tungsten carbide crystalline phases (hexagonal WC and W2C and cubic WC1-x) was determined for WxCv/TiO2 photocatalyst, the solely presence of 2–5 nm cubic WC1-x NPs onto TiO2 was confirmed for WC1-x/TiO2_US.The presence of tungsten carbide NPs onto TiO2 improves the photocatalytic behavior of TiO2 in terms of hydrogen production. The effect of tungsten carbide NPs in the C2–C4 products derived from ethanol is discussed and the reusability of the photocatalyst is also studied. 相似文献
18.
Jun Xing Yu Hang Li Hai Bo Jiang Yun Wang Hua Gui Yang 《International Journal of Hydrogen Energy》2014
Photocatalytic hydrogen production from water or organic compounds is a promising way to resolve our energy crisis and environmental problems in the near future. Over the past decades, many photocatalysts have been developed for solar water splitting. However, most of these photocatalysts require cocatalyst to facilitate H2 evolution reaction and noble metals as key cocatalysts are widely used. Consequently, the condition of noble metal cocatalyst including the size and valence state etc plays the key role in such photocatalytic system. Here, the size and valence state effect of Pt on photocatalytic H2 evolution over platinized TiO2 photocatalyst were studied for the first time. Surprisingly, it was found that Pt particle size does not affect the photoreaction rate with the size range of several nanometers in this work, while it is mainly depended on the valence state of Pt particles. Typically, TOFs of TiO2 photodeposited with 0.1–0.2 wt% Pt can exceed 3000 h−1. 相似文献
19.
Sangmin Jeong Kyong-Hwan Chung Heon Lee Hyunwoong Park Ki-Joon Jeon Young-Kwon Park Sang-Chul Jung 《International Journal of Hydrogen Energy》2017,42(27):17386-17393
This study examined the effects of liquid phase plasma irradiation on the photocatalytic decomposition of water for hydrogen evolution. TiO2 and metal-loaded TiO2 nanocrystallites were introduced as photocatalysts. Na-Y zeolite was applied as a support for the TiO2 nanocrystallites. The photocatalytic activities of the photocatalysts were estimated for hydrogen production from water. Hydrogen evolution appeared in the photodecomposition of water without photocatalysts. This was caused by the decomposition of water by plasma irradiation in water directly. The hydrogen evolution efficiency improved with increasing conductivity of water. The rate of hydrogen evolution was increased by the metal loading (Ni, Co, Fe) on the TiO2 surface. Na-Y zeolite can be used as an efficient photocatalytic support for the fixation of TiO2. The TiO2 nanocrystallites were incorporated above 40 wt% on Na-Y support. 相似文献
20.
Yuan Lin Siyuan Yang Yunpeng Liu Shengsen Zhang Hongjuan Wang Hao Yu Feng Peng 《International Journal of Hydrogen Energy》2017,42(31):19942-19950
CuO1?x cluster-modified TiO2 (CuO1?x/TiO2) photocatalysts were prepared by an in-situ photoreduction deposition of Cu on TiO2 powder support using copper acetate as a Cu source. The prepared samples without any Pt co-catalyst present an especially high photocatalytic H2-evolution activity under solar light irradiation with 5% glycerol as sacrificial agent. The optimal CuO1?x/TiO2 catalyst with only 1 wt% CuO1?x exhibits a high activity of 1725 μmol h?1 g?1 for H2 evolution, which reaches 120 times that of TiO2. The high photocatalytic activity of H2 production is attributed to the highly dispersed CuO1?x nano clusters on the surface of the TiO2. In addition, Pt/CuO1?x/TiO2 was also prepared by loading Pt on CuO1?x/TiO2 sample, and its photocatalytic hydrogen evolution activity is enhanced 1.8 times compared with that of Pt/TiO2 for overall water splitting reaction under solar light, demonstrating that a small amount CuO1?x wondrously improves the photocatalytic activity of Pt/TiO2 for overall water splitting reaction. This paper reports an economic and simple approach to prepare a photocatalyst with high hydrogen-production activity. 相似文献