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1.
Cerium (Ce3+) doped TiO2 powder was synthesized by a sol-gel method and characterized by Transmission Electron Microscope (TEM), X-ray Diffraction (XRD), UV–Vis Diffuse Reflectance Spectroscopy (UV-DRS), Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The Ce3+ doping strongly reduced the band gap of the TiO2 from 3.2 eV (UV) to 2.7 eV (visible region). The photocatalytic activity of Ce3+ doped TiO2 catalysts was evaluated by hydrogen production from sulphide wastewater under visible light illumination. The photocatalytic production of H2 was studied in a batch recycle tubular photocatalytic reactor. The results show that 0.4% Ce3+–TiO2 suspended in 500 mL of simulated sulphide wastewater irradiated at 150 W visible lamp produced maximum H2 of 6789 μmol h?1. It was noticed that the Ce3+ doped TiO2 performs well than Nano TiO2 and P25 TiO2 photocatalysts. 相似文献
2.
《International Journal of Hydrogen Energy》2020,45(13):7574-7583
Hydrogen is the future fuel and energy carrier, which has numerous applications. During combustion, produces only water vapour instead of greenhouse gas emissions. Photocatalytic production of hydrogen as a clean fuel from sulphide wastewater arises as a necessary option that must be considered. Here we report the performance of CNT added CdZnS/Fe2O3 for hydrogen recovery from highly toxic sulphide containing wastewater. The prepared photocatalysts were characterised for XRD (structure), UV-DRS (band gap), HRTEM (particle size), XPS (binding energy), SEM (morphology) and ICP (elemental composition). The photocatalytic hydrogen recovery was performed using novel trapezoidal photocatalytic reactor. The synthesized novel CNT - CdZnS/Fe2O3 nano-photocatalyst has highest production of hydrogen (2679 μmol/h) than plain CdZnS/Fe2O3 (2009 μmol/h).The feasibility studies were conducted to optimize the operating variables viz., S2- (sulphide ion) concentrations, SO32- (sulphite ion) concentrations, catalyst amount, light irradiation and volume of wastewater. Reusability studies under natural solar irradiation were performed and the CNT deposited CdZnS/Fe2O3 photocatalyst was found to be stable upto seven runs. 相似文献
3.
Three types of high-performance photocatalytic reactors were developed for gas-phase photocatalytic hydrogen (H2) production from hydrogen sulphide (H2S) and effective photocatalytic decomposition of gaseous H2S at a very low concentration is investigated. In this paper, three lab-scale photocatalytic reactors viz., packed bed photocatalytic reactor, catalyst coated fixed bed photocatalytic reactor and catalyst dispersed photocatalytic reactors were developed to study the performance of reactors on hydrogen production. The novel photocatalyst (CdS + ZnS)/Fe2O3 and the optimized catalyst dosage, H2S gas flow rate, pollutant concentration, light irradiations were used. The experimental result indicates that packed bed photocatalytic reactor can effectively splits the H2S into hydrogen (i.e. 98%) and rapidly decompose H2S toward zero concentration than the other two reactors. Hence the bench-scale photocatalytic reactor was fabricated in packed bed reactor and the maximum hydrogen conversion achieved from hydrogen sulphide was found to be 98%. 相似文献
4.
Stability of photocatalyst plays an important role in efficient hydrogen recovery from sulphide waste streams. This research focuses on the stability and efficiency of visible light active photocatalysts viz., RuO2/CuGa1.6Fe0.4O4, ZnFe2O3, (CdS + ZnS)/Fe2O3 and Ce/TiO2 for H2 production. RuO2/CuGa1.6Fe0.4O4 photocatalyst was found to give maximum hydrogen production of 8370 μmol/h. The reusability of the photocatalysts was tested by multiple cycles of catalyst regeneration along with H2 production. The result shows that (CdS + ZnS) coated iron oxide core shell particles were found to be stable than other prepared nano photocatalysts. It is also demonstrated that H2S can be split into hydrogen and sulphur under visible light irradiation using sulphide and sulphite reaction media at room temperature. This research paper will help in search of stable photocatalysts in recovering hydrogen from sulphide wastewater along with sulphur separation. 相似文献
5.
Xiaoliang Li Yi Gao Jiawen Liu Xin Yu Zhonghua Li 《International Journal of Hydrogen Energy》2017,42(18):13031-13038
We successfully synthesized novel Ti3+ doped TiO2 and Ti3+ doped Ag/AgITiO2 nanoparticles with efficient visible-light photocatalytic activity for hydrogen production by facile one-step solvothermal method. The as-prepared Ti3+ doped TiO2 nanoparticles displayed excellent visible-light absorption and visible-light driven hydrogen production activity (115.3 μmol g?1 h?1), while the commercial TiO2 had no visible-light response. Moreover, the as-prepared Ti3+ doped Ag/AgITiO2 nanoparticles in this experiment showed highly enhanced visible-light absorption and efficient visible-light driven activity for hydrogen (571.0 μmol g?1 h?1), which was 4.95 times as high as that of the as-prepared TiO2 nanoparticles. And the surface areas of the as-prepared TiO2 and Ti3+ doped Ag/AgITiO2 catalysts were up to 138.829 m2 g?1 and 102.988 m2 g?1, much higher than that of the commercial TiO2 (55.516 m2 g?1). Finally, the visible-light photocatalytic mechanism of the Ti3+ doped Ag/AgITiO2 nanoparticles for hydrogen generation was also proposed in detail. 相似文献
6.
Fe3+ doped TiO2 photocatalysts were prepared by hydrothermal treatment for the photocatalytic water splitting to produce stoichiometric hydrogen and oxygen under visible light irradiation. It was found that hydrothermal treatment at 110 °C for 10 h was essential for the synthesis of highly stabilized Fe3+ doped TiO2 photocatalysts. The synthesized photocatalysts were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS) and BET surface area techniques. The doping of highly stabilized Fe3+ in the titania matrix leads to significant red shift of optical response towards visible light owing to the reduced band gap energy. Optimum amount of Fe3+ doped TiO2, 1.0 wt% Fe/TiO2, showed drastically improved hydrogen production performance of 12.5 μmol-H2/h in aqueous methanol and 1.8 μmol-H2/h in pure water, respectively. This Fe/TiO2 photocatalyst was stable for 36 h without significant deactivation in the water splitting reaction. 相似文献
7.
Gullapelli Sadanandam Kannekanti Lalitha Valluri Durga Kumari Muthukonda V. Shankar Machiraju Subrahmanyam 《International Journal of Hydrogen Energy》2013
Glycerol is the main by-product during the trans-esterification of vegetable oils to biodiesel. In this study, we investigate the process of photocatalytic hydrogen production from glycerol aqueous solution, with the use of cobalt doped TiO2 photocatalyst under solar light irradiation. Cobalt doped TiO2 photocatalysts are prepared by impregnation method and these catalysts are characterized by XRD, EDAX, DRS, TEM, EPR and XPS techniques. DRS studies clearly show the expanded photo response of TiO2 into visible region on impregnation of Co2+ ions on surface of TiO2. XPS studies also show change in the binding energy values of O1s, Ti 2p and Co 2p, indicating that Co2+ ions are in interaction with TiO2. Maximum hydrogen production of 220 μ mol h−1 g−1 is observed on 2 wt% cobalt doped TiO2 catalysts in pure water under solar irradiation. A significant improvement in hydrogen production is observed in glycerol: water mixtures; and maximum hydrogen production of 11,021 μ mol h−1 g−1 is obtained over 1 wt% cobalt doped TiO2 in 5% glycerol aqueous solutions. Furthermore, to evaluate some reaction parameters such as cobalt wt% on TiO2, glycerol concentration, substrate effect (alcohols) and pH of the solution on the hydrogen production activity are systematically investigated. When the catalysts are examined under UV irradiation, a 3–4 fold increase in activity is observed where this activity seems to decrease with time; however, a continuous activity is observed under solar irradiation on these catalysts. The decreased activity could be ascribed the loss of cobalt ions under UV irradiation, as evidenced by EDAX and TEM analysis. A possible explanation for the stable and continuous activity of cobalt doped TiO2 photocatalysts under solar irradiation is proposed. 相似文献
8.
The controllable photocatalytic hydrolysis of alkali‐metal borohydrides is studied for hydrogen generation in this work. The results indicate that the photocatalysis of P25 TiO2 controllably promotes the hydrogen generation rates from alkali‐metal borohydride hydrolysis. Its apparent activation energy is calculated to be reduced from 57.20 to 53.86 kJ mol?1. This is due to the mechanism of photocatalytic hydrolysis: holes (h+) react with BH4‐ and OH? to form H2 and B(OH)4‐, meanwhile electrons (e?) react with H+ to from H2. In addition, Ti3+‐doped TiO2 with a crystalline‐disordered core‐shell structure can be generated during the photocatalytic hydrolysis process. The consumption of e? is identified as the rate‐limiting step in photocatalytic hydrolysis process. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
9.
《International Journal of Hydrogen Energy》2022,47(75):32121-32132
This study focused on the large band gap of TiO2 for its use as a photocatalyst under light emitting diode (LED) light irradiation. The photocatalytic activities of core–shell structured Au@TiO2 nanoparticles (NPs), nitrogen doped Au@TiO2 NPs, and Au@TiO2/rGO nanocomposites (NCs) were investigated under various light intensities and sacrificial reagents. All the materials showed better photocatalytic activity under white LED light irradiation than under blue LED light. The N-doped core–shell structured Au@TiO2 NPs (Au@N–TiO2) and Au@TiO2/rGO NCs showed enhanced photocatalytic activity with an average H2 evolution rate of 9205 μmol h?1g?1 and 9815 μmol h?1g?1, respectively. All these materials showed an increasing rate of hydrogen evolution with increasing light intensity and catalyst loading. In addition, methanol was more suitable as a sacrificial reagent than lactic acid. The rate of hydrogen evolution increased with increasing methanol concentration up to 25% in DI water and decreased at higher concentrations. Overall, Au@TiO2 core–shell-based nanocomposites can be used as an improved photocatalyst in photocatalytic hydrogen production. 相似文献
10.
P. Gomathisankar T. Kawamura H. Katsumata T. Suzuki S. Kaneco 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(1):110-116
The photocatalytic hydrogen generation from aqueous methanol solution using TiO2 photocatalyst was investigated with the aid of simultaneous metal deposition. The photocatalytic hydrogen evolution with pure TiO2 was very small. The simultaneous deposition for various metals was therefore evaluated. As a result, the additions of Au and Cu ions were effective for the improvement of photocatalytic hydrogen production. Methanol concentration and metal ion concentration were optimized for the system. The optimal methanol concentrations were 90 and 80 vol% in the case of addition of Au and Cu ions, respectively. Under the optimal conditions, the photocatalytic hydrogen production using TiO2 photocatalyst with the aid of simultaneous Cu and Au deposition were approximately 25 and 120 times larger than those obtained with bare TiO2. 相似文献
11.
《International Journal of Hydrogen Energy》2022,47(18):10250-10260
Pd nanoparticles (NPs) loading, main group metal ions doped TiO2 nanosheets were prepared by a hydrothermal method, followed by photo-deposition of Pd. The samples were characterized, and their photocatalytic hydrogen production activities were tested in a methanol aqueous solution. The effects of cationic charge, radius and concentration of the doping ions (Na+, K+, Mg2+, Al3+) on the photocatalytic activities were investigated systematically. The photocatalytic reaction mechanism was discussed by considering the three aspects: specific surface area, light absorption and charge transfer/separation. The results show that the cation dopings significantly increased the photocatalytic activities of the TiO2 nanosheets, which may be attributed to the enhanced UV-vis light absorption and accelerated charge transfer/separation of the catalysts. Particularly, the Pd/0.2%K+-TiO2 possesses the highest photocatalytic H2 production activity (76.6 μmol h?1), which is more than twofold higher than that of the undoped Pd/TiO2. The apparent quantum efficiency of hydrogen evolution system reaches 3.0% at 365 nm. The high activity of the Pd/K+-TiO2 may be attributed to the lower electronegativity of K+, caused by the lower cationic charge or the larger cationic radius, compared to Na+, Mg2+ and Al3+. The doping metal cations with higher electronegativity may compete electrons with H+, which eventually partly depressed the reduction of H+ to H2. 相似文献
12.
Kyong-Hwan Chung Sangmin Jeong Heon Lee Sun-Jae Kim Ki-Joon Jeon Young-Kwon Park Sang-Chul Jung 《International Journal of Hydrogen Energy》2017,42(38):24099-24107
Photocatalytic decomposition of acetaldehyde-contained wastewater was assessed for the degradation of pollutants and the production of hydrogen. Liquid phase plasma was applied in the photoreaction as a light source. The evolution of hydrogen and acetaldehyde degradation were characterized by the photocatalytic decomposition system. Ni-loaded TiO2 photocatalysts and various porous materials were introduced to the photocatalytic reaction. The photochemical decomposition by irradiation of the liquid phase plasma without photocatalysts produced some hydrogen evolution with the degradation of acetaldehyde, which was attributed to the decomposition of the reactant by active species generated by the irradiation of liquid phase plasma. The Ni loading on TiO2 brought out an enhancement of acetaldehyde degradation and hydrogen evolution. In the photocatalysis of acetaldehyde-contained wastewater using the liquid phase plasma, hydrogen evolution was accelerated due to the additional hydrogen production by the photocatalytic decomposition of acetaldehyde. The porous materials could be used as an effective photocatalytic support. MCM-41 mesoporous material has acted as a highly efficient photocatalytic support to the TiO2 photocatalyst. 相似文献
13.
In this study, we investigate the physical properties and photocatalytic activities of TiO2 thin films doped with low valence (Fe3+, Co2+, and Ni2+) and high valence (Mo5+, Nb5+, and W6+) cations. Clear difference in results from various analytical tools between groups was identified. The presence of different oxidation states and a higher degree of crystallinity in the high valence cation doped-TiO2 thin films seemed beneficial in terms of the transfer and separation of photo-generated electrons and holes in the TiO2 medium and on the surface, resulting in higher photocatalytic conversion of trichloroetylene. 相似文献
14.
《International Journal of Hydrogen Energy》2020,45(51):27012-27025
This work reports the morphological and photocatalytic hydrogen generation properties of CNT/Pt composites with and without functionalization by carboxylic/oxygen groups. The composites with and without functionalization were named f-CNT/Pt and CNT/Pt, respectively. Several f-CNT/Pt and CNT/Pt composites with different content of Pt NPs (from 0 to 30 wt%) were synthesized and analyzed by scanning electron microscopy (SEM). Those images revealed that the composites without functionalization presented higher agglomerations of Pt nanoparticles (NPs). Furthermore, the average sizes of the Pt NPs in the named f-CNT/Pt composites (2.3–2.9 nm) were lower than these in the CNT/Pt composites (2.5–3.1 nm). The hydrogen generation rates were also calculated from the decomposition of pure water under UV irradiation (365 nm) and found maximum values of 45.4 and 193.9 μmol·h−1 g−1 for the CNT/Pt and f-CNT/Pt composites (they contained 20 wt% of Pt NPs), respectively. Additional experiments for hydrogen generation were achieved using sodium sulfite as sacrificial agent; in this case, a maximum value of 13850 μmol·h−1 g−1 was obtained for the f-CNT/Pt composite. The f-CNT/Pt composites produced more hydrogen than the CNT/Pt composites because they presented higher content of defects; this was confirmed by the Raman spectra. We also showed that the Pt NPs acted as electron trap centers, which delayed the recombination of the photogenerated electrons and holes, this in turn, enhanced the hydrogen generation rates of the composites (the hydrogen generation was maximized by varying the content of Pt NPs deposited on the CNTs). The CNT/Pt composites presented here were simpler and easier to synthesize than the previous published ternary systems based on TiO2, CNTs and Pt NPs. 相似文献
15.
T.C. Bhagya Arunima Rajan S S.M.A. Shibli 《International Journal of Hydrogen Energy》2021,46(30):16360-16372
The significance of Sn dopant on the photocatalytic performance of Iron/Titanium nanocomposite towards photocatalytic hydrogen generation by water splitting reaction is investigated. Iron/Titanium nanocomposite modified by Sn4+ dopant acts as a suitable photocatalyst for induced visible light absorption facilitating pronounced charge separation efficiency. Various characterization techniques reveal the heterojunction formation of hematite Fe2O3 with anatase - rutile mixed phase of TiO2 employing Sn doping, where Sn4+ dopant accomplishes the phase transformation of anatase to rutile, entering into the TiO2 lattice. This extended the lifetime of photogenerated charge carriers and enhanced the quantum efficiency of the photocatalyst. The band gap of the nanocomposite is tuned to ~2.4 eV, favoring visible light absorption. A hydrogen generation activity of 1102.8 μmol, approximately five times higher than the lone system (216.5 μmol) is achieved for the 5% Sn doped system for an average of 5 h. Heterojunctions of hematite with anatase-rutile mixed phase, generated as a consequence of tin doping facilitated the enhanced hydrogen generation activity of photocatalyst. 相似文献
16.
Caolong Li Jian Yuan Bingyan Han Li Jiang Wenfeng Shangguan 《International Journal of Hydrogen Energy》2010
The CdS/TiO2 composites were synthesized using titanate nanotubes (TiO2NTs) with different pore diameters as the precursor by simple ion change and followed by sulfurization process at a moderate temperature. Some of results obtained from XRD, TEM, BET, UV–vis and PL analysis confirmed that cadmium sulfide nanoparticles (CdSNPs) incorporated into the titanium dioxide nanotubes. The photocatalytic production of H2 was remarkably enhanced when CdS nanoparticles was incorporated into TiO2NTs. The apparent quantum yield for hydrogen production reached about 43.4% under visible light around λ = 420 nm. The high activity might be attributed to the following reasons: (1) the quantum size effect and homogeneous distribution of CdSNPs; (2) the synergetic effects between CdS particles and TiO2NTs, viz., the potential gradient at the interface between CdSNPs and TiO2NTs. 相似文献
17.
Photocatalytic water splitting plays a challenging role as it is one of the most important reactions for solving energy, environmental problems and sustainability. Photocatalytic water splitting was improved by using a novel kind of magnetically separable core shell nano photocatalyst TiO2/Fe2O3, prepared by co-precipitation method. It was characterised for particle size (XRD), band gap (UV-DRS), morphology (SEM), particle size (HRTEM), elemental composition (EDS) and electrochemical studies. Photocatalytic splitting of water was examined in tubular reactor of 500 mL capacity with various sacrificial agents viz., methanol, ethanol, acetic acid, lactic acid, EDTA and triethanolamine. To enhance the hydrogen production, various operating parameters viz., effect of sacrificial agents, catalytic dosage, light irradiation and recycle flow rate were optimized. With the optimized operating parameters (0.2 g catalyst dosage, 60 mL/min recycle flow rate, 96 W/m2 light irradiation and EDTA as sacrificial agent) the maximum hydrogen achieved was 2700 μmol/h for the quantum yield of 3.86% at 550 nm. The reusability studies were conducted and the TiO2 coated Fe2O3 core shell particles were found to be stable than the plain TiO2 nano particles. Effective charge transfer from TiO2 to Fe2O3 and the suppression of e?/h+ pair recombination attributed significant enhancement in photoactivity, thereby increasing the hydrogen production. 相似文献
18.
Katherine Villa Xavier Domènech Sixto Malato Manuel I. Maldonado José Peral 《International Journal of Hydrogen Energy》2013
Few studies have been published about large scale heterogeneous photocatalysis hydrogen generation with simultaneous removal of organic pollutants. The purpose of the present work was to study the simultaneous photocatalytic hydrogen production and organic pollutant removal under direct solar irradiation at pilot-plant scale. The experiments were performed in a Compound Parabolic Collector (CPC) at the Plataforma Solar de Almería (PSA). The efficiencies of two different photocatalytic systems, one based on a nitrogen doped and platinized TiO2, and the other using a platinized CdS–ZnS composite were evaluated. Formic acid and glycerol were used as sacrificial electron donors. Also, experiments using real municipal wastewaters were carried out showing simultaneous hydrogen generation and partial water pollutant removal. The largest amounts of hydrogen were obtained with aqueous solutions of formic acid, although the experiments with real wastewater gave moderate amounts of hydrogen, pointing towards the possible future use of such waters for photocatalytic hydrogen generation. 相似文献
19.
《International Journal of Hydrogen Energy》2020,45(13):7764-7778
Titanium dioxide remains a benchmark photocatalyst with high stability, low cost, and less toxicity, but it is active only under UV light; thus, in practical applications using visible light, its catalytic reactions are stalled. To enhance its catalytic activity under visible light, non-metal/codoped TiO2 structures are being studied. These structures improve the photocatalytic activity of TiO2 in visible light by reducing its energy bandgap. This might be useful in wastewater treatment for the photocatalytic degradation of organic contaminants under visible and UV light irradiation. In this intensive review, we describe recent developments in TiO2 nanostructured materials for visible-light driven photocatalysis, such as (i) mechanistic studies on photo-induced charge separation to understand the photocatalytic activity and (ii) synthesis of non-metal doped/codoped TiO2 and TiO2 nanostructured hybrid photocatalysts. Furthermore, the effects of various parameters on their photocatalytic efficiency, photodegradation of various organic contaminants present in wastewater, and photocatalytic disinfection are delineated. 相似文献
20.
R. Sasikala V. Sudarsan C. Sudakar R. Naik L. Panicker S.R. Bharadwaj 《International Journal of Hydrogen Energy》2009
Synthetic approaches/methodologies can change the properties of nanoparticles significantly. In this study, the photocatalytic property of self (Ti3+) doped TiO2 nanoparticles was modified by synthesizing through different routes. Solvothermal (T-Sol), sonochemical (T-Son) and polyol (T-Pol) methods were employed to prepare TiO2 nanoparticles and the photocatalytic activities of these samples were compared with that of the sample prepared by precipitation using ammonia solution (T-Ppt). All samples had particle size below 30 nm except T-Son, where small nanoparticles existed as large spherical agglomerates with size around 500 nm. Surface area and porosity measurements of these different TiO2 samples showed a significant dependency on the synthesis method. UV–Visible absorption spectra showed the onset of absorption at ∼440 nm for all samples due to the presence of defect levels originating from anion vacancies. Photocatalytic activity for hydrogen generation decreased in the order T-Sol > T-Son > T-Pol > T-Ppt and the observed activity is correlated with their physical properties such as surface area and crystallinity. The hydrogen yield was highly enhanced by the addition of Pd metal as co-catalyst on the surface of TiO2 photocatalysts. Present experiments clearly demonstrate the importance of synthesis route to improve the photocatalytic activity of TiO2. 相似文献