Amount Of Hydrogen Production Research Articles

Ordered mesoporous CeO2/ZnO composite with photodegradation concomitant photocatalytic hydrogen production performance

In this study, ordered mesoporous zinc oxide (ZnO) precursor was prepared by template method, and then CeO2/ZnO composite was synthesized by hydrothermal method which showed the chrysanthemum-like particle morphology with the ordered mesoporous on the surface of the material. In the prepared composite, heterojunctions were formed between ZnO and CeO2, which induced effective charge separation, and the photocatalytic activity of the composites was enhanced. The photocatalytic hydrogen production concurrent organic pollutants degradation performances were shown in the prepared material. The 10 wt% CeO2 doped sample exhibited the best photocatalytic activity whose hydrogen production amount was 27.104 mmol/g in 3 h, and the photocatalytic degradation efficiency of methylene blue (MB) was about 97.4% in 150 min under visible light irradiation. The photocatalytic hydrogen production performance was study in pollutants water, the hydrogen production amount was 63.59 mmol/g in MB water solution without CH3OH (MeOH) sacrificial agent which was about 2.4 time as in clean water with MeOH sacrificial agent. The vast H2 was produced during the organic pollutants photo-degradation process, and the organic pollutants photo-degradation efficiency was not reduced.

Thermal degradation of waste plastics in a two-stage pyrolysis-catalysis reactor over core-shell type catalyst

A core-shell type catalyst was applied to convert polyethylene (PE) plastic wastes into hydrogen using a two-stage pyrolysis-catalysis reactor. The effects of catalyst: plastic ratio, reaction temperature, and the suppression of coke formation on catalytic performance were investigated. Ni-Ce bimetallic catalyst was synthesized via modified polyol method, and the silica coating with different Ni:Si molar ratio was prepared with the extension of Stöber method. Different thickness of silica shell was synthesized and tested for hydrogen production from PE waste. The encapsulation of Ni-Ce core by silica shell could effectively inhibit the sintering of nanoparticles under high temperature conditions. The highest amount of hydrogen production was found when the catalyst: plastic weight ratio was 1.0, and the catalytic reaction temperature was 800 °C. The core-shell catalyst also exhibited great ability of coking resistance, showing great catalytic performance within 5 times of reuse.

Three-dimensional ordered hollow sphere composite Pt/TiO2-ZrO2: enhanced performance of photocatalytic degradation and photocatalytic hydrogen evolution

In this paper, a three-dimensional ordered hollow sphere (3DOH) structure composite Pt/TiO2-ZrO2 was prepared by using polystyrene (PS) colloidal spheres as the template and combining with two-step vacuum impregnation method, of which the composition, crystalline structure, morphology, and surface physicochemical properties were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance (UV-vis/DRS), photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and nitrogen adsorption-desorption measurements. The results illustrate the crystal type of 3DOH Pt/TiO2-ZrO2 is mainly anatase TiO2 and tetragonal ZrO2 phase, which exhibits a three-dimensional ordered hollow sphere structure. Hollow spheres are arranged orderly; moreover, the composite shows a strong absorption in the visible region due to the effect of surface plasmon absorption (SPA) after doping Pt nanoparticles. Meanwhile, the photocatalytic activity of 3DOH Pt/TiO2-ZrO2 was investigated by using Congo red as the model molecule. The results show that 3DOH Pt/TiO2-ZrO2 has good photocatalytic activity under multi-modes photocatalytic experiments, and its activity is higher than that of P25, ZrO2, and other Pt/TiO2-ZrO2 not treated by PS colloidal spheres. In addition, the total amount of hydrogen production of 3DOH Pt/TiO2-ZrO2 is 100 times as much as the commercial P25 in the photocatalytic hydrogen evolution experiment (8 h), which shows an excellent photolysis of water hydrogen production activity.

Magnetic ZnFe2O4@ZnSe hollow nanospheres for photocatalytic hydrogen production application

Magnetic ZnFe2O4@ZnSe hollow nanospheres were fabricated by a two-step method and applied for visible light photocatalytic water splitting. Magnetic ZnFe2O4 hollow nanosphere was prepared by using the carbonaceous microsphere as a template, and ZnSe nanoparticles were in site grown on the ZnFe2O4 surface. Through optimizing the reaction time, ZnFe2O4@ZnSe hollow nanospheres exhibited efficient light absorption and improved photocatalytic performance, and ZnFe2O4@ZnSe-20 with suitable ZnSe shell thickness possessed highest hydrogen production amount in 6 h (16897.3 μmol/g). The experimental results revealed that the formation of heterojunction between ZnSe and ZnFe2O4 effectively separated and transferred the photo-induced electrons and holes, and inhibited the electron-hole pairs recombination. In addition, the magnetic recyclability of ZnFe2O4@ZnSe hollow nanospheres was beneficial to further photocatalytic hydrogen production application.

TiO2 nanosheets with exposed {001} facets co-modified by AgxAu1−x NPs and 3D ZnIn2S4 microsphere for enhanced visible light absorption and photocatalytic H2 production

A novel AgxAu1−x/ZnIn2S4/TiO2 photocatalyst with high photoactivity under visible light illumination is designed in this work, in which ZnIn2S4 displays a 3D flower-like microsphere structure, while TiO2 nanosheets with highly active {001} facets (TiO2 NS) are tightly embedded in the interspaces of ZnIn2S4 microspheres, and AgxAu1-x nanoparticles (NPs) are loaded on its surface, respectively. The exquisite design of AgxAu1−x/ZnIn2S4/TiO2 makes it possess remarkable superiority in photocatalysis. Firstly, by the dual modification of ZnIn2S4 and AgxAu1−x, the AgxAu1−x/ZnIn2S4/TiO2 displays a strong absorption in visible light region, and their absorption region can be modulated by changing the ratio of Ag and Au in AgxAu1-x nanoparticles due to the plasmon coupling effect of Ag and Au. Secondly, the high separation and transfer efficiency of photogenerated carriers is achieved in AgxAu1-x/ZnIn2S4/TiO2 by utilizing TiO2 as the electron transfer intermediary of ZnIn2S4 and AgxAu1−x. All of these make AgxAu1−x/ZnIn2S4/TiO2 exhibit an evident enhancement in the photocatalytic activity of H2 production. Significantly, the hydrogen production amount and rate of Ag0.2Au0.8/ZnIn2S4/TiO2 with 60 wt% ZIS after 10 h are 9862 μmol/g and 986.2 μmol/g/h, which is around 2098 times of pristine TiO2. The apparent quantum yield of Ag0.2Au0.8/ZnIn2S4/TiO2 after 10 h is about 1.47%. Moreover, the cycling test reveals that AgxAu1−x/ZnIn2S4/TiO2 shows the high stability in photocatalytic water spitting. Based on the characterization and photocatalytic results, the proposed photocatalytic mechanism is proposed.

Three-Dimensional Structure of PANI/CdS NRs-SiO₂ Hydrogel for Photocatalytic Hydrogen Evolution with High Activity and Stability.

Three-dimensional PANI/CdSNRs-SiO2 hydrogel (CdS NRs-PANI-SiO2) was synthesized by loading polyaniline (PANI) onto the semiconductor CdS nanorods (NRs) surface and loading the binary complex on SiO2 gel. The structure, optical properties, and electrochemical properties of the composite were studied in detail. The hydrogen production amount of CdS NRs-PANI (3%)-SiO2 (20%) increased in comparison with CdS NRs and reached 43.25 mmol/g in 3 h under visible light. The three-dimensional structure of SiO2 hydrogel increased the specific surface area of the catalyst, which was conducive to exposing more active sites of the catalyst. In addition, the conductive polymer PANI coated on CdS NRs played the role of conductive charge and effectively inhibited the photo-corrosion of CdS NRs. In addition, the recovery experiment showed that the recovery rate of the composite catalyst reached 90% and hydrogen production efficiency remained unchanged after five cycles, indicating that the composite catalyst had excellent stability.

Enhanced photoelectrochemical stability of GaN photoelectrodes by Al2O3 surface passivation layer.

Photoelectrochemical (PEC) water splitting is one of the most promising hydrogen production methods because of its high efficiency, renewable resources and harmless by-products. Gallium nitride (GaN) is suitable for PEC water splitting because it has excellent stability in electrolyte and band gap energy which straddles the redox potential of water (Vredox = 1.23 V). These characteristics allow this material to split water stably without external bias. However, the stability of GaN is still not sufficient for practical applications. In this study, we investigated the properties of GaN photoelectrodes with aluminum oxide (Al2O3) thin film as a protection layer for increasing stability. In a long-term stability test, Al2O3-coated GaN showed more stable photocurrent than that of bare GaN. The total hydrogen production amount was also improved in Al2O3-coated samples than bare GaN. These results indicate that the Al2O3 protection layer significantly enhances stability and hydrogen production.

Comparative kinetic modeling of growth and molecular hydrogen overproduction by engineered strains of Thermotoga maritima

Thermotoga maritima is an anaerobic hyperthermophilic bacterium known for its high amounts of hydrogen (H2) production. In the current study, the kinetic modeling was applied on the engineered strains of T. maritima that surpassed the natural H2 production limit. The study generated a kinetic model explaining H2 overproduction and predicted a continuous fermentation system. A Leudking-Piret equation-based model predicted that H2 production by Tma200 (0.217 mol-H2 g−1-biomass) and Tma100 (0.147 mol-H2 g−1-biomass) were higher than wild type (0.096 mol-H2 g−1 -biomass) with reduced rates of maltose utilization. Sensitivity analysis confirmed satisfactory fitting of the experimental data. The slow growth rates of Tma200 (0.550 h−1) and Tma100 (0.495 h−1) are compared with the wild type (0.663 h−1). A higher maintenance energy along with growth and non-growth H2 coefficients corroborate the higher H2 productivity of the engineered strains. The modeled data established a continuous fermentation system for the sustainable H2 production.

Optimization for enhanced hydrogen production from Rhodobacter sphaeroides using response surface methodology

In the present study, Rhodobacter sphaeroides isolated from sewage water was investigated for photoproduction of hydrogen under different cultural conditions. The variation was done in carbon and nitrogen sources along with growth factors. It was found that lactose promoted more amounts of hydrogen production under anaerobic light conditions followed by mannitol, galactose, and sucrose respectively. Uracil was observed as a better nitrogen source as compared to histidine and thiourea. After screening most appropriate carbon source, nitrogen source and growth factor by the classical approach, statistical optimization technique opted for the enhancement of hydrogen production. The response surface methodology adopted in the present work is an efficient tool for strategic experimental design for optimizing process parameters of a multivariable process. Firstly, experiments were performed according to Box-Behnken design. The model predicted is quadratic with a high value of R2 i.e. 0.9681 and maximum production recorded was 6.8 ml/30 ml. Thereafter, Central composite design based experiments were performed and 7.6 ml/30 ml production was achieved with an R2 value of 0.8848 fitted inthe quadratic model. The work presented here suggests a green approach of enhanced hydrogen production to meet the future demand of clean fuel.

Parametric analysis of water electrolysis by dual electrolytes and cells

ABSTRACTIn this study, sulfuric acid and potassium hydroxide are used as the electrolytes, separated by proton exchange membrane, to produce hydrogen. The effects of electrolyte concentrations, applied voltage, single or dual cells, and temperature on the hydrogen production rate and energy efficiency are investigated. Experimental results show that the amount of hydrogen production increases with voltage, and the dual electrolytes and cells can yield the best hydrogen production rate and energy efficiency. With 1-M KOH plus 1-M H2SO4 as electrolytes in separated cells, the highest hydrogen production rate is about 0.95 L/hr. Results also show that the rise of electrolyte temperature can significantly increase the hydrogen production rate up to 50%, and the energy efficiency up to 20%. Keeping a low PH value in cathodeand high anode PH value in anode indeed enhances the efficiency of hydrogen production rate.

MELCOR UNCERTAINTY STUDY ON IN-VESSEL HYDROGEN GENERATION

MELCOR is an integral severe accident analysis program which simulates the responses of the light water reactor during a severe accident. Because the value of modeling parameters involves uncertainty, and the uncertainties of major output parameters as predicted by the integral programs are relatively large, a methodology in this study was developed to quantify the uncertainties of input variables of MELCOR. Multiple calculations of MELCOR were performed with inputs combinations generated from Latin Hypercube Sampling (LHS). The regression method was used to determine the impact of input variables on the target output parameters. TZXMX, PORDP, and FCELR were screened out to have important effect with the in-vessel hydrogen production. On the other hand, the results of the calculations were analyzed with a Chi-Square test to determine the 95th percentile with a 95% confidence level value of the amount of in-vessel hydrogen production, the 95/95 of upper bound value of in-vessel hydrogen generation is 1064.03 kg. The results of the analyses provide guidance for the code users to study the uncertainty of input variables.

Quantification of hydrogen production by intestinal bacteria that are specifically dysregulated in Parkinson's disease

Oral administration of hydrogen water ameliorates Parkinson’s disease (PD) in rats, mice, and humans. We previously reported that the number of putative hydrogen-producing bacteria in intestinal microbiota is low in PD compared to controls. We also reported that the amount of hydrogen produced by ingestion of lactulose is low in PD patients. The decreased hydrogen production by intestinal microbiota may be associated with the development and progression of PD. We measured the amount of hydrogen production using gas chromatography by seven bacterial strains, which represented seven major intestinal bacterial groups/genera/species. Blautia coccoides and Clostridium leptum produced the largest amount of hydrogen. Escherichia coli and Bacteroides fragilis constituted the second group that produced hydrogen 34- to 93-fold lower than B. coccoides. Bifidobacterium pseudocatenulatum and Atopobium parvulum constituted the third group that produced hydrogen 559- to 2164-fold lower than B. coccoides. Lactobacillus casei produced no detectable hydrogen. Assuming that taxonomically neighboring strains have similar hydrogen production, we simulated hydrogen production using intestinal microbiota that we previously reported, and found that PD patients produce a 2.2-fold lower amount of intestinal hydrogen compared to controls. The lower amount of intestinal hydrogen production in PD was also simulated in cohorts of two other countries. The number of hydrogen-producing intestinal bacteria may be associated with the development and progression of PD. Further studies are required to prove its beneficial effect.

Improvement of photofermentative biohydrogen production using pre-treated brewery wastewater with banana peels waste

In this study, the impacts of banana peels pre-treatment stage on photofermentative hydrogen production of Rhodobacter sphaeroides 158 DSM using brewery wastewater (BWW) were investigated in a batch bioreactor. The experimental results indicate that banana peels pre-treatments can significantly enhance the cumulative hydrogen production. The maximum hydrogen production yield (408.33 mL H2 L−1wastewater) was achieved from the substrate, which was composed of 50% BWW pretreated with 1 g L−1 of banana peels for 2 h and 50% standard medium. This highest amount of hydrogen production was 2.7-folds higher than those that applied the same percentage of raw BWW as the substrate source.

Building a Thermostable Metabolon for Facilitating Coenzyme Transport and In Vitro Hydrogen Production at Elevated Temperature.

To facilitate coenzyme transport and in vitro enzymatic hydrogen production, a multi-enzyme metabolon comprising a miniscaffoldin containing three cohesins, a dockerin-containing mutant dehydrogenase, a dockerin-containing diaphorase, and a Histidine-tagged (His-tagged) NiFe hydrogenase was constructed. As the NiFe hydrogenase has very complicated structure and cannot be fused directly with a dockerin, a bifunctional peptide was designed. The bifunctional peptide, in which one terminus contains a modified dockerin binding the cohesin of the miniscaffoldin and the other, after chemical modification, binds the His-tag of NiFe hydrogenase, enabled His-tagged proteins to be integrated into the cohesin-dockerin-based metabolon. The metabolon exhibited an initial reaction rate 4.5 times that of the enzyme cocktail at the same enzyme loading, which indicated enhanced coenzyme transport of the metabolon. However, this metabolon was unstable owing to the degradation of the miniscaffoldin at elevated temperature. Glutaraldehyde was used to cross-link the metabolon for locking its spatial organization. The cross-linked metabolon not only exhibited 2.5 times the reaction rate of the enzyme cocktail, but also retained its stability at 70 °C. The amount of hydrogen production catalyzed by the cross-linked metabolon was nearly twice that of the metabolon without glutaraldehyde cross-linking and four times that of the enzyme cocktail at 70 °C after 22 h of reaction.

Fabrication of CdSe/CaTiO3 nanocomposties in aqueous solution for improved photocatalytic hydrogen production

Novel CdSe/CaTiO3 nanocomposites are prepared in aqueous phase and used for photocatalytic hydrogen production. The modification of CdSe QDs on the surface of CaTiO3 sheet-like structure effectively increases visible light absorption of nanocomposites, improves the separation and transfer of photoinduced electrons and prevents the recombination of electron-hole pairs. Experimental results show that obtained CdSe/CaTiO3 nanocomposites possess significantly enhanced photocatalytic hydrogen production performance. The photocatalytic hydrogen production amount of CdSe/CaTiO3 is 48 times higher than that of pure CaTiO3 and 4.14 times higher than that of CdSe QDs. Meanwhile, CdSe/CaTiO3 nanocomposites display high stability and recyclability, which is beneficial for photocatalytic hydrogen production application.

Nickel-based catalysts for hydrogen production by steam reforming of glycerol

As the renewable energy technologies are making progress every day, hydrogen energy technologies are taking huge part of this development. Nowadays, there are several industries using hydrogen. Also, the increase at biodiesel production amounts has increased the glycerol production as by-product. One of the main objectives of this study is to compare the effects Al2O3-, SiO2- and CeO2-supported nickel catalysts at steam reforming of glycerol in order to produce hydrogen. All catalysts were prepared by incipient to wetness method. The obtained steam reforming results showed that nickel catalysts supported on ceria showed the highest activity. Also the effect of nickel amount on CeO2 support material has been studied. The highest hydrogen amounts were obtained with 15 wt% nickel loading. Also the increase at water/glycerol ratio increased the hydrogen production amount. The highest hydrogen yield was obtained as 4.82 mol per glycerol mole, whereas the theoretical hydrogen yield is 7 mol, by using 15 wt% Ni/CeO2 catalyst, water/glycerol ratio of 15 and at 650 °C reaction temperature.

Light harvesting and charge management by Ni4S3 modified metal−organic frameworks and rGO in the process of photocatalysis

Harvesting and charge management is obtained by means of Ni4S3 modified Metal−organic Frameworks (MOF) and rGO, namely, the Uio-66 (Zr)/rGO combined with Ni4S3 photocatalyst was successfully prepared with the solvothermal method. The Ni4S3 acted as the electron transfer agent greatly improve the electrons transmission from the excited state dye to the rGO/MOF surface for proton reduction reaction. The hydrogen production amount over EY-sensitized rGO/MOF/Ni4S3 photocatalyst has reached 280 μmol for 5 h, which is about 14 times than that of the pure Ni4S3 photocatalyst and 185 times than that of the pure rGO/MOF photocatalyst under visible light irradiation (λ ≥ 420 nm). In the composite, the rGO acts as electron-transfer mediator and Ni4S3 serves as H2-evolution active site. A series of studies shown that the Ni4S3 modified MOF and rGO provided more active sites and improved the efficiency of photo-generated charge separation by means of several characterizations such as SEM, XRD, XPS, Element Mapping, UV–vis DRS, BET, Photocurrent, Voltammetric Scanning, Fluorescence Spectra and FTIR. and the results of which were in good agreement with each other. The photoelectron migration rate and photogenerated charge separation efficiency of the composite can be obviously increased with graphene as a good electron acceptor and transfer medium and Ni4S3 as hydrogen producing active site.

Cultivation of microalgal biomass using swine manure for biohydrogen production: Impact of dilution ratio and pretreatment

This study assessed the impact of swine manure (SM) dilution ratio on the microalgal biomass cultivation and further tested for biohydrogen production efficiency from the mixed microalgal biomass. At first, various solid/liquid (S/L) ratio of the SM ranged from 2.5 to 10 g/L was prepared as a nutrient medium for the algal biomass cultivation without addition of the external nutrient sources over a period of 18 d. The peak biomass concentration of 2.57 ± 0.03 g/L was obtained under the initial S/L loading rates of 5 g/L. Further, the cultivated biomass was subjected to two-step (ultrasonication + enzymatic) pretreatment and evaluated for biohydrogen production potential. Results showed that the variable amount of hydrogen production was observed with different S/L ratio of the SM. The peak hydrogen yield of 116 ± 6 mL/g TSadded was observed at the 5 g/L grown SM mixed algal biomass.

Enhanced photocatalytic hydrogen production of AgMO3 (M = Ta, Nb, V) perovskite materials using CdS and NiO as co-catalysts

The synthesis of AgMO3 (M = V, Nb, Ta) perovskite materials by solid state reaction and the additional deposition of CdS and NiO particles as co-catalysts using hydrothermal and impregnation methods, respectively, were performed in order to investigate their photocatalytic activities for hydrogen production. The structural and morphological properties were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). UV–vis spectroscopy (UV–vis) and physical adsorption analysis by BET method were used for optical and textural properties. The photocatalytic activities for hydrogen production were carried out under UV light in a Na2SO3 aqueous solution. The effect of loading amount and the nature of co-catalyst used is also discussed. The results showed that the electronic band structure of the AgMO3 (M = Ta, Nb, V) perovskite materials and the co-catalysts play an important role in the photocatalytic activity due to their band positions that allow an improvement in the photogenerated charge carrier transfer and in the hydrogen production amount. The best photocatalytic hydrogen production (4645 μmol g−1) was obtained with 5 wt% loading of CdS co-catalyst onto AgTaO3 perovskite compared to AgTaO3 material loaded with 2 wt% of NiO co-catalyst (1847 μmol g−1).

Impact of cultural conditions on photoproduction of hydrogen by Allochromatium sp. GSKRLMBKU-01 isolated from marine water of Visakhapatnam

In the present study, photoproduction of hydrogen by Allochromatium sp. strain GSKRLMBKU-01 isolated from marine water was measured under different cultural conditions. Hydrogen production was measured by using a Gas chromatography using argon gas as a carrier. Among different carbon and nitrogen sources used, succinate induced maximum hydrogen (5.68 ± 0.27 mL) production by immobilized cells, while free cells recorded 4.24 ± 0.30 mL of hydrogen under anaerobic light conditions. Immobilization of cells resulted in increased production of hydrogen. Ammonium chloride promoted more amounts of hydrogen production (2.68 ± 0.29 mL) by free cells, whereas glycine enhanced the hydrogen production upto 4.82 ± 0.36 mL in immobilized cells. In formic acid and urea, less hydrogen production was observed in both free and immobilized cells compared to other sources. Cumulative hydrogen production by the bacterium was recorded with the progress in incubation period. Incubation period of 192 h, pH of 7.0 and temperature at 30 °C were found to be optimum for the maximum hydrogen production. Significance of the above results was discussed in light of existing literature.