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In the present work, a ternary composite MoS2/soluble g-C3N4/CdS was synthesized using a facile one-pot hydrothermal reaction and conventional reflux reaction method. The composition, morphology, and properties of the ternary composite were characterized. The photocatalytic performance of the ternary composite was evaluated for hydrogen generation under LED lamp irradiation (450 nm < λ < 465 nm) with lactic acid (LA) used as a sacrificial reagent. The results demonstrated that the maximum hydrogen production reached 4869.6 μmol under the optimal hydrogen production conditions, including a composition of 20% soluble g-C3N4, 9% MoS2, a solution pH of 1, and an irradiation time of 6 hours. The corresponding hydrogen production rate for the ternary composite was calculated to be 8116 μmol g−1 h−1. Furthermore, a possible electron transfer mechanism of the ternary composite system was briefly explored. The interaction and synergistic effects between MoS2, soluble g-C3N4, and CdS in the ternary composite likely facilitate efficient electron transfer, resulting in enhanced photocatalytic activity for hydrogen production. Mechanistic research showed that the electron transfer pathway represented either a double or single type II heterojunction photocatalytic system. [ABSTRACT FROM AUTHOR]

The redox state of carbon sources directly affected the ratio of NADH/NAD+which was coupled to the hydrogen production byBacillus sp. FS2011. The addition of the inhibitor of pyruvate dehydrogenase multi-enzyme complex (PDHc)E1 could regulate hydrogen production by FS2011 or pretreated compost in batch cultivation. With the addition of appropriate amount of inhibitor, hydrogen production via the NADH pathway was increased, leading to the higher overall hydrogen production. The maximum hydrogen yields of 307.6 ± 13.21 mL/g by FS2011 with the inhibitor of 80 ppm and 362.1 ± 10.1 mL/g by pretreated compost with the inhibitor of 60 ppm were observed, which were increased by 8.7% and 17.8% compared with the controls, respectively. Meanwhile the production of soluble metabolic byproducts such as butyrate, acetate and so on were decreased, resulting in reducing the difficulty of wastewater treatment. [ABSTRACT FROM AUTHOR]

A noble-metal-free catalyst, namely Co(II) complex [Co(dbp) 2 ]Cl 2 (dbp = 4,4′-dimethyl-2,2′-bipyridyl), had been prepared for photocatalytic H 2 generation. The H 2 generation was achieved by the constructed homogeneous photocatalytic system comprising of [Co(dbp) 2 ]Cl 2 as catalyst, Eosin Y as photosensitizer and triethanolamine as sacrifice agent under visible-light-driven (λ > 420 nm). The maximum H 2 yield of 169.2 μmol appeared at target catalyst of 4.0 × 10 −4 M, EY 2− of 4.0 × 10 −4 M and 10% TEOA (v/v) at pH 9 in CH 3 CN/H 2 O of 1:1 (v/v), indicating that this complex could also be used as a potential photocatalytic material for H 2 evolution under the irradiation of visible light. In addition, the H 2 generation mechanism was also briefly discussed. [ABSTRACT FROM AUTHOR]

SUMMARY A noble-metal-free molecular catalyst, [Co(dmbp)3]Cl2 (dmbp = 4,4'-dimethyl-2,2'-bipyridyl) was prepared for photocatalytic H2 generation. A three-component photocatalytic system was constructed by combination of [Co(dmbp)3]Cl2 as catalyst, Eosin Y as photosensitizer and triethylamine as sacrificial electron donor to give an efficient H2 generation system under visible-light irradiation (λ > 420 nm). The maximum H2 yield was up to 249.2 turnover number (vs. catalyst) over 2 h irradiation under the conditions with catalyst of 4.0 × 10−4 M, 10% TEA (v/v), EY2− of 4.0 × 10−4 M and pH 10 in MeCN/H2O (1 : 1,v/v). Furthermore, the dynamics behaviors of the photolysis system were also briefly discussed. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the predominant H2-producing bacterial strain was isolated from a bio-reactor fed with lesser panda manure, and identified as Clostridium sp. based on 16S rDNA gene analysis. The bio-pretreatment of corn stalk was found to be most effective at ambient temperature of 25°C, microbe additive of 7.5g/kg with saccharification period of 15 days under the anaerobic condition. The maximum H2-production yield (176ml H2/g-TS) and rate (18ml H2/g-TSh−1) were achieved at operating pH 5.5, 36°C and substrate concentration of 15g/L. The H2 content in the biogas was 44.3–57.2%(v/v) and there was no significant methane gas observed. During the optimal period of H2 production, the ORP values stayed in the lower level ranging from −445mV to −455mV. The results indicated that the effluent was composed mostly of butyric acid and acetic acid, which accounted for 70–80% of total VFAs, followed by small amounts of butanol and propionate. [Copyright &y& Elsevier]

Abstract: A hydrogen producing strain newly isolated from anaerobic sludge in an anaerobic bioreactor, was identified as Clostridium beijerinckii Fanp3 by 16S rDNA gene sequence analysis and detection by BioMerieux Vitek. The strain could utilize various carbon and nitrogen sources to produce hydrogen, which indicates that it has the potential of converting renewable wastes into hydrogen. In batch cultivations, the optimal initial pH of the culture medium was between 6.47 and 6.98. Using 0.15M phosphate as buffer could alleviate the medium acidification and improve the overall performance of C. beijerinckii Fanp3 in hydrogen production. Culture temperature of 35°C was established to be the most favorable for maximum rate of hydrogen production. The distribution of soluble metabolic products (SMP) was also greatly affected by temperature. Considering glucose as a substrate, the activation energy (E a) for hydrogen production was calculated as 81.01kcal/mol and 21.4% of substrate energy was recovered in the form of hydrogen. The maximal hydrogen yield and the hydrogen production rate were obtained as 2.52mol/mol-glucose and 39.0ml/g-glucose h−1, respectively. These results indicate that C. beijerinckii Fanp3 is an ideal candidate for the fermentative hydrogen production. [Copyright &y& Elsevier]

Photocatalytic water splitting of water for hydrogen evolution is one of the effective methods to obtain clean hydrogen energy. In the present work, the following materials were synthesized: two nickel quinoxaline thiolate complexes [NBu 4 ] 2 [Ni(qdt) 2 ] (1 , Bu = n-butyl, qdt = quinoxaline-dithiol), [NBu 4 ] 2 [Ni(qdt) 2 (NO 2) 2 ] (2) and water-soluble MPA-CdSe quantum dots (MPA-CdSe QDs, MPA = 3-mercaptopropionic acid). Subsequently, an efficient three-component photocatalytic hybrid system for hydrogen evolution was developed and tested under visible light irradiation, in which one of the target complex 1 or 2 was used as the catalyst, triethylamine (TEA) was used as the sacrificial electron donor, and MPA-CdSe QDs were used as the light harvesting reagent. The turnover numbers (TON) for H 2 evolution of 8974 (vs. complex 1) and 6532 (vs. complex 2) were obtained under the optimal conditions with TEA concentration of 5 %, pH = 12, and concentration of complex 1 or 2 of 1 × 10−5 mol L−1 after 13 h of irradiation (λ > 420 nm) in pure water. The mechanism investigation indicated that critical steps of hydrogen production was formation of hydride intermediates Ni(II)-H and Ni(I)-H spices, followed by the reaction of two Ni(II)-H or Ni(I)-H species with protons generating H 2 molecules and regenerating the catalyst Ni(II). We have constructed a hybrid photocatalytic H 2 evolution system containing nickel quinoxaline thiolate complexes 1–2 as photocatalyst, MPA-CdSe quantum dots (QDs) (MPA = Mercaptopropionic acid) as photosensitizer (PS) and triethylamine (TEA) as sacrificial reagent in pure water under visible light irradiation. H 2 evolution performance and mechanism was explored systematically. The result suggested that the turnover numbers (TON) was 8974 (vs. complex 1) and 6532 (vs. complex 2) respectively, under the optimal conditions with TEA concentration of 5 %, pH = 12, and concentration of complex 1 or 2 of 1 × 10−5 mol L−1 after 13 h of irradiation (λ > 420 nm). The mechanism investigation indicated that critical steps of hydrogen production was formation of hydride intermediates Ni(II)-H and Ni(I)-H spices, followed by the reaction of two Ni(II)-H or Ni(I)-H species with protons generating H 2 molecules and regenerating the catalyst Ni(II). [Display omitted] • Two new nickel-quinoxaline dithiolate complexes and water-soluble MPA-CdSe quantum dots. • The maximum hydrogen production turnover numbers (TON) is 8974 (vs. complex 1). • Mechanism research showed Ni(II)-H and Ni(I)-H species are the key H 2 generation intermediates. [ABSTRACT FROM AUTHOR]

Abstract: The cellulosic hydrogen production from cornstalk based on the integrating dilute acid with enzymatic hydrolysis was investigated using response surface methodology (RSM). The dilute acid pretreatment of cornstalk with the concentration of 1.5% H2SO4, 121 °C and 60 min was found to be most effective in the first prehydrolysis stage. Thereafter, the process parameters of enzymatic hydrolysis of the solid residue, which derived from acid-pretreated cornstalk, were further optimized by a three factor-five level central composite design (CCD) with temperature (X1 ), pH (X2 ), and enzyme loading (X3 ) as the independent variables. The optimal parameters of enzymatic hydrolysis of substrate were observed to be 52 °C of temperature, pH 4.8 and 9.4 IU/g of enzyme loading. In this case, the total soluble sugar obtained in the hydrolysis stages was 562.1 ± 6.9 mg/g-TVS, and the maximum hydrogen yield from cornstalk by anaerobic mixed microflora was 209.8 ml/g-TVS. Biodegradation mechanism of cornstalk for hydrogen production was further discussed based on analyzing changes in the physical structure and chemical composition of cornstalk during the hydrolysis and fermentation processes. [Copyright &y& Elsevier]

Abstract: Strategies were adopted to cost-efficiently produce cellulose-hydrogen by anaerobic fermentation in this paper. First, cellulase used for hydrolyzing cellulose was prepared by solid-state fermentation (SSF) on cheap biomass from Trichoderma viride. Several cultural conditions for cellulase production on cheap biomass such as moisture content, inoculum size and culture time were studied. And the components of solid-state medium were optimized using statistical methods to further improve cellulase capability. Second, the crude cellulase was applied to cellulose-hydrogen process directly. The maximal hydrogen yield of 122 ml/g-TVS was obtained at the substrate concentration of 20 g/L and cultured time of 53 h. The value was about 45-fold than that of raw corn stalk wastes. The hydrogen content in the biogas was 44–57%(v/v) and there was no significant methane gas observed. [Copyright &y& Elsevier]

A new photosensitive compound based on triphenylamine donor and ruthenium(II), namely [Ru(bpy) 2 (TPAD)](PF 6 ) 2 ( PS1 , bpy = 2,2′-bipyridine, TPAD = N-(4-(1H-imidazo[4,5-f][1,10] phenanthroline-2-yl)phenyl)-N-phenylbenzenamine), had been synthesized and characterized by elemental analysis, 1 H NMR, MS spectra, UV, PL and CV measurements. The target photocatalyst, PS1 /0.5 wt% Pt/TiO 2 , was prepared by sensitizing PS1 to 0.5 wt% Pt/TiO 2 and characterized by SEM and XRD. The highest hydrogen evolution reached to 9500 μmol·(g·catalyst) −1 (475 μmol, 31.7 TON and TOF 5.8 vs. PS1 ) under the optimal conditions with 0.05 g·L −1 of PS1 , and 5% of TEOA at pH 11 with the irradiation of 5.5 h. The mechanism of hydrogen evolution was also briefly discussed in the present work. [ABSTRACT FROM AUTHOR]

In this paper, the high concentration of corn stalk (60 g/L) was employed as feedstock to produce bio-hydrogen and methane by combining hydrogen fermentation and anaerobic digestion. In the first stage of hydrogen fermentation, the effects of several key parameters, such as strain enhancement technique, cetyl trimethyl ammonium bromide (CTAB), NH 4 HCO 3 on hydrogen production from cornstalk were investigated and optimized. The maximum hydrogen yield of 79.8 ± 1.5 ml H 2 /g-TS and hydrogen production rate of 3.78 ml/g-cornstalk h was observed at fixed acidizing cornstalk of 60 g/L, strains Bacillus sp . FS2011 dosage of 10%(v/v), CTAB of 30 mg/L, NH 4 HCO 3 of 1.2 g/L and initial pH of 7.5 ± 0.5 at 36 ± 1 °C, respectively. In the second stage of anaerobic digestion, the effluent from hydrogen production bio-reactor was further employed as the feedstock to produce methane by methanogenic bacteria, the maximum methane yield of 227 ± 2.5 ml CH 4 /g-COD and COD removal rate of 95 ± 1% was recorded. The interesting observations were that the total amount of the organic wastewater produced in a higher substrate concentration (60 g/l) by hydrogen fermentation was reduced by about two-thirds compared with that of traditional low substrate concentration (≤20 g/l). [ABSTRACT FROM AUTHOR]

The low conversion efficiency of substrate is one of the main bottlenecks in dark fermentation for bio-H2 production. Herein, an enhanced H2 yield from corn stalk was achieved by integrating dark fermentation and single chamber microbial electrolysis cells (MECs). In the dark fermentation stage, a H2 yield of 129.8 mL H2/g-corn stalk and an average H2 production rate of 1.73 m3/m3 d were recorded at 20 g/L of corn stalk and initial pH 7.0. The effluent from dark fermentation was diluted and further employed as feedstock to generate H2 by MECs. A H2 yield of 257.3 mL H2/g-corn stalk, an HPR of 3.43 ± 0.12 m3/m3 d and an energy efficiency of 166 ± 10% were obtained with the effluent COD of 3995.5 mg/L under 0.8 V applied voltage. During MECs operation stage, about 90 ± 2% of acetate was converted to H2 and the corresponding COD removal reached 44 ± 2% in MECs. Overall, the H2 yield can reach 387.1 mL H2/g-corn stalk by integrating dark fermentation and MECs, which had nearly tripled as against that of dark fermentation. [ABSTRACT FROM AUTHOR]

A new organic–inorganic photosensitive coordination compound [RuL(bpy)2](PF6)2 (to represent by TM1) had been synthesized by reaction of L (L = 2-hydroxyl-5-(imidazo-[4,5-f]-1,10-phenanthrolin) benzoic acid) with bipyridyl ruthenium, and further characterized by UV–vis, IR, NMR MS and CV. The target photocatalyst 6 wt% TM1-0.5 wt% Pt-TiO2 (Ⅰ) was obtained by sensitization of Pt-loaded TiO2 with TM1. The H2 production activity of target photocatalyst Ⅰ was systematically evaluated by the reaction of photocatalytic H2 production from water under visible light irradiation. The maximum H2 evolution of 386.7 μmol in irradiation 3 h and H2 production rate of 2578 μmol · h−1 · g−1 was detected under the optimal conditions with pH 5, target photocatalyst Ⅰ 50 mg and 5% sacrificial reagent TEOA (v/v). [ABSTRACT FROM AUTHOR]

Abstract: The bio-hydrogen production potential from corn stalk was significantly affected by microwave irradiation pretreatment of cow dung compost in batch tests. The maximum hydrogen yield of 144.3 ml/g-corn stalk and hydrogen production rate of 3.6 ml/g-corn stalk h−1 were observed using the pretreated compost by microwave radiation of 1.5 min at fixed Na2CO3 dosage of 800 mg/l, Fe dosage of 400 mg/l, substrate concentration of 20 g/l, which increased about 99.6% and 85.2% compared with that of the control. The effects of microwave irradiation on microbial characteristics were further discussed by Atomic Force Microscope (AFM), determination of protein content and PCR-DGGE. The four dominant hydrogen-producing strains had been isolated and confirmed to be Bacillus amyloliquefaciens, Bacillus licheniformis, Bacillus subtilis and Enterococcus faecium, respectively. The diversity and symbiosis relations of the mixed bacteria were also observed in fermentation hydrogen production process. [Copyright &y& Elsevier]

Abstract: The effects of pretreatment method of cow dung compost, which was employed as natural hydrogen bacteria source, on the microbial community, population distribution of microbes and hydrogen production potential were investigated in the batch tests. The maximum hydrogen yield of 290.8 mL/L-culture appeared in the pretreated method A (infrared drying) by dark fermentation. The pretreated method of compost significantly affected microbial succession, population distribution of microbes. Both Clostridium sp. and Enterobacter sp. were found to be two species of preponderant hydrogen-producing bacteria, the next best was Bacteroides sp. and Veillonella sp., the last was Lactobacillus sp. and Streptococcus sp., which were also essential. The results showed that the mutualism and symbiosis relations of the mixed bacteria played a critical role in hydrogen fermentation process. [Copyright &y& Elsevier]

Abstract: Effects of pretreatment of natural bacterial source and raw material on biohydrogen production in fermentative biohydrogen production process were investigated systematically. Biohydrogen production from stale corn slurry was found to be feasible and effective by A1 (water soak) pretreated compost and B1 (gelatinization) pretreated stale corn. The results were further confirmed by the verification test with working volume of 8 L, in which the maximum hydrogen yield of 262 mL H2/g-substrate, hydrogen production rate of 39 mL/g h−1 and the corresponding hydrogen content of 50% was observed at fixed substrate concentration of 10 g/L, working pH 5.0–5.5 and 36 ± 1 °C. The effluent was mostly composed of acetate and butyrate. Subsequently, two new hydrogen producing strains were isolated from the effluent sludge in the running bioreactor, and they were preliminarily identified as Clostridium and Enterobacter, respectively, according to the routine screening examinations. [Copyright &y& Elsevier]

Abstract: The key process parameters of solid state enzymolysis for the generation of soluble sugar (SS) and bio-hydrogen production from corn stalk were optimized by the response surface methodology (RSM) based on a three factor-five level central composite design (CCD), respectively. The result showed that the optimal solid state enzymolysis condition from corn stalk was 47.7 °C, SCED of 0.054 g/g and 10.3 days for the maximum SS yield of 526 mg/g-TVS. Correspondingly, the optimal enzymolysis conditions from corn stalk appeared at 46.3 °C, SCED of 0.049 g/g and 7.5 days for the maximum hydrogen yield of 205.5 mL/g-TVS from the hydrolyzed substrate by the next dark fermentation. In addition, the bio-hydrogen production mechanism from corn stalk was preliminary investigated by XRD and SEM analyses. The results suggested that the solid state enzymolysis of substrate played a vital role in the effective conversion of corn stalk into bio-hydrogen by dark fermentation. [Copyright &y& Elsevier]

Abstract: A hydrogen producing strain F.P 01 was newly isolated from cow dung sludge in an anaerobic bioreactor. The strain F.P 01 was a mesophilic and facultative anaerobic bacterium, which exhibited gram-negative staining in both the exponential and stationary growth phases, and a regular long rod-shaped bacteria with the size of 0.6–0.9 μm × 1.2–2.5 μm, and also could biodegrade a variety of carbohydrates such as glucose, xylose, maltose, etc. The effects of important process parameters on hydrogen producing of F.P 01 were further investigated from hydrogen fermentation of maltose by strain F.P 01, including substrate concentration, medium pH, etc. And the results showed that hydrogen production potential and hydrogen production rate from maltose of this strain F.P 01 was180 mLH2/g-maltose and 4.0 mLH2/h, respectively. The corresponding hydrogen concentration of 58–73% was also be observed. Both butyric acid and acetic acid as main by-product was left in the reactor. [Copyright &y& Elsevier]