Highest Hydrogen Production Yield Research Articles

High-yield hydrogen and methane production via supercritical water gasification of glucose using Ni/Cu-doped CeO2 catalyst: Synthesis process optimization utilizing RSM

High-yield hydrogen and methane production via supercritical water gasification of glucose using Ni/Cu-doped CeO2 catalyst: Synthesis process optimization utilizing RSM

Directional Electron Flow in a Selenoviologen-Based Tetracationic Cyclophane for Enhanced Visible-Light-Driven Hydrogen Evolution.

Directional electron flow in the photocatalyst enables efficient charge separation, which is essential for efficient photocatalysis of H2 production. Here, we report a novel class of tetracationic cyclophanes (7) incorporating bipyridine Pt(II) and selenoviologen. X-ray single-crystal structures reveal that 7 not only fixes the distances and spatial positions between its individual units but also exhibits a box-like rigid electron-deficient cavity. Moreover, host-guest recognition phenomena are observed between 7 and ferrocene, forming host-guest complexes with a 1 : 1 stoichiometry. 7 exhibits good redox properties, narrow energy gaps, and strong absorption in the visible range (370-500 nm) due to containing two selenoviologen (SeV2+) units. Meanwhile, the femtosecond transient absorption (fs-TA) reveals that 7 has stabilized dicationic biradical, efficient charge separation, and facilitates directional electron flow to achieve efficient electron transfer due to the formation of rigid cyclophane and electronic architecture. Then, 7 is applied to visible-light-driven hydrogen evolution with high hydrogen production (132 μmol), generation rate (11 μmol/h), turnover number (221), and apparent quantum yield (1.7 %), which provides a simplified and efficient photocatalytic strategy for solar energy conversion.

Directional Electron Flow in a Selenoviologen‐Based Tetracationic Cyclophane for Enhanced Visible‐Light‐Driven Hydrogen Evolution

AbstractDirectional electron flow in the photocatalyst enables efficient charge separation, which is essential for efficient photocatalysis of H2 production. Here, we report a novel class of tetracationic cyclophanes (7) incorporating bipyridine Pt(II) and selenoviologen. X‐ray single‐crystal structures reveal that 7 not only fixes the distances and spatial positions between its individual units but also exhibits a box‐like rigid electron‐deficient cavity. Moreover, host–guest recognition phenomena are observed between 7 and ferrocene, forming host–guest complexes with a 1 : 1 stoichiometry. 7 exhibits good redox properties, narrow energy gaps, and strong absorption in the visible range (370–500 nm) due to containing two selenoviologen (SeV2+) units. Meanwhile, the femtosecond transient absorption (fs‐TA) reveals that 7 has stabilized dicationic biradical, efficient charge separation, and facilitates directional electron flow to achieve efficient electron transfer due to the formation of rigid cyclophane and electronic architecture. Then, 7 is applied to visible‐light‐driven hydrogen evolution with high hydrogen production (132 μmol), generation rate (11 μmol/h), turnover number (221), and apparent quantum yield (1.7 %), which provides a simplified and efficient photocatalytic strategy for solar energy conversion.

Comparative Analysis of Various Seed Sludges for Biohydrogen Production from Alkaline Pretreated Rice Straw

The present work studied the effects of alkali pretreatment on the cellulosic biomass of rice straw. The improvement in the cellulose content and reduction in the lignin and hemicellulose percentage was observed with alkali pretreatment. Fourier transformation infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) analysis confirm the modification in the surface structure of alkali rice straw. Further, the study investigated the potential of different types of seed sludge as inoculum sources for dark fermentative biohydrogen production. In comparison to other sludge samples (beverage industry, food industry, and sewage treatment plant sludge), the mixed culture of sewage treatment plant sludge had the highest cumulative volume of biohydrogen (90.52 mL), as well as the highest hydrogen production yield (0.75 moleH2/mole) with the substrate utilization of 86.72%. The results provide information on the best sludge source for enhancing biohydrogen production in the dark fermentation method.

Concentrated Solar Light Photoelectrochemical Water Splitting for Stable and High-Yield Hydrogen Production.

Photoelectrochemical water splitting is a promising technique for converting solar energy into low-cost and eco-friendly H2 fuel. However, the production rate of H2 is limited by the insufficient number of photogenerated charge carriers in the conventional photoelectrodes under 1 sun (100mWcm-2) light. Concentrated solar light irradiation can overcome the issue of low yield, but it leads to a new challenge of stability because the accelerated reaction alters the surface chemical composition of photoelectrodes. Here, it is demonstrated that loading Pt nanoparticles (NPs) on single crystalline GaN nanowires (NWs) grown on n+-p Si photoelectrode operates efficiently and stably under concentrated solar light. Although a large number of Pt NPs detach during the initial reaction due to H2 gas bubbling, some Pt NPs which have an epitaxial relation with GaN NWs remain stably anchored. In addition, the stability of the photoelectrode further improves by redepositing Pt NPs on the reacted Pt/GaN surface, which results in maintaining onset potential >0.5V versus reversible hydrogen electrode and photocurrent density >60mAcm-2 for over 1500 h. The heterointerface between Pt cocatalysts and single crystalline GaN nanostructures shows great potential in designing an efficient and stable photoelectrode for high-yield solar to H2 conversion.

Research on Pure Hydrogen Production Using a Fuel-Processing System Combined with a PSA System

Research was conducted to improve the system efficiency of a fuel-processing system combined with a hydrogen-purification system to supply hydrogen to a 10 kW residential building proton-exchange membrane fuel cell (PEMFC). The system consists of a steam-reforming reactor, a water–gas shift reactor, heat exchangers and a pressure swing adsorption (PSA) system, increasing the purity of the produced hydrogen by over 99.97%. Aspen Plus® and Aspen adsorption® simulators were used to optimize operating conditions by calculating thermal efficiency and hydrogen-production yield under various temperature and pressure conditions in the reformer. To optimize the hydrogen-production system, simulations were performed under conditions of 1 to 10 atm and 600 to 1000 °C, and simulations were also performed while maintaining the PSA pressure at 9 atm. The overall system efficiency was expressed as a function of methane conversion, and the methane conversion was expressed as a function of reformer temperature and pressure. The fuel-processing system showed the highest thermal efficiency of 82.40% at a pressure of 1 atm and a temperature range of 800 °C. For the combined system of a fuel-processing system and a hydrogen-purification system, the highest hydrogen-production yield was 43.17% at 800 °C and 1 atm.

Hydrogen generation from the hydrolysis of ethylenediamine bisborane using Ni/NixByZr and Pd‐Ni/NixByZr as highly active catalysts

AbstractEthylenediamine bisborane (EDAB), containing 11.49% hydrogen by weight, ranks third among notable amine boranes in terms of hydrogen content and has some advantages due to the limit the practical use of AB for the applications of hydrogen storage. In this work, EDAB was synthesized and its catalytic hydrolysis was studied for the hydrogen production. For this purpose, Ni/NixByZr and PdNi/NixByZr catalysts were prepared by using the co‐precipitation with NaBH4 and impregnation method. XRD, XPS, SEM–EDX, and multi‐point BET were used to characterize catalysts. Reusability test, kinetic analyses were done. It has been observed that both Ni/ NixByZr and PdNi/ NixByZr catalysts enhance the hydrogen production yield and reduces the reaction time. The highest hydrogen production yield and the shortest reaction time of EDAB hydrolysis were reached as 99.67% and 215 s at 55°C with PdNi/NixByZr catalyst. The catalytic efficacy of PdNi/NixByZr catalyst is 115.58 mL min−1 g−1, for the hydrolysis of EDAB at 298 K. Activation energy for Pd‐Ni/NixByZr and Ni/NixByZr catalysts were reported as 27.04 and 53.81 kJ.mol−1.

Photocatalytic Properties of ZnO:Al/MAPbI3/Fe2O3 Heterostructure: First-Principles Calculations.

We report on theoretical investigations of a methylammonium lead halide perovskite system loaded with iron oxide and aluminum zinc oxide (ZnO:Al/MAPbI3/Fe2O3) as a potential photocatalyst. When excited with visible light, this heterostructure is demonstrated to achieve a high hydrogen production yield via a z-scheme photocatalysis mechanism. The Fe2O3: MAPbI3 heterojunction plays the role of an electron donor, favoring the hydrogen evolution reaction (HER), and the ZnO:Al compound acts as a shield against ions, preventing the surface degradation of MAPbI3 during the reaction, hence improving the charge transfer in the electrolyte. Moreover, our findings indicate that the ZnO:Al/MAPbI3 heterostructure effectively enhances electrons/holes separation and reduces their recombination, which drastically improves the photocatalytic activity. Based on our calculations, our heterostructure yields a high hydrogen production rate, estimated to be 265.05 μmol/g and 362.99 μmol/g, respectively, for a neutral pH and an acidic pH of 5. These theoretical yield values are very promising and provide interesting inputs for the development of stable halide perovskites known for their superlative photocatalytic properties.

Pincer–Ruthenium-Catalyzed Reforming of Methanol─Selective High-Yield Production of Formic Acid and Hydrogen

Pincer–Ruthenium-Catalyzed Reforming of Methanol─Selective High-Yield Production of Formic Acid and Hydrogen

Polypropylene pyrolysis and steam reforming over Fe-based catalyst supported on activated carbon for the production of hydrogen-rich syngas

The purpose of this study is to explore a method for the high-yield production of hydrogen by pyrolysis and steam reforming of polymer plastics. The developed Fe-based catalyst supported on activated carbon was applied to reactions with polypropylene for hydrogen production. The effects of iron loading (%) in the catalyst, the total catalyst amount, and the water content in the reaction atmosphere on the performance of hydrogen and gas production were investigated. Under the optimal conditions, the hydrogen yield without water added reached 38.73 mmol/gPP, and this yield was significantly improved by adding water into the reaction atmosphere. By optimizing the amount of water added, the hydrogen yield reached 112.71 mmol/gPP. The surface morphology and structural components of the fresh and used catalysts were characterized, and the morphology and quantity of carbon deposition on the catalyst were analysed. The catalytic stability of the 15Fe/AC catalyst was determined by repeating the test 10 times under the optimal reaction conditions. As the reaction time increased, the selectivity of the catalyst for hydrogen decreased and that for hydrocarbons increased. Moreover, the experimental method used in this study had excellent hydrogen production capacity. Thus, this study provided a novel method for the high-efficiency production of hydrogen by pyrolysis and steam reforming of polymer plastics.

Facile integration of core–shell catalyst and Pd-Ag membrane for hydrogen production from low-temperature dry reforming of methane

Dry reforming of methane (DRM) is an important way of conversion of CH4 and CO2, two greenhouse gases, for the production of hydrogen. In this study, a catalytic membrane reactor combining an ultra-thin Pd-Ag alloy membrane with a coke-resistant Ni-SiO2@CeO2 core–shell catalyst was developed for high yield hydrogen production from DRM. The performance of membrane in the presence of gases such as CO, CO2 and CH4 was evaluated, and very little reduction in H2 flux (∼2.5 %) was observed in the presence of these gases at the relevant reaction conditions. The catalyst was tested for DRM reaction in both fixed bed reactor (FBR) and catalytic membrane reactor (CMR) to evaluate its performance at different reaction conditions. In a catalytic membrane reactor, the removal of hydrogen resulted in 1.5 times higher methane conversion compared to the calculated conversion at thermodynamic equilibrium at the used reaction conditions when hydrogen is not removed from the reaction mixture. Around 70 % of the produced H2 was recovered from the reaction stream, by virtue of the high H2 flux through the ultra-thin Pd-Ag membrane. Further, the competing reverse water gas shift reaction, that consumes the produced H2, was drastically suppressed by using membrane reactor. The suppression of reverse water gas shift reaction (RWGS) in CMR was confirmed by analyzing downstream gases using gas chromatography mass spectrometer, the result showed significantly lower H2O content for CMR than FBR. Thus, the coupling of ultra-thin membrane with a core shell catalyst synergistically improved the performance of the dry reforming of methane.

Simulation and design of an energy accumulator around the hydrogen energy vector

This work demonstrates the study of the numerical modelling and a design of a compact energy generator based on green hydrogen. This generator aims allowing the energy storage, electricity, cold and heat productions as well as a supply the energy for the production of the sanitary hot water. The generator is considered to be powered by 30 solar cells panels and will mainly consist of a Proton Exchange Membrane (PEM) electrolyzer compiled with a Metal Hydride (MH) tank, a PEM fuel cell, and a system of heat exchangers sized to recover the heat from the electrolyzer, PEM fuel cell and MH tank. Furthermore, the generator will contain an adsorber to manage air conditioning (cooling and heating) and a production of the sanitary hot water. A converter block is included in the generator, in particular, a Buck-booster to raise the voltage of the solar panels and the DC-AC converter for the electricity consumption in the household. The desorption of the hydrogen contained in the tank MH will take place using the heating resistance. In overall, the designed generator is foreseen to have a dimension of 1800 × 1000 × 500 mm and its role is to allow integration of the hydrogen energy for the tertiary and residential sectors. As such it is a suitable choice of components for the cost reduction and high yield hydrogen production, storage, and consumption.

Defected tungsten disulfide decorated CdS nanorods with covalent heterointerfaces for boosted photocatalytic H2 generation

Owing to their intrinsic and pronounced charge carrier transport when facing the formidable challenge of inhibiting severe surface charge recombination, one-dimensional (1D) CdS nanostructures are promising for advancing high-yield hydrogen production. We herein demonstrate an efficient strategy of boosting interfacial carrier separation by heterostructuring 1D CdS with defective WS2. This process yields solid covalent interfaces for high flux carrier transfer that differ distinctively from those reported structures with physical contacts. As a nonnoble cocatalyst, WS2 can accept photogenerated electrons from CdS, and the sulfur vacancies existing at its edges can effectively trap electrons as active sites for H2 evolution. Moreover, due to its strong negative property, the H+ from the aqueous solution can gather around WS2. WS2 possesses a lower reaction barrier than CdS, which expedites the kinetic process for the reaction. The optimized sample exhibits a high photocatalytic H2 evolution rate of 183.4 µmol/h (10 mg photocatalyst), which is as far as we know among the top in the records for CdS-based photocatalysts. We believe this present work will be inspiring in addressing the interfacial charge carrier transfer by constructing covalent heterointerfaces.

Carbon nanotubes and (Mg10Ni)85Ce15 synergistically activate Mg-Al alloy waste for efficiently hydrolysis hydrogen generation

Hydrogen generation via Mg-Al alloy waste (MA) hydrolysis is regarded as a potential and promising strategy for portable hydrogen generators. An efficient modification method to obtain rapid kinetics and high yield for hydrolysis H2 generation needs to be further explored. At present, it is difficult to achieve rapid and high-yield hydrogen production process while maintaining high capacity. In this work, carbon nanotubes (CNTs) and (Mg10Ni)85Ce15 (MNC15) were creatively employed as additives to synergistically activate MA. Different content of additives was respectively or simultaneously employed through high energy ball milling process to investigate their synergistic effect. The results show that the simultaneous addition of MNC15 and CNTs can significantly improve the hydrolysis kinetics and hydrogen yield of MA. MA-5CNTs-10MNC15 can generate 806.6 mL·g−1 H2 with 0.92 yield at 328 K with initial 10 min. The thermodynamic behaviors of MA and activated MA were investigated in detail and the rate-controlling steps were further analysed via different hydrolysis stages. When 10 wt% CNTs added, Ea decreases from 33.6 kJ·mol−1 to 8.1 kJ·mol−1. The Ea of MA-5CNTs-10MNC15 can reach to 15.8 kJ·mol−1. The rate-controlling steps were confirmed to transform from three-dimensional interface to one dimensional-diffusion process. The synergistic activation effect was creatively explained by nucleation and growth up mechanism on the basis of the increased nucleation rate by MNC15 and enlarged growth space by CNTs. This work may provide a novel and efficient modified strategy for transforming Mg alloy waste into pure H2, which may pave way for the application of portable hydrogen generators.

Engineering 2D Materials for Photocatalytic Water-Splitting from a Theoretical Perspective.

Splitting of water with the help of photocatalysts has gained a strong interest in the scientific community for producing clean energy, thus requiring novel semiconductor materials to achieve high-yield hydrogen production. The emergence of 2D nanoscale materials with remarkable electronic and optical properties has received much attention in this field. Owing to the recent developments in high-end computation and advanced electronic structure theories, first principles studies offer powerful tools to screen photocatalytic systems reliably and efficiently. This review is organized to highlight the essential properties of 2D photocatalysts and the recent advances in the theoretical engineering of 2D materials for the improvement in photocatalytic overall water-splitting. The advancement in the strategies including (i) single-atom catalysts, (ii) defect engineering, (iii) strain engineering, (iv) Janus structures, (v) type-II heterostructures (vi) Z-scheme heterostructures (vii) multilayer configurations (viii) edge-modification in nanoribbons and (ix) the effect of pH in overall water-splitting are summarized to improve the existing problems for a photocatalytic catalytic reaction such as overcoming large overpotential to trigger the water-splitting reactions without using cocatalysts. This review could serve as a bridge between theoretical and experimental research on next-generation 2D photocatalysts.

Biotechnology under extreme conditions: Lichens after extreme UVB radiation and extreme temperatures produce large amounts of hydrogen

The present study demonstrates biotechnological applications of the lichen Pleurosticta acetabulum, specifically the production of large amounts of hydrogen even after the lichen exposure to extreme conditions such as a) extreme UVB radiation (1.7 mW/cm2 = 1000 J m−2 min−1) over different time periods (4, 20 & 70 h) and b) combined exposure of the lichen to high intensity UVB radiation and extreme low (−196 °C) or extreme high temperatures (+70 °C). The results highlight that the extremophilic and polyextremophilic behavior of lichens both in dehydrated and in regenerated form, under extreme conditions not necessarily recorded on earth, is compatible with their biotechnological uses. The lichen viability was measured using fluorescence induction techniques (OJIP-test), which record changes in the molecular structure and function of the photosynthetic mechanism, while its ability to produce molecular hydrogen was measured through thermal conductivity gas chromatography (GC-TCD) analysis. Hydrogen is a promising fuel for the future. The exciting result of a lichen micro-ecosystem is its ability to expel its moisture and remain in an inactive state, protecting itself from extreme conditions and maintaining its ability to high yield hydrogen production in a closed system, with the sole addition of water and without the need for additional energy. Our results expand the potential use of lichens for future biotechnological applications in extreme Earth environments, but also in environments on other planets, such as Mars, thus paving the way for astrobiotechnological applications.

Hydrothermal co-gasification of sorghum biomass and çan lignite in mild conditions: An optimization study for high yield hydrogen production

In this study, response surface methodology (RSM) combined with a 3–factor and 3–level Box–Behnken design (BBD) was performed to obtain high yield hydrogen production from hydrothermal co–gasification of sorghum biomass and low rank Çan lignite in a batch type reactor at 500 °C. The individual and the combined effects of the process parameters of coal amount (%) of the coal/biomass mixtures, initial water volume (mL) of the reactor and amount of the coal/biomass mixtures (kg) on system pressure, total gas yield, hydrogen production and product distribution were determined. Water volume directly affected the system pressure and the reaction medium was supercritical water medium above 48.2 mL with a pressure of 22.06 MPa. The highest values of both total gas volume and hydrogen gas volume were reached by gasification of 5.0 g of feedstock. It has been observed that total gas volume and hydrogen volume were directly affected by the water volume in the reactor and the coal ratio of the coal-biomass mixtures. The highest total gas and hydrogen volumes can be achieved under the conditions where the higher levels of water volume of the reactor and lower levels of coal percentage of the coal/biomass mixture were combined. Optimum conditions for maximum hydrogen production with 5.0 g of coal/biomass mixture were determined with numerical optimization as coal percentage of 25.6% and initial water volume of 68.5 mL. By combining the impregnated K2CO3 (3%, (w/w)) and CaO catalysts an excellent hydrogen selectivity was achieved. The hydrogen selectivity was drastically increased from 32.0% to 70.8% by capturing more than 99% of CO2 with a H2/CO2 mol ratio of 88.5.

Evaluation of the effects of process parameters on co–gasification of Çan lignite and sorghum biomass with response surface methodology: An optimization study for high yield hydrogen production

Temperature, steam flow rate and coal/biomass ratio in the feedstock are the key factors that affect the performances co–gasification processes. In this study, co–gasification of sorghum biomass with high sulphur (5.61%) containing Çan lignite has been performed. The individual and simultaneous effects of temperature, water flow rate and coal/sorghum biomass ratio in feedstock were evaluated by Box–Behnken design (BBD) combined with response surface modelling (RSM). The significance of the quadratic models, independent variables and their interactions on the responses of carbon conversion efficiency (CCE, %), total gas, hydrogen, carbon monoxide, carbon dioxide, methane volumes (m3) and amount of H2S precipitated as CdS (g), were determined by analysis of variance (ANOVA). Temperature and coal/biomass ratio of the feedstock were found as the most effective process parameters on total gas yield and the composition of the produced gas and interaction effects were effective between temperature/water flow rate and temperature/biomass ratio. Coal/biomass ratio of feedstock was the only parameter that has a significant effect on the amount of H2S. Optimum conditions for maximum hydrogen production were determined with numerical optimization as temperature of 888 ± 3 °C, water flow rate of 1.8 × 10−3 m3/s and biomass ratio of the coal/biomass mixture of 25.9%. Results showed that sorghum biomass is a good candidate for high yield hydrogen production in co–gasification process with coal.

Tailoring of structural and optical parameters of corncobs through ball milling pretreatment

Enzymatic fermentation of lignocellulose biomass has shown great potential of hydrogen production but the yield is limited due to the complex structure of cellulose and hemi-celluloses. For the bio-hydrogen production from biomass, the pretreatment of biomass plays a vital role to increase the hydrogen yield. In the present work highly efficient pretreatment by mall milling of corncob biomass has been employed to optimize the thermo-physical and optical properties of corncob powder by employing state of art techniques including scanning electron microscope, x-rays diffractometer, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The morphological observations from microscopic images are consisted with x-ray diffraction results where the broadening in the peaks suggests the smaller particle size (large surface area) after pretreatment. From the decomposition kinetic parameters and apparent activation energy calculation by FWO and DAEM methods, the sample S2 with lowest activation energy, can have highest hydrogen production yield which is consistent with our previous findings. The broadening in the absorption peak near 1046 cm−1 suggests that CO stretching vibration (cellulose and hemicellulose)mode has been changed after different ball milling. By tailoring their activation energies through ball milling one can optimize thermo-dynamic characteristics for enhancement of biohydrogen production.

Hydrogen Production by Microbial Electrolysis Using Nickel and Platinum Deposited EPPG Electrodes

In this study nickel and platinum deposited edge plane pyrolized graphite (EPPG) electrodes were used in microbial electrolysis for high yield hydrogen production. EPPG electrodes were used as working electrode (anode) and metal deposited EPPG electrodes were used as cathode. 2.0 g/L glucose was used in the electrolyte as substrate, and Shewanella oneidensis MR-1was used as exoelectrogenic bacteria. The most effective cathode material was found to be Pt-deposited EPPG. The optimum electrolysis potential for maximum hydrogen production was determined as 0.7V. Maximum hydrogen yield was found as 2.44 mol H2/mol glucose at optimum conditions with Pt-deposited EPPG cathode. Keywords : hydrogen, microbial electrolysis, EPPG, Shewanella oneidensis MR-1 DOI : 10.7176/JSTR/5-2-17