Search

Summary: Pristine WSe2 based electrocatalyst shows poor reaction kinetics in electrochemical hydrogen evolution reaction due to a lack of active atomic sites and an inert basal plane. Herein, we report an active system of non‐metallic plasmonic WSe2/WO3−x, supported by highly conductive and eco‐friendly Ag/cellulose paper electrodes. An air thermal annealing technique is used to enrich the p‐WO3−x dopants in WSe2, which is significant for substantially improving electrocatalytic behaviour as well as photo responsive performance in the near‐infrared (NIR) region. The WSe2/WO3−x dramatically decreases the overpotential of HER from −330 to −150 mV (at 10 mA/cm2) owing to homo doping and generation of Se‐vacancies. Surface plasmons resonances of p‐WO3−x give the contributions to injection of photogenerated electrons and overpotential as low as −120 mV can be achieved under the illumination of NIR light. These results represent significant advances in light‐enhanced electrocatalysis and would provide potential applications for commercial hydrogen generation. Novelty Statement: Novel WSe2/WO3−X hybrid nanosheets‐based electrocatalysts exhibit the light‐enhanced hydrogen evolution reaction. WO3−X enriched WSe2 nanosheets exhibit rapid electrochemical charge transport due to p‐homodoping and Se‐vacancies. Overall, the 3D‐porous structure of cellulose paper and 2D‐ WSe2/WO3−X leads the promising optimisation. [ABSTRACT FROM AUTHOR]

Summary: It reports how to increase the overall catalytic performance of precious platinum nanocatalysts in hydrolytic dehydrogenation of ammonia borane which requires enhancement of both catalytic activity and reusability of the nanocatalysts as well as the fraction of active sites over the total platinum atoms. The following approaches are reported for increasing the utilization efficiency of platinum‐based nanocatalysts: (i) The use of colloidal nanoparticles is an efficient way of increasing catalytic activity. However, colloidal platinum(0) nanoparticles are unstable against agglomeration and therefore not reusable. (ii) Supporting the platinum(0) nanoparticles on large surface area materials can increase their stability. Carbonaceous support materials provide moderate activity for platinum(0) nanoparticles but not stability because of the weak metal‐support interaction. (iii) Selecting suitable oxide support can help in increasing the catalytic efficiency of platinum nanocatalysts. Particularly, using reducible oxides as support provides a favorable metal‐support interaction leading to a notable increase in the catalytic activity and stability of platinum(0) nanoparticles. (iv) The utilization efficiency of the precious platinum nanocatalysts can be significantly enhanced by downsizing the nanoparticles and lowering the relative amount of platinum down to single‐atom; that is, using the single‐atom platinum nanocatalyst which, however, is limited by the amount of platinum as it cannot be increased because of unavoidable agglomeration. (v) The reusability of platinum(0) nanoparticles can be increased by using magnetic powder materials as support. Thus, the magnetically separable Pt0/CoFe2O4 and Pt0/Co3O4 nanoparticles possess superior catalytic activity plus outstanding reusability and hence, provide significant enhancement in catalytic performance or utilization efficiency of platinum(0) nanocatalysts in the evolution of H2 from the hydrolysis of ammonia borane. Consequently, all these ultimately lower the cost of platinum nanocatalysts. [ABSTRACT FROM AUTHOR]

Summary: Chemical looping hydrogen generation (CLHG) is a hydrogen production process with broad prospects for its advantages of not requiring H2 purification process and direct CO2 capture. Presently, the research on the integrated system of CLHG focuses on the impact of integrated processes and operating variables on the overall energy efficiency and exergy efficiency of the system. However, the research on the matching relationship between quantity and quality in the process of energy conversion is insufficient, and the flow direction of exergy and the specific exergy destruction process for equipment are not clear. The integrated system of coal gasification (CG) and three reactors CLHG was established in this paper with a hydrogen production efficiency of 42.55% and system exergy efficiency of 52.98%. This paper studied the exergy flow direction and efficiency of the equipment in the system, providing the improved direction for the amelioration of the system; a detailed description was present on the change process of energy quality in each equipment with energy quality factor, and the concept of energy quality factor ratio was proposed as an evaluation tool for matching the quantity and quality of energy in the system. It is calculated that the ratio of energy quality factor of the integrated system of CG and CLHG is 0.944. By comparing with the energy quality ratio of the traditional CG hydrogen production system (0.896), it can be concluded that the integrated system of CG and CLHG has a better energy matching relationship. [ABSTRACT FROM AUTHOR]

Summary: Nuclear and hydrogen are considered to be the most promising alternatives energy sources in terms of meeting future demand and providing a CO₂‐free environment, and interest in the development of more cost‐effective hydrogen production plants is increasing—and nuclear‐powered hydrogen generation plants may be a viable alternative. This paper is a report on investigating the application of new generation nuclear power plants to hydrogen production and development of an associated techno‐economic model. In this paper, theoretical and computational assessments of generations II, III+, and IV nuclear power plants for hydrogen generation scenarios have been reported. Technical analyses were conducted on each reactor type—in terms of the design standard, fuel specification, overnight capital cost, and hydrogen generation. In addition, a theoretical model was developed for calculating various hydrogen generation parameters, and it was then extended to include an economic assessment of nuclear power plant‐based hydrogen generation. The Hydrogen Economic Evaluation Program originally developed by the International Atomic Energy Agency was used for calculating various parameters, including hydrogen production and storage costs, as well as equity, operation and maintenance (O&M), and capital costs. The results from each nuclear reactor type were compared against reactor parameters, and the ideal candidate reactor was identified. The simulation results also verified theoretically proven results. The main objective of the research was to conduct a prequalification assessment for a cogeneration plant, by developing a model that could be used for technical and economic analysis of nuclear hydrogen plant options. It was assessed that high‐temperature gas‐cooled reactors (HTGR‐PM and PBR200) represented the most economical and viable plant options for hydrogen production. This research has helped identify the way forward for the development of a commercially viable, nuclear power‐driven, hydrogen generation plant. [ABSTRACT FROM AUTHOR]

Summary: In the chemical looping hydrogen generation process, CoFe2O4 is regarded as one of the most excellent candidates for oxygen carriers (OCs). In this paper, the synergistic effect of Cu and Ce added to CoFe2O4 was studied. The doping of Cu and Ce improved the reactivity of CoFe2O4 with methane, and also increased the hydrogen yield and purity. The results indicated that the introduction of Cu and Ce facilitated the deep reduction of CoFe2O4, which was ascribed to the enhanced migration capacity of lattice oxygen. In addition, the addition of Cu inhibited the decomposition of CH4 and alleviated carbon deposition. The Cu4Ce4‐CoFe had a suitable Cu/Ce mass ratio, which was more conducive to the formation of excellent synergistic effect to enhance hydrogen production and weaken carbon deposition. The Cu4Ce4‐CoFe exhibited outstanding H2 yield (15.42 mmol·g−1) and H2 purity (99.13%). In addition, the reactivity of OC decreased to some extent with the cyclic experiment when the Cu4Ce4‐CoFe was used, the H2 yield decreased from ∼15.21 to ∼10.86 mmol·g−1 over 10 experimental cycles. In conclusion, Cu and Ce co‐doping is an effective strategy to obtain OCs with preeminent hydrogen production performance and anti‐carbon deposition performance. [ABSTRACT FROM AUTHOR]

Summary: There are various methods to produce hydrogen from water splitting as a substitute energy resource for fossil fuels in accordance with the global environmental crisis. Among these, water photocatalysis is considered one of the most renewable and sustainable processes simulated the solar energy utilized system in nature. During a half century, different kinds of photocatalysts were developed to convert photon energy into chemical energy to induce redox potential under visible light irradiation condition. In the beginning step, semiconductor materials, such as transition metal oxides, were explored extensively to use as a photocatalyst for hydrogen generation. However, semiconductor has limitations to act as an effective photocatalyst for water splitting due to the large band gap and recombination of charge carriers. Therefore, several kinds of modifications of structure or components have been studied to design visible light active photocatalysts for water splitting to generate hydrogen. Their performance was improved substantially by adding a noble metal or sensitizer to adjust the band gap and reduce the recombination of photoinduced charge carriers. Considering solar light‐induced photocatalytic hydrogen generation, various visible light active photocatalysts have been derived from carbon chain organic compounds and lattice crystals. This review classifies the visible light active photocatalysts as follows: (a) structural and chemical components of modified graphitic carbon nitride (g‐C3N4), (b) exfoliated perovskites, and (c) π‐bond conjugated polymers to produce hydrogen from water splitting. The hydrogen evolution efficiency of photocatalysts shows a great difference under visible light (λ > 400 nm) irradiation according to the three‐dimensional structure and electron transfer pathway. This is because the capability of restricting the recombination of photoinduced charge carriers and the band gap between the valence band and the conduction band of photocatalysts is dependent on the morphology and electrostatic interactions among components. This paper reviews visible light photocatalysts, that is, g‐C3N4 based materials, layered perovskites, and conjugated polymers, to provide integrated insight into photocatalytic water splitting to obtain hydrogen. [ABSTRACT FROM AUTHOR]

Summary: This paper investigates the exergy and energy rationality of a near‐future, two‐step hydrogen production system in the Black Sea on a custom‐built hydrogen ship with 100% onboard wind, wave, and solar energy system. In the first step of this concept, hydrogen will be produced from the low‐salinity seawater by electrolysis utilizing the onboard renewable energy. Part of the hydrogen produced will be used in the second step, which is the major production step, claiming the H2S gas, which is exceptionally rich in the seawater. The hydrogen and sulfur products will be shipped by hydrogen‐powered shuttle ships to the nearby city of Sinop to blend hydrogen with the natural gas (NG) to form a hydrogen city. Thus this project presents a novel coupling of the land‐side and the sea‐side operations with renewable energy and hydrogen in an exergy‐based minimum CO2 emissions responsibilities. This on‐board H2S exploration concept for hydrogen and sulfur production is compared with the current NG explorations in the Black Sea and the use of NG on the landside. A detailed comparison of the total carbon footprint shows that NG explorations in the Black Sea will be responsible for direct and indirect‐nearly avoidable (due to exergy destructions) CO2 emissions, while the ever‐increasing H2S threat faced by all Black Sea countries will remain at an increasing rate. A new exergy‐based optimum H2S claim depth calculation and control algorithm for onboard operations have also been developed and designed, which shows that economy‐based optimization—if ever exists—will be responsible for nearly avoidable CO2 emissions, while the on‐board hydrogen production and utilization on the land side have a minimal environmental footprint. None of the earlier studies available in the literature concerning the exact harmful effects of hydrocarbons address exergy rationality. Renewable energy systems like wind turbines and solar energy systems, along with other renewable and waste energy systems like geothermal and wave energy are mostly treated individually, which are not free from large exergy destructions. Therefore, future energy plans with environmental concerns must be carried out from the source to the very last point of demand sectors. This is the specific attribute of this research. Novelty Statement: None of the studies about the exact harmful effects of hydrocarbons involve exergy rationality and the consequences of this ignorance on the environment and overall energy budget and economy. Renewable energy systems like wind turbines and solar energy systems, along with other renewable and waste energy systems like geothermal and wave energy are mostly treated individually, which are not free from exergy destructions. For example, a solar photovoltaic (PV) plant generates power but releases heat back without claiming it. This unclaimed heat represents about 50% of the unit exergy of the available solar energy and leads to exergy destruction that is responsible for nearly avoidable CO2 emissions because destroyed thermal exergy has to be offset by spending additional fuel in another system, which most likely is using fossil fuels in a boiler. The term nearly precedes the word avoidable, because exergy destructions may not be completely avoided. Even solar and wind energy systems have exergy destruction components during their operation. Yet, a solar PV and heat system would be a much better choice from the exergy rationality point of view. Although the ongoing increase in the renewable shares in the energy stock, it is essential to follow where the power is used in the built environment. For example, according to Global Wind Energy Council, within the next 10 years 234 GW, within the next 30 years 1400 GW offshore wind power capacity is expected to be installed. However, these installations will never know where this electricity and how this electricity is used in an energy/exergy balance and rationality when coupled to the landside through national and international grids. Therefore, future energy plans with environmental concerns must be carried out from the source to the very last point of demand sectors. Whether off‐shore or land‐based, wind turbines just generate electric power without asking where the electricity goes and how rational it is used in the built environment. There is no control over the best way of utilizing this wind energy. Instead, hydrogen production with renewables and utilization in next‐generation fuel cells produces power and heat (pending on heat distribution tariffs for the fifth‐generation district energy systems and LowEx applications, the temperature is the best fit for LowEx applications). The interrupted and unpredictable characteristics of renewables are offset by hydrogen storage. [ABSTRACT FROM AUTHOR]

Interest in evaluation of severe accidents induced by extended station blackout (ESBO) has significantly increased after Fukushima. In this paper, the severe accident process under the high and low pressure induced by an ESBO for a small integrated pressurized water reactor (IPWR)-IP200 is simulated with the SCDAP/RELAP5 code. For both types of selected scenarios, the IP200 thermal hydraulic behavior and core meltdown are analyzed without operator actions. Core degradation studies firstly focus on the changes in the core water level and temperature. Then, the inhibition of natural circulation in the reactor pressure vessel (RPV) on core temperature rise is studied. In addition, the phenomena of core oxidation and hydrogen generation and the reaction mechanism of zirconium with the water and steam during core degradation are analyzed. The temperature distribution and time point of the core melting process are obtained. And the IP200 severe accident management guideline (SAMG) entry condition is determined. Finally, it is compared with other core degradation studies of large distributed reactors to discuss the influence of the inherent design characteristics of IP200. Furthermore, through the comparison of four sets of scenarios, the effects of the passive safety system (PSS) on the mitigation of severe accidents are evaluated. Detailed results show that, for the quantitative conclusions, the low coolant storage of IP200 makes the core degradation very fast. The duration from core oxidation to corium relocation in the lower-pressure scenario is 53% faster than that of in the high-pressure scenario. The maximum temperature of liquid corium in the lower-pressure scenario is 134 K higher than that of the high-pressure scenario. Besides, the core forms a molten pool 2.8 h earlier in the lower-pressure scenario. The hydrogen generated in the high-pressure scenario is higher when compared to the low-pressure scenario due to the slower degradation of the core. After the reactor reaches the SAMG entry conditions, the PSS input can effectively alleviate the accident and prevent the core from being damaged and melted. There is more time to alleviate the accident. This study is aimed at providing a reference to improve the existing IPWR SAMGs. [ABSTRACT FROM AUTHOR]

Summary: Currently, recycling waste aluminum materials are of significant importance for reducing environmental pollution and improving economic efficiency. In this paper, aluminum (Al) powder prepared from waste Al cans with magnetic grinding method was directly used in hydrolysis for hydrogen generation. The prepared waste Al cans powder was characterized by scanning electron microscope (SEM), X‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET), atomic absorption spectrophotometer (AAS), and density analysis. The results showed that grinding time, NaOH concentration, and reaction temperature affected the hydrolysis rate and hydrogen yield markedly; 1 g of Al cans powder with grinding time of 40 minutes could produce 1296‐mL hydrogen within 6 minutes under the optimal reaction conditions. The reaction kinetics study demonstrated that the hydrolysis of Al cans powder is kinetically controlled while hydrolysis of Al cans flakes is diffusively controlled. The hydrolysis mechanism was also predicted based on the experimental results and kinetic study. The generation of hydrogen from hydrolysis of waste Al cans powder with low‐concentrated alkaline solution is a promising way to diminish environmental pollution and instrument corrosion. [ABSTRACT FROM AUTHOR]

Summary: Organic liquid intermediates were generated during the coal‐to‐biohydrogen fermentation process. The study on the generation of these organic liquid intermediates can provide information on the biogenic gas formation mechanism. In this paper, high volatile bituminous coal from Yima colliery was collected as an effective carbon source. The indigenous microflora extracted from a coal mine water was used as the bacterial source to set up simulation experiment to get biogenic gas. Then, gas chromatography and ultraviolet spectrophotometry, combined with liquid‐liquid extraction gas chromatography–mass spectrometry, were used to analyze the gas composition, as well as the production of saccharide, pyruvic acid, and volatile intermediates in the bioreactor fluids. The results show that the gases generated from the fermentation experiment contained hydrogen, carbon dioxide, and nitrogen. Twelve volatile component types were detected in the bioreactor fluids: straight alkanes, branched alkanes, alkenes, alcohols, aldehydes, ketones, acids, lipids, amines, quinolones, phenols, and epoxy alkanes. The key components of organic intermediates produced were saccharides, pyruvic acid, organic acids and alcohol, straight alkanes, and amide. Saccharides, pyruvic acid, alkanes, and organic acids were closely related to the generation of hydrogen and carbon dioxide, whereas amide stimulated nitrogen generation. Three stages are divided in the fermentation process. The first stage is hydrolysis, where the total, reducing, and polysaccharides production reached a maximum, with generation of long‐chain fatty acids as well as other liquid organics. The second stage is hydrogen production stage, which includes peak hydrogen production and hydrogen production stabilization stages. In the peak hydrogen production stage, saccharide production rapidly decreases, with an initial increase and subsequent decrease in pyruvic acid, straight alkanes, and branched alkanes. With the production of acetic acid and hydrogen, carbon dioxide production was initially slow but then rapidly increases. In stabilization of hydrogen generation stage, the saccharides were mostly consumed, pyruvic acid and branched alkanes' production increased slowly, but straight alkanes' production continued to decrease. In this stage, the production of acetic acid, hydrogen, and carbon dioxide was relatively stable, and the production of amide and nitrogen increased slowly. The third stage is the homoacetogenic stage, where pyruvic acid and branched alkane production continued to increase and straight alkanes' production continued to decrease. The pyruvic acid production increased abnormally, while amide and nitrogen production began to decrease and gas production nearly terminates. The liquid phase intermediate plays an important role in the coal‐fermenting hydrogen generation process and in revealing the hydrogen generation mechanism. [ABSTRACT FROM AUTHOR]

In this paper, a brief review and comparison of the engine waste heat recovery technologies have been made. These five technologies are electric turbocompounding systems (ETC), thermodynamic organic Rankine cycle (ORC), thermoelectric generators (TEG), hydrogen generation by using exhaust gas heat energy, and hybrid pneumatic power systems (HPPS). According to comparison results, the HPPS system can achieve the highest fuel economy improvement among the five technologies. Though there are their own benefits by utilizing these different technologies, their disadvantages prevent the application of these advanced technologies to different extent. Besides, a combined evaluation method consisting of grey relational analysis and analytic hierarchy process has been applied to assess the five new engine waste heat recovery technologies from the perspective of technical, economic, and environmental aspect. Based on the final results of the new evaluation method, the HPPS was found to be the most promising WHR technology for vehicle engines. But because of the emphasis on economic benefit, TEG was found to be more favorable for working conditions, like power plant and marine engine. What is more, as is shown in the sensibility analysis, the weighing of the environment relevant factors can prominently influence the comparison results between ETC and HPPS. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Hydrogen, the inevitable fuel of the future, can be generated from biomass through promising thermochemical methods. Modern-day thermochemical methods of hydrogen generation include fast pyrolysis followed by steam reforming of bio-oil, supercritical water gasification and steam gasification. Apart from the aforementioned methods, a novice technique of employing combined slow pyrolysis and steam gasification can be also engaged to produce hydrogen of improved yield and quality. This review paper discusses in detail about the existing hydrogen generation through thermochemical methods. It elaborates the merits and demerits of each method and gives insight about the combined slow pyrolysis and steam gasification process for hydrogen generation. The paper also elaborates about the various parameters affecting integrated slow pyrolysis and steam gasification process. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In order to achieve the hydrogen economy and respond to initial hydrogen demand appropriately, a hydrogen production and operation methodology is required to secure the economic feasibility of long-term on-site HRS. This study proposes a novel investment strategy for on-site hydrogen production to meet future hydrogen demand. The optimal investment strategy based on the dual-modal mode of combined autothermal reforming (ATR) and steam methane reforming (SMR) is proposed for hydrogen production using natural gas (NG) as a raw material. To predict hydrogen demand from 2020 to 2030, the machine learning (ML) technique was adopted. R 2 and MSE as result using ML were 0.9936 and 6.88 × 10 − 5 , respectively. In addition, the ATR-SMR hydrogen strategy (ASHS) process was analyzed and compared with the SMR-SMR and ATR-ATR hydrogen strategy (SSHS and AAHS) processes in terms of optimal operation rate, storage tank management, economics, and environmental impacts. The operation rate of proposed hydrogen production processes was determined by the hydrogen demand and storage tank level, and the optimal investment plan to install additional hydrogen process depends on the total amount of hydrogen production. In this study, these results were observed due to the effective combination of the strengths of ATR and SMR. Consequently, the ASHS had the best cost-effectiveness (LCOH at $5.63/kg H2) and environmental friendliness (unit CO2eq emissions at 10.21 kg CO2eq/kg H2 and 1.73 kg CO2eq/kg H2 with CCS). This study includes sensitivity analysis and a comparison of CO2 taxes by the country for three proposed hydrogen production processes. It could contribute to the optimal operation of the on-site hydrogen production system in preparation for future hydrogen demand. [ABSTRACT FROM AUTHOR]

In this paper, graphite and Fe2O3 are introduced into MgH2 powder by the method of hydrogenation after magnetic grinding. Hydrogen storage materials which composite of MgH2–5 wt.% C and MgH2–5 wt.% C–5 wt.% Fe2O3 are successfully prepared. The physical structure of these materials was analyzed and characterized by XRD, SEM, etc. Furthermore, the influence of graphite and Fe2O3 on the hydrolysis of MgH2 was systematically investigated. The results show that MgH2–C–Fe2O3 composite powder has the fastest hydrogen release rate in municipal drinking water and the highest conversion rate. Graphite and Fe2O3 can effectively reduce the activation energy of the hydrolysis reaction of MgH2 and improve the hydrolysis kinetics of MgH2. The synergistic effect of the coaddition of graphite and Fe2O3 can significantly increase the hydrolysis conversion rate of MgH2 and improve the hydrolysis kinetics. [ABSTRACT FROM AUTHOR]

This paper investigates solar radiation-induced photocatalytic hydrogen generation using spinel ZnFe2O4 (ZFO) photocatalysts fabricated using different routes, viz., solid state reaction (SSR), polymer complex (PC), microwave sintering (μW) and self-propagating combustion (SPC) method. The physicochemical properties of the photocatalysts like crystallinity, surface area, band gap and band energetics is studied as it influences their photochemical behavior. The study reveals a high crystallinity of the ZFO photocatalysts, those are synthesized using SSR, PC and μW methods, where SSR method yields the larger dimension crystallites of ~53 nm. The nanoparticles obtained from SPC methodology exhibit a relatively large surface area and a smaller crystallite size of around ~18 nm. Monodispersed particles with comparatively large surface area are obtained in the case of PC method. ZFO obtained from μW synthesis exhibits enhanced optical properties, thus favoring high absorption of solar photons. A relatively more negative flat band potential is displayed by the μW samples (−0.543 vs normal hydrogen electrode) as estimated from the electrochemical measurements. Consequently, these samples yield a higher quantum yield (0.19%) for hydrogen evolution even without co-catalyst loading. On the contrary, the photocatalysts obtained by SSR and PC methods did display an enhancement in the quantum yield as compared to the μW samples but only after Pt co-catalyst loading. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Hydrogen energy is considered as one of the ideal solutions for the fulfilment of the ever increasing energy demand. It is mainly due to the following two reasons: firstly, it can be produced from a very abundant source, that is, water; and secondly, it does not leave any harmful effect on the environment. Thermochemical cycles are amongst the most promising ways to generate hydrogen from water in an environment-friendly manner. Sulfur-iodine cycle is one of the most efficient thermochemical cycles. In this paper, we discuss synthesis of Pt/zirconia catalysts for HI decomposition reaction, which is one of the important steps of S-I thermochemical cycle. The catalysts were characterized by X-ray diffraction, scanning electron microscopy (SEM), field emission gun-SEM, transmission electron microscopy, N2 adsorption and H2 chemisorption. The catalytic activity and stability of these catalysts, for liquid phase decomposition of hydriodic acid was evaluated. Conversion is found to be dependent on the noble metal loading, with 18.7% conversion for 2% Pt/ZrO2 catalyst as compared with 2.7% of without catalyst, although the specific activity is highest for 0.5% Pt/ZrO2 catalyst. The catalyst was found to be stable under liquid phase HI decomposition reaction conditions. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, activated aluminum powder was prepared by magnetic grinding with a homemade equipment and hydrolyzed in alkaline solution to produce hydrogen. The results showed that the prepared aluminum powder could improve hydrolysis reactivity effectively and have high hydrogen yield in alkaline solution (up to 1340 mL/g). It was found that grinding time, reaction temperature and grinding media could significantly affect the hydrolysis reaction while alloy components had little effect. Aluminum powder ground for 40 min can produce hydrogen 1340 mL/g within 6 min under optimal reaction temperature of 323 K. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents, the numerical analysis of heat and mass transfer during hydrogen generation in an array of fuel cylinder bars, each coated with a cladding and a steam current flowing outside the cylinders. The analysis considers the fuel element without mitigation effects. The system consists of a representative periodic unit cell where the initial and boundary-value problems for heat and mass transfer were solved. In this unit cell, we considered that a fuel element is coated by a cladding with steam surrounding it as a coolant. The numerical simulations allow describing the evolution of the temperature and concentration profiles inside the nuclear reactor and could be used as a basis for hybrid upscaling simulations. [ABSTRACT FROM AUTHOR]

Ultra-high-performance fibre-reinforced concrete (UHPFRC) is a specialized type of concrete (to create a very dense matrix) that is used for both new construction and renovation projects in order to improve the lifespan of structures. Researchers analyse and evaluate only the microstructure, porosity, and fresh and hardened concrete properties of UHPFRC but limited their exploration on the reduction of the mechanical properties of UHPFRC due to the presence of metallic particles and micro-fractures that occur during the generation of hydrogen. Hence, the present study aims to eliminate the existing problem by hybridization approach (mixing of bio-nano-silica (nS) and polypropylene) with different percentages to further improve the strength properties of UHPFRC. The result showed that the compressive strength is increased by 15.5% compared to traditional concrete due to the filling ratio of nS in the pores of the concrete; in addition, the fibre's surface and roughness also contributed to the strength enhancement. [ABSTRACT FROM AUTHOR]

We prepared a perovskite material, copper-doped strontium titanate (Cu-SrTiO3), using the chemical bath deposition method and cast it on a CuFeO2/Cu photoelectrode to generate hydrogen from sanitation water splitting. This preparation method considers a simple mass product and does not depend on complex techniques. The prepared perovskite materials had a compact nano-/microstructure. Both CuFeO2 and Cu-SrTiO3/CuFeO2 exhibited excellent optical properties, with bandgap values of 1.4 and 1.26 eV, respectively. Here, the prepared CuFeO2 and Cu-SrTiO3 thin films are used as photoelectrodes for hydrogen generation, and their current-voltage relationship is analyzed under various conditions, such as different light intensities, wavelengths, and temperatures. This approach is promising for using wastewater as a source of hydrogen gas without requiring any additional electrolyte, making it a dual-purpose approach for both hydrogen generation and wastewater treatment. Through the electrochemical study, increasing the light intensity from 25 to 100 mW.cm-2 resulted in a corresponding increase in the produced J ph values from -1.02 to -1.292 mA.cm-2. Similarly, the J ph values increased from -1.25 to -1.91 mA.cm-2 as the temperature increased from 30 to 70°C. We also calculated all thermodynamic parameters, the quantum efficiency (QE), and incident photon to current conversion efficiency (IPCE). For the Cu-SrTiO3/CuFeO2/Cu photoelectrode, the activation energy ( E a ) value was 14.14 kJ mol-1, while the Δ H ∗ and Δ S ∗ values were 11.46 kJ·mol-1 and 34.9 kJ-1·mol-1, respectively. Additionally, the IPCE value was 3.31%. The prepared photoelectrode showed high stability and low cost, making it a potential candidate for industrial applications. [ABSTRACT FROM AUTHOR]

Biopolymer-based catalysts like chitosan, chitin, and cellulose offer sustainability and high efficiency both as the catalyst or catalyst support in a broad range of applications, especially in hydrogen evolution reactions. This review focused on hydrogen evolution catalysts of chitosan, chitin, cellulose, and carbon materials obtained from these biopolymers to highlight the opportunities of these sustainable catalysts in this field. All the reports in this area could be classified as one of the photocatalysts, electrocatalysts, and photoelectrocatalysts, and their mechanisms were clarified in the beginning. Then, the results of catalysts obtained from each of these biopolymers were discussed separately to reveal the roles of the biopolymers. It was concluded that all of the biopolymers enjoy some common benefits like hydrogen bonding, chelating with transition metals, easy chemical modification, high performance, and potential to be used as the precursors of carbon or porous materials. Among them, chitosan showed outstanding merit due to the better performance in metal grafting, amendment, and ability of hydrogen bonding. Moreover, it provides highly active nitrogen-doped carbon as the support of transition metals in the hydrogen generation, enhancing the reaction rate by retarding the charges recombination. [ABSTRACT FROM AUTHOR]

In a severe nuclear power plant accident, the molten core can be released into the reactor pit and interact with sacrificial concrete. In this paper, a simulation study is presented that aims to address the influence of sacrificial concrete properties on molten core-concrete interaction (MCCI). In particular, based on the MELCOR Code, the ferrosiliceous concrete used in European Pressurized Water Reactor (EPR) is taken into account with respect to the different ablation enthalpy and Fe2O3 and H2O contents. Results indicate that the concrete ablation rate as well as the hydrogen generation rate depends much on the concrete ablation enthalpy and Fe2O3 and H2O contents. In practice, the ablation enthalpy of sacrificial concrete is the higher the better, while the Fe2O3 and H2O content of sacrificial concrete is the lower the better. [ABSTRACT FROM AUTHOR]

Summary: Ammonia borane (AB) is a potential material for chemical hydrogen storage because of its outstanding stability, high hydrogen density, and the development of highly effective hierarchical catalysts for AB hydrolysis. Herein, the hierarchical Co@Ni metal‐organic framework (MOF) nanocolumn arrays (NCAs) on nickel foam (NF) were fabricated through a simple hydrothermal reaction, and the prepared catalysts were characterized using different techniques. The hierarchical Co@Ni‐MOFNCA/NF acts as a catalyst for AB methanolysis for hydrogen production. The catalysts exhibited outstanding performance towards AB methanolysis with the TOF of TOF of 20.54 mol H2 mol catalyst−1 min−1. As a result, the activation energy of the Co@Ni‐MOF NCA catalyst is 39.72 kJ mol−1 which is compared with some commercial solid support materials such as Al2O3 and AC. Additionally, the effects of nanocatalyst loading and temperatures were studied for the Co@Ni‐MOF NCA catalyst. Further, a complete investigation proposes that the outstanding catalytic performance of the Co@Ni‐MOF NCA catalyst could be attributed to the synergy between Co and Ni‐MOF NCA. [ABSTRACT FROM AUTHOR]

The research on hydrogen generation and application has attracted widespread attention around the world. This paper is to demonstrate that sodium aluminum hydride can be synthesized under simple and mild reaction condition. Being activated through organics, aluminum powder reacts with hydrogen and sodium hydride to produce sodium aluminum hydride under atmospheric pressure. The properties and composition of the sample were characterized by FTIR, XRD, SEM, and so forth. The results showed that the product through this synthesis method is sodium aluminum hydride, and it has higher purity, perfect crystal character, better stability, and good hydrogen storage property. The reaction mechanism is also discussed in detail. [ABSTRACT FROM AUTHOR]

Summary: MXene, which are known as two‐dimensional transition metal carbides have received heavy interest due to their rich elemental diversity and many fascinating physical and chemical properties. Here, Rh (0) nanoparticles deposited MXene catalysts were synthesized by an easy wet‐impregnation method for hydrogen production. Rh (0) nanoparticles were conveniently loaded on the surface of MXene (Rh/MXene) were used as an effective nanocatalyst for the hydrogen production from the hydrolysis of ammonia‐borane (AB). The morphological and structural characterizations of Rh/MXene catalysts show that Rh nanoparticles were successfully deposited on the surface of MXene substrates. Rh (0) nanoparticles with an average size of 2.55 nm were homogeneously dispersed and deposited on the MXene surface. The Rh/MXene displayed good catalytic performance in the hydrogen production via the hydrolysis of AB, and the turnover frequency value at 25°C was 288.4 min−1, which is comparable to most of the synthesized catalysts. The Rh/MXene catalyst displaying good activity in seven consecutive catalytic cycles can be considered a good nanocatalyst candidate for hydrogen production from the hydrolysis of AB. [ABSTRACT FROM AUTHOR]

Summary: Microbial electrolysis cells (MECs) are one of the most promising innovation amongst bio‐electrochemical systems for biohydrogen production. A wide variety of wastewaters and organic wastes that is, sodium acetate, glucose, glycerol, domestic wastewater, sugar industries effluent, food processing wastewater, industrial wastewater, etc. can be utilized as substrates in MEC. The objective of this comprehensive review is to study the effects of reactor configuration, electrode materials, and substrates on the maximum hydrogen production rate (HPR) and columbic efficiency (CE) of the MEC system. The obtained results were summarized based on reactor configuration, substrate concentration, electrodes, applied voltage, HPR, and CE. Despite this significant progress, MEC technology still requires substantial developments to be recognized as a commercially viable technology. At the end of this review, the most promising future perspectives were also discussed which could be the appealing solutions for various problems associated with MEC technology. This review supports energy engineers and researchers to analyze the performance of various MECs for future assistance in research. [ABSTRACT FROM AUTHOR]

To prevent total meltdown of the uncovered and overheated core, the reflooding with water is a necessary accident management measure. Because these actions lead to the generation of hydrogen, which can cause further problems, the related phenomena are investigated performing experiments and computer simulations. In this paper, for the experiments of loss of coolant accidents, performed in Forschungszentrum Karlsruhe, QUENCH-03 and QUENCH-06 are modelled using RELAP5/SCDAPSIM and ASTEC codes. The performed benchmark allowed analysing different modelling features. The recommendations for the model development are presented. [ABSTRACT FROM AUTHOR]

Summary: In this study, lab‐made modified graphite cathodes were used to design and implement floating PV assisted alkaline electrolysis cell. The influence of temperature on PV performance was studied both experimentally and theoretically, and the PV module performance was investigated in floating as well as non‐floating modes. Power generation of floating PV panel and non‐floating PV panel at four different air temperatures was examined. Although there was no substantial improvement in power generation at 6°C or 16°C, values improved by 6.25% and 10.75% at 24°C and 37°C, respectively. For alkaline electrolysis cell part of this system, the graphite (G) cathode was galvanostatically coated with nickel (G/Ni) and decorated with cobalt nano‐particles (G/Ni/Co). The characterization of the electrode was achieved using X‐Ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The Co(111)‐decorated Ni was determined by XRD, the electrode surface was very rough in FE‐SEM micrographs, the detected features provided a larger contact area that supported the formation of simultaneous electrochemical reactions. The electrochemical behavior of electrodes were determined in 1 M KOH by cyclic voltammetry (CV). The modified cathode (G/Ni/Co) enhanced the hydrogen production performance owing to lower hydrogen onset potential. Electronic structure calculations were carried out in order to investigate water as well as proton adsorption on a Co‐decorated Ni(111) surface. Density Functional Theory (DFT) calculations identified the role of Co cluster and Ni surface on water and proton adsorptions. According to our knowledge of the literature to date, the practical and theoretical analysis of a floating PV assisted‐an alkaline electrolysis system that worked with the laboratory‐made electrodes has not been performed before. Results showed that floating PV panels were beneficial than land mounted panels and the G/Ni/Co enhanced the hydrogen generation performance of the system. [ABSTRACT FROM AUTHOR]

The presence of a stable stratified gas cloud inside the containment near or at the flammability limit may lead to deflagration or even detonation which may challenge the containment and cause a radioactive material release into the environment. To mitigate this risk, a number of approaches have been proposed, for example, containment inerting or venting and use of passive autocatalytic recombiners or igniters. However, for these measures to be effective, a thorough analysis of the hydrogen dispersion and associated phenomena is indispensable during the design phase as well as the mitigation phase during a severe accident. In this work, a MAAP analysis is performed to assess the hydrogen risk in a typical pressurized water reactor (PWR) containment. An extended station blackout (SBO) was chosen as an initiating event given its high contribution to the core damage frequency. RCS depressurization and external injection are mitigation techniques implemented consecutively to extend the coping capability of the plant for the extended SBO scenario. A sensitivity study is performed to select the combination of timing and flow rate that generate the most severe case for the "in-vessel phase of hydrogen generation." Subsequently, a number of passive autocatalytic recombiners (PARs) were implemented to mitigate the hydrogen risk during the first three days of the accident. The Shapiro diagram is used to assess the flammability condition of the containment atmosphere based on MAAP analysis. The results show that the gas mixture composition is acceptable in the majority of the containment compartments and only marginally acceptable in the cavity. Even under the conservative conditions of the accident, the simulation results confirmed the sufficiency of recombiners alone without igniters in the low hydrogen concentration zones, while for compartments close to the sources, additional mitigation may be needed. [ABSTRACT FROM AUTHOR]

Summary: The use of renewable energy sources is the main strategy toward a low‐carbon society. A promising alternative for the production of hydrogen gas is the water‐splitting thermochemical cycles activated by solar energy. This work presents an experimental study of a two‐stage thermochemical cycle for hydrogen production. It is based on the carbothermic reduction of iron ore (Fe2O3) and the re‐oxidation of it with steam can be powered by concentrated solar energy. Samples studied were self‐reducing pellets. The first stage of the proposed cycle consists in the reduction of hematitic iron oxide into its own metal at temperatures above 1173 K. The second phase of the cycle consists of iron metal oxidation by steam, which produces hydrogen gas. Sponge iron samples obtained in this work had a specific surface area of 35.05 m2/g measured by the BET method, which is a high value compared to specific surface areas obtained from conventional processes. It was shown that at 973 K the hydrogen gas production rate is slower, whereas at 1073 K and at 1173 K the sample reached 63% of its maximum oxygen gain between 2 and 7.5 minutes, respectively. As the hydrogen gas production rate is also proportional to the iron oxidation rate, it was shown to be very important to balance out the hydrogen gas production over the entire cycle time as a function of temperature. Finally, the analyzed thermochemical cycle can also operate with any other renewable carbon source. [ABSTRACT FROM AUTHOR]

Summary: In this study, a CoNi/CoFe2O4 electrocatalyst with durian‐like structure was in‐suit fabricated on the conductive substrate of nickel foam using a hydrothermal method followed by a unipolar pulse electrodeposition (UPED), which was further applied for the production of hydrogen in a microbial electrolysis cell. The CoNi/CoFe2O4/NF electrode prepared with a pulse voltage of −1.2 V by the UPED exhibited the outstanding electrocatalytic activity and durability with the rate of hydrogen production achieved as high as 1.25 ± 0.0625 m3/(m3 day). The excellent performance of the electrocatalyst is attributed to the unique multilayer layered structure, which consisted of macroscopic porous NF, CoFe2O4 nanosheets, and CoNi double hydroxide nanosheets. The hierarchical architecture is binder‐free and beneficial for exposing catalytic active sites, enhancing mass transport, and large specific surface area for MEC hydrogen production. It is expected to the CoNi/CoFe2O4/NF composite electrode application in the practical microbial electrolysis cells to produce hydrogen during the treatment of wastewater. Highlights: A CoNi/CoFe2O4 electrocatalyst was prepared for microbial electrolysis cell.The electrocatalysts had unique multilevel hierarchical architecture.The electrocatalysts exhibited a high H2 production rate of 1.25 ± 0.0625 m3/(m3 day). [ABSTRACT FROM AUTHOR]

Summary: Electrochemical water splitting is known to be one of the most potential pathways for hydrogen generation. However, this process is limited by the sluggish cathodic hydrogen evolution reaction (HER) kinetics. Nitrogen‐doped materials have been exploited for the development of efficient electrocatalysts because of their tunable electronic properties. Herein, we illustrate a facile route to construct the core‐shell architecture in NiSe2@nitrogen‐doped carbon (NiSe2@NC) as efficient catalysts for the HER. NiSe2@NC samples were prepared through a two‐step process involving pyrolysis and selenization at various temperatures from a nitrogen‐rich Ni‐based metal‐organic framework (MOF) precursor. NiSe2@NC‐500°C was considered as the optimal sample because it showed outstanding catalytic properties for the HER with low overvoltages of 161 and 220 mV to deliver a current density of 10 mA/cm2 in acidic and alkaline solutions, respectively. In addition, NiSe2@NC‐500°C exhibited excellent stability after 2000 cycles and 12 h of operation. The high catalytic performance was attributed to the synergistic effect of the core‐shell structure and the carbon layers doped with high pyridinic‐N content, which play a vital role in providing a large number of active centers, imparting high conductivity, and enhancing the durability of the electrocatalyst. This account may open an approach to the design and fabrication of low‐cost electrode materials for HER. [ABSTRACT FROM AUTHOR]

Summary: In this study, a novel hybrid photoelectrochemical (PEC)–photocatalytic (PC) hydrogen evolution reaction (H‐PEC@PC@HER) reactor was developed, in which, the PC and PEC hydrogen evolution reactions were simultaneously performed to maximize the light absorption and investigated the synergetic interactions between these processes. Solvothermally synthesized reduced graphene oxide (RGO)‐Cd0.60Zn0.40S‐Pt composite was used as the functional photocatalyst for these reactions in H‐PEC@PC@HER reactor. The illumination of the RGO‐Cd0.60Zn0.40S‐Pt photocatalyst and photoanode was provided at the same time, thus while some of the incoming light was absorbed by the RGO‐Cd0.60Zn0.40S‐Pt photocatalyst, the light passing without being absorbed was also absorbed by the photoanode. Consequently, the utilization of the solar light spectrum was maximized with the PC reaction of RGO‐Cd0.60Zn0.40S‐Pt powder and PEC reaction of RGO‐Cd0.60Zn0.40S‐Pt photoanode. The results showed that the hydrogen production rate in the H‐PEC@PC@HER increased ca. 8.2% with respect to that of the single PC reaction. It was observed that the hydrogen production rate in the H‐PEC@PC@HER system enhanced with time due to the enhancing PEC reaction in the residual Na2S/Na2SO3 electrolyte. When compared with the results in fresh electrolyte, the photocurrent density of the RGO‐Cd0.60Zn0.40S‐Pt photoelectrode increased from 1.0 to 1.41 mA/cm2 in the residual Na2S/Na2SO3 electrolyte with a reported enhancement of 17.4% in the photocurrent density. It was proposed that S2O32− ions produced with the PC reaction were used as the hole‐recleavaging reagent of the RGO‐Cd0.60Zn0.40S‐Pt photoelectrode in the PEC system. [ABSTRACT FROM AUTHOR]

Summary: Development of economically viable cathode catalysts with practicability in the treatment of real effluents is one of the strenuous efforts among the multidisciplinary approaches in microbial electrolysis cell (MEC). Treatment of industrial effluents using this technology had resulted in simultaneous energy production in the form of hydrogen along with wastewater treatment, promoting both energy and environmental benefits. In this study, two metal oxides such as, Nickel Oxide (NiO) and Cobalt oxide (Co3O4) were employed as the cathode catalyst using sugar industry effluent as the substrate for biohydrogen production in the MEC. The addition of NiO and Co3O4 on nickel foam (NF) has demonstrated better hydrogen evolution performance than the control (uncoated) cathode. Electrochemical characterization of the modified cathodes revealed the improved capability analogous to the current density and hydrogen production rate (HPR) obtained in the experimentation. The best performance was achieved by NiO/NF with the maximum HPR of 3.39 ± 0.03 mmol/L/D, coloumbic efficiency of 58 ± 1.4%, hydrogen recovery of 27 ± 1.8% and COD removal efficiency of 52 ± 1.6% when operated with the applied voltage of 1.0 V. Hence, the potential of metal oxides was demonstrated for the candidature of efficient and economical cathode materials in MECs. [ABSTRACT FROM AUTHOR]

Summary: In this study, a novel integrated structure for generation of the oxygen, hydrogen, power, and hot water by employing thermochemical reactors and solar dish collectors is proposed. The presented process including solar dish collectors, sulfur‐iodine thermochemical cycle, and Organic Rankine Cycle. In this configuration, for 5854 kmol/h of inlet water, 2236 kmol/h of oxygen, and 4432 kmol/h of hydrogen are produced. This system can provide 22 666 kW of power that 22 026 kW is utilized in the sulfur‐iodine reaction. So, the net electrical power is found to be 640 kW. A general exergy analysis is carried out on the whole structure and equipment to find its exergy losses and improvement potential to enhance the exergy efficiency of the system. The total exergy efficiency of the process is calculated 56.33% and its exergy destruction is obtained 382 301.31 kW. Heat exchangers and solar collectors have the highest values of destructed exergy, which about 69% of destructed exergy is related to them. These devices have a strong potential for enhancement. The results showed that component P1 (pump) has the lowest exergy efficiency that is 15.58%, while its exergy destruction is not the greatest. Therefore, for having a better examination of this structure, both exergy efficiency and exergy destruction parameters should be evaluated simultaneously. Moreover, a sensitivity analysis is applied to survey the performance of some performance indicators vs different design parameters. It is concluded that by an increase in generated heat by solar collectors, exergy efficiency, energy efficiency, oxygen, and hydrogen production faces increment. [ABSTRACT FROM AUTHOR]

Summary: To solve the problems of excessive CO2 emission and low resource utilization, which exist in the original hydrogen production process that occurs in an oil refinery, the original natural gas steam reforming process is improved by proposing a new coupled energy‐effective hydrogen production process from liquefied natural gas (LNG) with a CO2 capture and storage (CCS) unit; this is based on the background that the oil refinery takes the LNG of the adjacent receiving station as feedstock to produce hydrogen products. The newly designed process recovers the high‐grade cold energy released by the raw LNG during gasification to liquefy the CO2 generated in the process, which achieves energy integration to the greatest extent and improves the energy utilization efficiency. Meanwhile, the unreacted raw gas is recycled to improve the resource utilization. Moreover, to obtain the optimal operating parameters of the new process for further evaluation of its advantages, the global optimization model with the optimal overall economic benefit as the objective function is established and the best‐operating conditions for the new process with optimal economic benefit are obtained. The result of the energy analysis of the thermodynamic process indicates the exergy efficiency of the new process reaches 60.14%. Compared with the original process, even though the total energy consumption of the new process is increased, the economic benefit still grows by 123.6 million CNY/year owing to the increasing of CO2 product benefit with a high recovery rate of 99.5% in the hydrogen production process and an overall CO2 recovery rate of 69.72%. This study can provide theoretical references for the design and actual production of the hydrogen production process from natural gas. [ABSTRACT FROM AUTHOR]

Summary: Considering the low temperature demand (~550°C maximum) and high efficiency (~43%), Cu–Cl thermochemical water splitting cycle has immense potential as a futuristic scalable hydrogen generation process. CuCl/HCl electrolysis is the crucial hydrogen generation step in the Cu–Cl thermochemical cycle. The efficiency of this electrolysis process is highly dependent on the performance of the membrane electrode assembly (MEA) employed. To explore the suitability of the platinized membrane for this step, in this study, we have investigated a Pt/Nafion‐117 MEA prepared by in‐situ impregnation‐reduction method for CuCl/HCl electrolysis. A single‐cell PEM‐type electrolyser (4 cm2 active area) consisting of serpentine channels (2 cm × 2 cm) grooved in graphite flow field plates was designed and fabricated to carry out the CuCl/HCl electrolysis. Platinum electrocatalyst was deposited on Nafion‐117 membrane on the cathodic side by reduction of hexachloroplatinic acid (H2PtCl6) with sodium borohydride (NaBH4) by the impregnation‐reduction method which served as the MEA. Monodispersed nanocrystalline Pt particles formed a ~30 μm thick electrocatalyst layer on the membrane. Pt/Nafion‐117 MEA was found to be effective for CuCl /HCl electrolysis. In a PEM‐type electrolyser with Ar‐purged 0.2 M CuCl in ~2 M HCl solution as anolyte flowing at ~ 8.8 mLmin−1, a current density of ~100 mA cm−2 was achieved at a cell voltage of 1 V. However, undesired Cu‐crossover could be noticed from anode to cathode side during operation. [ABSTRACT FROM AUTHOR]

Summary: Sand samples from Tampa (T) and Panama (P) City beaches in Florida were used as catalysts for dehydrogenation of NaBH4 in methanol. T and P sand samples were sieved to <250, 250 to 500, and >500 μm sizes, and the smallest fractions resulted in faster hydrogen generation rates (HGR), 565 ± 18 and 482 ± 24 mL H2 (min.g of catalyst)−1, respectively. After various base/acid treatments, HGR values of 705 ± 51 and 690 ± 47 mL H2 (min g of catalyst)−1 for HCl‐treated T and P sand samples were attained, respectively. Next, T and P sand samples were modified with polyethyleneimine (PEI) that doubled the HGR values, 1344 ± 103, and 1190 ± 87 mL H2 (min.g of catalyst)−1 and increased ~8‐fold, 4408 ± 187, and 3879 ± 169 mL H2 (min g of catalyst)−1, correspondingly after protonation (PEI+). The Ea values of T and P sand samples were calculated as 24.6 and 25.9 kJ/mol, and increased to 36.1, and 36.6 kJ/mol for T‐PEI+ and P‐PEI+ samples, respectively. [ABSTRACT FROM AUTHOR]

Summary: Commercially available open‐cell polyurethane foams (OCPUF) have been successively functionalized with bio‐inspired polydopamine coating (OCPUF@PDA), and activated with cobalt nanoparticles (OCPUF@PDA@Co). The resulting soft structured catalytic support (S2CS) has been used as a highly efficient tool for the release of dihydrogen from a commercially available alkaline sodium borohydride solution at room temperature. With a diluted solution containing 0.4 wt% NaBH4 and 0.4 wt% NaOH, the hydrogen generation rate was of 76.4 ± 3.18 L·h−1·gcat−1 after stabilization of the catalytic activity. The catalytic tool could be used for 10 runs. [ABSTRACT FROM AUTHOR]

Improving the efficiency of photocatalytic water splitting to produce hydrogen is currently a hot topic in research. TiO2 nanosheets are a good carrier of photocatalytic materials and have become attractive materials in the new century because of their high active surface exposure characteristics and special morphology. Considering the advantages and disadvantages of conventional chemical and physical methods that are used for preparing TiO2 nanosheets, an optimized scheme for the preparation of TiO2 nanosheets via hydrothermal calcination was proposed. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and UV-visible diffuse reflection absorption spectra (DRS) were used to characterize the structure and morphology of the TiO2 nanosheets, and differences in the photocatalytic water splitting hydrogen production activity of the different calcination temperatures were compared. The suitable calcination temperature of the TiO2 nanosheets was 400°C, and the hydrogen production rate was 270 μmol/h, which indicated that the sheet structure was beneficial for improving the photocatalytic water splitting hydrogen production performance of the material. It is hoped that this work will support the regulation of the surface morphology and surface modification of nanomaterials. [ABSTRACT FROM AUTHOR]

In this study, VVER‐1000/V446 nuclear reactor modeling using RELAP5/SCDAP3.4 code to investigate the reactor core behavior during severe accident conditions in a LBLOCA scenario along with station‐black‐out (SBO) is carried out. The analyses are performed in two stages, before and after the core heat up, without considering operator's action on the accident management. Fuel assemblies in the core are grouped into five based on average power peaking factors and are modeled in SCDAP code. For each group a corresponding channel is modeled in RELAP5 code plus a bypass channel. In the first stage, the study of ECCS and KWU tanks efficiency to keep the reactor core in the safe condition, the calculation of the elapsed time before the reactor core heat up and the estimation of available time for operator's action to avoid core degradation, are investigated. In the second part the results of Hydrogen production rate, cladding oxide thickness, cladding damage level, release of fission products into the coolant are studied. Analysis of the scenario by the code shows the production of around 350kg Hydrogen with the maximum rate of about 1kg/s and releasing a large amount of FPs in the order of 10kg. The results also demonstrate that the operators have ∼3 h before the fuel rod cladding rupture and ∼2.5 h before the inception of exothermic steam‐zirconium reaction. Finally, using a geometric mesh for the lower plenum and applying the COUPLE code, the results show that the core slumping into the lower plenum and the lower plenum rupture occur at 17561 and 18370 seconds after the onset of accident, respectively. [ABSTRACT FROM AUTHOR]

The salinity, chemical properties, and migration characteristics of groundwater in coal measures are the key factors that affect the generation, migration, and reservoir of hydrogen sulfide (H2S) in low-rank coal seams. Taking the Jurassic coal and rock strata in the southeastern margin of the Junggar basin as the research object, according to the hydrogeological characteristics of the coal measures, the region is divided into 4 hydrogeological units. The coalbed methane contains a large number of secondary biogas. Along the direction of groundwater runoff, the salinity and the pH value increase gradually. The salinity in the hydrogeological units is low; it is not conducive to the propagation of sulfate-reducing bacteria and the formation of hydrogen sulfide of the Houxia, the south of Manasi River, and Hutubi and Liuhuangou area, the western region of the Miquan. The high salinity center and depressions of low water level (hydrodynamic stagnation zone) in the hydrogeological unit of the Liuhuanggou and the Miquan are the main areas for the production and enrichment of H2S in the low-rank coal. The high salinity in water is formed by infiltration, runoff, and drought evaporation. At the same time, the deep confined water environment closed well; in conditions of hydrocarbon-rich, under the action of sulfate-reducing bacteria, bacterial sulfate reduction will occur and hydrogen sulfide formed. According to the circulation characteristics of water bearing H2S in the region, imbricate and single bevel two kind generation and enrichment mode of hydrogen sulfide under the action of hydrodynamic control. The solubility of hydrogen sulfide in pure water and solutions of NaCl and Na2SO4 with different molar concentrations was calculated. The H2S solubility of groundwater in coal measures of 4 hydrogeological units was estimated. [ABSTRACT FROM AUTHOR]

Summary: (Al2Ga)‐xIn (x = 0, 2, 4, 6, 8 wt%) ternary aluminum (Al) alloys with different weight ratio of In for hydrolysis H2 generation were prepared by melting‐casting technique. The phase compositions and microstructures of Al‐rich alloys were investigated by X‐ray diffraction (XRD) and high resolution scanning electron microscope (HR‐SEM) equipped with an energy dispersive spectrometer (EDS). The effect of In addition ratio on microstructures and H2 generation performance were investigated, and the hydrolysis mechanism for Al‐Ga‐In ternary Al‐based alloys has been proposed. Al phase as matrix phase in the Al‐Ga‐In ternary alloy mainly determines the hydrolysis behavior, and the second phase In strongly promotes the hydrolysis process. The increase of In content can accelerate the H2 generation rate as well as the final capacity and generation yield in neutral water. The generation yields for (Al2Ga)‐x In (x = 2, 4, 6, 8 wt%) alloys at 50°C are 0.56, 0.59, 0.62, and 0.66, respectively. The raising hydrolysis temperature can elevate the initial hydrolysis rate, final H2 generation capacity, and yield. The H2 generation capacities of (Al2Ga)‐8In alloy at 50°C, 60°C, and 70°C are 262, 290, and 779 mL·g−1, respectively. [ABSTRACT FROM AUTHOR]

Aims: To date, the ROS-generating capacities of macrophages in different activation states have not been thoroughly compared. This study is aimed at determining the nature and levels of ROS generated following stimulation with common activators of M1 and M2 macrophages and investigating the potential for this to impact fibrosis.Results: Human primary and THP-1 macrophages were treated with IFN-γ+LPS or IL-4-activating stimuli, and mRNA expression of established M1 (CXCL11, CCR7, IL-1β) and M2 (MRC-1, CCL18, CCL22) markers was used to confirm activation. Superoxide generation was assessed by L-012-enhanced chemiluminescence and was increased in both M(IFN-γ+LPS) and M(IL-4) macrophages, as compared to unpolarised macrophages (MΦ). This signal was attenuated with NOX2 siRNA. Increased expression of the p47phox and p67phox subunits of the NOX2 oxidase complex was evident in M(IFN-γ+LPS) and M(IL-4) macrophages, respectively. Amplex Red and DCF fluorescence assays detected increased hydrogen peroxide generation following stimulation with IL-4, but not IFN-γ+LPS. Coculture with human aortic adventitial fibroblasts revealed that M(IL-4), but not M(IFN-γ+LPS), enhanced fibroblast collagen 1 protein expression. Macrophage pretreatment with the hydrogen peroxide scavenger, PEG-catalase, attenuated this effect.Conclusion: We show that superoxide generation is not only enhanced with stimuli associated with M1 macrophage activation but also with the M2 stimulus IL-4. Macrophages activated with IL-4 also exhibited enhanced hydrogen peroxide generation which in turn increased aortic fibroblast collagen production. Thus, M2 macrophage-derived ROS is identified as a potentially important contributor to aortic fibrosis. [ABSTRACT FROM AUTHOR]

Summary: In this study, reduced graphene oxide (RGO)‐Cd(1 − x)ZnxS nanocomposites have been synthesized with the solvothermal method in one pot. Moreover Pt, Ru, and Rh nanoparticles have been loaded on the RGO‐Cd(1 − x)ZnxS nanocomposites as cocatalysts with the aim of increasing the photocatalytic (PC) performance for hydrogen evolution reaction. The structure of Cd(1 − x)ZnxS blend transforms from cubic to hexagonal structure during the PC hydrogen evolution reaction (PCHER) at the room temperature. This photo‐induced phase transformation (PIPT) enhances not only the hydrogen evolution rate, but also the stability of the photocatalysts. Interestingly, RGO triggers the PIPT process only during the PCHER under solar light illumination. On the other hand, the loading of Pt, Ru, and Rh cocatalysts do not affect the PIPT process. However, they enhance the PC and photoelectrochemical (PEC) hydrogen production activity of RGO‐Cd(1 − x)ZnxS photocatalyst. PEC performance increases about 5.5 times when Pt (5%) and RGO are added to the Cd0.60Zn0.40S catalyst. RGO‐Cd0.60Zn0.40S including 1.5% Rh photocatalyst reaches a remarkable PC hydrogen production rate of 135 μmolh−1 with QE of 23.3% at 460 nm. Therefore, Rh cocatalyst appears as a good alternative to Pt. [ABSTRACT FROM AUTHOR]

Summary: Carbon black (CB) obtained from used car tire rubbers were treated with concentrated sulfuric and nitric acids. The oxidized CB (CB‐COO‐Na+) is subsequently modified with epichlorohydrin (ECH) and amines including polyethylene imine (PEI). These modified CBs such as CB‐PEI are used as metal‐free catalysts in methanolysis of sodium borohydride (NaBH4) to produce hydrogen. The hydrogen generation rate (HGR) of 3089 ± 44.69 mL.min‐1.g‐1 is accomplished at room temperature with CB‐PEI‐hydrochloric acid (HCl) catalyst. The resulting activation energy of 34.7 kJ/mol for the temperature range of −20°C to +30°C compares favorably to most of alternative catalysts reported in literature while reaction catalyzing capabilities of CB‐PEI‐HCl particles extend to the subzero temperature range (−20°C‐0°C). The reuse and regeneration studies conducted for the CB‐PEI‐HCl catalyst showed that these catalysts do provide complete conversion at every use up to five consecutive runs and retain 50 ± 2.5% of the original hydrogen generation rate at the fifth consecutive reuse. The CBs‐based catalysts are fully regenerated with HCl treatment. [ABSTRACT FROM AUTHOR]

Influence of hydrogen pressure and internal hydrogen contents on short-term strength, plasticity, and plane-stress fracture toughness of 05Cr19Ni55 alloys at pressure up to 30 MPa was investigated. It was established that the crack resistance parameters Kc of alloys decrease with displacement rates decreasing similar to elongation (δ) and reduction of area (ψ) of smooth specimens. The maximum hydrogen influence is achieved at strain rate speeds less than 0.1 mm/min and hydrogen pressures above 15 MPa when δ and Kc of prehydrogenated samples are reduced by 3 times. The plane-strain conditions required for the evaluation of KІc were fulfilled on compact tension 05Cr19Ni55 alloy specimens with thickness above 20 mm under hydrogen pressure 30 MPa and preliminary dissolved hydrogen concentration above 20 wppm. Regardless of the test conditions, the value of the characteristics of plasticity (δ, ψ) and fracture toughness (Kс) of alloy (TO1) specimens oriented in the transverse direction (orientation TV) is significantly lower than that of specimens oriented in the longitudinal direction (LT). Alloy cleaning by vacuum arc remelting and optimization of heat treatment regime increase their hydrogen resistance. [ABSTRACT FROM AUTHOR]

Current H2-proton exchange membrane fuel cell systems available for commercial applications employ heavy and high-risk physical hydrogen storage containers. However, these compressed or liquefied H2-containing cylinders are only suitable for ground-based electric vehicles, because although highly purified H2 can be stored in a cylinder, it is not compatible with unmanned aerial vehicles (UAVs), which require a lighter and more stable energy source. Here, we introduce a chemical hydrogen storage composite, composed of ammonia borane (AB) as a hydrogen source and various heterogeneous catalysts, to elevate the thermal dehydrogenation rate. Nanoscale SiO2 catalysts with a cotton structure dramatically increase the hydrogen evolution rate on demand, while simultaneously lowering the startup temperature for AB thermolysis. Results show that the dehydrogenation reaction of AB with a cotton-structured SiO2 nanocatalyst composite occurs below 90°C, the reaction time is less than a minute, and the hydrogen generation yield is over 12 wt%, with an activation energy of 63.9 kJ·mol-1. [ABSTRACT FROM AUTHOR]

Summary: Hydrogen becomes one of the most clean energy sources. The major issues on hydrogen are lack of practical clean and high‐temperature processes and possible practical storage of clean hydrogen. An energy intensive of clean hydrogen storage via chemical and liquid fuel production route is the current demand. This article reviewed the most recent research for hydrogen (H2) production by using several methods, such as thermochemical process, thermal decomposition, biological approaches, electrolysis, and photocatalytic method. H2 storage types, including physical and chemical approaches, were also reviewed. The produced H2 was stored as valuable chemicals and fuels via CO2 hydrogenation reaction. Reactor designs are the illustrated number of design ranging from the fixed bed to the continuous stirred tank reactor. Catalyst type, catalytic system, and the related mechanism of CO2 hydrogenation reaction to form alcohol, alkanes, and carboxylic acid were also discussed in detail. [ABSTRACT FROM AUTHOR]