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Solar-driven water splitting by inorganic semiconductor photocatalysts is considered a promising method to produce hydrogen fuel. Loading inorganic semiconductor on cellulose fiber to construct photocatalytic paper contributes to the dispersion and recycling of photocatalyst. In addition, the photocatalytic paper floating on water can build a solid–gas biphase photocatalytic interface (photothermal-generated steam/photocatalytic paper/hydrogen), replacing the traditional liquid–solid–gas triphase photocatalytic interface (liquid water/photocatalyst/hydrogen) for improving photocatalytic kinetics. Here, we design and synthesize a photocatalytic composite paper with zinc sulfide (ZnS) anchored onto cellulose fibers (CF) with the help of polydopamine (PDA). PDA achieves high load and uniform distribution of ZnS on cellulose fibers, and forms the ZnS/PDA heterojunction to increase photogenerated charge separation efficiency and photocatalytic stability. Solid–gas biphase photocatalytic interface constructed by the CF/PDA/ZnS composite paper minimizes the interface barriers of hydrogen transport and water molecular adsorption for improving hydrogen evolution rate. The CF/PDA/ZnS composite paper shows a high hydrogen production rate up to 18706.8 μmol h−1 g−1. Stable loading of ZnS/PDA heterojunction in composite paper contributes to the photocatalytic stability. In the third photocatalytic cycle, the hydrogen evolution rate of CF/PDA/ZnS composite paper remains 96.4%. This work inspires that anchoring of inorganic semiconductor on cellulose fibers with the help of PDA can be a promising strategy for designing efficient photocatalytic paper for solar hydrogen production. [ABSTRACT FROM AUTHOR]

The authors of the title paper (Appl Phys A 126:394, 2020) report to have grown a new nonlinear optical potassium hydrogen oxalate (KHO) single crystal, which exhibits second harmonic generation response. In this comment, it is shown that these claims are erroneous since KHO is a well-known solid which crystallizes in the centrosymmetric P21/c space group. [ABSTRACT FROM AUTHOR]

To improve the hydrogen detection performance, a flexible palladium-based hydrogen sensor was designed and fabricated on normal photocopy paper. The paper substrate offers advantages such as light weight, low cost, flexibility and unique surface texture. A conventional vacuum evaporation technique was utilized for 60 nm palladium deposition on the paper and glass substrates. The unique surface texture of the paper effectively increased the surface area to volume ratio for the sensing element, which achieved a higher gas response with faster speed than the glass-based sensor. In addition, we investigated the temperature impacts on sensing performance of the paper-based hydrogen sensor at room temperature and 50 °C. Furthermore, the flexibility test results of the paper-based hydrogen sensor showed that the sensing performances were impervious to mechanical bending of 5.7°. [ABSTRACT FROM AUTHOR]

Highly dispersed Cobalt doped ZnS nanostructures were successfully fabricated on the surfaces of graphene sheets via a simple hydrothermal method. X-ray diffraction (XRD), X-ray photocurrent spectroscopy (XPS), Raman spectroscopy (RS), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) were utilized to analyze the structural characteristics of the cobalt doped ZnS decorated with graphene Co x Zn 1 - x S rGO nanostructures (NSs). UV-visible optical absorption (UV-vis) studies were conducted to investigate their optical properties. In laboratory studies utilizing water and visible light, the photocatalytic activity of Co x Zn 1 - x S rGO NSs at (x = 0, 1, 2, 4 and 6 atm.%) were evaluated. Graphite Oxide (GO) was successfully transformed into sheets of graphene and Co x Zn 1 - x S rGO NSs possessed a crystalline structure according to the findings of XRD, RS and FTIR analysis. SEM investigation showed graphene sheets enhanced with ZnS NSs possessed cuboidal, spheroidal form of structure and displayed a paper like appearance. UV-vis confirmed a noticeable rapid increase in transmittance along the UV wavelength area and confirmed a highly transparent NSs in the wavelength range of (180-800 nm). Calculations using density functional theory (DFT) revealed that the Co NSs have more negative conduction bands than ZnS, allowing for effective electron transfer from cobalt to ZnS and exhibiting a band gap decrease as Co content increased. The Co 0.04 Zn 0.96 S rGO NSs sample had the highest photocatalytic activity, measured at 7648.9 μ mol h - 1 . A combination of improved dispersion properties, greater surface area, increased absorption and enhanced transfer of photogenerated electrons, Co x Zn 1 - x S rGO NSs increased the photocatalytic hydrogen generation activity. [ABSTRACT FROM AUTHOR]

Catalytic hydrolysis of ammonia borane (AB) can be applied as an on-demand hydrogen production system. Low-cost and highly active catalysts towards AB hydrolysis are highly desirable for the industrial application of this technology. In this paper, we have reported the synthesis of Cu3P-Co2P nanoplatelets by a simple method and the formation process of the final products. It is revealed that Cu2O–Co(OH)2 composite nanoplatelets are obtained after hydrothermal reaction, which are transformed into Cu3P-Co2P nanoplatelets during the phosphorization process. In AB hydrolysis, the Cu3P-Co2P nanoplatelets exhibit high catalytic activity with the hydrogen generation rate of 4.03 LH2 gcat.−1 min−1, which is much higher than those for many noble-metal-free catalysts in the documents. It is discovered that AB hydrolysis follows the pseudo-first-order kinetics with respect to the catalyst dosage and pseudo-zero-order kinetics with respect to the AB amount. In view of the cheapness and high performance, the Cu3P-Co2P nanoplatelets can be a promising catalyst candidate to AB hydrolysis for hydrogen production. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries as one of the most promising technologies for energy storage applications have been attracting increasing attentions. A crucial challenge for the commercialization of lithium–sulfur batteries is the poor stability of lithium sulfide against moisture, which may lead to the release of toxic hydrogen sulfide gas. However, the risk of hydrogen sulfide releasing from lithium–sulfur batteries under the limiting conditions is still unclear. In this paper, we herein investigate the mechanism of hydrogen sulfide releasing in lithium–sulfur batteries, and evaluate the effect of battery discharging on the generation of hydrogen sulfide. The production of sulfion and hydrogen sulfide is qualitatively/qualitatively studied. According to above results, the behavior of hydrogen sulfide formation in the batteries is elucidated based on thermodynamic simulation. Furthermore, the effect of discharging of lithium–sulfur batteries on the hydrogen sulfide releasing is qualitatively calculated. These results show that the hydrogen sulfide is indeed produced from the discharging products of lithium–sulfur battery under the acid condition, the findings can also provide some guidelines or suggestions for the practical applications of lithium–sulfur battery. [ABSTRACT FROM AUTHOR]

Generally, a stand-alone flash-binary geothermal power plant loses most of its input energy, so its efficiency declines accordingly. Its overall ability can be augmentable by utilizing structural modification and waste heat recovery leading to the most suitable exergetic performance with lower costs. On this account, the current paper suggests and investigates an innovative waste heat recovery for a dual-flash binary geothermal power plant. The integrated process consists of a Rankine cycle, a reverse osmosis desalination, and a proton exchange membrane electrolyzer. Here, two main processes, i.e., waste heat-to-power and power-to-hydrogen/freshwater, are regarded. Accordingly, the applicability of the system is examined from the energy, exergy, and economic points of view. Thus, a relevant sensitivity analysis is applied to the response variables where the effect of separator 2 pressure is more significant than other parameters. In addition, a non-dominated sorting genetic algorithm-II (NSGA-II) method is implemented to optimize the system thermodynamically and economically. The optimum state reveals an exergy efficiency of 43.83% and a levelized cost of products of 4.54 $/MWh. In this situation, the net output power and production rate of freshwater and hydrogen are estimated at 6474 kW, 22.51 kg/s, and 1.84 kg/h, respectively. Graphical representation of the novel devised renewable energy-fueled trigeneration setup [ABSTRACT FROM AUTHOR]

The employment of spin polarization under an external magnetic field holds great potential for the improvements of photocatalytic performance. However, owing to the huge difference in dielectric properties between ferromagnetic oxide and polymers, the photogenerated excitons with spin states are often limited to the ferromagnetic oxide wells, which leads to unsatisfactory activity. In this paper, a single-atom Co-doped C3N4 photocatalyst is successfully synthesized for photocatalytic water splitting and simultaneous oxidation of benzylamine. Under a tiny external magnetic field (24.5 mT), the hydrogen production rate could reach at 3979.0 µmol·g−1·h−1, which is about 340 times that of C3N4. Experimental results and theoretical calculations indicate that the interaction of Co d and N p orbital changes the symmetry center of C3N4, resulting in an increase in dielectric constant and spin polarization. Moreover, magnetic fields further promote parallel electron spin, and the increased number of charges with the parallel spin-down state is likely to dissociate under the action of an external magnetic field. On the other hand, the Co-N bond provides a huge built-in electric field and active site for strengthening the charge transfer and surface reaction. This work not only deepens the understanding of spin polarization, but also enriches methods to accelerate electron-hole separation. [ABSTRACT FROM AUTHOR]

In the recent years, molybdenum disulfide (MoS2) has been widely used in various optical applications. MoS2 has decent optical band gap and can be used as photocatalyst for hydrogen production applications. In this paper, we reported the synthesis of flower-like nickel (Ni)-doped MoS2. The as-prepared Ni@MoS2 has optical band gap of 1.71 eV which was lower than that of the pristine MoS2 (1.90 eV). Thus, Ni@MoS2 was further used as photocatalyst for hydrogen evolution. The effect of different dose (5, 10, 15, 20 and 25 mg) of the photocatalyst (Ni@MoS2) was also examined. The photocatalytic investigations exhibited the generation of good hydrogen production amount (2021.5 µmol g−1) with reasonable hydrogen generation rate of 404.3 µmol g−1 h−1 using 25 mg Ni@MoS2. These findings suggested that doping may significantly improve the photocatalytic hydrogen production. The proposed Ni@MoS2 also presented good stability and reusability for hydrogen production. [ABSTRACT FROM AUTHOR]

Steam oxidation of beryllium dust, which will inevitably be formed and accumulated in the vacuum chamber of the ITER thermonuclear reactor, can occur in emergency situations associated with the water flow from the cooling system of the first wall or divertor into the vacuum chamber (LOCA-type accident). This process is accompanied by the release of free hydrogen, which creates a risk of fire or explosion when mixing with air. The safety analysis of a thermonuclear reactor should include numerical estimates of the degree of oxidation and the amount of hydrogen released. The paper presents an engineering model that allows, with a given steam content in the volume of the chamber, to determine the rate of hydrogen production during the oxidation of beryllium dust layers and the total amount of hydrogen formed during an accident. An analytical assessment of the oxidation rate of the dust layer is carried out. [ABSTRACT FROM AUTHOR]

The paper presents a fundamentally new design for a hydrogen generator. Hydrogen is released during the reaction of activated aluminum and water. Bismuth, tin, and calcium oxide were used as the activating additives. The hydrogen generator results in an Al oxidation reaction at a temperature of 100–350°C and a pressure of about 4 atm. An average hydrogen production rate of 30 mL/(s g) was achieved with a hydrogen yield of 95–99% of the theoretically possible value. In continuous generation mode, the average productivity of the hydrogen generator was ~1.5 kW (140 mL H2/s). [ABSTRACT FROM AUTHOR]

In the field of photocatalysis, the recombination of photogenerated holes and electrons is still an urgent problem to be solved. Among many measures, constructing heterojunction is one of the commonly used methods to adjust the carrier transfer path and accelerate the electron transfer. In this paper, Fe2O3/NiS p–n heterojunction composite catalyst was synthesized by solvothermal method. Through XRD, SEM and XPS characterization and analysis, it was found that the composite catalyst was composed of NiS nanoparticles and hexagonal Fe2O3 nanosheets. The specific surface area test results showed that Fe2O3/NiS had a larger specific surface area, which could provide more active sites for the H2 production reaction. By adjusting the ratio between Fe2O3 and NiS, the optimal composite photocatalyst was obtained. The hydrogen production rate reached 5.82 mmol g−1 h−1, which was 58.2× that of single Fe2O3 and 2.7× that of single NiS. The NiS p-type semiconductor and Fe2O3n-type semiconductor were successfully coupled. Under the action of the p–n heterojunction interface and the built-in electric field, the photogenerated electrons and holes of the composite catalyst could be quickly transferred and separated. This result was also confirmed by a series of characterizations such as photoluminescence spectrum and photoelectrochemical experiments. Fe2O3 and NiS formed p–n heterojunctions, and the mixed interface structure between them provided a new hydrogen-producing active center for each. Moreover, the construction of p–n heterojunction promoted the separation of electrons (e−) and holes (h+), so that Fe2O3/NiS exhibited excellent hydrogen evolution performance. [ABSTRACT FROM AUTHOR]

Catalytic CO oxidation on platinum group metals can exhibit nonlinear behaviors like catastrophe, bistability, and hysteresis, which are indicative of self-organizing processes occurring in the course of the oxidation reaction. As a result, the system demonstrates a multi-branch nonlinear input/output relationship for which the output value depends not only on the instantaneous input values, but also on the history of operations. Traditional linear control approaches may cause unstable operation in the CO oxidation reaction. In this paper, a nonlinear control strategy is proposed to solve the control problem. The control strategy incorporates a PI controller and a switching control strategy by which the control system can maintain a high regulating performance while preventing unstable operation. It may be applied to control operations in industrial processes of catalytic CO oxidation. [ABSTRACT FROM AUTHOR]

The present paper reports about the superior performance of some amine-based proton sources in enhancing the photocatalytic efficiency of Fe2O3–TiO2 composite during a water-splitting reaction. The band gap of the Fe2O3–TiO2 catalyst is tuned to 2.3 eV by varying the Fe content. The heterojunctions generated in the photocatalyst facilitate effective charge carrier migration suppressing the electron–hole recombination rate. The enhanced photocatalytic activity of the catalyst is studied using an experimental setup comprising a solar simulator (AAA) and a hydrogen gas chromatograph. The effect of proton sources viz, aniline hydrogen chloride (AH), diethylamine hydrogen chloride (DAH) and triethylamine hydrogen chloride (TAH), on the photocatalytic performance of the catalyst is explored and studied in detail. These proton sources serve as electron donors that stimulate photogenerated electron–hole separation that results in high quantum efficiency of the Fe2O3–TiO2 photocatalyst. A very high hydrogen generation rate of 880 μmol h−1 is achieved with the DAH-assisted Fe2O3–TiO2, whereas it is just 323 μmol h−1 with the Fe2O3–TiO2 alone. The enhancement in the hydrogen generation rate is attributed to the high basic nature, distinct hole scavenging action, low electron–hole recombination rate and the swift interfacial charge – transfer process. The effect of other proton source-assisted catalysts are also discussed in detail. [ABSTRACT FROM AUTHOR]

In this paper, a simple one-pot thermal synthesis method was used to successfully prepare Cu2+/biochar-doped TiO2 composite catalytic materials. The photocatalytic hydrogen production performance of the composites under different environmental conditions (dark, solar, and visible light irradiation) was analyzed in a biomass photocatalytic system using a corn straw suspension as a sacrificial agent. The Cu2+/biochar-doped TiO2 materials were characterized by SEM, TEM, XRD, FT-IR, XPS, and UV analysis. The photoelectric properties of the Cu2+/biochar-doped TiO2 composites were also analyzed, and the charge separation mechanism of photogenerated carriers under different environmental conditions was investigated. Compared with pure TiO2, the hydrogen production rate of Cu2+/biochar-doped TiO2 is 23.6 times higher under visible light irradiation and 16.8 times higher under simulated solar irradiation. Using density functional theory, a crystal structure model of Cu2+/biochar-doped TiO2 was established to analyze its energy band structure and density of states. An analysis of the mechanism shows that under simulated sunlight irradiation, the synergistic effect of the TiO2 doped with Cu2+ and biochar causes the formation of a potential Schottky heterojunction on the surface and induces interfacial charge transfer. Furthermore, under visible light irradiation, the photocatalytic production of hydrogen by the Cu2+/biochar-doped TiO2 composite is mainly due to the surface plasmon resonance mechanism of Cu ion-doped TiO2. [ABSTRACT FROM AUTHOR]

Adjusting the interlayer structure of carbon nitride is expected to adjust its physicochemical properties, thereby enhancing photocatalytic activity. In this paper, alkaline metal ion-intercalated carbon nitride was prepared by molten salt co-pyrolysis. Alkali metal ions acted as mediators to provide a new migration path for the photogenerated electrons of g-C3N4. The intercalation of K+ and Na+ reduced the bandgap value of carbon nitride, expanded the visible light absorption range, and promoted the separation and migration of charge carriers. As a result, the hydrogen production rate of DCN1 reached 500 μmol g−1 h−1, which was 10 times than that of pristine g-C3N4. Experimental and theoretical methods were used to explain the improvement of photocatalytic efficiency after K+ and Na+ were intercalated into the interlayer of g-C3N4. Our work provided a new idea for the design of high-efficiency hydrogen evolution photocatalysts via intercalation method. [ABSTRACT FROM AUTHOR]

Bioethanol is a renewable energy source carrier mainly produced from the biomass fermentation process. Reforming of bioethanol for hydrogen production is the most promising method from the renewable energy source. Production of hydrogen from ethanol reforming process is not only environmentally friendly, but also it produces greater opportunities for use of renewable energy source, which are available and affect the catalytic activity of the process. This paper reviewed the various reforming processes and associated noble and non-noble catalysts and supporting layers for the reforming process. Among that, electrochemical reforming of bioethanol is found to be cost-effective, and hydrogen production is also found to be of high purity. Hydrogen production from ethanol through various reforming processes is still in the research for better hydrogen production. Hydrogen production through the process of reforming can be widely used for fuel cell operations. [ABSTRACT FROM AUTHOR]

The saccharification of Chlorella sp. biomass by single and combined commercial carbohydrase enzymes, Termamyl SC, Dextrozyme GA, and Cellic CTec2, was investigated. A substrate concentration of 100-g volatile solids (VS)/L was optimal for all the enzymes used. The optimal enzyme dosages for Termamyl SC, Dextrozyme GA, and Cellic CTec2 were 160-units/g VS, 320-units/g VS, and 40–filter paper units/g VS, respectively. The maximum reducing sugar yield, 130-mg/g VS, was obtained with a Dextrozyme GA treatment, which is equivalent to 38.37% hydrolysis efficiency based on carbohydrate content. A combined-enzyme treatment with Cellic CTec2, Termamyl SC, and Dextrozyme GA raised the reducing sugar yield and hydrolysis efficiency to 186.69-mg/g VS and 54.85%, respectively. Scanning and transmission electron microscopic images indicated morphological alterations in Chlorella sp. cells as an effect of enzyme treatment. Enzyme treatment improved the hydrogen production, hydrogen production rate, and hydrogen yield from Chlorella sp. biomass. The maximum hydrogen yield, 42.24-mL/g VSadded, was obtained from a Dextrozyme GA–hydrolyzed microalgae biomass. This was 82.46% higher than that obtained from untreated biomass (23.15-mL H2/g VSadded). Fourier-transform infrared analysis revealed that the functional groups of Chlorella sp. biomass, especially carbohydrates, were modified by both enzymatic treatment and the hydrogen fermentation process. This work demonstrated the efficient saccharification of Chlorella sp. biomass using combined cell wall– and starch-degrading enzymes. The results also elucidate that the pretreatment of Chlorella sp. biomass by commercial glucoamylase is a promising approach to solubilize internal starch granules and promote biohydrogen production without the addition of any cell wall–degrading enzyme. [ABSTRACT FROM AUTHOR]

To achieve the construction of efficient photocatalytic H2 generation systems, developing highly active and durable earth-abundant H2 generation cocatalyst is still a challenge. In this paper, we construct a noble-metal-free Ni3P–Ni composite, which displays strong chemical stability and high-efficiency as a cocatalyst to enhance the visible-induced photocatalytic activities in H2 generation of g-C3N4. Ni3P–Ni/g-C3N4 is prepared by one-step annealing of amorphous Ni–P nanoparticles and g-C3N4. The result verifies that both Ni3P and metallic Ni worked as electron cocatalysts and significantly enhanced the visible light H2 generation over g-C3N4. The optimum composite 2.0 wt.% Ni3P–Ni/g-C3N4 exhibits a high H2 generation rate of 203.3 μmol g−1 h−1, which is 1.6, 2.7, and 53.5 times as much as those obtained on Ni3P/g-C3N4, Ni/g-C3N4, and pure g-C3N4 respectively. Photoluminescence and photoelectrochemical analysis confirm that the metallic Ni plays multifunctional roles in boosting the H2 generation under visible light, which could both accept the photo-generated electrons from g-C3N4 and enhance the electron transfer to Ni3P for further H2 generation. This investigation provides a route to the rational design and development of earth-abundant metal phosphide and metal composites, which could be utilized as noble-metal-free cocatalysts for the improvement of H2 generation activity. Spherical Ni3P–Ni particles with metallic Ni spread over the inner and outer surface of Ni3P sphere was synthesized and hybrid with g-C3N4. The specific structure of spherical Ni3P–Ni leads to adequate contact area between ternary Ni3P, Ni, and g-C3N4. Ni with high electrical conductivity could act as an electron transfer bridge between g-C3N4 and Ni3P, leading to effective charge separation and enhanced photocatalytic hydrogen generation. [ABSTRACT FROM AUTHOR]

Solar is one of the most promising energy sources because of the abundance of solar radiation in certain parts of the world. One of the main limiting factors of using traditional photovoltaic cells is that they require a lot of space to generate a significant amount of power. The alternative method, the concentrated photovoltaic (CPV) module, does not utilize the infrared part of the spectrum; thus, the concentrated photovoltaic thermal (CPVT) module was developed. In this paper, the design of a CPVT system coupling with an organic Rankine cycle (ORC) is analyzed where the CPVT thermal receiver acts as a heat exchanger in ORC to generate additional electrical power. The generated power by hybrid CPVT–ORC system is converted to hydrogen by an electrolysis system to store power. The performance of hydrogen production system using an integrated CPVT–ORC power generation system is analytically evaluated, and the results of the modeling and analyses are presented, involving assessments of the influence of varying several design parameters on the rate of hydrogen production. The CPVT and ORC together produce up to 1152 W of electricity under 160 suns solar concentration. When all the electricity is supplied to an electrolyzer, 0.1587 kg of 99.99% pure hydrogen is produced and stored for future use in a fuel cell. The electrolyzer operates at up to 57% efficiency and has an average performance of 725.5 kWh kg−1. The results revealed that coupling ORC to the CPVT enables the system to improve the electrical power generation and consequently diurnal hydrogen production increases up to 30%. [ABSTRACT FROM AUTHOR]

In this paper, the stable structure of Mo-edge of 2H-MoS2 in water and the H2 evolution mechanism at Mo-edge in 2H-Mo7S17 cluster were investigated by the B3LYP method of the density functional theory. The calculations suggested that the stable structure of the Mo-edge in gas and water was different. The Mo-edge with the upright S bonded by one Mo atom was more stable in water while the S atom of Mo-edge was bonded by two Mo atoms to generate a stable Mo-edge in gas. The adsorption energy of H on S was higher than that on Mo at Mo-edge; as a result, the hydrogen evolution reactions on S and Mo were limited by the Heyrovsky and Volmer step, respectively. In hydrogen evolution reaction, the Volmer reaction occurs on S to produce Mo7S17HS, leading to the aggregation of electron on Mo and thus decreasing the barriers for H2 evolution reaction on Mo. Subsequently, the Mo in Mo7S17HS severing as active sites efficiently catalyzed hydrogen evolution reaction through the Volmer–Heyrovsky mechanism, in which the Volmer reaction was identified as the rate-determining step with a potential barrier of 17.9 kcal/mol, being close to the experimental value of 19.9 kcal/mol. [ABSTRACT FROM AUTHOR]

Rational design and fabrication of phase junction is an important way and strategy to enhance the photocatalytic performance. In this paper, rutile/anatase phase junction is obtained in rutile nanoparticles decorated anatase thin film by laser ablation. The hydrogen generation of rutile/anatase composite film is 49.6 μL, which is remarkably higher than that of both anatase thin film and rutile decorated layer. The quantity of phase junctions between rutile and anatase is considered as a key factor of photocatalytic improvement by varying the amount of rutile nanoparticles. Moreover, the excellent photocatalytic stability of rutile/anatase composite film is also exhibited. [ABSTRACT FROM AUTHOR]

Unicellular green algae Chlamydomonas reinhardtii are known to make hydrogen photoproduction under the anaerobic condition with water molecules as the hydrogen source. Since the hydrogen photoproduction occurs for a cell to circumvent crisis of its survival, it is only temporary. It is a challenge to realize persistent hydrogen production because the cells must withstand stressful conditions to survive with alternation of generations in the cell culture. In this paper, we have found a simple and cost-effective method to sustain the hydrogen production over 14 days in the original culture, without supply of fresh cells nor exchange of the culture medium. This is achieved for the cells under hydrogen production in a sulfur-deprived culture solution on the {anaerobic, intense light} condition in a desiccator, by periodically providing a short period of the recovery time (2 h) with a small amount of TAP(+S) supplied outside of the desiccator. As this operation is repeated, the response time of transition into hydrogen production (preparation time) is shortened and the rate of hydrogen production (build up time) is increased. The optimum states of these properties favorable to the hydrogen production are attained in a few days and stably sustained for more than 10 days. Since generations are alternated during this consecutive hydrogen production experiment, it is suggested that the improved hydrogen production properties are inherited to next generations without genetic mutation. The properties are reset only when the cells are placed on the {sulfur-sufficient, aerobic, moderate light} conditions for a long time (more than 1 day at least). [ABSTRACT FROM AUTHOR]

Hierarchical Bi2Fe4O9/BiOI S-scheme nanoflower heterostructures are prepared by hydrothermal method, which exhibit exceptional photo-piezoelectric catalytic performance. The tight binding between the sheets ensures the efficient electron transport, and provides a large interface area and adequate reaction sites for photo-piezoelectric catalytic reactions. At the same time, because the water flow in the water body produces hydraulic shear force on the material, the material produces piezoelectric effect. Bi2Fe4O9/BiOI exhibit a remarkable degradation efficiency of 99.4% for tetracycline and a hydrogen production rate of 4089.36 µmol h−1 g−1. The observed behavior can be explained by the combined influence of the formation of S-scheme structure and the process of photo-piezoelectric catalysis, confirmed by in-situ XPS, transient/steady-state fluorescence and piezoelectric response force test. The excellent stability of the material suggests its possible use in the sectors of energy and environment. This work introduces novel concepts for the future advancement of photo-piezoelectric synergistic catalysis. [ABSTRACT FROM AUTHOR]

The g-C3N4 was peeled off into nanosheets structure by ultrasonic, and then combined with TiO2 nanorods, the obtained composite was subjected to secondary high-temperature calcination to obtain a photocatalyst with smaller interfacial spacing, high photoelectron transfer rate and high photocatalytic performance. The structure was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Raman spectrometry, Fourier transform infrared (FTIR) spectroscopy. It was found that g-C3N4 in the form of nanosheets was uniformly attached to the surface of TiO2 nanorods. UV–Vis diffuse reflection spectra (UV–Vis) and Photoluminescence (PL) spectra were obtained to confirm that full coverage of the ultraviolet region to the visible region was achieved and the recombination of photogenerated electron–hole pairs was effectively inhibited. Degradation experiments and hydrogen evolution experiments showed that the composites photocatalytic properties were enhanced. The degradation rate of rhodamine B (RhB) at 35 min is achieved 98.5%, hydrogen production rate as high as 150 umol/g/h. The catalyst has very good photocatalytic stability. The research in this paper has an important impact on the photocatalytic preparation of hydrogen. [ABSTRACT FROM AUTHOR]

In this paper, we describe the main processes occurring during the generation of vacancies in aluminum in the presence of hydrogen by ab initio methods using the SCAN functional. Hydrogen is shown to reduce the generation energy of vacancies from 2.8 to 0.8 eV. In this case, the eight hydrogen atoms located in the tetrahedral lattice voids around single aluminum atom greatly facilitate its movement to the interstitial site. The dependence of the activation energy of hydrogen embrittlement of aluminum on the hydrogen concentration in aluminum and temperature is calculated based on the kinetic strength concept. Hydrogen is shown to reduce the time of aluminum destruction only if its mole fraction in aluminum is greater than the critical level (~ 3 × 10–4 at T = 293 K). [ABSTRACT FROM AUTHOR]

The blade is a crucial component in an aero engine. In electrochemical machining of blades, the shaping law of the leading/trailing edge is intricate because of the complexity of the flow field and electric field distributions at these locations. This paper researches the formation of the leading/trailing edge. The dissolution process of the leading/trailing edge is simulated using an initial cathode and then its forecasted profile is obtained. The cathode is then adjusted according to the deviations between the forecasted profile and the model. Meanwhile, a coefficient between the deviations and the corrected value of the cathode is obtained after optimization simulation and the optimal value is about 1.17. Then, an optimal cathode is acquired by using the optimal coefficient. In addition, the effects of the thermal and hydrogen generation are also considered. The temperature increases to 8.28 K and the bubble rate increases to 25.30% at the electrolyte outlet. Furthermore, verification experiments are performed with the optimal cathode. The results show that the margin edges are formed and the accuracy is 0.13 mm of the leading edge, while the allowance of the profile at the electrolyte outlet is larger than that at the inlet, which means that the bubble rate is dominant in the inter-electrode gap. The results indicate that the design method for the leading/trailing edge is appropriate and can be used for manufacturing other complex components such as blisks and diffusers. [ABSTRACT FROM AUTHOR]

This paper is a contribution to the development of microwave plasma-based technology for hydrogen (H2) production from a so-called synthetic biogas, considered as a mixture of methane (CH4) and carbon dioxide (CO2). The efficiency of hydrogen production via reforming of CH4 in the synthetic biogas flowing through a waveguide-supplied metal cylinder-based microwave plasma source (MPS) operating at atmospheric pressure was tested experimentally. The MPS operated at a frequency of 915 MHz. The working plasma-forming gas was a mixture of CH4:CO2 of volume ratios from 0 to 1. Its flow rate was varied from 3 to 12 m3/h. The microwave power absorbed by the plasma was up to 7.5 kW. The experiment showed that using this kind of MPS, the plasma processing of the synthetic biogas can be run stably at high flow rates (up to 12 m3/h). The optimal CH4:CO2 ratio in terms of high energy efficiency of the microwave plasma reforming of CH4 was found to be 40:60. The maximum achieved hydrogen production rate was 156 g(H2)/h at a microwave absorbed power of 7.5 kW (at a flow rate of 6 m3/h) with the energy efficiency of hydrogen production of 21 g(H2)/kWh. The maximum energy yield of hydrogen production of 24 g(H2)/kWh was achieved at 4.5 kW of the microwave absorbed power (the hydrogen production rate was 108 g(H2)/h in this condition). The maximum methane conversion degree and maximum hydrogen selectivity were 86.5% and 73.3%, respectively at an absorbed microwave power of 6.5 kW (at 3 m3/h). [ABSTRACT FROM AUTHOR]

Highlights: This review systematically summarizes the source of electricity, the key choice of catalyst, and the potentiality of electrolyte for prospective hydrogen generation. Each section provides comprehensive overview, detailed comparison and obvious advantages in these system configurations. The problems of hydrogen generation from electrolytic water splitting and directions of next-generation green hydrogen in the future are discussed and outlooked. Green hydrogen from electrolysis of water has attracted widespread attention as a renewable power source. Among several hydrogen production methods, it has become the most promising technology. However, there is no large-scale renewable hydrogen production system currently that can compete with conventional fossil fuel hydrogen production. Renewable energy electrocatalytic water splitting is an ideal production technology with environmental cleanliness protection and good hydrogen purity, which meet the requirements of future development. This review summarizes and introduces the current status of hydrogen production by water splitting from three aspects: electricity, catalyst and electrolyte. In particular, the present situation and the latest progress of the key sources of power, catalytic materials and electrolyzers for electrocatalytic water splitting are introduced. Finally, the problems of hydrogen generation from electrolytic water splitting and directions of next-generation green hydrogen in the future are discussed and outlooked. It is expected that this review will have an important impact on the field of hydrogen production from water. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) water splitting is a promising approach for sustainable hydrogen production. Previous studies have focused on devices operated at atmospheric pressure, although most applications require hydrogen delivered at elevated pressure. Here, we address this critical gap by investigating the implications of operating PEC water splitting directly at elevated pressure. We evaluate the benefits and penalties associated with elevated pressure operation by developing a multiphysics model that incorporates empirical data and direct experimental observations. Our analysis reveals that the operating pressure influences bubble characteristics, product gas crossover, bubble-induced optical losses, and concentration overpotential, which are crucial for the overall device performance. We identify an optimum pressure range of 6–8 bar for minimizing losses and achieving efficient PEC water splitting. This finding provides valuable insights for the design and practical implementation of PEC water splitting devices, and the approach can be extended to other gas-producing (photo)electrochemical systems. Overall, our study demonstrates the importance of elevated pressure in PEC water splitting, enhancing the efficiency and applicability of green hydrogen generation. Solar water splitting devices, though often demonstrated at atmospheric pressure, need to deliver H2 at high pressure for many applications. Here the authors use multiphysics model to evaluate the benefits and penalties of elevated pressure operation, identifying the optimum pressure range to enhance efficiency. [ABSTRACT FROM AUTHOR]

The on-site hydrogen supply is a key issue for the commercialization of the fuel cells, which is one of the important ways for realizing a hydrogen-economy society. Composite NaNH2–NaBH4 is regarded as a promising high-capacity hydrogen storage material. In this paper, the composite NaNH2–NaBH4 (2/1) was synthesized via a solid-state ball milling method. To improve the hydrogen generation kinetics, a multiplex metal boride Mg–Co–B was selected as the catalyst. It was found that Na3BN2 and metal Na were byproducts in the thermal decomposed sample by X-ray diffraction analysis. Thermogravimetry and differential thermal analysis indicated that the main decomposition stages of the catalyst promoted NaNH2–NaBH4 material were split into three stages. The activation energy of the Mg–Co–B promoted NaNH2–NaBH4 (2/1) material below 300 °C was 76.4 KJ/mol, which is only 47.9% of that of the pristine NaNH2–NaBH4 (2/1), and implying much better hydrogen generation kinetics. [ABSTRACT FROM PUBLISHER]

Highlights: This review systematically summarizes the source of electricity, the key choice of catalyst, and the potentiality of electrolyte for prospective hydrogen generation. Each section provides comprehensive overview, detailed comparison and obvious advantages in these system configurations. The problems of hydrogen generation from electrolytic water splitting and directions of next-generation green hydrogen in the future are discussed and outlooked. Direct regeneration method has been widely concerned by researchers in the field of battery recycling because of its advantages of in situ regeneration, short process and less pollutant emission. In this review, we firstly analyze the primary causes for the failure of three representative battery cathodes (lithium iron phosphate, layered lithium transition metal oxide and lithium cobalt oxide), targeting at illustrating their underlying regeneration mechanism and applicability. Efficient stripping of material from the collector to obtain pure cathode material has become a first challenge in recycling, for which we report several pretreatment methods currently available for subsequent regeneration processes. We review and discuss emphatically the research progress of five direct regeneration methods, including solid-state sintering, hydrothermal, eutectic molten salt, electrochemical and chemical lithiation methods. Finally, the application of direct regeneration technology in production practice is introduced, the problems exposed at the early stage of the industrialization of direct regeneration technology are revealed, and the prospect of future large-scale commercial production is proposed. It is hoped that this review will give readers a comprehensive and basic understanding of direct regeneration methods for used lithium-ion batteries and promote the industrial application of direct regeneration technology. [ABSTRACT FROM AUTHOR]

Geothermal energy is an abundant natural resource in many regions around the world. However, in some areas, the temperature of the geothermal energy resource is too low to be efficiently harvested. Organic Rankine cycles (ORCs) are known for recovering heat from low-temperature resources and generating electricity. Furthermore, half-effect absorption chillers (HEACs) are designed to produce cooling with low-temperature resources. This study proposes a novel configuration that utilizes an ORC for electricity generation, a HEAC for cooling production, and a PEM electrolysis system to produce hydrogen. The power section consists of two turbines, one driven by the vapor produced from the geothermal flow expansion, which powers the PEM section, while the other turbine in the ORC is used to drive pumps and electricity production. First, the system is thermoeconomically analyzed for an initial set of inputs. Then, various parameters are analyzed to determine their influences on system performance. The analyses reveal that the system can work with geothermal source temperatures as low as 80 °C, but the exergy and energy (thermal) efficiencies decrease to around 17% under the base settings. Furthermore, the system is capable of working with resource temperatures up to 170 °C. Ten parameters are found to affect the system's efficiency and effectiveness. To optimize the system, the Non-dominated Sorting Genetic Algorithm II (NSGA-II) is implemented to find the optimum conditions. The objective functions are exergy efficiency and unit polygeneration cost (UPGC), which can conflict. The optimization shows that the exergy efficiency of the system can reach 48% in the optimal conditions (for a heat source temperature of 112 °C and a mass flow rate of geothermal fluid of 44 kg/s), with a hydrogen production rate of 1.1 kg/h. [ABSTRACT FROM AUTHOR]

Herein, a novel Pt anchoring WO3 nanoarray catalyst is reported and its application as HzOR and HER bifunctional electrocatalysts which shown to have superior bifunctional performance for HzOR/HER under alkaline conditions. The Pt/WO3/NF requires an ultrasmall overpotential of 34.6 and 226.38 mV to achieve 10 and 100 mA cm−2 for the hydrazine oxidation reaction (HzOR), respectively. When used for HER-HzOR electrolysis, Pt/WO3/NF requires low voltages of 0.717 V and 1.049 V at 100 and 200 mA cm−2, respectively. [ABSTRACT FROM AUTHOR]

Recent advancements in membrane-assisted seawater electrolysis powered by renewable energy offer a sustainable path to green hydrogen production. However, its large-scale implementation faces challenges due to slow power-to-hydrogen (P2H) conversion rates. Here we report a modular forward osmosis-water splitting (FOWS) system that integrates a thin-film composite FO membrane for water extraction with alkaline water electrolysis (AWE), denoted as FOWSAWE. This system generates high-purity hydrogen directly from wastewater at a rate of 448 Nm3 day−1 m−2 of membrane area, over 14 times faster than the state-of-the-art practice, with specific energy consumption as low as 3.96 kWh Nm−3. The rapid hydrogen production rate results from the utilisation of 1 M potassium hydroxide as a draw solution to extract water from wastewater, and as the electrolyte of AWE to split water and produce hydrogen. The current system enables this through the use of a potassium hydroxide-tolerant and hydrophilic FO membrane. The established water-hydrogen balance model can be applied to design modular FO and AWE units to meet demands at various scales, from households to cities, and from different water sources. The FOWSAWE system is a sustainable and an economical approach for producing hydrogen at a record-high rate directly from wastewater, marking a significant leap in P2H practice. Green hydrogen production faces increased water risks due to scarce supplies of water. Here, authors develop a modular forward osmosis-water splitting system that utilises wastewater effluent to generate high-purity hydrogen, providing a sustainable solution for water and energy security. [ABSTRACT FROM AUTHOR]

Water splitting using solar light and an efficient photocatalyst is one of the new methods of hydrogen production that has attracted much attention today because of its importance in the energy crisis. Hence, a composite material containing molybdenum disulfide (MoS2) and g-C3N4 was synthesized and used in the photocatalytic process. For this purpose, in the first instance, the photocatalytic activity of MoS2/g-C3N4 was confirmed by the decolorization pathway of Rhodamine B (Rh B) under visible light irradiation. Then, MoS2/g-C3N4 was carefully identified by SEM, XRD, PL, UV–Vis, EDS, and FT-IR analysis. Results of characteristic peaks and composite surface morphology confirm that the structural integrity of the primary photocatalyst sample was intact after combination with MoS2 despite chemical interactions. The Brunner–Emmet–Teller (BET) surface area, total per valume, and average pore diameter of the sample are close to 15 m2g−1, 0.07 cm3g−1, and 19.5 nm, respectively. Then, the hydrogen production process under solar light was simulated using MoS2/g-C3N4 photocatalyst and the Production rate was measured using a gas chromatography system (GC). In addition, the Eosin-Y dye solution is also used as a sensitizer to increase the photocatalyst activity under visible light. The g-C3N4/MoS2-Triethanolamine (TEOA) mixture showed the best quantum efficiency when compared to all other sacrificial agents. Investigation of the factors affecting the catalyst activity showed that the parameters of exposure time, the concentration of photocatalyst, and triethanolamine (TEOA) percent used as a sacrificial agent affect water-splitting reaction efficiency. Further measurements showed that the highest hydrogen production rate of 1905 µmol g−1 h−1 is accessible. Accordingly, the g-C3N4 composite with MoS2 can be a promising photocatalyst for high-efficiency water splitting. Besides, the photocatalytic mechanism is demonstrated to well-fit into the S-scheme pathway with apparent evidence. [ABSTRACT FROM AUTHOR]

With the increasing scarcity of resources, the search for green and available energy has become an urgent need. Among them, photocatalytic decomposition of water to hydrogen production has been widely studied. According to zeta potential and XRD characterization, NiCo2O4 and CuS were successfully reassembled by electrostatic self-assembly to construct S-scheme heterojunction induced by built-in electric site, which can accelerate the reaction. At the same time, under simulated visible light irradiation, the composite catalyst can rapidly decompose aqueous triethanolamine solution to produce hydrogen. The composite catalyst has high photocatalytic activity and shows a durable and efficient hydrogen generation effect. By studying the photogenerated carrier separation and transfer of the catalyst, the results show that the composite catalyst can accelerate the photogenerated carrier separation and transfer, so that it can participate in the photocatalytic reaction faster. It provides various insights into the construction of different heterojunctions in binary composite catalysts. [ABSTRACT FROM AUTHOR]

Bismuth vanadate (BiVO) is a promising candidate material for photocatalytic hydrogen generation and photocatalytic degradation of organics. BiVO has four phases in nature: tetragonal-1, tetragonal-2, orthogonal and monoclinic. In this paper, first-principle calculations were performed to investigate their structural stability, band structures and optical properties. It is illustrated that the stable phase is pressure-dependent and the most stable ones are T-1 (under 0 GPa), T-2 (under 2 GPa) and M phase (under 4, 6 and 8 GPa). BiVO in all cases are indirect band-gap semiconductors and the band gaps decrease with increasing pressure. Moreover, the external pressure might enhance hybridization of O 2p, V 3d and Bi 6s orbitals, and shift the band edges to lower energies. As a result, the optical curves, such as, dielectric function, optical reflectivity, absorption coefficient and refractive index, red shift with pressure in the low energy region, and BiVO in T-2 and M phases has almost the same optical properties in spite of different lattice structures. So the optical properties of BiVO could be tuned by changing pressure to some degree, which is beneficial to the optical applications. [ABSTRACT FROM AUTHOR]

This paper is mainly concerned with the investigation of steady, three-dimensional flow of H2O/NaC6H9O7 base fluids with Fe3O4/Al2O3 nanoparticles past a Riga plate implanted in a non-Darcian porous medium with internal heat generation/absorption effects. Water (H2O) and Sodium Alginate (NaC6H9O7) are the base fluids, whereas Magnetite (Fe3O4) and Aluminium oxide (Al2O3) happens to be the nanoparticles. The numerical plan for non-Newtonian fluid Sodium Alginate is isolated through the Casson model. Suitable transformations on governing equations yield strong non-linear differential equations. The non-linearity of the basic equations and additional mathematical difficulties led to use numerical method. Plots for the outcomes of various related variables are furnished. The local skin friction coefficient and the local Nusselt number have been expounded. The results end up to signify that the local skin friction coefficient and the local Nusselt number are diminished for larger values of porosity parameter and the local inertia coefficient. [ABSTRACT FROM AUTHOR]

The hydrolysis of ammonia borane is secure and promising for producing and employing hydrogen in mild conditions. Synthesis of bimetallic catalysts is an efficient way to boost the hydrogen generation rate. The regulation and control of synergistic effect is a key role for rational design of bimetallic catalysts with high performance. Herein, the bimetallic CoCu catalysts were prepared using co-reduction and sequential reduction methods, respectively, to control the ratio and distribution of Co and Cu. The as-prepared catalysts exhibited excellent catalytic performance due to the synergistic effect between Co and Cu, and the appropriate ratio of Co and Cu was studied. The distribution of Co and Cu in catalysts have the significant influence on the catalytic performance in AB hydrolysis. The stronger interaction between Co and Cu in Co1Cu1/g–C3N4, in which Cu is in intimate contact with Co, optimized the electronic structure of catalyst surface and facilitated the reaction process. Therefore, the hydrogen generation rate over Co1Cu1/g–C3N4 was much higher than that over the catalysts prepared by the sequential reduction method. This work provides a fundament understanding of the structure–activity relationships of catalysts, and the essential insights into the preparation of catalysts for hydrogen generation. [ABSTRACT FROM AUTHOR]

Silver bismuth sulphide is a ternary material that has attracted attention due to its good properties and several applications. Here, the detailed methods of synthesizing silver bismuth sulphide including successive ionic layer and reaction, Bridgman, microwave, mechanical milling, pyrolysis, deposition, sol–gel and chemical methods are discussed. To understand the properties of the silver bismuth sulphide, characterization tools are required, some of these tools are highlighted. Its photocatalytic, sensing, photovoltaic, photothermal, hydrogen generation, usage in the treatment of cancer and other medical applications are also comprehensively reviewed. Lastly, future perspectives on the synthesis and applications of silver bismuth sulphide are suggested. [ABSTRACT FROM AUTHOR]

Plasmonic systems convert light into electrical charges and heat, mediating catalytic transformations. However, there is ongoing controversy regarding the involvement of hot carriers in the catalytic process. In this study, we demonstrate the direct utilisation of plasmon hot electrons in the hydrogen evolution reaction with visible light. We intentionally assemble a plasmonic nanohybrid system comprising NiO/Au/[Co(1,10-Phenanthrolin-5-amine)2(H2O)2], which is unstable at water thermolysis temperatures. This assembly limits the plasmon thermal contribution while ensuring that hot carriers are the primary contributors to the catalytic process. By combining photoelectrocatalysis with advanced in situ spectroscopies, we can substantiate a reaction mechanism in which plasmon-induced hot electrons play a crucial role. These plasmonic hot electrons are directed into phenanthroline ligands, facilitating the rapid, concerted proton-electron transfer steps essential for hydrogen generation. The catalytic response to light modulation aligns with the distinctive profile of a hot carrier-mediated process, featuring a positive, though non-essential, heat contribution. Direct participation of plasmon-induced hot electrons in the photoelectrocatalytic synthesis of hydrogen. This report solves a long-lasting contentious issue surrounding plasmonic materials on catalytic applications. [ABSTRACT FROM AUTHOR]

Hydrogen as a new energy source, it can be made by photocatalytic technology. However, the photocatalyst is the key to the efficient decomposition of water to produce hydrogen. Functional complexes are porous materials with high crystallinity, which have the characteristics of both organic and inorganic materials. For this reason, two complexes [Mn3(Medpq)2(CIN)6]·H2O (1) and [Cd3(Medpq)2(CIN)2(Ac)4] (2) (HCIN = cinnamic acid, Medpq = 2-methyldipyrido[3,2-f:2′,3′-h]quinoxaline) were synthesized by a hydrothermal process. Combined with the unique electronic structure and group of the complex and the unique semiconductor energy band structure and excellent chemical stability of g-C3N4, the complex/g-C3N4 composite materials were constructed to solve the defect of low utilization rate of light energy and improve quantum efficiency in the internal structure. The experiment proved that complex 1/g-C3N4 photocatalytic rates of hydrogen production 715.8 μmol h−1 g−1, and complex 2 photocatalytic rates of hydrogen production 1622.9 μmol h−1 g−1, about double and fourfold that of pure g-C3N4 (407.6 μmol h−1 g−1) consequently, high-performance of the hydrogen production from water decomposition was realized. The two functional complexes [Mn3(Medpq)2(CIN)6]·H2O (1) and [Cd3(Medpq)2(CIN)2(Ac)4] (2) have the characteristics of both organic and inorganic materials and significantly enhance visible-light photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

The rising adverse effects of climate change call for a rapid shift to low-carbon energy and reducing our dependence on fossil fuels. For that, biorefineries appear as promising alternatives to produce energy, chemicals, and fuels using biomass and waste as raw materials. Here, we review catalytic aqueous-phase reforming to convert biomass and organic waste carbohydrates into renewable hydrogen, with focus on reforming basics; catalyst design; reforming of model compounds, wastewater and biomass; economics and life cycle assessment. We found that platinum and palladium are technically highly effective, yet their high price may limit upscaling. Alternatively, addition of tin to nickel gives acceptable results and improves hydrogen selectivity from 35 to 90%. We observed that hydrogen production decreases from 14% for crude glycerol to 2% for pure glycerol, thus highlighting the need to do experiments with real wastewater. The rare experiments on real wastewater from brewery, juice, tuna, and cheese industries have given hydrogen production rates of up to 149.7 mg/L. Aqueous-phase reforming could be shortly competitive with prices around 3–6 USD per kg of hydrogen, which are nearing the current market prices of 2–3 USD per kg. [ABSTRACT FROM AUTHOR]

We here report the synthesis, characterization, and catalytic performance of new supported Pd(0) catalysts. The catalysts were characterized by SEM, TEM, XRD, FT-IR, VSM, XPS, TG and AAS. The results showed that the catalyst exhibited good catalytic activity in the reaction of degradation of 4-NP and organic dyes MO and MB in water with NaBH4 and amino borane (AB) as the hydrogen sources. At the same time, the catalyst has good recoverability and is easily recovered and recycled from the reaction mixture by applying an external magnet and reusing it in five cycles without significant loss in activity. In the present work, our deliberately designed experiments demonstrate that Ni@Pd immobilized on the surface of hollow Fe3O4@PPy-Gly (HFPG) under mild condition. It exhibits high activity for the reduction of 4-NP and organic dyes by NaBH4 and AB. [ABSTRACT FROM AUTHOR]

This paper demonstrates the benefit of using spinel (ZnAlO) as a support for copper catalysts in hydrogen generation. We have investigated the influence of catalyst pre-treatment, support composition and copper content on the physicochemical and catalytic properties of copper catalysts supported on ZnAlO in the methanol steam reforming. The physicochemical properties of the catalysts were examined by X-ray diffraction, temperature-programmed reduction, specific surface area and porosity, X-ray photoelectron spectroscopy, FTIR and chemisorption methods. The reduced copper catalysts showed higher conversion of methanol and higher hydrogen production. We also found that the presence of Cu and Cu species on the catalyst surface strongly influences the reaction yield and hydrogen production. FTIR measurements performed for copper catalysts confirmed that increasing of aluminium content in the case of catalytic systems caused the growth of adsorbed species on the catalyst surface. [ABSTRACT FROM AUTHOR]

Bacterial sulfate reduction (BSR) is one of the key factors leading to the anomalous accumulation of hydrogen sulphide in coal mines. Environmental factors such as temperature and pH play a crucial role in the metabolism and degradation of coal by sulfate-reducing bacteria (SRB). In this study, coal samples were selected from Shengli Coal Mine, and SRB strains were isolated and purified from mine water using a dilution spread-plate anaerobic cultivation method. Based on single-factor experiments and response surface methodology (RSM), the impact of temperature, pH, oxidation–reduction potential (ORP), chemical oxygen demand to sulfate ratio (COD/SO42−) on the generation of hydrogen sulphide during brown coal BSR was analyzed. The results showed that the anaerobic degradation of coal by SRB was inhibited by either too high or too low a temperature to produce hydrogen sulfide, and the greatest production of hydrogen sulfide occurred at a temperature of about 30 °C; The greatest production of hydrogen sulfide occurred at an initial ambient pH of 7.5; COD/SO42− ratio of around 2.0 is most conducive to hydrogen sulphide generation; the lower ORP value is more favorable for hydrogen sulfide generation. The optimal conditions obtained by RSM were: temperature of 30.37 °C, pH of 7.64 and COD/SO42− of 1.96. Under these conditions, the hydrogen sulfide concentration was 56.79 mg/L, the pH value was 8.40, the ORP value was −274 mV, and the SO42− utilization rate was 58.04%. The RSM results showed that temperature, ambient pH and COD/SO42− had a significant effect on hydrogen sulfide production, and the degree of effect was: ambient pH > temperature > COD/SO42−. [ABSTRACT FROM AUTHOR]

Hydrides of magnesium composites with additives of intermetallic TiFe and suboxide Ti3Fe3O were synthesized by mechanical milling in a hydrogen atmosphere. The addition of graphite reduces the particle size of the composites. The influence of catalytic additives and graphite on the hydrolysis of magnesium hydride was studied. The dependence of the amount of hydrogen obtained by hydrolysis on the time of composite milling was found. [ABSTRACT FROM AUTHOR]

The electrochemical kinetics of matrix precipitates -metastable MgZn2 (ɳ′) and GP II zones towards environmentally assisted cracking (EAC) have been investigated using cathodic polarization tests and slow strain rate tests. Retrogression and re-aging treatment (RRA) and modified interrupted aging treatment (MA3) are employed to produce high fractions of ɳ′ and GP II zones respectively. The higher ɳ′ fraction resulted in a three times higher hydrogen evolution on the alloy, thus decreasing the elongation values in the cathodically charged and uncharged 3.5 wt pct NaCl solution. Furthermore, the gauge surface of the ɳ′ dominated alloy showed pitting along the grain boundaries in 3.5 wt pct NaCl solution and a high amount of sub grain formation when tested in cathodically charged solution. On the other hand, long transgranular cracks were observed in the case of the alloy dominated with GP II zones, suggesting that the higher coherency of GP II zones promoted the formation of planar slip events. To correlate the effect of hydrogen on dislocation generation, dislocation densities were calculated using XRD peak broadening methodology. It suggested that the cathodic charging resulted in a 1.5 times higher dislocation density for the alloy with a higher volume fraction of GP II zones. Such a variation caused a higher drop in tensile strength for the case of the alloy having higher GP II zones in the cathodically charged condition. [ABSTRACT FROM AUTHOR]

Highlights: The process of machine learning is introduced in detail. Recent developments in machine learning for low-dimensional electrocatalysts are briefly reviewed. Future directions and perspectives for machine learning in hydrogen evolution reaction are critically discussed. Efficient electrocatalysts are crucial for hydrogen generation from electrolyzing water. Nevertheless, the conventional "trial and error" method for producing advanced electrocatalysts is not only cost-ineffective but also time-consuming and labor-intensive. Fortunately, the advancement of machine learning brings new opportunities for electrocatalysts discovery and design. By analyzing experimental and theoretical data, machine learning can effectively predict their hydrogen evolution reaction (HER) performance. This review summarizes recent developments in machine learning for low-dimensional electrocatalysts, including zero-dimension nanoparticles and nanoclusters, one-dimensional nanotubes and nanowires, two-dimensional nanosheets, as well as other electrocatalysts. In particular, the effects of descriptors and algorithms on screening low-dimensional electrocatalysts and investigating their HER performance are highlighted. Finally, the future directions and perspectives for machine learning in electrocatalysis are discussed, emphasizing the potential for machine learning to accelerate electrocatalyst discovery, optimize their performance, and provide new insights into electrocatalytic mechanisms. Overall, this work offers an in-depth understanding of the current state of machine learning in electrocatalysis and its potential for future research. [ABSTRACT FROM AUTHOR]