Highly mass activity electrocatalysts with ultralow Pt loading on carbon black for hydrogen evolution reaction

Pt-based nanocatalysts offer excellent prospects for various industries.However,the low loading of Pt with excellent performance for efficient and stable nanocatalysts still presents a considerable challenge.In this study,nanocatalysts with ultralow Pt content,excellent performance,and carbon black as support were prepared through in-situ synthesis.These~2-nm particles uniformly and stably dispersed on carbon black because of the strong s-p-d orbital hybridizations between carbon black and Pt,which suppressed the agglomeration of Pt ions.This unique structure is beneficial for the hydrogen evolution reaction.The catalysts exhibited remarkable catalytic activity for hydrogen evolution reaction,exhibiting a potential of 100 mV at 100 mA·cm^(-2),which is comparable to those of commercial Pt/C catalysts.Mass activity(1.61 A/mg)was four times that of a commercial Pt/C catalyst(0.37 A/mg).The ultralow Pt loading(6.84wt%)paves the way for the development of next-generation electrocatalysts.

Study on the hydrogen absorption properties of a YGdTbDyHo rare-earth high-entropy alloy

This study investigated the microstructure and hydrogen absorption properties of a rare-earth high-entropy alloy(HEA),YGdTbDyHo.Results indicated that the YGdTbDyHo alloy had a microstructure of equiaxed grains,with the alloy elements distributed homogeneously.Upon hydrogen absorption,the phase structure of the HEA changed from a solid solution with an hexagonal-close-packed(HCP)structure to a high-entropy hydride with an faced-centered-cubic(FCC)structure without any secondary phase precipitated.The alloy demonstrated a maximum hydrogen storage capacity of 2.33 H/M(hydrogen atom/metal atom)at 723 K,with an enthalpy change(ΔH)of-141.09 kJ·mol^(-1)and an entropy change(ΔS)of-119.14 J·mol^(-1)·K^(-1).The kinetic mechanism of hydrogen absorption was hydride nucleation and growth,with an apparent activation energy(E_(a))of 20.90 kJ·mol^(-1).Without any activation,the YGdTbDyHo alloy could absorb hydrogen quickly(180 s at 923 K)with nearly no incubation period observed.The reason for the obtained value of 2.33 H/M was that the hydrogen atoms occupied both tetrahedral and octahedral interstices.These results demonstrate the potential application of HEAs as a high-capacity hydrogen storage material with a large H/M ratio,which can be used in the deuterium storage field.

Hydrogen sulfide reduces oxidative stress in Huntington's disease via Nrf2

The pathophysiology of Huntington's disease involves high levels of the neurotoxin quinolinic acid. Quinolinic acid accumulation results in oxidative stress, which leads to neurotoxicity. However, the molecular and cellular mechanisms by which quinolinic acid contributes to Huntington's disease pathology remain unknown. In this study, we established in vitro and in vivo models of Huntington's disease by administering quinolinic acid to the PC12 neuronal cell line and the striatum of mice, respectively. We observed a decrease in the levels of hydrogen sulfide in both PC12 cells and mouse serum, which was accompanied by down-regulation of cystathionine β-synthase, an enzyme responsible for hydrogen sulfide production. However, treatment with NaHS(a hydrogen sulfide donor) increased hydrogen sulfide levels in the neurons and in mouse serum, as well as cystathionine β-synthase expression in the neurons and the mouse striatum, while also improving oxidative imbalance and mitochondrial dysfunction in PC12 cells and the mouse striatum. These beneficial effects correlated with upregulation of nuclear factor erythroid 2-related factor 2 expression. Finally, treatment with the nuclear factor erythroid 2-related factor 2inhibitor ML385 reversed the beneficial impact of exogenous hydrogen sulfide on quinolinic acid-induced oxidative stress. Taken together, our findings show that hydrogen sulfide reduces oxidative stress in Huntington's disease by activating nuclear factor erythroid 2-related factor 2,suggesting that hydrogen sulfide is a novel neuroprotective drug candidate for treating patients with Huntington's disease.

Effects of Phosphate Adsorption on Adsorption-Desorption and Availability of Cu and Zn Ions in Ultisols and Alfisols

Surface charge, secondary adsorption- desorption and form distribution of Cu2+ and Zn2+ in Ultisols and Alfisols having adsorbed phosphate were studied by potentiometric titration, adsorption equilibrium and sequential extraction method, respectively. The soil surface negative charges increased whereas the amount of positive charges decreased with increase of P adsorbed. The soil secondary adsorption capacity for Cu2+ and Zn2+ was positively significantly correlated with the amount of P adsorbed by the soils, which could be described by the Langmuir equation. The amounts of Cu2+ and Zn2+ desorption from soils were decreased after P adsorption by the soils and the relationship between them was linear. After the soils adsorbed P, form distribution of Cu2+ and Zn2+ in soils changed remarforbly.

Interaction Between Charge Characteristics and Cu^(2+) Adsorption-Desorption of Soils with Variable or Permanent Charge

Charge characteristics and Cu2+ adsorption-desorption of soils with variable charge (latosol) and permanent charge (brown soil) and the relationship between them were studied by means of back-titration and adsorption equilibrium respectively. The amount of variable negative charge was much less in variable-charge soil than in permanent-charge soil and increased with the pH in the system, but the opposite trend occurred in the points of zero charge (PZCs). The amount of Cu2+ ions sorbed by permanent-charge soil was more than that by variable-charge soil and increased with the increase of Cu2+ concentration within a certain range in the equilibrium solution. The amount of Cu2+ ions desorbed with KC1 from permanent-charge soil was more than that from variable-charge soil, but the amount of Cu2+ ions desorbed with de-ionized water from permanent-charge soil was extremely low whereas there was still a certain amount of desorption from variable-charge soil. The increase of PZC of soils with variable or permanent charge varied with the increment of Cu2+ ions added. When the same amount of Cu2+ ions was added, the increments of PZC and variable negative surface charge of permanent-charge soil were different from those of variable-charge soil.

An Experimental Study on the Conductivity Changes in Coal during Methane Adsorption-Desorption and their Influencing Factors

During the processes of methane adsorption and desorption,the internal structure of coal changes,accordingly leading to changes in electrical conductivity.In this paper,using low rank coal seams of the Yan'an Formation in the Dafbsi field as the research subject,the relationship between coal resistivity,methane adsorption quantity,and equilibrium pressure is analyzed through proximate analysis,mercury injection tests,low temperature liquid nitrogen adsorption tests,and coal resistivity measurements during methane adsorption and desorption.The results show that during the process of pressure rise and methane adsorption,the conductivity of coal increases,resulting from heat release from methane adsorption,coal matrix swelling and adsorbed water molecules replaced by methane,but the resistivity reduction gradually decreases.The relationship between coal resistivity and methane adsorption quantity and equilibrium pressure can be described by a quadratic function.During the processes of depressurization and desorption,the resistivity of coal rebounds slightly,due to decalescence of methane desorption,coal matrix shrinkage and water-gas displacement,and the relationship coincides with a linear function.Methane adsorption leads to irreversible changes in coal internal structure and enhances the coal conductivity,and resistivity can not be restored to the initial level even after methane desorption.The resistivity and reduction rate of durain are higher than those of vitrain,with relatively greater homogeneous pore throat structure and fewer charged particles in the double electric layer.In addition,moisture can enhance the conductivity of coal and makes it change more complexly during methane adsorption and desorption.

Adsorption-Desorption Characteristics of Chlorimuron-Ethyl in Soils

The adsorption-desorption characteristics of chlorimuron-ethyl in soils were investigated to provide the basic data for evaluating the safety in field and the risk to water resource. The adsorption-desorption experiment was conducted by the batch equilibration and HPLC techniques; furthermore, data were analyzed with 5 mathematic models to describe the characteristics and mechanism of adsorption-desorption and translocation of the herbicide in soils. The results showed that the adsorption-desorption isotherms of chlorimuron-ethyl fitted for the Freundlich model well, and the physical reaction presents the main contribution during the adsorption-desorption process. The adsorption values （Kads-f） of chlorimuron-ethyl in 8 types of soil ranged from 0.798 to 6.891. The isotherms of 2# （Jiangxi clay） and 3# （Jiangxi sand loam） soils belong to the S-type curve, while the isotherms of another 6 type soils belong to the L-type isotherm. The results of desorption indicated that the hysteresis phenomena appeared during the desorption process, and the hysteresis coefficients （H） of the herbicides in 8 soils varied from 0.259-0.980. Furthermore, Kads-f and desorption values （Kads-f） increased with the OM （%） and the clay content increasing, while the values decreased with the soils pH increasing. The H values decreased with the OM and the clay content increasing, and increased with the soils pH increasing. It can be concluded that the low adsorption abilities of chlorimuron-ethyl in test soils and un-reversible adsorption existed in the process, which will induce the great translocation of the herbicide after application in field. It can be transported to ground or groundwater causing risk to environments. The physical and chemical properties of soils, including the OM, the clay content, and the pH of soil were the dominating factors during the adsorption-desorption.

Temperature Effect on Boron Adsorption-Desorption Kinetics in Soils

The effect of temperature on the properties of boron adsorption-desorption in brown-red soil, yellowbrown soil and calcareous alluvial soil of Hubei Province was investigated with the mobile displacement technique. The experimental data of B adsorption-desorption amounts and reaction t line at 25 and 40℃ were fitted by the zero-order, first-order and parabolic diffusion kinetic equations. The adsorption process was in conformity with the parabolic diffusion law at both the temperatures, and the values of rate constant of the parabolic diffusion equation in B adsorption were 0.138, 0.124 and 0.105 mg kg-1 min-1/2 at 25℃, and 0.147, 0.146 and 0.135 mg kg-1 min-1/2 at 40℃ for the brown-red soil, yellow-brown soil, and calcareous alluvial soil, respectively. The relationship between amount of B desorption and reaction time could be well described by the first-order kinetic equation, and the corresponding values of rate constant were 0.0422, 0.0563 and 0.0384 min-1 at 25℃, and 0.0408, 0.042 3 and 0.0401 min-1 at 40℃ for the brown-red soil, the yellow-brown soil and the calcareous alluvial soil, respectively. Therefore, the desorption process of B might be related to the amount of B adsorbed in soil. The higher the temperature, the lower the amount of B adsorption for the same soil in the same reaction time. The values of the apparent activation energy of B adsorption in the three soils calculated with the rate constants of parabolic diffusion equation were 3.27, 8.44 and 12.99 kJ mol-1, respectively, based on the experimental data of B adsorption amounts and reaction time at 25 and 40℃.

Integration of morphology and electronic structure modulation on cobalt phosphide nanosheets to boost photocatalytic hydrogen evolution from ammonia borane hydrolysis

The controllable and safe hydrogen storage technologies are widely recognized as the main bottleneck for the accomplishment of sustainable hydrogen energy.Ammonia borane(AB)has regarded as a competitive candidate for chemical hydrogen storage.However,developing efficient yet high-performance catalysts towards hydrogen evolution from AB hydrolysis remains an enormous challenge.Herein,cobalt phosphide nanosheets are synthesized by a facile salt-assisted along with low-temperature phosphidation strategy for simultaneously modulating its morphology and electronic structure,and function as hydrogen evolution photocatalysts.Impressively,the Co_(2)P nanosheets display extraordinary performance with a record high turnover frequency of 44.9 min^(-1),outperforming most of the noble-metal-free catalysts reported to date.This remarkable performance is attributed to its desired nanosheets structure,featuring with high specific surface area,abundant exposed active sites,and short charge diffusion paths.Our findings provide a novel strategy for regulating metal phosphides with desired phase structure and morphology for energy-related applications and beyond.

Geochemistry and origins of hydrogen-containing natural gases in deep Songliao Basin,China:Insights from continental scientific drilling

The different reservoirs in deep Songliao Basin have non-homogeneous lithologies and include multiple layers with a high content of hydrogen gas.The gas composition and stable isotope characteristics vary significantly,but the origin analysis of different gas types has previously been weak.Based on the geochemical parameters of gas samples from different depths and the analysis of geological settings,this research covers the diverse origins of natural gas in different strata.The gas components are mainly methane with a small amount of C_(2+),and non-hydrocarbon gases,including nitrogen(N_(2)),hydrogen(H_(2)),carbon dioxide(CO_(2)),and helium(He).At greater depth,the carbon isotope of methane becomes heavier,and the hydrogen isotope points to a lacustrine sedimentary environment.With increasing depth,the origins of N_(2)and CO_(2)change gradually from a mixture of organic and inorganic to inorganic.The origins of hydrogen gas are complex and include organic sources,water radiolysis,water-rock(Fe^(2+)-containing minerals)reactions,and mantle-derived.The shales of Denglouku and Shahezi Formations,as source rocks,provide the premise for generation and occurrence of organic gas.Furthermore,the deep faults and fluid activities in Basement Formation control the generation and migration of mantle-derived gas.The discovery of a high content of H_(2)in study area not only reveals the organic and inorganic association of natural-gas generation,but also provides a scientific basis for the exploration of deep hydrogen-rich gas.

Deformable Catalytic Material Derived from Mechanical Flexibility for Hydrogen Evolution Reaction

Deformable catalytic material with excellent flexible structure is a new type of catalyst that has been applied in various chemical reactions,especially electrocatalytic hydrogen evolution reaction(HER).In recent years,deformable catalysts for HER have made great progress and would become a research hotspot.The catalytic activities of deformable catalysts could be adjustable by the strain engineering and surface reconfiguration.The surface curvature of flexible catalytic materials is closely related to the electrocatalytic HER properties.Here,firstly,we systematically summarized self-adaptive catalytic performance of deformable catalysts and various micro–nanostructures evolution in catalytic HER process.Secondly,a series of strategies to design highly active catalysts based on the mechanical flexibility of lowdimensional nanomaterials were summarized.Last but not least,we presented the challenges and prospects of the study of flexible and deformable micro–nanostructures of electrocatalysts,which would further deepen the understanding of catalytic mechanisms of deformable HER catalyst.

Mg/MgO interfaces as efficient hydrogen evolution cathodes causing accelerated corrosion of additive manufactured Mg alloys:A DFT analysis

The corrosion rates of additive-manufactured Mg alloys are higher than their as-cast counterparts,possibly due to increased kinetics for the hydrogen evolution reaction on secondary phases,which may include oxide inclusions.Scanning Kelvin Probe Force Microscopy demonstrated that MgO inclusions could act as cathodes for Mg corrosion,but their low conductivity likely precludes this.However,the density of state calculations through density functional theory using hybrid HSE06 functional revealed overlapping electronic states at the Mg/MgO interface,which facilitates electron transfers and participates in redox reactions.Subsequent determination of the hydrogen absorption energy at the Mg/MgO interface reveals it to be an excellent catalytic site,with HER being found to be a factor of 23x more efficient at the interface than on metallic Mg.The results not only support the plausibility of the Mg/MgO interface being an effective cathode to the adjacent anodic Mg matrix during corrosion but also contribute to the understanding of the enhanced cathodic activities observed during the anodic dissolution of magnesium.

Electron-distribution control via Pt/NC and MoC/NC dual junction:Boosted hydrogen electro-oxidation and theoretical study

The scarcity,high cost and susceptibility to CO of Platinum severely restrict its application in alkaline hydrogen oxidation reaction(HOR).Hybridizing Pt with other transition metals provides an effective strategy to modulate its catalytic HOR performance,but at the cost of mass activity due to the coverage of modifiers on Pt surface.Herein,we constructed dual junctions'Pt/nitrogen-doped carbon(Pt/NC)andδ-MoC/NC to modify electronic structure of Pt via interfacial electron transfer to acquire Pt-MoC@NC catalyst with electron-deficient Pt nanoparticles,simultaneously endowing it with high mass activity and durability of alkaline HOR.Moreover,the unique structure of Pt-MoC@NC endows Pt with a high COtolerance at 1,000 ppm CO/H_(2),a quality that commercial Pt-C catalyst lacks.The theoretical calculations not only confirm the diffusion of electrons from Pt/NC to Mo C/NC could occur,but also demonstrate the negative shift of Pt d-band center for the optimized binding energies of*H,*OH and CO.

Classification and technical target of water electrolysis for hydrogen production

Continuous efforts are underway to reduce carbon emissions worldwide in response to global climate change.Water electrolysis technology,in conjunction with renewable energy,is considered the most feasible hydrogen production technology based on the viable possibility of large-scale hydrogen production and the zero-carbon-emission nature of the process.However,for hydrogen produced via water electrolysis systems to be utilized in various fields in practice,the unit cost of hydrogen production must be reduced to$1/kg H_(2).To achieve this unit cost,technical targets for water electrolysis have been suggested regarding components in the system.In this paper,the types of water electrolysis systems and the limitations of water electrolysis system components are explained.We suggest guideline with recent trend for achieving this technical target and insights for the potential utilization of water electrolysis technology.

Precisely Control Relationship between Sulfur Vacancy and H Absorption for Boosting Hydrogen Evolution Reaction

Ef fective and robust catalyst is the core of water splitting to produce hydrogen.Here, we report an anionic etching method to tailor the sulfur vacancy(VS) of NiS_(2) to further enhance the electrocatalytic performance for hydrogen evolution reaction(HER). With the VS concentration change from 2.4% to 8.5%, the H* adsorption strength on S sites changed and NiS_(2)-VS 5.9% shows the most optimized H* adsorption for HER with an ultralow onset potential(68 m V) and has long-term stability for 100 h in 1 M KOH media. In situ attenuated-total-reflection Fourier transform infrared spectroscopy(ATR-FTIRS) measurements are usually used to monitor the adsorption of intermediates. The S-H* peak of the Ni S_(2)-VS 5.9% appears at a very low voltage, which is favorable for the HER in alkaline media. Density functional theory calculations also demonstrate the Ni S_(2)-VS 5.9% has the optimal |ΔG^(H*)| of 0.17 e V. This work offers a simple and promising pathway to enhance catalytic activity via precise vacancies strategy.

Deep eutectic solvents:Green multi-task agents for sustainable super green hydrogen technologies

While reliance on renewable energy resources has become a reality, there is still a need to deploy greener and more sustainable methods in order to achieve sustainable development goals. Indeed, green hydrogen is currently believed to be a reliable solution for global warming and the pollution challenges arising from fossil fuels, making it the resilient fuel of the future. However, the sustainability of green hydrogen technologies is yet to be achieved. In this context, generation of green hydrogen with the aid of deep eutectic solvents(DESs) as green mixtures has been demonstrated as a promising research area. This systematic review article covers green hydrogen generation through water splitting and biomass fermentation when DESs are utilized within the generation process. It also discusses the incorporation of DESs in fuel cell technologies. DESs can play a variety of roles such as solvent, electrolyte, or precursor;colloidal suspension and reaction medium;galvanic replacement, shape-controlling, decoration, or extractive agent;finally oxidant. These roles are relevant to several methods of green hydrogen generation, including electrocatalysis, photocatalysis, and fermentation. As such, it is of utmost importance to screen potential DES formulations and determine how they can function in and contribute throughout the green hydrogen mobility stages. The realization of super green hydrogen generation stands out as a pivotal milestone in our journey towards achieving a more sustainable form of development;DESs have great potential in making this milestone achievable. Overall, incorporating DESs in hydrogen generation constitutes a promising research area and offers potential scalability for green hydrogen production, storage,transport, and utilization.

MOLECULAR BEAM STUDIES ON ADSORPTION-DESORPTION KINETICS OF CO AND H_2 ON Ni SURFACE

Adsorption-desorption kinetics of CO and H_2 on Ni surface were studied with molecular beam relaxation spectrometry. It is found that there are two adsorbed states in the substrate temperature range 330K<T<480K and 720K<T<900K respectively for CO/Ni system. These results can be explained by a precursor state model. Their kinetic parameters: E_(aα)=14.6kJ/mol, E_(dx)=49.3kJ/mol; E_(aβ)= 68.6kJ/mol, E_(dβ)=200.6kJ/mol. It is shown that there are two adsorbed states in the low (350K<T<430K) and high (550K<T<625K) temperature range respectively for H_2/Ni system. These results can be explained by a direct dissociative model. Their kinetic parameters:E_(dl)=26.3kJ/mol, E_(dh)=103.7kJ/mol.

Theoretical analysis of hydrogen solubility in direct coal liquefaction solvents

The cyclic hydrogenation technology in a direct coal liquefaction process relies on the dissolved hydrogen of the solvent or oil participating in the hydrogenation reaction.Thus,a theoretical basis for process optimization and reactor design can be established by analyzing the solubility of hydrogen in liquefaction solvents.Experimental studies of hydrogen solubility in liquefaction solvents are challenging due to harsh reaction conditions and complex solvent compositions.In this study,the composition and content of liquefied solvents were analyzed.As model compounds,hexadecane,toluene,naphthalene,tetrahydronaphthalene,and phenanthrene were chosen to represent the liquefied solvents in chain alkanes and monocyclic,bicyclic,and tricyclic aromatic hydrocarbons.The solubility of hydrogen X(mol/mol)in pure solvent components and mixed solvents(alkanes and aromatics mixed in proportion to the chain alkanes+bicyclic aromatic hydrocarbons,bicyclic saturated aromatic hydrocarbons+bicyclic aromatic hydrocarbons,and bicyclic aromatic hydrocarbons+compounds containing het-eroatoms composed of mixed components)are determined using Aspen simulation at temperature and pressure conditions of 373–523 K and 2–10 MPa.The results demonstrated that at high temperatures and pressures,the solubility of hydrogen in the solvent increases with the increase in temperature and pressure,with the pressure having a greater impact.Further-more,the results revealed that hydrogen is more soluble in straight-chain alkanes than in other solvents,and the solubility of eicosanoids reaches a maximum of 0.296.The hydrogen solubility in aromatic ring compounds decreased gradually with an increase in the aromatic ring number.The influence of chain alkanes on the solubility of hydrogen predominates in a mixture of solvents with different mixing ratios of chain alkanes and aromatic hydrocarbons.The solubility of hydrogen in mixed aromatic solvents is less than that in the corresponding single solvents.Hydrogen is less soluble in solvent compounds containing heteroatoms than in compounds without heteroatoms.

Unsaturated bi-heterometal clusters in metal-vacancy sites of 2D MoS2 for efficient hydrogen evolution

The valence states and coordination structures of doped heterometal atoms in two-dimensional(2D)nanomaterials lack predictable regulation strategies.Hence,a robust method is proposed to form unsaturated heteroatom clusters via the metal-vacancy restraint mechanism,which can precisely regulate the bonding and valence state of heterometal atoms doped in 2D molybdenum disulfide.The unsaturated valence state of heterometal Pt and Ru cluster atoms form a spatial coordination structure with Pt–S and Ru–O–S as catalytically active sites.Among them,the strong binding energy of negatively charged suspended S and O sites for H+,as well as the weak adsorption of positively charged unsaturated heterometal atoms for H*,reduces the energy barrier of the hydrogen evolution reaction proved by theoretical calculation.Whereupon,the electrocatalytic hydrogen evolution performance is markedly improved by the ensemble effect of unsaturated heterometal atoms and highlighted with an overpotential of 84 mV and Tafel slope of 68.5 mV dec^(−1).In brief,this metal vacancy-induced valence state regulation of heterometal can manipulate the coordination structure and catalytic activity of heterometal atoms doped in the 2D atomic lattice but not limited to 2D nanomaterials.

Strong metal–support interaction boosts the electrocatalytic hydrogen evolution capability of Ru nanoparticles supported on titanium nitride

Ruthenium(Ru)has been regarded as one of the most promising alternatives to substitute Pt for catalyzing alkaline hydrogen evolution reaction(HER),owing to its inherent high activity and being the cheapest platinum-group metal.Herein,based on the idea of strong metal–support interaction(SMSI)regulation,Ru/TiN catalysts with different degrees of TiN overlayer over Ru nanoparticles were fabricated,which were applied to the alkaline electrolytic water.Characterizations reveal that the TiN overlayer would gradually encapsulate the Ru nanoparticles and induce more electron transfer from Ru nanoparticles to TiN support by the Ru–N–Ti bond as the SMSI degree increased.Further study shows that the exposed Ru–TiN interfaces greatly promote the H_(2) desorption capacity.Thus,the Ru/TiN-300 with a moderate SMSI degree exhibits excellent HER performance,with an overpotential of 38 mV at 10 mA cm^(−2).Also,due to the encapsulation role of TiN overlayer on Ru nanoparticles,it displays super long-term stability with a very slight potential change after 24 h.This study provides a deep insight into the influence of the SMSI effect between Ru and TiN on HER and offers a novel approach for preparing efficient and stable HER electrocatalysts through SMSI engineering.