Reaction Of Hydrogen Research Articles

Effect of Halide Ion Additives during Electrodeposition of Nanocatalysts

Platinum (Pt) and platinum ruthenium (PtRu) alloy catalysts are of interest for the development of green energy technologies such as hydrogen and direct methanol fuel cells. However, the high cost of Pt dictates that the precious metal be used as efficiently as possible so the surface area available to catalyze reactions per mass is maximized. Alloying Pt with different metals such as Ru is also of interest due to the increased activity and tolerance to contaminants that the additional metal imparts to the Pt. Industrial nanoparticle synthesis depends on scalable techniques such as electrodeposition. And a feature of this technique is that the morphology of electrodeposited structures is heavily influenced by the composition of the electrodeposition solution.This work describes how the presence of excess Cl- and Br- ions in an aqueous solution of metal salts affects the morphology of Pt and PtRu electrodeposited onto glassy carbon electrode substrates. The addition Br- ions and mixtures of the two halides resulted in smaller nanoparticles as observed by scanning electron microscopy and, therefore, higher surface areas compared to Pt electrodeposited in the absence of these halide species. Consequently, the mass activity towards the oxygen reduction reaction, one half of the reaction in hydrogen fuel cells, was highest when Pt was electrodeposited in the presence of Br- ions. The PtRu particles were also tested for their activity and resistance to carbon monoxide poisoning as a function of composition and halide additives. These results show that halide ions can be used beneficially in electrocatalyst synthesis without a negative impact on the activity of these catalysts, in contrast to what has been suggested in some prior studies. Presented herein is a simple method to tune the surface area and properties of electrodeposited nanocatalysts.1 Gautam, S.; Hadley, A. M. K.; Gates, B. D. Controlled Growth of Platinum Nanoparticles during Electrodeposition using Halide Ion Containing Additives. J. Electrochem. Soc. 2022, 169, 112508.

(Invited) Fruitful and False Analogies between Polymer Electrolyte Fuel Cells and Electrolyzers

In the past 20 years polymer electrolyzer membrane fuel cells (PEMFCs) received great attention as a clean alternative for powering mobility and stationary applications. Resultingly, there has been a rich amount of research by public, private and university investigators particularly focusing on membranes, catalysts, transport and cost. Yields of great advances were made, though scant attention was given to the generation of this hydrogen and polymer electrolyte membrane water electrolysis (PEMWE) was the neglected stepsister, sentenced to back chapters, footnotes, and small conference rooms. Now however the opportunity for hydrogen generated from renewables, "green hydrogen" has been widely seen as an opportunity to not only provide hydrogen for these PEMFC applications, but also seemingly intractable CO2 emitters as ammonia generation and steel and petroleum refining. As numerous government agencies have announced eye-popping targets for green electrolysis and the complementary research funding, the temptation is to take the beautiful evening gown woven of PEMFC research and adorn the overlooked stepsister. .Zealous PEMFC researchers have not surprisingly reversed course and focused attention on making, rather than consuming hydrogen. Exploitation of the PEMFC and PEMWE analogy is tempting, as many of the materials and reactions are the same or similar. Noteworthy, there are the polymer electrolyte membrane, expensive PGM catalysts, a very fast hydrogen reaction and very slow oxygen reaction. Yearning for faster kinetics and facile heat management, both also have pushed operation to higher temperatures and suffer the accelerated degradation that goes with it. Using these analogies has has generated some benefits, particularly in lower catalyst loading and conductive membrane resistance. Keeping in mind the differences is key however, as PEMWE will generally need to operate at much higher currents, under higher pressures, for far longer durations.This talk will look at what PEMWE has and has the potential to learn from PEMFC research. We will look at materials, their key aspects and how optimizing for each is different, with a focus on costs, the use of hydrocarbon materials, chemical and mechanical durability strategies and recycling. Use cases will also be explored, particularly how the need for high hydrogen production pressures (>30 bar) changes the electrode assembly as well as the balance of stack.

Structural simplification of the 3‐nitroimidazo[1,2‐a]pyridine antileishmanial pharmacophore: Design, synthesis, and antileishmanial activity of novel 2,4-disubstituted 5-nitroimidazoles

Abstract As part of our ongoing antileishmanial structure–activity relationship study, a structural simplification of the 3‐nitroimidazo[1,2‐a]pyridine ring to a 5-nitroimidazole moiety was conducted. A series of novel 2,4-disubsituted 5-nitroimidazole derivatives, including the 5-nitroimidazole analog of Hit A and the 4-phenylsulfonylmethyl analog of fexinidazole, were obtained by using the vicarious nucleophilic substitution of hydrogen (VNS) reaction, to substitute position 4, and by using the tetrakis(dimethylamino)ethylene methodology to modulate position 2. The molecular structures of eight novel 5-nitroimidazoles were characterized by 1H NMR, 13C NMR, LC/MS, and HRMS. The in vitro antileishmanial activity of these compounds was evaluated against the promastigote form of Leishmania infantum and their influence on cell viability was assessed on the human hepatocyte HepG2 cell line. The 4-phenylsulfonylmethyl analog of fexinidazole showed the best selectivity index of the series, displaying good activity against both the promastigote form of L. infantum (EC50 = 0.8 µM, SI > 78.1) and the promastigote form of Leishmania donovani (EC50 = 4.6 µM, SI > 13.6), and exhibiting low cytotoxicity on the HepG2 cell line (CC50 > 62.5 µM).

Thermodynamic and kinetic considerations of the link between underground hydrogen storage and reductive carbonate dissolution and methane production. Are limestone reservoirs unsuitable for UHS?

Storing hydrogen underground for cyclic injection/retrieval may help move the world towards a decarbonised economy. In search of suitable long-term reservoirs, the potential reactivity of the matrix with hydrogen plays a major role. This is especially poignant for carbonate minerals, due to their abundance, ubiquity, and much faster dissolution kinetics compared to silicates. Geochemical modelling studies invariably find hydrogen-induced reductive carbonate dissolution and methane production (HIRCDAMP) whereas experimental studies, for the most part, do not support this view. To answer the question of how far injected hydrogen may oxidise, protonate and cause reductive dissolution of carbonates, a thermodynamic approach based on standard redox and overall cell potentials, as well as Gibbs free energies, was chosen. Together with observations on kinetic constraints, a consistent picture emerges in which purely inorganically driven reduction of (bi)carbonate to methane by hydrogen oxidation is not likely to occur. Rather, the formation of intermediate carbon species (e.g., formate) could be a kinetically and thermodynamically more favourable pathway than that to methane. It follows that geochemical models that question the long-term viability of hydrogen injection into carbonate-bearing reservoirs need to be revised, toning down any alleged, yet by experimental studies not substantiated, hydrogen reactivity in the absence of any catalyst and/or microbial activity.

Recovered water from fuel cells as a supply for Maisotsenko evaporative cooling systems in a hydrogen-powered urban bus

The EU ban on the sale of new petrol and diesel cars from 2035 requires finding sustainable alternatives both from an energy and an environmental point of view. The path now seems to be drawn towards a total electrification of public and private transportation sectors. However, the issue of the limited range of electric vehicles, particularly for heavy-duty ones, still needs to be addressed. The development of fuel cell vehicles powered by compressed hydrogen, not relying exclusively on batteries, can achieve ranges comparable to those powered by fossil-fuel. The development of hydrogen vehicles must proceed in parallel with increasing the efficiency of passenger compartment air conditioning, which requires a significant share of the total energy consumed. An efficient alternative to common vapor compression cooling systems is represented by evaporative coolers, in which water evaporation is used to cool an air flow. This study investigates the feasibility of utilizing the recovered water from the exhaust gas of a hydrogen PEM fuel cell, powering an urban bus, within a commercial indirect evaporative cooling system employing the Maisotsenko cycle. The cooling capacity of the proposed system was calculated to verify the possibility of implementing it on an urban bus. The water available at the cathode of the fuel cell and the water required by the evaporative cooler were evaluated under various conditions and compared. The calculations demonstrate that even under intense weather conditions, where approximately 40 kg of water may be required every hour, at least 10 % of water needed by the evaporative cooling system can be provided by the water produced through the hydrogen reaction. In mild weather conditions or by cooling the exhaust, it is possible to significantly increase the share of pure water supplied to the evaporative system. The integration of hydrogen fuel cells and evaporative coolers in bus equipment can be an energy-efficient, win–win solution. This configuration enables the dual utilization of the hydrogen employed to drive the fuel cell.

Experimental study and correlation analysis for the effect of hydrogen pressure on biomass fluidized hydropyrolysis under N2-H2 mixed atmosphere

The utilization of fluidized bed reactors for the biomass hydropyrolysis vapor upgrading is essential in the conversion of biomass into liquid fuels. Conducting pyrolysis experiments in fluidized bed reactors with a N2-H2 mixed atmosphere is advantageous for system operation as it allows for lower minimum operating velocities, enhances pyrolysis efficiency, and reduces heat loss. This research examines the impact of hydrogen pressure in a bubbling fluidized bed reactor using a N2-H2 mixed carrier gas, with poplar wood as the feedstock and Ni-Moγ/Al2O3 as the catalyst. Through experimental and correlation analyses, significant relationships are observed between hydrogen pressure and the production of liquid and gas-phase products, with varying effects attributed to changes in hydrogen ratio and reaction pressure. Elevated hydrogen ratios facilitate secondary reactions such as the CO2 hydrogenation, resulting in a decline in CO2 production and an elevation in the yields of light hydrocarbons and aqueous phase products. Augmenting the reaction pressure to enhance hydrogen pressure aids in promoting hydrogen saturation and cracking, and amplifying the hydrogen pressure through an increase in the reaction pressure at a specific hydrogen ratio proves more efficacious in enhancing both the quantity and quality of bio-oil produced. In the context of poplar hydropyrolysis vapor upgrading utilizing a Ni-Moγ/Al2O3 catalyst, a hydrogen ratio of 50 % at a reaction pressure of 1.5 MPa emerged as the preferred option for achieving a 12 % bio-oil yield with a moderate average bio-oil carbon number and satisfactory hydrogenation levels. This comprehensive investigation examines the influence of hydrogen pressure on biomass hydropyrolysis, highlighting variations in the impacts of changes in hydrogen ratio and reaction pressure on pyrolysis results. These results offer a theoretical framework for discerning distinctions between hydropyrolysis investigations carried out in pure hydrogen atmospheres versus mixed N2-H2 atmospheres.

Synthesis of a CCC-NHC pincer Mn complex: An earth abundant catalyst for synthesis of α-alkylated ketones, 2-oxindole derivatives via borrowing hydrogen and one-pot synthesis of quinolines

A CCC-NHC pincer Mn complex was prepared and was characterized by 1H and 13C NMR spectroscopy, mass spectroscopy, elemental analysis, and single crystal X-ray crystallography. Its catalytic activities were demonstrated through diverse chemical transformations including cross-coupling borrowing hydrogen reactions and dehydrogenative cyclization reactions, which resulted in the formation of both C–C and C–N bonds. These cascade reactions involved multiple processes, including dehydrogenation, condensation, and hydrogenation. Under optimized conditions, Mn catalyst affectively converted a broad substrate scope. The different reactions yielded saturated ketones (isolated yields, 42 %–92 %), 2-oxindole derivatives (isolated yields, 70 %–83 %), and quinoline derivatives (isolated yields, 70 %–89 %). These atom economical transformations produce only water molecules as by-products enhancing their environmental friendliness. The catalyst utilized earth-abundant Mn potentially reduce costs. Catalytic cycles were proposed for borrowing hydrogen and acceptorless dehydrogenative cyclization reactions based on control experiments. These included oxidation, aldol condensation, and hydrogenation reactions.

Electrocatalytic Hydrogen Evolution Reaction of Cobalt Triaryl Corrole Bearing Nitro Group

The use of non–precious metals for electrocatalytic hydrogen reaction (HER) is particularly important for energy conservation and environmental protection. In this work, three new cobalt corroles containing o−, m−, and p−nitrobenzyl (1, 2, 3) at the meso 10−position of the corrole macrocycle were synthesized, and their electrocatalytic hydrogen evolution reaction in organic and neutral aqueous systems was also investigated. The results show that these three cobalt corroles have significant catalytic HER activity in both systems, and the catalytic efficiency follows 1 > 3 > 2, which indicates that the position of the nitro group can affect the catalytic property of the complexes. In the organic phase, when using trifluoroacetic acid or p−toluenesulfonic acid as the proton source, the electrocatalytic HER may undergo an EECC (E: electron transfer, C: proton coupling) pathway. In a neutral aqueous system, the HER turnover frequency value of 1 is up to 137.4 h−1 at 938 mV overpotential.

Unlocking the Potential of MXene in Catalysis: Decorated Mo2CTx Catalyst for Ammonia Synthesis under Mild Conditions.

Ammonia, which is one of the most important chemicals for the synthesis of dyes, pharmaceuticals, and fertilizers, is produced by the reaction of molecular hydrogen with nitrogen, over an iron-based catalyst at 400-500 °C under pressure of over 100 bar. Decreasing the operating temperature and pressure of this highly energy-intensive process, developed by Haber and Bosch over 100 years ago, would decrease energy consumption in the world. In this work, we used two-dimensional Mo2CTx MXene as a support for a cobalt-based catalyst. The MXene functionalized by Co showed catalytic activity for ammonia synthesis from H2 and N2 at temperatures as low as 250 °C, without any pretreatment. The developed catalyst was highly active for ammonia synthesis, demonstrating a high rate of up to 9500 μmol g-1activephase h-1 at 400 °C under ambient pressure in steady-state conditions, and did not suffer from any deactivation after 15 days of reaction. The apparent activation energy (Ea) was found to be in the range of 68-74 kJ mol-1, which is in line with values reported for highly active catalysts. This improved catalyst may decrease the energy consumption in the synthesis of ammonia and its derivatives, as well as facilitate the use of ammonia as a hydrogen carrier for renewable energy storage.

Hydrogenation of calcite and change in chemical bonding at high pressure: Diamond formation above 100 GPa

Synchrotron X-ray diffraction (XRD) and Raman spectroscopy in laser heated diamond anvil cells and first principles molecular dynamics (FPMD) calculations have been used to investigate the reactivity of calcite and molecular hydrogen (H2) at high pressures up to 120 GPa. We find that hydrogen reacts with calcite starting below 0.5 GPa at room temperature forming chemical bonds with carbon and oxygen. This results in the unit cell volume expansion; the hydrogenation level is much higher for powdered samples. Single-crystal XRD measurements at 8–24 GPa reveal the presence of previously reported III, IIIb, and VI calcite phases; some crystallites show up to 4% expansion, which is consistent with the incorporation of ≤ 1 hydrogen atom per formula unit. At 40–102 GPa XRD patterns of hydrogenated calcite demonstrate broadened features consistent with the calcite VI structure with incorporated hydrogen atoms. Above 80 GPa, the CO stretching mode of calcite splits suggesting a change in the coordination of CO bonds. Laser heating at 110 GPa results in the formation of CC bonds manifested in the crystallization of diamond recorded by in situ XRD at 300 K and 110 GPa and by Raman spectroscopy on recovered samples commenced with C13 calcite. We explored several theoretical models, which show that incorporation of atomic hydrogen results in local distortions of CO3 groups, formation of corner-shared CO polyhedra, and chemical bonding of H to C and O, which leads to the lattice expansion and vibrational features consistent with the experiments. The experimental and theoretical results support recent reports on tetrahedral C coordination in high-pressure carbonate glasses and suggest a possible source of the origin of ultradeep diamonds.

Copper-Catalyzed Borrowing Hydrogen Reaction for α-Alkylation of Amides with Alcohols.

We report the first example of copper-catalyzed α-alkylation of acetamides with alcohols via a borrowing hydrogen strategy. Catalyzed by the in situ-generated copper particles, acetamides and various substituted benzyl or alkyl alcohols were transformed into functionalized amides in good yields with excellent selectivity. Compared with previous work, this process is simple using commercially available Cu(OAc)2 as a precatalyst, without an additional ligand or a metal complex, and easier. Mechanistic studies revealed that aldehyde and α,β-unsaturated amides were the intermediates of this reaction and also disclosed the role of copper in alcohol dehydrogenation and C═C bond hydrogenation.

PROSPECTS FOR THE IMPLEMENTATION OF BIOLOGICAL METHANATION TECHNOLOGIES IN UKRAINE

The search and development of alternative energy sources as a substitute for scarce natural gas is an extremely important task for the Ukrainian economy. Methanation, that is, the reaction of converting carbon dioxide and hydrogen to produce synthetic renewable methane, is one way to solve this problem. The directions and features of methanation technologies implemented today in the world are considered. The structural diagram and production of components of biological methanation technology as the most promising for Ukraine are described. Two concepts of biomethanation are considered: in-situ and ex-situ. In-situ methanation is a combination of anaerobic digestion and biological methanation processes in a single digester. However, when implementing such methanation, difficulties arise due to differences in the optimal conditions for the occurrence of these processes. Ex-situ methanation occurs in separate reactors, where it is possible to autonomously establish optimal conditions for acetogenesis and methanogenesis. Thus, the in-situ concept, compared to the ex-situ concept, is much cheaper and easier to implement, but is still much more difficult to implement the methanation process. The relevance of introducing methanation technologies in Ukraine is due to the active development and implementation of bioenergy technologies using large bioresources existing in the country. A promising direction for the implementation of methanation technologies in Ukraine is the use of biological methanation technologies for the production of biomethane and synthetic renewable methane. Establishing the production of biomethane and synthetic renewable methane will also help solve such pressing problems as accumulating unstable electricity from solar and wind power plants, which can become a powerful stimulator for the development of these areas of alternative energy. In addition, methanation protects the environment from CO2, converting it from a greenhouse gas into a fuel. Bibl. 18, Fig. 2.

Synthesis of quinazolinone derivatives with a seven‐membered ring using borrowing hydrogen methodology

In this study, we synthesized 23 quinazolinone derivatives with the seven-membered C-ring through intramolecular borrowing hydrogen reaction of 3-(3-hydroxypropyl)-2-(1H-indol-2-yl)-quinazolin-4(3H)-one, in yields ranging from 31 % to 68 %. The reaction took place in the presence of cesium carbonate and DMF, using triphenylphosphine ruthenium chloride (PPh3)3RuCl2 as a catalyst and Xantphos as a ligand. Water was the only byproduct. Furthermore, pharmacological activity tests were conducted on these compounds, revealing that some of the products exhibited anti-inflammatory and anticancer properties.

Electrothermal-assisted all-weather solar steam generator based on hydrogel implantation strategy

Using solar energy to treat sewage is a feasible scheme to alleviate the shortage of water resources and reduce carbon emissions. However, the fluctuation of sunlight intensity poses a great challenge to the stability of the treatment process, which hinders its application in the actual water treatment scene. Herein, based on the adhesion of hydrogel, an electrothermal-assisted all-weather solar steam generator with sandwich structure was synthesized through hydrogel implantation strategy, in which polyacrylamide hydrogel with thermal grease-modified heating wires was implanted as the middle heat conduction layer, the photothermal evaporation layer as the upper layer and the waste heat evaporation layer as the bottom layer. The electrothermal assisted solar evaporator (EASE) perfectly achieves the superposition of photothermal and electrothermal effects, and can achieve high interfacial water evaporation performance under extremely low auxiliary working voltage. Applying a low voltage of 2 V to both ends of the evaporator can achieve a high evaporation rate of 4.58 kg m−2h−1 under 1 solar irradiation, which is similar to the sum of the evaporation rate under only 1 solar illumination (2.22 kg m−2h−1) and a 2 V voltage input (2.26 kg m−2h−1). More interestingly, the suitable thickness of the hydrogel layer not only ensures the transfer of heat between layers, but also weakens the heat loss caused by the water flow effect. The implantation strategy ensures the stability of the water structure and inhibits the hydrogen reaction of electrolytic water in the electrothermal process. This work provides an important theoretical and practical reference for the preparation of all-weather solar interface water purification equipment.

A binary catalytic system of sulfonated metal–organic frameworks and deep eutectic solvents towards highly efficient synthesis of 5-hydroxymethylfurfural from fructose

The green synthesis of 5-hydroxymethylfurfural (HMF) from biomass feedstocks is a crucial step for the development of sustainable fuels, resins and plastics. Here, a novel binary catalytic system was developed with metal–organic frameworks (MOFs) and deep eutectic solvents (DESs), which synergically exhibited a superior fructose dehydration efficiency with a HMF yield of 98.5% within 40 min. The replacement from terephthalic acid to 2,5-furandicarboxylic acid as the organic ligand in MOFs catalysts altered the coordination microenvironment of metal nodes, resulting in remarkably enhanced fructose conversion rates. The formation of hierarchical porous structures and moderated Brønsted acid sites in sulfonated MOFs further promoted the HMF production. Notably, HMF could be readily separated from the MOFs-DESs system and the MOF catalyst maintained stable performance after six recycles. Theoretical calculations clarified a positive correlation between the hydrogen bond interaction (between fructose and DESs components) energy and reaction efficiency. This study provided a new strategy to couple hierarchical solid acid catalysts with functional solvents binary towards effective and sustainable upgrading of biomass-derived molecules.

Two-step synthesis of new fused systems based on [1,2,5]oxadiazolo[3,4-b]quinoxaline by a combination of the Scholl reaction and nucleophilic aromatic substitution of hydrogen (SNH)

Two-step synthesis of new fused systems based on [1,2,5]oxadiazolo[3,4-b]quinoxaline by a combination of the Scholl reaction and nucleophilic aromatic substitution of hydrogen (SNH)

Enhanced Hydrogen Generation through Low-Temperature Plasma Treatment of Waste Aluminum for Hydrolysis Reaction.

This study investigates the low-temperature hydrogen plasma treatment approach for the improvement of hydrogen generation through waste aluminum (Al) reactions with water and electricity generation via proton-exchange membrane fuel cell (PEM FC). Waste Al scraps were subjected to ball milling and treated using two different low-temperature plasma regimes: Diode and magnetron-initiated plasma treatment. Hydrolysis experiments were conducted using powders with different treatments, varying molarities, and reaction temperatures to assess hydrogen generation, reaction kinetics, and activation energy. The results indicate that magnetron-initiated plasma treatment significantly enhances the hydrolysis reaction kinetics compared to untreated powders or those treated with diode-generated plasma. Analysis of chemical bonds revealed that magnetron-initiated hydrogen plasma treatment takes advantage by promoting a dual procedure: Surface cleaning and Al nanocluster deposition on top of Al powders. Moreover, it was modeled that such H2 plasma could penetrate up to 150 Å depth. Meanwhile, electricity generation tests demonstrate that only 0.2 g of treated Al powder can generate approximately 1 V for over 300 s under a constant 2.5 Ω load and 1.5 V for 2700 s with a spinning fan.

Coverage, repulsion, and reactivity of hydrogen on High-Entropy alloys

Modeling hydrogen evolution reaction (HER) activity probability on IrPdPtRhRu(111) high-entropy alloys. Determining hydrogen coverages based on ligand effects and generalized hydrogen–hydrogen repulsion.The rate of H2 formation is highly impacted by the level of hydrogen coverage on the catalyst surface. In search of optimal catalytic properties high-entropy alloys (HEA) are promising candidates that utilize the compositional space of multiple elements. Based on simulations of HEA model (111) surfaces with a range of hydrogen coverages, distributions of binding energies are used to construct a framework that approximates the probability that adsorbed hydrogen may lead to the formation of H2 as a function of applied potential. By optimizing the alloy compositions for the highest activity probability at given potentials the best and most efficient catalyst candidates for HER can be identified. Treating hydrogen–hydrogen repulsion effects and binding energy separately, we find that the repulsion is larger for HEAs than for pure metals. Differing isotherm slopes in the mean adsorption and desorption energies demonstrate a possible hysteresis for hydrogen adsorption on HEAs.

One-step hydrothermal synthesis of nanowire-like W/Mo-Ni3S2/NF electrocatalysts for highly efficient hydrogen evolution reactions

The design of nanostructures and the adjustment of components are very important to improve the performance of hydrogen evolution electrocatalysts. In this paper, Ni, W and Mo trimetallic catalysts are studied from the aspects of morphology, structure and electronic transfer, and a better combination of hydrogen reaction efficiency is obtained. The W/Mo co-doped nickel sulfide electrocatalyst was synthesized on Ni foam by one-step hydrothermal method. As anticipated, the individual incorporation of either tungsten (W) or molybdenum (Mo) into the electrocatalyst did not yield satisfactory enhancements in hydrogen evolution reaction (HER) performance. However, when both W and Mo were co-doped onto the electrocatalyst, a significant improvement in catalyst material performance was observed. Hence, the coexistence of W and Mo is the key to improve HER electrocatalytic activity. In 1 M KOH solution, the W/Mo-Ni3S2/NF electrocatalyst exhibited exceptional HER activity with an overpotential of only 136 mV at a current density of 10 mA·cm−2 and demonstrated excellent cycle stability exceeding 20 hours. In this paper, the strategy of bimental co-doping composite is adopted to adjust the structure of nickel sulfide, which provides reference value for the design of reasonable and efficient HER electrocatalyst.

N2 cleavage by silylene and formation of H2Si(μ-N)2SiH2

Fixation and functionalisation of N2 by main-group elements has remained scarce. Herein, we report a fixation and cleavage of the N ≡ N triple bond achieved in a dinitrogen (N2) matrix by the reaction of hydrogen and laser-ablated silicon atoms. The four-membered heterocycle H2Si(μ-N)2SiH2, the H2SiNN(H2) and HNSiNH complexes are characterized by infrared spectroscopy in conjunction with quantum-chemical calculations. The synergistic interaction of the two SiH2 moieties with N2 results in the formation of final product H2Si(μ-N)2SiH2, and theoretical calculations reveal the donation of electron density of Si to π* antibonding orbitals and the removal of electron density from the π bonding orbitals of N2, leading to cleave the non-polar and strong NN triple bond.