Water Hydrogen Research Articles

The nature of the hydrophobic interaction varies as the solute size increases from methane's to C60's.

The hydrophobic interaction, often combined with the hydrophilic or ionic interactions, makes the behavior of aqueous solutions very rich and plays an important role in biological systems. Theoretical and computer simulation studies have shown that the water-mediated force depends strongly on the size and other chemical properties of the solute, but how it changes with these factors remains unclear. We report here a computer simulation study that illustrates how the hydrophobic pair interaction and the entropic and enthalpic terms change with the solute size when the solute-solvent weak attractive interaction is unchanged with the solute size. The nature of the hydrophobic interaction changes qualitatively as the solute size increases from that of methane to that of fullerene. The potential of mean force between small solutes has several well-defined extrema, including the third minimum, whereas the potential of mean force between large solutes has the deep contact minimum and the large free-energy barrier between the contact and the water-bilayer separated configurations. The difference in the potential of mean force is related to the differences in the water density, energy, and hydrogen bond number distributions in the vicinity of the pairs of hydrophobic solutes.

An Interstitial Boron Inserted Metastable Hexagonal Rh Nanocrystal for Efficient Hydrogen Oxidation Electrocatalysis

AbstractConstructing metastable phase structure plays an important role in changing the physicochemical properties and improving the catalytic performance of nanocrystals. Unfortunately, the synthesis of metastable phase metallic nanocrystals is highly challenging, mainly due to the thermodynamically unstable ground‐state. Here, we report a synthesis of unconventional metastable hexagonal rhodium nanocrystal (Bint−Rhhcp/C) via interstitial boron insertion. The insertion of boron atoms into the interstitial sites of cubic Rh lattice not only induces the atomic arrangements from face‐centered cubic (fcc) to hexagonal close‐packed (hcp), but also stabilizes the metastable hexagonal Rh structure. Benefiting from the phase transition and interstitial boron doping, the Bint−Rhhcp/C catalyst exhibits remarkable catalytic performance toward hydrogen oxidation reaction (HOR) under alkaline media, with a mass activity of 1.413 mA μgPGM−1. Experimental measurements including in situ surface‐enhanced infrared absorption spectroscopy (SEIRAS) and density functional theory (DFT) calculations indicate that the strengthened adsorption of hydroxyl species on the electrode surface of Bint−Rhhcp/C is responsible for the reconstruction of interfacial water structure and increased water proportions in the gap region in the electric double layers. As a result, the increased water connectivity and hydrogen bond network facilitate high‐efficiency hydrogen transfer across the interface, thereby boost the alkaline HOR performance.

Enhanced solar-driven photoelectrocatalytic water treatment and hydrogen evolution with triplet-triplet annihilation upconversion with Mo-doped BiVO4 nanocomposite films

Enhanced solar-driven photoelectrocatalytic water treatment and hydrogen evolution with triplet-triplet annihilation upconversion with Mo-doped BiVO4 nanocomposite films

Dynamic anti-correlations of water hydrogen bonds

Water is characterized by strong intermolecular hydrogen bonds (H-bonds) between molecules. The two hydrogen atoms in one water molecule can form H-bonds of dissimilar length. Although intimately connected to water’s anomalous properties, the details and the origins of the asymmetry have remained elusive. We study water’s H-bonds using the O-D stretching vibrations as sensitive reporters of H-bonding of D2O and HOD in dimethylformamide. Broader inhomogeneous linewidths of the OD band of HOD compared to the symmetric and asymmetric OD stretching modes of D2O together with density functional theory calculations provide evidence for markedly anti-correlated H-bonds: water preferentially forms one weak and one strong H-bond. Coupling peaks in the spectra for D2O directly demonstrate anti-correlated H-bonds and these anti-correlations are modulated by thermal motions of water on a sub-picosecond timescale. Experimentally inferred H-bond distributions suggest that the anti-correlations are a direct consequence of the H-bonding potential of XH2 groups, which we confirm for the ND2 group of urea. These structural and dynamic insights into H-bonding are essential for understanding the relationship between the H-bonded structure and phase behavior of water.

Photothermal Synergistic Hydrogen Production via a Fly-Ash-made Interfacial Vaporific System.

Employing UV-vis spectrum for hydrogen generation and vis-IR spectrum to elevate reaction temperatures and induce phase transitions effectively enhances yield and purifies water, demonstrating a judicious strategy for solar energy utilization. This study presents an interfacial photothermal water splitting system that utilizes all-inorganic, economical industrial by-products known as fly ash cenospheres (FAC) for solar-driven hydrogen generation. In this system, the yield reaches 254.8µmol h-1cm-1, representing an 89% augmentation compared to that of the three-phase system. In situ experiments, combined with theoretical calculation, reveal the system's robust light absorption capacity, facilitating rapid gas separation, thus improves the solar-to-hydrogen (STH) efficiency. Furthermore, the system demonstrates strong performance in turbid water and scalability for expansive applications, achieving a hydrogen yield exceeding 50 L h-1 m-2 from various water sources. Facilitating large-scale hydrogen production and water purification, it thereby establishing its potential as a viable solution for sustainable energy generation.

Synthesis of Magnéli phases in a high-speed electric discharge plasma jet

Relevance. Currently, there is an active search for photocatalytic materials suitable for water decomposition and hydrogen production that exhibit activity when exposed to visible light, and are also accessible, chemically stable and safe. In this regard, a number of materials with the general formula TinO2n-1 (n=2–10) are distinguished, they are called Magnéli phases. Despite the fact that Magnéli phases exhibit significantly higher photocatalytic activity compared to traditional titanium oxides (rutile, anatase, brookite), their practical application is currently extremely difficult due to the complexity of their synthesis. Promising approaches are those that provide well-controlled conditions with the possibility of rapid stabilization of the system, among which plasma synthesis methods stand out. Aim. To develop a method for synthesizing a product containing Magnéli phases in a high-speed jet of electric discharge plasma. Objects. Dispersed materials obtained in the Ti-O system. Methods. Plasma dynamic synthesis, X-ray diffractometry (X-ray phase analysis), scanning electron microscopy, transmission electron microscopy. Results. Using a high-speed jet of electric discharge plasma generated by a coaxial magnetoplasma accelerator, experimental studies were performed on the synthesis of non-stoichiometric titanium oxides in a carbon dioxide environment. The composition and microstructure of the obtained dispersed products were studied. It was revealed that the materials contain Magnéli phases TinO2n−1, as well as traditional stoichiometric rutile and anatase. From the point of view of the efficiency of obtaining Magnéli phases, the single-pulse mode of operation is more attractive (content over 50%), while the efficiency of CO2 conversion is higher in the multi-pulse mode (up to 10% of CO2 is converted into CO). A distinctive feature of the synthesized materials at both the micro- and nanolevels is the tendency to form particles with a high degree of sphericity. The nanofraction of the products mainly consists of rounded particles with sizes up to hundreds of nanometers, of which the Magnéli phases primarily include nanoparticles with a characteristic highly defective crystalline structure with dislocation shifts.

Combined application of biochar and silicon nanoparticles enhance soil and wheat productivity under drought: Insights into physiological and antioxidant defense mechanisms

Agricultural drought periods are enhanced by the change in global climate that threatens food security. One of the main factors affecting soil and wheat productivity worldwide is drought stress. Especially, in semi-arid climates, studies are not found about adding organic amendments may be a viable way to reduce the adverse impacts of drought on crops while enhancing soil qualities and water use efficiency. In this study, we aimed to explore the effects of combined application of biochar (BC = 5 %) and silicon nanoparticles (SiNP = 900 mg/L) on soil and wheat drought resistance. Drought stress was applied at the three most critical growth stages of wheat, tillering (DTS), flowering (DFS), and grain filling (DGFS) stages, then evaluated the soil nutrients and wheat drought physiological resistance under applied treatments (BC, SiNP, BC+SiNP). Results showed that combined treatment of BC and SiNP greatly reduced the adverse effects of drought by enhancing plant height (9.36 %), spike length (25.63 %), number of fertile tillers (29.26 %), grains per spike (10.86 %), thousand-grain weight (18.25 %), and biological yield (16.34 %) with comparison to the control application. Additionally, physiological measures like water use efficiency (20.58 %), stomatal conductance (29.26 %), chlorophyll a (16.25 %), chlorophyll b (18.96 %), transpiration rate (21.65 %), photosynthetic rate (22.94 %), electrolyte leakage (-17.77 %), MDA (29.25 %), hydrogen peroxide (-19.88 %), superoxide dismutase (11.19 %), catalase (9.26 %), peroxidase (18.59 %), nitrogen (14.81 %), phosphorus (13.89 %), and potassium (17.61 %) were also meaningfully improved by treated application. BC and SiNP also significantly amended the organic carbon, nitrogen, and minerals percentage in soil. In conclusion, using the synergistic application of BC and SiNP could be a successful strategy to promote the biological soil properties, plant growth, yield, and quality of wheat crops as compared to all other treatments via dropping the dangerous effects of drought stress.

Effect of hydrogen bonding strength on the structure and properties of phase-separated hydrogel from gelatin

Dynamic bonded tough hydrogels often contain phase-separated structures that facilitate multiscale energy dissipation. However, the influence of bonding strength on the phase-separated structures and properties of hydrogels has been understudied. In this work, the hydrogen bonding strength within phase-separated gelatin/acrylic acid copolymer hydrogels was modulated by varying the methyl group content in the acrylic acid copolymer. It was found the mechanical properties of the hydrogels are determined by a synergistic effect between water content and hydrogen bond strength. Both weak and strong hydrogen bonds resulted in the hydrogel with high water content and low mechanical strength. It was observed that the chain dense regions within the hydrogels became more condensed and larger with increasing hydrogen bonding strength. The high water content in gels with strong hydrogen bonds is attributed to the formation of condensed chain dense regions, which prevent significant shrinkage of the hydrogel. The combination of high water content and condensed chain dense regions resulted in sparse chain loose regions within the hydrogel, which provided water channels for ion transport, enabling high ionic conductivity even at a reduced water content of 28.9 wt%.

The Impact of Water Injection and Hydrogen Fuel on Performance and Emissions in a Hydrogen/Diesel Dual-Fuel Engine

The Impact of Water Injection and Hydrogen Fuel on Performance and Emissions in a Hydrogen/Diesel Dual-Fuel Engine

Hydroxyl‐Binding Induced Hydrogen Bond Network Connectivity on Ru‐based Catalysts for Efficient Alkaline Hydrogen Oxidation Electrocatalysis

AbstractUnderstanding the role of adsorbed intermediates at the polarized catalyst‐electrolyte interface on the structure of electrical double layer (EDL) is essential for developing highly efficient electrocatalysts. Here, we prepared a series of unconventional face‐centered‐cubic (fcc) phase Ru‐based catalysts (i.e. fcc‐Ru, fcc‐RuCr, and fcc‐RuCrW) by rational tuning the binding energetics of hydroxyl intermediate to engineer the electrochemical interface and boost the performance of alkaline hydrogen oxidation reaction (HOR). The introduction of oxyphilic metals Cr and W can regulate the orbital occupation of Ru, promote the adsorption of hydroxyl species, resulting in an anomalous behavior that HOR performance under alkaline media exceeds acidic media. Experimental results and theoretical calculations unravel that the modulated adsorption of hydroxyl species on the electrode surface are responsible for the reconstruction of interfacial water structure and dynamic evolution of free water molecules from nearest to the electrode surface to above the gap region in the EDL, thereby leading to significantly increased water connectivity and hydrogen bond network. Our work reveals a new understanding of the surface intermediates in controlling the dynamic process of interfacial water and hydrogen bonding network in HOR electrocatalysis, and will guide rational design of advanced electrocatalysts through electrochemical interfacial engineering.

Standalone green hydrogen production powered by photovoltaic panels and solar atmospheric water harvesting hybrid system: Experimental investigation

The current study experimentally investigates the performance of a hybrid standalone solar system of atmospheric water harvesting (AWH) and solar photovoltaic powering electrolyzer for green water and green hydrogen production. The system prototype is designed, constructed, and tested under outdoor summer and winter climate conditions of Alexandria, Egypt at different operating and design enhancement conditions. Water electrolyzes concept for green hydrogen production system driven by a photovoltaic panel and silica gel absorption/desorption atmospheric water harvesting solar still concept with insertion of porous sheet metals for freshwater production is performed and evaluated. The results show a rise of the AWH freshwater production of (60% and 120%) and (146% and 260%) in summer and winter, respectively with the insertion of one and two porous metal sheets, respectively. The maximum rise of the AWH efficiency is 82% in summer and 53.4% in winter by using 2 porous metal sheets. The hydrogen production rate of the system in summer is higher than that of winter by about 25%. System efficiency is almost doubled when electrolyzer KOH concentration increased from 4 gm/kg to 12 gm/kg water. The average daily system efficiency of the AWH, electrolyzer, and overall system reaches 11.6%, 65.1%, and 2.6% when operating at a KOH concentration of 12 gm/kg with two porous metal sheets. The study contributes to achieving mainly SDG goals 6, 7, and 13.

Portable dual-functional hygroscopic device for efficient atmospheric water harvesting and hydrogen production in diverse environments

Developing integrated functional atmospheric water harvesting and hydrogen production devices based on cost-effective porous carbon materials is crucial for advancing their implementation and addressing multiple environmental challenges. Here, we fabricate a dual-functional hygroscopic composite device (HCD) under mild conditions, capable of obtaining clean water and hydrogen using sunlight and atmospheric moisture. The hierarchical HCD is designed as an ideal solar absorber by incorporating polyvinyl alcohol hydrogel into macroporous carbon and hosting dispersed LiCl and NiCoP10 catalyst. The HCD features hygroscopic and dual-functional photothermal interfaces with kinetic differentiation, exhibiting excellent machinability, high light absorptivity, optimized hygroscopic components, and favorable water evaporation enthalpy. This design, combined with a customized strategy, ensures consistently efficient performance of HCD, achieving a notable daytime water production performance of 3.89 kg·m−2·d−1 at a low total cost of 27.68 $·kg−1·d. The HCD can catalyze ammonia borane hydrolysis to generate hydrogen in various environments including cold and water-scarce conditions. Furthermore, the HCD shows potential for hydrogen energy system, achieving an open circuit voltage output ranging from 0.41 to 0.493 V. The miniaturized HCD flexibly provides a comprehensive solution for water and energy applications in complex environments, with significant potential for widespread implementation.

Estimation of the ratio of exchangeable organically bound hydrogen to total organically bound hydrogen in flatfish flesh.

The exchangeability of hydrogen atoms within organic molecules in vivo with ambient water hydrogen is uncertain. We assessed this by administrating the tracer deuterium to the fish. Flatfish were retained in deuterium-elevated seawater for 48h, and the deuterium-to-hydrogen (D/H) ratios in the flesh samples were measured. Rapid in vivo equilibration between exchangeable organically bound hydrogen (Ex-OBH) and tissue-free water (TFW) hydrogen was indicated by the linear relationship between the D/H ratios of total organically bound hydrogen (t-OBH) and TFW. The estimated ratio of Ex-OBH to t-OBH (fe) in vivo was 7.2±0.0%, while there was no in vivo production rate of non-exchangeable organically bound deuterium (Nx-OBD). In contrast to this estimation of no production of Nx-OBD in vivo, the D/H values of Nx-OBH measured by equilibration in vitro increased, consequently reducing the value of fe in vitro to some extent compared to that of fe in vivo. This indicated that a certain portion of Ex-OBH in vivo was not exchangeable during the equilibration in vitro.

Change of Hydrogen in Heavy Water and Activation of Unsaturated Fatty Acid by Specially Processed Water

Change of Hydrogen in Heavy Water and Activation of Unsaturated Fatty Acid by Specially Processed Water

Contribution of Copper Slag to Water Treatment and Hydrogen Production by Photocatalytic Mechanisms in Aqueous Solutions: A Mini Review.

Hydrogen has emerged as a promising energy carrier, offering a viable solution to meet our current global energy demands. Solar energy is recognised as a primary source of renewable power, capable of producing hydrogen using solar cells. The pursuit of efficient, durable, and cost-effective photocatalysts is essential for the advancement of solar-driven hydrogen generation. Copper slag, a by-product of copper smelting and refining processes, primarily consists of metal oxides such as hematite, silica, and alumina. This composition makes it an attractive secondary resource for use as a photocatalyst, thereby diverting copper slag from landfills and generating 0.113 μmol/g h of hydrogen, as noted by Montoya. This review aims to thoroughly examine copper slag as a photocatalytic material, exploring its chemical, physical, photocatalytic, and electrochemical properties. Additionally, it evaluates its suitability for water treatment and its potential as an emerging material for large-scale solar hydrogen production.

Inferring the existence of hydrogen bonds directly from statistical analysis of molecular dynamics trajectories.

As a demonstration of how fundamental chemical concepts can be gleaned from data using machine learning methods, we demonstrate the automated detection of hydrogen bonds by statistical analysis of molecular dynamics trajectories. In particular, we infer the existence and nature of electrostatically driven noncovalent interactions by examining the relative probability of supramolecular configurations with and without electrostatic interactions. Then, using Laplacian eigenmaps clustering, we identify hydrogen bonding motifs in hydrogen fluoride, water, and methanol. The hydrogen bonding motifs that we identify support traditional geometric criteria.

Dual functionality of cathode microporous layers: Reducing hydrogen permeation and enhancing performance in proton exchange membrane water electrolyzers

Hydrogen permeation and cell performance are critical factors for the safe and efficient operation of proton exchange membrane (PEM) water electrolysis. In this study, the effects of a cathode microporous layer (MPL) on water transport, hydrogen permeation, and cell performance in a proton exchange membrane water electrolyzer (PEMWE) were investigated. Results reveal that adding an MPL between the catalyst layer (CL) and the porous transport layer (PTL) at the cathode reduces interfacial contact resistance by approximately 60 % under 400 N cm−2, leading to superior performance. The wettability of the MPL plays a crucial role in water transport and hydrogen permeation in PEMWEs. The hydrophobic MPL-P-CB4, which uses polytetrafluoroethylene (PTFE) as a binder with a carbon black (CB) loading of 4 mgCB cm−2, enhances the crossover of water and hydrogen from the cathode to the anode through back diffusion, exceeding the technical safety criterion of 2 vol% H2 in the anode product gas (50 % lower explosion limit) at 2.0 A cm−2. However, the hydrophilic MPL with Nafion ionomers as binders (MPL-N-CB4) facilitates efficient removal of water and hydrogen from the cathode CL to the cathode flow field via capillary pressure, resulting in only 0.2 vol% H2 in O2 at 2.0 A cm−2. Consequently, a hydrophilic MPL is optimal for achieving superior performance and low-hydrogen-crossover in a PEMWE cathode. This study provides valuable insights for designing the PTL/CL interface in next-generation PEMWE cathodes.

Leidenfrost effect in the flash vaporization of hydrogen peroxide and water mixtures

The Leidenfrost effect, a phenomenon where a droplet levitates on a heated surface due to rapid vaporization, has been extensively studied with various liquids. However, the behavior of binary mixtures, specifically those involving hydrogen peroxide (H2O2) and water, remains relatively unexplored. This study investigates such mixtures, focusing on the ejection dynamics of secondary droplets under different temperatures and solution concentrations. High-speed imaging is used to capture the evolution of droplets upon impacting a hot surface. The results reveal a significant increase in droplet fragmentation and ejection with increasing temperature and hydrogen peroxide concentration. Droplet ejection volume increased by a factor of 2.5 when the temperature was 60 °C over the Leidenfrost point, while it increased by a factor of 1.7 when comparing a solution of 10% wt. H2O2 up to a concentration of 50%. A comprehensive analysis of the observed phenomena is proposed. The impact of hydrogen peroxide's thermal decomposition on systems such as H2O2 vapor decontamination enclosures is revealed. The main difficulty in obtaining highly concentrated H2O2 gas is attributed to the Leidenfrost effect ejecting secondary droplets.

Molecular Interactions and Structural Transformations in Water Complexes with Azoles in Solid Films: IR and DFT Study

AbstractAzoles are widely used as bioactive substances, herbicides, catalysts, corrosion inhibitors, polymeric compositors, organometallic ligands, and optical elements’ components. The interaction with water plays a crucial role in many applications of azoles. The objective of this study is to observe the molecular interaction and structural transformations of 1,2‐ and 1,3‐diazoles’, 1,2,3‐ and 1,2,4‐triazoles’ complexes with water molecules. We have selected the most valuable for application and theoretical interest azoles with different molecular structures, which have allowed us to consider the basic features of their aqueous complexes. We used the IR study method allowing to fix water intermediates in the solid phase. We have also employed the hybrid B3LYP functional DFT method with GD3BJ dispersion correction. At the cluster formation, the hydrogen atom transfer arises, providing a labile spatial arrangement of the water system. The formation of azoles’ complexes with a hydronium ion having relatively low binding energy allows the reshaping of the complexes’ structure at the hydrogen atom cluster‐to‐cluster transition. The complex formation is accompanied by the hydrogen atom transfer with the participation of both water and azole hydrogen atoms. This transfer provides the mobile spatial arrangement of clusters and hydrogen atom transition from donor to acceptor centers.

Hydrogen Spillover-Bridged Interfacial Water Activation of WCx and Hydrogen Recombination of Ru as Dual Active Sites for Accelerating Electrocatalytic Hydrogen Evolution.

Tungsten carbide (WCx) is a promising alternative to platinum catalysts for hydrogen evolution reaction (HER). However, strong tungsten-hydrogen bond hinders hydrogen desorption while favoring H+ reduction, thus limiting HER kinetics. Inspired by the phenomenon of hydrogen spillover in heterogeneous catalysis, a ruthenium (Ru) doped-driven activated hydrogen migration from WCx surface to Ru is reported. This approach achieved high activity with an ultralow overpotential of 9.0mV at 10 mA·cm-2 and superior stability at an industrial-grade current density of 1.0 A·cm-2 @ 1.65V. In situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS)and operando electrochemical impedance spectra revealed that this exceptional hydrogen production-which surpasses that of previously reported Pt/C catalysts-is attributable to the outstanding ability of WCx to induce water dissociation and hydrogen spillover from WCx to Ru surface. During the HER process, the rigid interfacial water network negatively affected the HER efficiency under alkaline conditions. The WCx sites disrupted this rigid structure, facilitating the contact between activated hydrogen (H*) and WCx sites. Subsequently, H* migrates to Ru surface, where hydrogen recombination occurs to produce H2. This work paves a new avenue for the construction of coupled catalysts at the atomic scale to facilitate HER electrocatalysis.