Redistribution Of Electron Density Research Articles

Automated iterative Csp3-C bond formation.

Fully automated synthetic chemistry would substantially change the field by providing broadon-demandaccess to small molecules. However, the reactions that can be run autonomously are still limited. Automating the stereospecific assembly of Csp3-C bonds would expand access to many important types offunctional organic molecules1. Previously, methyliminodiacetic acid (MIDA) boronates were used to orchestrate the formation of Csp2-Csp2 bonds and were effective building blocks for automating the synthesis of many small molecules2, but they are incompatible with stereospecific Csp3-Csp2 and Csp3-Csp3 bond-forming reactions3-10. Here we report that hyperconjugative and steric tuning provide a new class of tetramethyl N-methyliminodiacetic acid (TIDA) boronates that are stable to these conditions. Charge density analysis11-13 revealed that redistribution of electron density increases covalency of the N-B bond and thereby attenuates its hydrolysis. Complementary steric shielding of carbonyl π-faces decreases reactivity towards nucleophilic reagents. The unique features of the iminodiacetic acid cage2, which are essential for generalized automated synthesis, are retained by TIDA boronates. This enabled Csp3 boronate building blocks to be assembled using automated synthesis, including the preparation of natural products through automated stereospecific Csp3-Csp2 and Csp3-Csp3 bond formation. These findings will enable increasingly complex Csp3-rich small molecules to be accessed via automated assembly.

Redistribution of electronic density in channels of metal–Organic frameworks for high-performance quasi-solid lithium metal batteries

Metal-organic frameworks (MOFs) have attracted intensive interests as solid electrolytes (SEs) due to their talents in facilitating ion transport and chemical tunability. Developing functional MOFs-based conductors with better capacity for ion transport is greatly favored for solid-state batteries (SSBs). Inspired by the function of electron-withdrawing fluorine for both ion transport and regulating solid electrolyte interphase (SEI) formation, herein, we designed and synthesized two Ce-MOFs (Ce-UiO-66-4F and Ce-UiO-66-4Cl) constructed with halogen-decorated ligands. Both the simulated calculation and experimental results show that the exposed -F or -Cl functional groups in pores can regulate the electron-distribution property in channels and promote ions transport, achieving high ionic conductivity (2.16 × 10−4 S cm−1 at room temperature), wide electrochemical window (4.8 V) and lower interfacial impedance. Moreover, such halogen-decorated MOFs can participate the electrochemical formation of SEI and suppress the growth of lithium dendrites. Benefiting from these advantages, the assembled SSBs exhibit high performances even under high-voltage and high-loading conditions. This work thus provides a universal strategy for developing bifunctional MOFs for promoting ion-conductivity and regulating SEI formation.

A bonding evolution theory study of the reaction between methylidyne radical, CH(X2Π), and cyclopentadiene, C5H6

AbstractIn the present work, bonding evolution theory (BET) is applied to gain insight about the complex reaction between methylidyne radical, CH (X2Π) and cyclopentadiene, C5H6. The novelty of this work is that all reaction pathways take place in the doublet electronic state and an unpaired electron is always present. Therefore, taking the aforementioned reaction as explicative example, we have shown how to apply the BET tool to these kinds of open‐shell systems, by splitting the wavefunctions into the corresponding alpha and beta parts. As an added value, we have included a point‐by‐point description of the algorithm we use to make it available for the readers. Hence, a complete analysis of bond breaking/forming and charge redistribution along the multi‐channels connecting reactants to products via the transition states and intermediates is presented. We show how the BET brings about the representation of the electronic flow in complex molecular rearrangements like the one herein studied, yielding a transparent rationalization based on the electron density redistribution. The present study allows us to conclude that along the different processes giving rise to the benzene product, the breaking of a CC sigma bond initiates the electronic rearrangement in two cases, but not in the third one. The last step in these processes can be described as an initial weakening of the CH bond with a quasi‐hydride formation and a final retro‐transfer of electrons from the quasi‐hydride to the CH bond. On the other hand, in the way to the fulvene product, the breaking of the CC sigma bond takes place after previous electronic redistribution. Neither the last step of the fulvene formation process nor the interesting H transfer described in the second one, can be explained without the wavefunction splitting technique herein detailed and exemplified.

Discretization and Encapsulation of Palladium inside the Cavity of Crown Ether within the Interlayer of Layered Double Hydroxide for Enhanced Activity: A Case Study with Hydrogenation Reaction

AbstractThe activity of the noble metal‐based heterogeneous catalysts is limited by weak metal–support interactions, aggregation, and low surface to volume (S/V) ratio. The activity can be augmented in many ways. Among them, the discretization of the active sites and redistribution of electron density around the metal atom is an important one. In this work, these two phenomena are studied concerning a model reaction, hydrogenation of p‐nitrophenol (p‐NP). Herein, 1,4,7,10,13‐pentaoxacyclopentadecane ether is introduced in the basal space of layered double hydroxide (LDH) to encapsulate noble Pd0 atom inside the cavity of the crown molecule strategically. The modified LDH (Pda‐ECC‐L0.10@in situ CoAl LDH) augments the properties, like, high S/V ratio and nonaggregation of active sites by forming nonagglomerative discrete catalytic (DNSC) sites within the cavity of crown ether in the basal space. The developed catalyst exhibits higher turnover frequency demonstrating the improved activity due to the formed DNSC sites and redistributes electron density around the Pd atoms by LDH layers and crown molecules. Thus, the present material synthesis route can be considered as a stand‐alone method for preparation of the supported sub‐nanometer noble metal catalyst with higher activity and can be exploited for reactions where noble metal catalyst are used.

Hollow Covalent Organic Framework Cages with Zn Ion‐Implantation Promoting Photocatalytic H2 Evolution

AbstractAbstract: Covalent organic frameworks (COFs) are emerging as a class of photocatalyst for solar energy utilization. The separation of photogenerated excitons in COFs is crucial for their photocatalytic performance. Herein, we report a strategy to tune the electronic structure of COFs by implanting Zn ions within the framework to facilitate the separation and utilization of the photoinduced charges. Zn ions are incorporated within the shell of hollow COF cages (Zn@H‐TpPa) by a sacrificial template method with a formation of hollow cages. The implantation of Zn ions within the framework results in a redistribution of electron density and an increment of the polarity of the COF, as evidenced by experimental and computational analyses, and thus contributes to the separation and transport of charge carries. The Zn@H‐TpPa shows enhanced photocatalytic H2 production efficiency as compared to TpPa. The results demonstrate a new way to optimize the electronic structure of COFs for photocatalysis.

Copper(I) halide complexes with n,n’-diallylthiomorpholinium chloride: synthesis and crystal structure

By means of alternating current electrochemical technique, basing on ethanolic solutions of CuCl 2 ·2H 2 O or CuBr 2 and N,N’-diallylthiomorpholinium chloride, the two isostructural s-complexes of [C 4 H 8 NS(C 3 H 5 ) 2 Cu Hal 2 ] composition were obtained in a single crystal form and characterized by X-ray single crystal method: sp. gr. P 2 1 / c , Z = 4, Hal = Cl ( І ) – a = 7.7763(4), b = 13.1892(5), c = 13.1761(6) Å, β = 103.470(5)°, V = 1314.2(1) Å 3 , r calc. = 1.611 g/сm 3 , m (MoK a ) = 2.20 mm −1 , q max. = 28.8°, 10141 measured, 2659 used reflections, R ( F 2 ) = 0.032, S = 1.07; Hal = 1,04Br/0,96Cl ( ІІ ) – a = 7.9771(3), b = 13.2391(5), c = 13.1422(5) Å, β = 103.942(4), V = 1347.1(1) Å 3 , r calc. = 1.80 g/см 3 , m (MoK a ) = 5.02 mm −1 , q max. = 29.0°, 21269 measured, 2772 used reflections, R ( F 2 ) = 0.027, S = 1.08. In the crystal structure of the studied compounds, the trigonal-pyramidal coordination environment of Cu(I) includes sulfur atoms of the organic cation and three chloride anions (compound I ) or chloride/bromide mixture (compound II ). Atoms occupying position Hal (2) perform a bridging function and connect individual coordination polyhedrons into dimeric topological units {L 2 Cu 2 Hal 4 }. These dimers through hydrogen bonding are linked into a three-dimensional framework. None of the available allylic groups of the N,N’-diallylthiomorpholinium cation are coordinated to the copper(I) ion. In our opinion, this feature of the discussed crystal structure of [(C 4 H 8 NS(C 3 H 5 ) 2 )Cu Hal 2 ] compounds is explained by the influence of competition between the sulfur atom and the C=C bond of the allyl group of the cation during complexation in solution and the redistribution of electron density in the crystal structure of solid compounds due to hydrogen contacts C–H… Hal . Keywords : N,N’-diallylthiomorpholinium; copper(І); s-complexes; crystal structure.

Localized Electron Density Redistribution in Fluorophosphate Cathode: Dangling Anion Regulation and Enhanced Na‐Ion Diffusivity for Sodium‐Ion Batteries (Adv. Funct. Mater. 4/2022)

Anionic Doping In article number 2109694, Hong Yu, Cheng-Feng Du, Xing-Long Wu, and co-workers develop Cl-doped Na3V2(PO4)2O2F (NVPO2−xClxF) as superior cathode material for sodium-ion batteries. In NVPO2−xClxF, Cl doping tunes the electronic structure and causes the electron redistribution on vanadium center/dangling anions. As a result, a revised redox behavior of vanadium and increased Na+- diffusivity/electrochemical properties are achieved.

Tracing electron density changes in langbeinite under pressure.

Pressure is well known to dramatically alter physical properties and chemical behaviour of materials, much of which is due to the changes in chemical bonding that accompany compression. Though it is relatively easy to comprehend this correlation in the discontinuous compression regime, where phase transformations take place, understanding of the more subtle continuous compression effects is a far greater challenge, requiring insight into the finest details of electron density redistribution. In this study, a detailed examination of quantitative electron density redistribution in the mineral langbeinite was conducted at high pressure. Langbeinite is a potassium magnesium sulfate mineral with the chemical formula [K2Mg2(SO4)3], and crystallizes in the isometric tetartoidal (cubic) system. The mineral is an ore of potassium, occurs in marine evaporite deposits in association with carnallite, halite and sylvite, and gives its name to the langbeinites, a family of substances with the same cubic structure, a tetrahedral anion, and large and small cations. Single-crystal X-ray diffraction data for langbeinite have been collected at ambient pressure and at 1 GPa using a combination of in-house and synchrotron techniques. Experiments were complemented by theoretical calculations within the pressure range up to 40 GPa. On the basis of changes in structural and thermal parameters, all ions in the langbeinite structure can be grouped into 'soft' (potassium cations and oxygens) and 'hard' (sulfur and magnesium). This analysis emphasizes the importance of atomic basins as a convenient tool to analyse the redistribution of electron density under external stimuli such as pressure or temperature. Gradual reduction of completeness of experimental data accompanying compression did not significantly reduce the quality of structural, electronic and thermal parameters obtained in experimental quantitative charge density analysis.

Localized Electron Density Redistribution in Fluorophosphate Cathode: Dangling Anion Regulation and Enhanced Na‐Ion Diffusivity for Sodium‐Ion Batteries

AbstractPolyanionic transition metal polyphosphate (TMPO)‐type Na3V2(PO4)2O2F (NVPO2F) is promising as cathode for large‐scale sodium‐ion batteries (SIBs) on account of its considerable capacity and highly stable structure. However, the redox of transition metal and phase transitions along with the (de)intercalation of Na+ lead to its slow kinetics and inferior rate performance. Herein, chlorine (Cl) is applied as a heteropical dopant to obtain Cl‐doped NVPO2F (NVPO2−xClxF) cathode material for SIBs. Density functional theory investigation reveals that Cl doping tunes the localized electronic density and structure in NVPO2F lattice, causing the electron redistribution on vanadium center and dangling anions. Hence, the NVPO2−xClxF cathode exhibits a revised redox behavior of vanadium for Na+ extraction/insertion, increases Na+ diffusion rate, as well as lowers charge transfer resistance. A Na+ storage mechanism of reversible transformations between three phases and V4+/V5+ redox couple for NVPO2−xClxF cathode is verified. The NVPO2−xClxF cathode reveals a high rate capacity of ≈63 mAh g−1 at 30C and great cycle stability over 1000 cycles at 10C. More importantly, outstanding rate property (314 Wh kg−1 at 5850 W kg−1) and cycling capability are obtained for the NVPO2−xClxF//3DC@Se full cell. This study demonstrates a brand‐new strategy to prepare advanced cathode materials for superior SIBs.

Spectral profiling, structural, molecular docking and ELF elucidation of bioactive molecule Benzoguanamine

• Computational reports disclose the presence of H- bonding. • Binding affinity of BG with anti-canceral proteins upholds that activity. • Drug likeness achieved to endorses new anti-canceral drug activity. Optimized geometry and vibrational wave numbers of the normal modes of Benzoguanamine (BG) have been investigated using Gaussian’09 at B1B95/6–31 G (d) level. Present work elucidates structural and spectral analysis of the title compound. Redistribution of electron density (ED) in various bonding and antibonding orbitals along with E(2) energies have been calculated by natural bond orbital (NBO) analysis to give clear evidence of stabilization originating from the hyper conjugation of various intra-molecular interactions. HOMO-LUMO analysis has been performed to analyze charge transfer interactions within the molecule. The chemical implication of the molecule was explained using ELF, LOL with contour maps. Molecular docking was performed with various target proteins inorder to confirm the biological activity of compound and drug likeness influences were designed to realize the biological assets of BG.

Selective Enhancement of SERS Spectral Bands of Salicylic Acid Adsorbate on 2D Ti3C2Tx-Based MXene Film

In this research, we have demonstrated that 2D Ti3C2Xn-based MXene (MXene) films are suitable for the design of surface-enhanced Raman spectroscopy (SERS)-based sensors. The enhanced SERS signal was observed for a salicylic acid molecule on Ti3C2Tx-based MXene film. Confirmation of the adsorption of the salicylic acid molecule and the formation of a salicylic acid–MXene complex were determined by experimental SERS-based spectral observations such as greatly enhanced out-of-plane bending modes of salicylic acid at 896 cm−1 and a band doublet at 681 cm−1 and 654 cm−1. Additionally, some other spectral features indicate the adsorption of salicylic acid on the MXene surface, namely, a redshift of vibrational modes and the disappearance of the carboxyl deformation spectral band at 771 cm−1. The determined enhancement factor indicates the value that can be expected for the chemical enhancement mechanism in SERS of 220 for out-of-plane vibrational modes. Theoretical modeling based on density functional theory (DFT) calculations using B3LYP/6311G++ functional were performed to assess the formation of the salicylic acid/MXene complex. Based on the calculations, salicylic acid displays affinity of forming a chemical bond with titanium atom of Ti3C2(OH)2 crystal via oxygen atom in hydroxyl group of salicylic acid. The electron density redistribution of the salicylic acid–MXene complex leads to a charge transfer effect with 2.2 eV (428 nm) and 2.9 eV (564 nm) excitations. The experimentally evaluated enhancement factor can vary from 220 to 60 when different excitation wavelengths are applied.

Unlocking the synergy of interface and oxygen vacancy by core-shell nickel phosphide@oxyhydroxide nanosheets arrays for accelerating alkaline oxygen evolution kinetics

Oxygen evolution reaction (OER) as a key process is of vital importance to sustainable and green hydrogen energy scenario. Its sluggish kinetics is tightly associated with stubborn O-O bond formation, where constructing stable superoxo/peroxo-like (O2)n− species (typically e.g. NiOO*) and activating them on the catalyst surfaces have been considered as one of most efficient strategies to accelerate oxygen evolution kinetics. Herein, we have purposely designed core-shell Ni5P4@NiOOH heterostructure nanosheet arrays, which are constructed by an in-situ electrochemical self-adaptive process of the corresponding Ni5P4 precursor, and therefore demonstrate a sharp rise in activation of NiOO* on surfaces by the synergy between interface and oxygen vacancy (Vo) created during OER. By the combination studies of contrast experiments with or without interface or oxygen vacancies and theoretical calculations, we find that the interface between Ni5P4 and amorphous NiOOH ultrathin layer can promote the redistribution of electron density on the catalyst surface and optimize the Gibbs free energy of multiple adsorbed intermediates, while the numerous Vo activates NiOO* species in the Ni5P4@NiOOH catalyst. The interface-Vo synergy therefore enables an ultralow overpotential of only 273 mV@50 mA cm−2 and a superior OER activity with up to 21- and 70-fold rise in kinetic current density under the overpotential of 270 mV over those of Ni(OH)2@NiOOH and NiO@NiOOH counterparts, respectively.

Ultrathin Fe2P nanosheet co-catalyst CdS nanorod: The promising photocatalyst with ultrahigh photocatalytic H2 production activity

Developing 2D ultra-thin materials as co-catalysts is an effective way to boost the photocatalytic activity of semiconductors, but it remains challenging to unveil the design principle. In this work, we prepared the ultrathin 2D Fe2P nanosheets with an average thickness of ca. 1.41 nm via the facile solvothermal method. Such 2D Fe2P nanosheets were used as co-catalyst to fabricate a 2D-1D type of Fe2P-CdS photocatalysts for visible-light-driven photocatalytic H2 evolution. Experimental and first-principles results show that the Fe2P nanosheets co-catalyst with metallic characteristics modified CdS nanorods to form a 2D-1D heterointerface with strong ionic interaction, which induces the electron density redistribution in Fe2P-CdS composite, resulting in a lower recombination rate of carriers. Moreover, Fe2P nanosheets also reduce the overpotential for hydrogen evolution, provide abundant active sites and enhance H2O adsorption, significantly promoting the release of H2. As a result, the 11 wt% Fe2P-CdS exhibited an extremely high photocatalytic performance (207.82 mmol·h−1·g−1), which is more than 78 times higher than that of the pristine CdS. This work demonstrates the potential of 2D Fe2P as a promising co-catalyst in photocatalysis and provides a useful guide on phosphide-based material designing.

Electronic structure and stability of hexanuclear complex [Cu6(hfa)4(dpm)4(OH)4

Interatomic interactions and charge state of atoms in hexanuclear complex [Cu6(hfa)4(dpm)4(OH)4] have been studied by the methods of quantum chemistry and X-ray photoelectron spectroscopy (XPS). The shape and energy position of the Cu2p3/2-lines indicate that all copper atoms state could be interpreted as Cu2+. It was also analyzed the quantum chemical and XPS data on atomic charge distribution for monoligandic bis-β-diketonate Cu(hfa)2 and Cu(dpm)2 complexes. The comparison of calculated and experimental data for monoligandic and hexanuclear complexes revealed the electronic density redistribution on the oxygen and copper atoms in 1 due to the charge transfer interaction between Cu(hfa)2- and Cu(dpm)-fragments with participation of the bridging OH-groups, which was confirmed by NBO analysis.

Dynamically Polarizable Force Fields for Surface Simulations via Multi-output Classification Neural Networks.

We present a general procedure to introduce electronic polarization into classical Molecular Dynamics (MD) force fields using a Neural Network (NN) model. We apply this framework to the simulation of a solid-liquid interface where the polarization of the surface is essential to correctly capture the main features of the system. By introducing a multi-input, multi-output NN and treating the surface polarization as a discrete classification problem, we are able to obtain very good accuracy in terms of quality of predictions. Through the definition of a custom loss function we are able to impose a physically motivated constraint within the NN itself making this model extremely versatile, especially in the modeling of different surface charge states. The NN is validated considering the redistribution of electronic charge density within a graphene based electrode in contact with an aqueous electrolyte solution, a system highly relevant to the development of next generation low-cost supercapacitors. We compare the performances of our NN/MD model against Quantum Mechanics/Molecular Dynamics simulations where we obtain a most satisfactory agreement.

Doping modification, defects construction, and surface engineering: Design of cost-effective high-performance electrocatalysts and their application in alkaline seawater splitting

The shortage of pure-water and high-energy consumption of low-grade water treatments force the development of direct seawater-electrolysis. Herein, experiments and calculations reveal the redistribution of electron density due to doping and vacancy defects, and confirm the contribution of multiple active sites to the dissociation and desorption of water with favorable thermodynamics. The Co/Ni-doped defect-rich Cu-based oxides (CNC-MO) nanoarrays promote water dissociation and hydrogen desorption via bonding with *OH and *H respectively, thus accelerating hydrogen evolution reaction (HER). The Ni/Co-doped defect-rich Cu-based sulfides (CNC-MS) nanorods modulate the adsorption state of *OH while effectively adsorbing and isolating *H to improve the oxygen evolution reaction (OER) kinetics. Asymmetric electrodes can achieve alkaline seawater electrolysis with 100 mA cm −2 at a voltage of 1.61 V. The corrosion resistance, high efficiency, and selectivity of electrodes can remain stable for 1200 h in a saline-alkali medium, and then gradually decline with sites blocking and deep corrosion. The aim of this work is to propose design strategies for the construction of high-performance electrocatalysts for seawater splitting while balancing multiple factors such as cost, efficiency, and durability. ● CuO x containing OVs and doped Ni/Co as dual sites accelerate H 2 O dissociation and H desorption to improve HER activity. ● CuS x accelerates proton-electron transfer, while SVs with Ni kinetically lower the energy barrier of OER intermediates. ● Active surface textures constructed by alloying and anodization greatly improve the catalytic active area of electrodes. ● Hierarchical layers composed of internal oxides and surface sulfides exhibit good resistance to COR and halide attack. ● Overall seawater splitting can be steady performed at 1.61 V with 100 mA cm −2 for more than 1200 h.

Estimation of ground and excited-state dipole moments of three symmetric carbocyanine dyes via the analysis of luminescence properties

The solvatochromic effect of solvents on the absorption and fluorescence spectra of three carbocyanine dyes, namely 1,1′,3,3,3′,3′-hexamethylindocarbocyanine chloride (HIC); 1,1′,3,3,3′,3′-hexamethylindodicarbocyanine iodide (HIDC); and 3,3′-diethyloxadicarbocyanine iodide (DODC), have been investigated. The experimental ground and excited-state dipole moments of the dyes have been estimated via the well-known models by Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet, and the Dimroth-Reichardt’s empirical model. The influence of the solvation effect on the luminescence quantum yields was also examined and a strong correlation between the luminescence quantum yield values and the solvent viscosity was established. The fluorescence signal enhancement sensitivities between dyes were compared based on the Förster-Hoffmann equation. DFT and TDDFT calculations at the CAM-B3LYP/6-31G(d,p) level of theory were performed for the analysis of the nature of the electron transitions in absorption and excitation processes. Six phases different in polarity were considered during these computations, namely the gas, toluene, chloroform, acetone, methanol, and water. Transition electron density plots, Mulliken atomic partial charges, and Mayer bond orders were used for the analysis of the redistribution of electron density upon excitation. The specific behavior of the dyes in the glycerol medium was interpreted via the analysis of non-covalent interactions between the dye and glycerol molecules in terms of the reduced density gradient method.

Ultrafast X-ray scattering offers a structural view of excited-state charge transfer

Intramolecular charge transfer and the associated changes in molecular structure in N,N'-dimethylpiperazine are tracked using femtosecond gas-phase X-ray scattering. The molecules are optically excited to the 3p state at 200 nm. Following rapid relaxation to the 3s state, distinct charge-localized and charge-delocalized species related by charge transfer are observed. The experiment determines the molecular structure of the two species, with the redistribution of electron density accounted for by a scattering correction factor. The initially dominant charge-localized state has a weakened carbon-carbon bond and reorients one methyl group compared with the ground state. Subsequent charge transfer to the charge-delocalized state elongates the carbon-carbon bond further, creating an extended 1.634 Å bond, and also reorients the second methyl group. At the same time, the bond lengths between the nitrogen and the ring-carbon atoms contract from an average of 1.505 to 1.465 Å. The experiment determines the overall charge transfer time constant for approaching the equilibrium between charge-localized and charge-delocalized species to 3.0 ps.

Regulating the Electronic Structure and Active Sites in Ni Nanoparticles by Coating N-Doped C Layer and Porous Structure for an Efficient Overall Water Splitting.

Developing efficient and robust bifunctional electrocatalysts are in high demand for the production of hydrogen by water splitting. Engineering an electrocatalyst with a regulated electronic structure and abundant active sites is an effective way to enhance the electrocatalytic activity. Herein, N-doped C-encapsulated Ni nanoparticles (Ni@N-C) are synthesized through a traditional hydrothermal reaction, followed by pyrolyzing under an Ar/H2 atmosphere. The electrochemical measurements and density functional theory (DFT) calculations reveal that the electron transfer between the Ni core and the N-C shell induces the electron density redistribution on Ni@N-C, which directly promotes the adsorption and desorption of H* on the N-doped carbon (N-C) layer and thus dramatically enhances hydrogen production. Taking advantage of the porous spherical structure and the synergistic effects between Ni and N-doped carbon (N-C) layer, we obtain a Ni@N-C electrocatalyst that exhibits remarkable hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity with low overpotentials of 117 and 325 mV, respectively. Impressively, the assembled cell using Ni@N-C as both anode and cathode exhibits excellent activity as well as stable cyclability for over 12 h.

Controlling the Sorption Activity of Clinoptilolites with Mechanical Activation

We have studied the effect of the phase composition of clinoptilolite rocks and the specific mechanical energy delivered to samples in a vibratory attritor on their physical properties and oil sorption capacity. Mechanical activation in air has been shown to cause amorphization, transformation of “zeolitic” water into “hydroxyl” water, and an electron density redistribution in the Al–O–Si framework of the clinoptilolite. Milling to a specific mechanical energy of 2.16 kJ/g leads to the formation of molecularly dense aggregates, which shows up as a decrease in specific surface area, demonstrated by BET measurements. An optimal approach for raising oil sorption capacity is mechanical activation of clinoptilolite–stilbite rock in air to a specific mechanical energy of 5.04 kJ/g.