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.

Hollow Ni Mo-based nitride heterojunction with super-hydrophilic/aerophobic surface for efficient urea-assisted hydrogen production

Hydrogen evolution reaction(HER)and urea oxidation reaction(UOR)are key reactions of the watercycling associated catalytic process/device.The design of catalysts with a super-hydrophilic/aerophobic structure and optimized electron distribution holds great promise.Here,we have designed a threedimensional(3D)hollow Ni/NiMoN hierarchical structure with arrayed-sheet surface based on a onepot hydrothermal route for efficient urea-assisted HER based on a simple hydrothermal process.The Ni/NiMoN catalyst exhibits super-hydrophilic/aerophobic properties with a small droplet contact angle of 6.07°and an underwater bubble contact angle of 155.7°,thus facilitating an escape of bubbles from the electrodes.Density functional theory calculations and X-ray photoelectron spectroscopy results indicate the optimized electronic structure at the interface of Ni and NiMoN,which can promote the adsorption/desorption of reactants and intermediates.The virtues combining with a large specific surface area endow Ni/NiMoN with efficient catalytic activity of low potentials of 25 mV for HER and 1.33 V for UOR at10 mA cm^(-2).The coupled HER and UOR system demonstrates a low cell voltage of 1.42 V at 10 mA cm^(-2),which is approximately 209 mV lower than water electrolysis.

A concise review on surface and structural modification of porous zeolite scaffold for enhanced hydrogen storage

Investigating zeolites as hydrogen storage scaffolds is imperative due to their porous nature and favorable physicochemical properties.Nevertheless,the storage capacity of the unmodified zeolites has been rather unsatisfactory(0.224%-1.082%(mass))compared to its modified counterpart.Thus,the contemporary focus on enhancing hydrogen storage capacities has led to significant attention towards the utilization of modified zeolites,with studies exploring surface modifications through physical and chemical treatments,as well as the integration of various active metals.The enhanced hydrogen storage properties of zeolites are attributed to the presence of aluminosilicates from alkaline and alkaline-earth metals,resulting in increased storage capacity through interactions with the charge density of these aluminosilicates.Therefore,there is a great demand to critically review their role such as well-defined topology,pore structure,good thermal stability,and tunable hydrophilicity in enhanced hydrogen storage.This article aimed to critically review the recent research findings based on modified zeolite performance for enhanced hydrogen storage.Some of the factors affecting the hydrogen storage capacities of zeolites that can affect the rate of reaction and the stability of the adsorbent,like pressure,structure,and morphology were studied,and examined.Then,future perspectives,recommendations,and directions for modified zeolites were discussed.

Understanding the catalysis of chromium trioxide added magnesium hydride for hydrogen storage and Li ion battery applications

This study explores how the chemical interaction between magnesium hydride(MgH_(2))and the additive CrO_(3) influences the hydrogen/lithium storage characteristics of MgH_(2).We have observed that a 5 wt.%CrO_(3) additive reduces the dehydrogenation activation energy of MgH_(2) by 68 kJ/mol and lowers the required dehydrogenation temperature by 80℃.CrO_(3) added MgH_(2) was also tested as an anode in an Li ion battery,and it is possible to deliver over 90%of the total theoretical capacity(2038 mAh/g).Evidence for improved reversibility in the battery reaction is found only after the incorporation of additives with MgH_(2).In depth characterization study by X-ray diffraction(XRD)technique provides convincing evidence that the CrO_(3) additive interacts with MgH_(2) and produces Cr/MgO byproducts.Gibbs free energy analyses confirm the thermodynamic feasibility of conversion from MgH_(2)/CrO_(3) to MgO/Cr,which is well supported by the identification of Cr(0)in the powder by X ray photoelectron spectroscopy(XPS)technique.Through high resolution transmission electron microscopy(HRTEM)and energy dispersive spectroscopy(EDS)we found evidence for the presence of 5 nm size Cr nanocrystals on the surface of MgO rock salt nanoparticles.There is also convincing ground to consider that MgO rock salt accommodates Cr in the lattice.These observations support the argument that creation of active metal–metal dissolved rock salt oxide interface may be vital for improving the reactivity of MgH_(2),both for the improved storage of hydrogen and lithium.

A general synthetic strategy for N, P co-doped graphene supported metal-rich noble metal phosphides for hydrogen generation

The exploitation of electrocatalysts with high activity and durability for HER is desirable for future energy systems,but it is still a challenge.NMPs have attracted increasing attentions,but the preparation process often needs toxic regents or dangerous reaction conditions.Herein,we develop a general green method to fabricate metal-rich NMPs anchored on NPG through pyrolyzing DNA cross-linked complexes.The obtained Ru_(2) P-NPG exhibits an ultrasmall overpotential of 7 mV at 10 mA cm^(2) and ultralow Tafel slope of 33 mV dec^(-1) in 1.0 mol L?1 KOH,even better than that of commercial Pt/C.In addition,Ru 2 P-NPG also shows low overpotentials of 29 and 78 mV in 0.5 mol L^(-1) H_(2)SO_(4) and 1.0 mol L^(-1) PBS,respectively.The superior activity can be attributed to the ultrafine dispersion of Ru 2 P nanoparticles for more accessible sites,more defects formed for abundant active sites,the two-dimensional plane structure for accelerated electron transfer and mass transport,as well as the regulation of electron distribution of the catalyst.Moreover,the synthetic method can also be applied to prepare other metal-rich noble metal phosphides(Pd_(3)P-NPG and Rh_(2)P-NPG),which also exhibits high activity for HER.This work provides an effective strategy for designing NMP-based electrocatalysts.

Effect of Different Morphologies Induced by Solvent on ZIF-67 Derived Co@NC for Catalytic Phenol Hydrogenation

The Co@NC catalysts with different morphologies were prepared by two step process,solvent control growth and pyrolysis method.The polyhedral Co@NC-67P-450 catalyst has a relatively high CoNx content and exhibits excellent phenol hydrogenation activity(conversion 96.9%)at 160℃,3 MPa,which is higher than that of leaf shaped Co@NC-67L-450 catalyst(conversion 75.4%).We demonstrated Co_(3)O_(4)was reduced to the Co^(0)during the reaction.Moreover,CoNx species contribute to the superior hydrogenation activity of phenol.The Co-based catalysts can be easily recovered through the magnetic separation and performed the high stability.

The effect of the carbon components on the performance of carbonbased transition metal electrocatalysts for the hydrogen evolution reaction

The hydrogen evolution reaction(HER)is a promising way to produce hydrogen,and the use of non-precious metals with an excellent electrochemical performance is vital for this.Carbon-based transition metal catalysts have high activity and stability,which are important in reducing the cost of hydrogen production and promoting the development of the hydrogen production industry.However,there is a lack of discussion regarding the effect of carbon components on the performance of these electrocatalysts.This review of the literature discusses the choice of the carbon components in these catalysts and their impact on catalytic performance,including electronic structure control by heteroatom doping,morphology adjustment,and the influence of self-supporting materials.It not only analyzes the progress in HER,but also provides guidance for synthesizing high-performance carbon-based transition metal catalysts.

Accelerating the practical application of MOFs for hydrogen storage-from performance-driven to application-oriented

Metal–organic frameworks(MOFs)are highly promising porous materials known for their exceptional porosity,extensive surface area,and customizable pore structures,making them an ideal solution for hydrogen storage.However,most MOFs research remains confined to the laboratory,lacking practical applications.To address this,the author proposes a shift towards practical applications,the creation of a comprehensive MOFs database,alignment of synthesis with practical considerations,and diversification of MOFs applications.These steps are crucial for harnessing the full potential of MOFs in real-world energy challenges.

Structure Regulation of Electric Double Layer via Hydrogen Bonding Effect to Realize High-Stability Lithium-Metal Batteries

The interfacial chemistry of solid electrolyte interphases(SEI)on lithium(Li)electrode is directly determined by the structural chemistry of the electric double layer(EDL)at the interface.Herein,a strategy for regulating the structural chemistry of EDL via the introduction of intermolecular hydrogen bonds has been proposed(p-hydroxybenzoic acid(pHA)is selected as proof-of-concept).According to the molecular dynamics(MD)simulation and density functional theory(DFT)calculation results,the existence of hydrogen bonds realizes the anion structural rearrangement in the EDL,reduces the lowest unoccupied molecular orbital(LUMO)energy level of anions in the EDL,and the number of free solvent molecules,which promotes the formation of inorganic species-enriched SEI and eventually achieves the dendrite-free Li deposition.Based on this strategy,Li‖Cu cells can stably run over 185 cycles with an accumulated active Li loss of only 2.27 mAh cm^(-2),and the long-term cycle stability of Li‖Li cells is increased to 1200 h.In addition,the full cell pairing with the commercial LiFePO_(4)(LFP)cathodes exhibits stable cycling performance at 1C,with a capacity retention close to 90%after 200 cycles.

Marrying luminescent metal nanoclusters to C_(3)N_(4) for efficient photocatalytic hydrogen peroxide production

Photocatalytic oxygen(O_(2))reduction has been considered a promising method for hydrogen peroxide(H_(2)O_(2))production.However,the poor visible light harvesting and low-efficient separation and generation of charge carriers of conventional photocatalysts strongly limited their photocatalytic H_(2)O_(2) generation performance.Herein,we design a highly efficient photocatalyst in this work by marrying luminescent gold-silver nanoclusters(AuAg NCs)to polyethyleneimine(PEI)modified C_(3)N_(4)(C3N4-PEI).The key design in this work is the utilization of highly luminescent AuAg NCs as photosensitizers to promote the generation and separation of charge carriers of C_(3)N_(4)-PEI,thereby ultimately producing abundant e−for O_(2) reduction under visible light illumination(λ≥400 nm).As a result,the as-designed photocatalyst(C3N4-PEI-AuAg NCs)exhibits excellent photocatalytic activity with an H_(2)O_(2) production capability of 82μM in pure water,which is 3.5 times higher than pristine C_(3)N_(4)(23μM).This interesting design provides a paradigm in developing other high-efficient photocatalysts for visible-light-driven H_(2)O_(2) production.

General approach for atomically dispersed precious metal catalysts toward hydrogen reaction

As a carbon-free energy carrier,hydrogen has become the pivot for future clean energy,while efficient hydrogen production and combustion still require precious metal-based catalysts.Single-atom catalysts(SACs)with high atomic utilization open up a desirable perspective for the scale applications of precious metals,but the general and facile preparation of various precious metal-based SACs remains challenging.Herein,a general movable printing method has been developed to synthesize various precious metal-based SACs,such as Pd,Pt,Rh,Ir,and Ru,and the features of highly dispersed single atoms with nitrogen coordination have been identified by comprehensive characterizations.More importantly,the synthesized Pt-and Ru-based SACs exhibit much higher activities than their corresponding nanoparticle counterparts for hydrogen oxidation reaction and hydrogen evolution reaction(HER).In addition,the Pd-based SAC delivers an excellent activity for photocatalytic hydrogen evolution.Especially for the superior mass activity of Ru-based SACs toward HER,density functional theory calculations confirmed that the adsorption of the hydrogen atom has a significant effect on the spin state and electronic structure of the catalysts.

Defect-engineered two-dimensional transition metal dichalcogenides towards electrocatalytic hydrogen evolution reaction

Recently,two-dimensional transition metal dichalcogenides(TMDs)demonstrated their great potential as cost-effective catalysts in hydrogen evolution reaction.Herein,we systematically summarize the existing defect engineering strategies,including intrinsic defects(atomic vacancy and active edges)and extrinsic defects(metal doping,nonmetal doping,and hybrid doping),which have been utilized to obtain advanced TMD-based electrocatalysts.Based on theoretical simulations and experimental results,the electronic structure,intermediate adsorption/desorption energies and possible catalytic mechanisms are thoroughly discussed.Particular emphasis is given to the intrinsic relationship between various types of defects and electrocatalytic properties.Furthermore,current opportunities and challenges for mechanical investigations and applications of defective TMD-based catalysts are presented.The aim herein is to reveal the respective properties of various defective TMD catalysts and provide valuable insights for fabricating high-efficiency TMD-based electrocatalysts.

Novel ternary metals-based telluride electrocatalyst with synergistic effects of high valence non-3d metal and oxophilic Te for pH-universal hydrogen evolution reaction

Electrocatalyst designs based on oxophilic foreign atoms are considered a promising approach for developing efficient pH-universal hydrogen evolution reaction(HER)electrocatalysts by overcoming the sluggish alkaline HER kinetics.Here,we design ternary transition metals-based nickel telluride(Mo WNi Te)catalysts consisting of high valence non-3d Mo and W metals and oxophilic Te as a first demonstration of non-precious heterogeneous electrocatalysts following the bifunctional mechanism.The Mo WNi Te showed excellent HER catalytic performance with overpotentials of 72,125,and 182 mV to reach the current densities of 10,100,and 1000 mA cm^(-2),respectively,and the corresponding Tafel slope of 47,52,and 58 mV dec-1in alkaline media,which is much superior to commercial Pt/C.Additionally,the HER performance of Mo WNi Te is well maintained up to 3000 h at the current density of 100 mA cm^(-2).It is further demonstrated that the Mo WNi Te exhibits remarkable HER activities with an overpotential of 45 mV(31 mV)and Tafel slope of 60 mV dec-1(34 mV dec-1)at 10 mA cm^(-2)in neutral(acid)media.The superior HER performance of Mo WNi Te is attributed to the electronic structure modulation,inducing highly active low valence states by the incorporation of high valence non-3d transition metals.It is also attributed to the oxophilic effect of Te,accelerating water dissociation kinetics through a bifunctional catalytic mechanism in alkaline media.Density functional theory calculations further reveal that such synergistic effects lead to reduced free energy for an efficient water dissociation process,resulting in remarkable HER catalytic performances within universal pH environments.

A Mg alloy with no hydrogen evolution during dissolution

Hydrogen evolution is normally associated with the corrosion or dissolution of Mg alloys in aqueous solutions.This work studied the corrosion behavior of sputtered pure Mg,Mg82Zn18(at.%),Mg64Zn36(at.%),and pure Zn in 3.5%Na Cl solution.Mg64Zn36had(ⅰ)an amorphous microstructure with some nano-scale grains,(ⅱ)a corrosion rate substantially lower than that of pure Mg,and(ⅲ)no hydrogen evolution during corrosion or anodic dissolution,because the positive corrosion potential retarded the cathodic hydrogen evolution.This is a new route to prevent hydrogen evolution during Mg corrosion,which has never previously been realized.

Towards the selectivity distinction of phenol hydrogenation on noble metal catalysts

Selective hydrogenation of phenol to cyclohexanone is intriguing in chemical industry.Though a few catalysts with promising performances have been developed in recent years,the basic principle for catalyst design is still missing owing to the unclear catalytic mechanism.This work tries to unravel the mechanism of phenol hydro-genation and the reasons causing the selectivity discrepancy on noble metal catalysts under mild conditions.Results show that different reaction pathways always firstly converge to the formation of cyclohexanone under mild conditions.The selectivity discrepancy mainly depends on the activity for cyclohexanone sequential hy-drogenation,in which two factors are found to be responsible,i.e.the hydrogenation energy barrier and the competitive chemisorption between phenol and cyclohexanone,if the specific co-catalyzing effect of H 2 O on Ru is not considered.Based on the above results,a quantitative descriptor,E b(one/pl)/E a,in which E a can be further correlated to the d band center of the noble metal catalyst,is proposed by the first time to roughly evaluate and predict the selectivity to cyclohexanone for catalyst screening.

Efficient hydrogen peroxide production enabled by exploring layered metal telluride as two electron oxygen reduction reaction electrocatalyst

It is of great interest to develop the novel transition metal-based electrocatalysts with high selectivity and activity for two electron oxygen reduction reaction(2e^(-) ORR).Herein,the nickel ditelluride(NiTe_(2)) with layered structure was explored as the 2e^(-) ORR electrocatalyst,which not only showed the highest 2e^(-) selectivity more than 97%,but also delivered a slight activity decay after 5000 cycles in alkaline media.Moreover,when NiTe_(2) was assembled as the electrocatalyst in H-type electrolyzer,the on-site yield of H_(2)O_(2) could reach up to 672 mmol h^(-1)g^(-1) under 0.45 V vs.RHE.Further in situ Raman spectra,theoretical calculation and post microstructural analysis synergistically unveiled that such a good 2e^(-) ORR performance could be credited to the intrinsic layered crystal structure,the high compositional stability,as well as the electron modulation on the active site Ni atoms by neighboring Te atoms,leading to the exposure of active sites as well as the optimized adsorption free energy of Ni to –OOH.More inspiringly,such telluride electrocatalyst has also been demonstrated to exhibit high activity and selectivity towards 2e^(-) ORR in neutral media.

A study of highly activated hydrogen evolution reaction performance in acidic media by 2D heterostructure of N and S doped graphene on MoO_(x)

Herein,a layer of molybdenum oxide(MoO_(x)),a transition metal oxide(TMO),which has outstanding catalytic properties in combination with a carbonbased thin film,is modified to improve the hydrogen production performance and protect the MoO_(x)in acidic media.A thin film of graphene is transferred onto the MoO_(x)layer,after which the graphene structure is doped with N and S atoms at room temperature using a plasma doping method to modify the electronic structure and intrinsic properties of the material.The oxygen functional groups in graphene increase the interfacial interactions and electrical contacts between graphene and MoO_(x).The appearance of surface defects such as oxygen vacancies can result in vacancies in MoO_(x).This improves the electrical conductivity and electrochemically accessible surface area.Increasing the number of defects in graphene by adding dopants can significantly affect the chemical reaction at the interfaces and improve the electrochemical performance.These defects in graphene play a crucial role in the adsorption of H^(+)ions on the graphene surface and their transport to the MoO_(x)layer underneath.This enables MoO_(x)to participate in the reaction with the doped graphene.N^(‐)and S^(‐)doped graphene(NSGr)on MoO_(x)is active in acidic media and performs well in terms of hydrogen production.The initial overpotential value of 359 mV for the current density of−10 mA/cm^(2)is lowered to 228 mV after activation.

Hydrogenic donor impurity states and intersubband optical absorption spectra of monolayer transition metal dichalcogenides in dielectric environments

The hydrogenic donor impurity states and intersubband optical absorption spectra in monolayer transition metal dichalcogenides(ML TMDs) under dielectric environments are theoretically investigated based on a two-dimensional(2D)nonorthogonal associated Laguerre basis set. The 2D quantum confinement effect together with the strongly reduced dielectric screening results in the strong attractive Coulomb potential between electron and donor ion, with exceptionally large impurity binding energy and huge intersubband oscillator strength. These lead to the strong interaction of the electron with light in a 2D regime. The intersubband optical absorption spectra exhibit strong absorption lines of the non-hydrogenic Rydberg series in the mid-infrared range of light. The strength of the Coulomb potential can be controlled by changing the dielectric environment. The electron affinity difference leads to charge transfer between ML TMD and the dielectric environment, generating the polarization-electric field in ML TMD accompanied by weakening the Coulomb interaction strength. The larger the dielectric constant of the dielectric environment, the more the charge transfer is, accompanied by the larger polarization-electric field and the stronger dielectric screening. The dielectric environment is shown to provide an efficient tool to tune the wavelength and output of the mid-infrared intersubband devices based on ML TMDs.

Metal derivative(MD)/g-C_(3)N_(4) association in hydrogen production:A study on the fascinating chemistry behind,current trend and future direction

Metal derivative/graphitic carbon nitride(g-C_(3)N_(4))association is found promising in providing sustainable hydrogen production by photocatalytic water splitting process.Number of works reported on the synthesis and application of various metal based g-C_(3)N_(4)composites are increasing day by day.Mechanism of charge separation varies according to the metal candidate that gets couple with g-C_(3)N_(4).The present article thus explores the interesting chemistry behind various metal based heterojunction and demonstrates the charge separation route.A thorough investigation has been done on the current research trend in the area.As many metal free g-C_(3)N_(4)composites are reported nowadays as an alternative to metal derivatives,here compares metallic and metal free derivatives of g-C_(3)N_(4)based on four critical requirements of an industrial catalyst,ie,activity,stability,cost and toxicity.Challenges and future direction in the area are also discussed with significance.The systematic discussion and schematic illustration of charge transfer process in different heterojunctions with reference to the reported systems,given in the article can definitely contribute to the design and development of more efficient g-C_(3)N_(4)based heterojunctions in future for hydrogen production application.

共价有机框架负载贵金属铂用于电催化析氢

我们探究了共价有机框架负载贵金属Pt的电催化析氢性能.以2,6-二氨基蒽醌和2,4,6-三甲酰基间苯三酚为构筑单元,采用溶剂热法合成了TP-DAAQ COF.随后通过金属前驱体浸渍法制备了Pt-TP-DAAQ COF.X射线粉末衍射,傅里叶红外光谱,氮气吸附/脱附等表明成功制备了TP-DAAQ COF和Pt-TP-DAAQ COF.电化学测试结果表明Pt-TP-DAAQ COF(其中含有5.8%的Pt)展现了比20%Pt/C优异的电催化活性.当电流密度为10 mA∙cm^(-2)时,Pt-TP-DAAQ COF的过电位为45 mV,Tafel斜率为29 mV∙dec^(‒1).这高效的电催化活性源于TP-DAAQ COF与Pt之间良好的协同效应.Pt-TP-DAAQ COF具有较大的比表面积和规整的一维孔道,使催化位点更易于与电解液中的物质发生接触和相互作用,从而增强了其催化性能.