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.

Memristive feature and mechanism induced by laser-doping in defect-free 2D semiconductor materials

Memristors as non-volatile memory devices have gained numerous attentions owing to their advantages in storage,in-memory computing, synaptic applications, etc. In recent years, two-dimensional(2D) materials with moderate defects have been discovered to exist memristive feature. However, it is very difficult to obtain moderate defect degree in 2D materials, and studied on modulation means and mechanism becomes urgent and essential. In this work, we realized memristive feature with a bipolar switching and a configurable on/off ratio in a two-terminal MoS_(2) device(on/off ratio ~100), for the first time, from absent to present using laser-modulation to few-layer defect-free MoS_(2)(about 10 layers), and its retention time in both high resistance state and low resistance state can reach 2×10^(4) s. The mechanism of the laser-induced memristive feature has been cleared by dynamic Monte Carlo simulations and first-principles calculations. Furthermore, we verified the universality of the laser-modulation by investigating other 2D materials of TMDs. Our work will open a route to modulate and optimize the performance of 2D semiconductor memristive devices.

Mechanical stimulation devices formechanobiology studies:a market,literature,and patents review

Significant advancements in various research and technological fields have contributed to remarkable findings on the physiological dynamics of the human body.Tomore closely mimic the complex physiological environment,research has moved from two-dimensional(2D)culture systems to more sophisticated three-dimensional(3D)dynamic cultures.Unlike bioreactors or microfluidic-based culture models,cells are typically seeded on polymeric substrates or incorporated into 3D constructs which are mechanically stimulated to investigate cell response to mechanical stresses,such as tensile or compressive.This review focuses on the working principles of mechanical stimulation devices currently available on the market or custom-built by research groups or protected by patents and highlights the main features still open to improvement.These are the features which could be focused on to perform,in the future,more reliable and accurate mechanobiology studies.

Oleogels for development of health-promoting food products

Metabolic health and the maintenance of good levels of triglycerides,high-density lipoprotein cholesterol,blood pressure and glucose levels are concerns that can greatly impact human quality of life.Healthdriven consumers’demands,together with technological innovations,have led to a diversification of the food industry.The fostering of off-the-shelf available and affordable healthy food products is necessary,as detrimental effects on human health from the ingestion of saturated fat sources urge the efforts to find alternatives.Oleogels can be tailored using specific triglycerides and oleogelators,that can be selected to yield targeted fatty acids,reduce higher levels of cholesterol with competing binding-molecules(e.g.phytosterols),reduce saturated fat content,lessen appetite(e.g.modelling the shape of foods)or carry exclusive bioactive compounds to be absorbed in the digestive tract.Oleogels are foreseen as an important technological advance in food science due to their versatility,easy processing and affordability.This review explored the strategies in place to develop and produce oleogels,foreseeing their introduction in foods and how they might represent an important source of functionality through the use of healthy molecules.It also explored how oleogels can act on the human overall metabolic health if they are used in human diet.

Fabrication of ultra-high strength magnesium alloys over 540 MPa with low alloying concentration by double continuously extrusion

We prepare a new type of patented biodegradable biomedical Mg-Nd-Zn-Zr(JDBM)alloy system and impose double continuously extrusion(DCE)processing.The lowest processing temperature is 250℃for JDBM-2.1Nd and 310℃for JDBM-2.8Nd,which increases with the Nd concentration.The highest yield strength of 541 MPa is achieved in JDBM-2.1 Nd samples when extruded at 250℃and the elongation is about 3.7%.Moreover,the alloy with a lower alloying element content can reach a higher yield strength while that with a higher alloying element content can reach a larger elongation after DCE processing.However,when extruded under the same conditions,the alloy with a higher alloying contents exhibits better tensile properties.

High-performance junction field-effect transistor based on black phosphorus/β-Ga2O3 heterostructure

Black phosphorous(BP),an excellent two-dimensional(2D)monoelemental layered p-type semiconductor material with high carrier mobility and thickness-dependent tunable direct bandgap structure,has been widely applied in various devices.As the essential building blocks for modern electronic and optoelectronic devices,high quality PN junctions based on semiconductors have attracted widespread attention.Herein,we report a junction field-effect transistor(JFET)by integrating narrow-gap p-type BP and ultra-wide gap n-typeβ-Ga2O3 nanoflakes for the first time.BP andβ-Ga2O3 form a vertical van der Waals(vdW)heterostructure by mechanically exfoliated method.The BP/β-Ga2O3 vdW heterostructure exhibits remarkable PN diode rectifying characteristics with a high rectifying ratio about 107 and a low reverse current around pA.More interestingly,by using the BP as the gate andβ-Ga2O3 as the channel,the BP/β-Ga2O3 JFET devices demonstrate excellent n-channel JFET characteristics with the on/off ratio as high as 107,gate leakage current around as low as pA,maximum transconductance(gm)up to 25.3μS and saturation drain current(IDSS)of 16.5μA/μm.Moreover,it has a pinch-off voltage of–20 V and a minimum subthreshold swing of 260 mV/dec.These excellent n-channel JFET characteristics will expand the application of BP in future nanoelectronic devices.

Stable overall water splitting in an asymmetric acid/ alkaline electrolyzer comprising a bipolar membrane sandwiched by bifunctional cobalt-nickel phosphide nanowire electrodes

Water splitting has been proposed to be a promising approach to producing clean hydrogen fuel.The two half-reactions of water splitting,that is,the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),take place kinetically fast in solutions with completely different pH values.Enabling HER and OER to simultaneously occur under kinetically favorable conditions while using exclusively low-cost,earth-abundant electrocatalysts is highly desirable but remains a challenge.Herein,we demonstrate that using a bipolar membrane(BPM)we can accomplish HER in a strongly acidic solution and OER in a strongly basic solution,with bifunctional self-supported cobaltnickel phosphide nanowire electrodes to catalyze both reactions.Such asymmetric acid/alkaline water electrolysis can be achieved at 1.567 V to deliver a current density of 10 mA/cm2 with ca.100%Faradaic efficiency.Moreover,using an“irregular”BPM with unintentional crossover the voltage needed to afford 10 mA/cm2 can be reduced to 0.847 V,due to the assistance of electrochemical neutralization between acid and alkaline.Furthermore,we show that BPM-based asymmetric water electrolysis can be accomplished in a circulated single-cell electrolyzer delivering 10 mA/cm2 at 1.550 V and splitting water very stably for at least 25 hours,and that water electrolysis is enabled by a solar panel operating at 0.908 V(@13 mA/cm2),using an“irregular”BPM.BPMbased asymmetric water electrolysis is a promising alternative to conventional proton and anion exchange membrane water electrolysis.

Intrinsic two-dimensional multiferroicity in CrNCl_(2) monolayer

Two-dimensional multiferroics,which simultaneously possess ferroelectricity and magnetism in a single phase,are well-known to possess great potential applications in nanoscale memories and spintronics.On the basis of first-principles calculations,a CrNCl_(2) monolayer is reported as an intrinsic multiferroic.The CrNCl_(2) has an antiferromagnetic ground state,with a N´eel temperature of about 88 K,and it exhibits an in-plane spontaneous polarization of 200 pC/m.The magnetic moments of CrNCl_(2) mainly come from the dxy orbital of the Cr cation,but the plane of the dxy orbital is perpendicular to the direction of the ferroelectric polarization,which hardly suppresses the occurrence of ferroelectricity.Therefore,the multiferroic exits in the CrNCl_(2).In addition,like CrNCl_(2),the CrNBr_(2) is an intrinsic multiferroic with antiferromagneticferroelectric ground state while CrNI_(2) is an intrinsic multiferroic with ferromagnetic-ferroelectric ground state.These findings enrich the multiferroics in the two-dimensional system and enable a wide range of applications in nanoscale devices.

Modulation effects of Cu modification and ligands (oxalate and borohydride) functionalization on Pt d-band center, upper d-band edge, and alloyed PtCe support acidity on semihydrogenation of acetylene

The modulating effects of Cu modification and oxalate or borohydride ligands functionalization on the structure,catalyst d-band center(εd),upper d-band edge(εu),and acetylene partial hydrogenation of expediently synthesized Ce alloyed Pt supported catalysts were investigated.Firstly,a 5 wt%Pt alloyed Ce was synthesized via flame spray pyrolysis.The PtCe sample was further supported on zeolite Y,ZY,(PtCe/ZY)and copper modified ZY(PtCe/Cu-ZY).Furthermore,the PtCe was supported on two other oxalate and borohydride ligands functionalized copper modified ZY(PtCe/CuX-ZY and PtCe/CuB-ZY,respectively).The high-angle annular darkfield scanning transmission electron microscopy(HAADF/STEM)data showed a reduction in the PtO average particle size from 2.65 nm in PtCeO_(2) to average 1.73,0.64,and 0.30 nm in PtCe/Cu-ZY,PtCe/CuX-ZY,and PtCe/CuB-ZY,which was corroborated by the electron energy-loss spectroscopy(EELS)results wherein nonhomogeneous mixing of elements was seen with segregated Pt clusters in the non-functionalized samples.Conversely,both PtCe/CuX-ZY and PtCe/CuBZY samples showed near-perfect homogeneity with no distinct Pt signals.The measuredεu values for PtCe,PtCe/Cu-ZY,PtCe/CuX-ZY,and PtCe/CuB-ZY are+1.85,+0.40,-0.15,and-0.19 eV,respectively.The positive values indicated strong metal-adsorbate bonding typical of large Pt sizes while the negative values indicated weak metal-adsorbate bonding due to highly downsized Pt sizes.The ethylene yield(YC2H4)over the PtCe sample showed depletion as the reaction temperature increased,while it reflected maxima at 120℃ with 55.3%YC2H4 over PtCe/ZY.The maxima shifted to 180℃ with enhanced YC2H4 of 71.4%in PtCe/Cu-ZY.On the contrary,both PtCe/CuX-ZY and PtCe/CuB-ZY exhibited a monotonous increase in YC2H4 up to the maximum C_(2)H_(2)conversion with YC2H4 of 81.9%and 92.1%at 180 and 160℃,respectively.These results showed that both the Cu modification and ligands functionalization were highly invaluable to enhance the properties and activities of the semihydrogenation of acetylene(SHA)catalysts.

Easy preparation of multifunctional ternary PdNiP/C catalysts toward enhanced small organic molecule electro-oxidation and hydrogen evolution reactions

The small organic molecule electro-oxidation(OMEO) and the hydrogen evolution(HER) are two important half-reactions in direct liquid fuel cells(DLFCs) and water electrolyzers,respectively,whose performance is largely hindered by the low activity and poor stability of electrocatalysts.Herein,we demonstrate that a simple phosphorization treatment of commercially available palladium-nickel(PdNi) catalysts results in multifunctional ternary palladium nickel phosphide(PdNiP) catalysts,which exhibit substantially enhanced electrocatalytic activity and stability for HER and OMEO of a number of molecules including formic acid,methanol,ethanol,and ethylene glycol,in acidic and/or alkaline media.The improved performance results from the modification of electronic structure of palladium and nickel by the introduced phosphorus and the enhanced corrosion resistance of PdNiP.The simple phosphorization approach reported here allows for mass production of highly-active OMEO and HER electrocatalysts,holding substantial promise for their large-scale application in direct liquid fuel cells and water electrolyzers.

石墨相氮化碳-硫化铋复合膜的染料分离与自清洁性能

随着废水零排放的标准与要求不断深化,高效可持续的膜分离水处理技术成为研究热点,但面临着水通量低、易污染等问题。本研究通过石墨相氮化碳(g-C_(3)N_(4))、细菌纤维素(BC)和硫化铋(Bi_(2)S_(3))三者的有机结合,经真空辅助抽滤法制备得到光催化自清洁复合膜。通过一系列表征手段对粉末及膜材料进行物相结构与元素能态分析,研究了g-C_(3)N_(4)和Bi_(2)S_(3)不同添加量对复合膜染料分离性能的影响规律,探讨了两者在光催化下对染料的降解机制。结果表明,60wt%的g-C_(3)N_(4)、10wt%的BC、30wt%的Bi_(2)S_(3)与复合膜的综合性能最佳,水通量和截留率分别为23.48 L·m^(−2)·h^(−1)和100%,长时间过滤中依然保持16.65 L·m^(−2)·h^(−1)的水通量和90%左右的染料截留,在光照下浸泡3 h后通量恢复率达到96.5%,表明了该膜具有良好的光催化自清洁性能。该研究为高通量、可持续分离膜的设计提供了新的思路及基础探索。

An integrated portable bio-monitoring system based on tough hydrogels for comprehensive detection of physiological activities

Advanced soft ion-conducting hydrogels have been developed rapidly in the integrated portable health monitoring equipment due to their higher sensitivity,sensory traits,tunable conductivity,and stretchability for physiological activities and personal healthcare detection.However,traditional hydrogel conductors are normally susceptible to large deformation and strong mechanical stress,which leads to inferior electro-mechanical stability for real application scenarios.Herein,a strong ionically conductive hydrogel(poly(vinyl alcohol)-boric acid-glycerol/sodium alginate-calcium chloride/electrolyte ions(PBG/SC/EI))was designed by engineering the covalently and ionically crosslinked networks followed by the salting-out effect to further enhance the mechanical strength and ionic conductivity of the hydrogel.Owing to the collective effects of the energy-dissipation mechanism and salting-out effect,the designed PBG/SC/EI with excellent structural integrity and robustness exhibits exceptional mechanical properties(elongation at break for 559.1%and tensile strength of 869.4 kPa)and high ionic conductivity(1.618 S·m^(-1)).As such,the PBG/SC/EI strain sensor features high sensitivity(gauge factor=2.29),which can effectively monitor various kinds of human motions(joint motions,facial micro-expression,faint respiration,and voice recognition).Meanwhile,the hydrogel-based Zn||MnO_(2)battery delivers a high capacity of 267.2 mAh·g^(-1)and a maximal energy density of 356.8 Wh·kg^(-1)associated with good cycle performance of 71.8%capacity retention after 8000 cycles.Additionally,an integrated bio-monitoring system with the sensor and Zn||MnO_(2)battery can accurately identify diverse physiological activities in a real-time and non-invasive way.This work presents a feasible strategy for designing high-performance conductive hydrogels for highly-reliable integrated bio-monitoring systems with excellent practicability.

Interface engineering of Co_(9)S_(8)/SnS heterostructure as a high-performance anode for lithium/sodium-ion batteries

Transition metal sulfide(TMS)anodes exhibit the characteristics of phase stability and high capacity for lithium/sodium-ion batteries(LIBs/SIBs).However,the TMS anodes often suffer from poor electronic conductivity,low ionic diffusion and large volume expansion during Li/Na-ion intercalation significantly impairing the Li/Na-storage performance.Herein,a long chain heterostructure composed of the Co_(9)S_(8) and SnS are first reported,which can generate rich phase interfaces,and small crystal domains.The unique structure can facilitate the properties of reactivity,conductivity and ionic diffusion.In addition,the heterostructure surface is modified by the N-doped carbon(N-DC@(CoSn)S),successfully improving the structural stability.The synergistic effects of Co_(9)S_(8)/SnS heterostructure and coated carbon layer effectively increase the capacity and cycling stability.The N-DC@(CoSn)S anode delivers enhanced high specific capacities of 820.6 mAh·g^(−1) at 1.0 A·g^(–1) after 500 cycles for LIBs and 339.2 mAh·g^(–1)at 0.5 A·g^(–1) after 1000 cycles for SIBs,respectively.This work is expected to provide a material design idea for preparing LIBs/SIBs with high capacity and long cycling life.

Diamond: asymmetry leads to continuous hardening

Naturally occurring and synthetic materials are often polycrystalline comprising various species of grain boundaries(GBs),many of which are randomly oriented.It is known that GBs play a pivotal role in affecting a broad range of material properties,and the nature of GBs is dedicated by grain orientation,growth history and processing conditions.

Realization of flexible in-memory computing in a van der Waals ferroelectric heterostructure tri-gate transistor

Combining logical function and memory characteristics of transistors is an ideal strategy for enhancing computational efficiency of transistor devices.Here,we rationally design a tri-gate two-dimensional(2D)ferroelectric van der Waals heterostructures device based on copper indium thiophosphate(CuInP_(2)S_(6))and few layers tungsten disulfide(WS_(2)),and demonstrate its multi-functional applications in multi-valued state of data,non-volatile storage,and logic operation.By co-regulating the input signals across the tri-gate,we show that the device can switch functions flexibly at a low supply voltage of 6 V,giving rise to an ultra-high current switching ratio of 107 and a low subthreshold swing of 53.9 mV/dec.These findings offer perspectives in designing smart 2D devices with excellent functions based on ferroelectric van der Waals heterostructures.

Mixed iridium-nickel oxides supported on antimony-doped tin oxide as highly efficient and stable acidic oxygen evolution catalysts

Proton exchange membrane(PEM)water electrolysis represents a promising technology for green hydrogen production,but its widespread deployment is greatly hindered by the indispensable usage of platinum group metal catalysts,especially iridium(Ir)based materials for the energy-demanding oxygen evolution reaction(OER).Herein,we report a new sequential precipitation approach to the synthesis of mixed Ir-nickel(Ni)oxy-hydroxide supported on antimony-doped tin oxide(ATO)nanoparticles(IrNiyO_(x)/ATO,20 wt.%(Ir+Ni),y=0,1,2,and 3),aiming to reduce the utilisation of scarce and precious Ir while maintaining its good acidic OER performance.When tested in strongly acidic electrolyte(0.1 M HClO_(4)),the optimised IrNi1Ox/ATO shows a mass activity of 1.0 mAµgIr^(−1) and a large turnover frequency of 123 s^(−1) at an overpotential of 350 mV,as well as a comparatively small Tafel slope of 50 mV dec^(−1),better than the IrOx/ATO control,particularly with a markedly reduced Ir loading of only 19.7µgIr cm^(−2).Importantly,IrNi1O_(x)/ATO also exhibits substantially better catalytic stability than other reference catalysts,able to continuously catalyse acidic OER at 10 mA cm^(−2) for 15 h without obvious degradation.Our in-situ synchrotron-based x-ray absorption spectroscopy confirmed that the Ir^(3+)/Ir^(4+)species are the active sites for the acidic OER.Furthermore,the performance of IrNi1Ox/ATO was also preliminarily evaluated in a membrane electrode assembly,which shows better activity and stability than other reference catalysts.The IrNi1Ox/ATO reported in this work is a promising alternative to commercial IrO_(2) based catalysts for PEM electrolysis.

High entropy materials as emerging electrocatalysts for hydrogen production through low-temperature water electrolysis

The production of hydrogen through water electrolysis(WE)from renewable electricity is set to revolutionise the energy sector that is at present heavily dependent on fossil fuels.However,there is still a pressing need to develop advanced electrocatalysts able to show high activity and withstand industrially-relevant operating conditions for a prolonged period of time.In this regard,high entropy materials(HEMs),including high entropy alloys and high entropy oxides,comprising five or more homogeneously distributed metal components,have emerged as a new class of electrocatalysts owing to their unique properties such as low atomic diffusion,structural stability,a wide variety of adsorption energies and multi-component synergy,making them promising catalysts for challenging electrochemical reactions,including those involved in WE.This review begins with a brief overview about WE technologies and a short introduction to HEMs including their synthesis and general physicochemical properties,followed by a nearly exhaustive summary of HEMs catalysts reported so far for the hydrogen evolution reaction,the oxygen evolution reaction and the overall water splitting in both alkaline and acidic conditions.The review concludes with a brief summary and an outlook about the future development of HEM-based catalysts and further research to be done to understand the catalytic mechanism and eventually deploy HEMs in practical water electrolysers.

In situ observation of the pseudoelasticity of twin boundary

Twin boundary(TB)is a special and fundamental internal interface that plays a key role in altering the mechanical and physical properties of materials.However,the atomistic deformation mechanism of TB re-mains under debate,of which the most concerned aspect is how TB would affect the mechanical strength and plasticity of a material.Herein,we introduce our new discovery that the pseudoelastic strain of a TB can recover with decomposition and escape of pile-up dislocations,demonstrated by imposing a sponta-neous pseudoelastic deformation with recoverable plastic bending strain up to 5.1%on a TB.We found that the steps on the curved TB gradually annihilated during the migration of the TB,which was in-duced by the slip of decomposition dislocations on the TB.The TB not only provides local strain harden-ing through interaction with dislocations during the loading stage but also acts as a channel for the fast movement of decomposition dislocations during the recovery stage.Beside,the TB can maintain excellent pseudoelasticity under a multicycle bending test,which may play an important role in improving the fa-tigue resistance of materials.These findings could open up a new avenue for optimizing the mechanical properties of materials by manipulating their twin boundaries at the nanoscale.

Anomalous refinement and uniformization of grains in metallic thin films

When a laser beam writes on a metallic film,it usually coarsens and deuniformizes grains because of Ostwald ripening,similar to the case of annealing.Here we show an anomalous refinement effect of metal grains:A metallic silver film with large grains melts and breaks into uniform,close-packed,and ultrafine(~10 nm)grains by laser direct writing with a nanoscale laser spot size and nanosecond pulse that causes localized heating and adaptive shock-cooling.This method exhibits high controllability in both grain size and uniformity,which lies in a linear relationship between the film thickness(h)and grain size(D),D∝h.The linear relationship is significantly different from the classical spinodal dewetting theory obeying a nonlinear relationship(D∝h5/3)in common laser heating.We also demonstrate the application of such a silver film with a grain size of~10.9 nm as a surface-enhanced Raman scattering chip,exhibiting superhigh spatial-uniformity and low detection limit down to 10-15 M.This anomalous refinement effect is general and can be extended to many other metallic films.

Recent advances of SiO_(x)-based anodes for sustainable lithium-ion batteries

The world is facing an ever-growing global energy crisis with unprecedented depth and complexity.The sustainable development of high energy density lithium-ion batteries for electric vehicles and portable electric devices has become a feasible way to deal with this problem.Silicon suboxides(SiO_(x))have been deemed as one of the most promising anode materials because of their ultrahigh theoretical lithium storage capacity,proper working potential,natural abundance,and environmental friendliness.However,the mass utilization of SiO_(x)-based anodes is severely obstructed by their low electrical conductivity and inevitable volume expansion.While lithium silicate and lithium oxide formed in the first lithiation process act as buffer layers to some extent,it is urgent to address the accompanying low initial Coulombic efficiency and unsatisfactory cycling stability.In this review,we summarized recent advances in the synthesis methods of SiO_(x)-based materials.Besides,the benefits and shortcomings of the various methods are briefly concluded.Then,we discussed the effective combination of SiO_(x) with carbon materials and designs of porous structure,which could considerably enhance the electrochemical performance in detail.Furthermore,progresses on the modified strategies,advanced characteristics and industrial applications for SiO_(x)-based anodes are also mentioned.Finally,the remaining challenges encountered and future perspectives on SiO_(x)-based anodes are highlighted.