Efficient lubrication of magnesium alloys is a highly challenging topic in the field of tribology.In this study,magnesium silicate hydroxide(MSH)nanotubes with serpentine structures were synthesized.The tribological b...Efficient lubrication of magnesium alloys is a highly challenging topic in the field of tribology.In this study,magnesium silicate hydroxide(MSH)nanotubes with serpentine structures were synthesized.The tribological behavior of AZ91D magnesium alloy rubbed against GCr15 steel was studied under lubricating oil with surface-modified MSH nanotubes as additives.The effects of the concentration,applied load,and reciprocating frequency on the friction and wear of the AZ91D alloy were studied using an SRV-4 sliding wear tester.Results show a decrease of 18.7–68.5%in friction coefficient,and a reduction of 19.4–54.3%in wear volume of magnesium alloy can be achieved by applying the synthetic serpentine additive under different conditions.A suspension containing 0.3 wt.%MSH was most efficient in reducing wear and friction.High frequency and medium load were more conducive to improving the tribological properties of magnesium alloys.A series of beneficial physical and chemical processes occurring at the AZ91D alloy/steel interface can be used to explain friction and wear reduction based on the characterization of the morphology,chemical composition,chemical state,microstructure,and nanomechanical properties of the worn surface.The synthetic MSH,with serpentine structure and nanotube morphology,possesses excellent adsorbability,high chemical activity,and good self-lubrication and catalytic activity.Therefore,physical polishing,tribochemical reactions,and physicalchemical depositions can occur easily on the sliding contacts.A dense tribolayer with a complex composition and composite structure was formed on the worn surface.Its high hardness,good toughness and plasticity,and prominent lubricity resulted in the improvement of friction and wear,making the synthetic MSH a promising efficient oil additive for magnesium alloys under boundary and mixed lubrication.展开更多
Precipitation is often used for the preparation of La(OH)_(3)with precipitants of liquid alkali and ammonia.To solve the problems of high cost and wastewater pollution caused by common precipitants,the active MgO synt...Precipitation is often used for the preparation of La(OH)_(3)with precipitants of liquid alkali and ammonia.To solve the problems of high cost and wastewater pollution caused by common precipitants,the active MgO synthesized by pyrolysis was used as the precipitant to prepare La(OH)_(3).The species distribution of LaCl_(3)and LaCl_(3)-MgCl_(2)mixed system solution was calculated,and the kinetic analysis of the precipi-tation process was carried out to confirm the key factors influencing the precipitation of La(OH)_(3).The results show that La(OH)_(3)with D_(50)of 5.57μm,a specific surface area of 25.70 m^(2)/g,a rod-like shape,and MgO content of 0.044 wt%,was successfully prepared by adding active MgO.The precipitation ratio of La reaches 99.92%.The La(OH)_(3)precipitation is controlled by the diffusion process.The activity of MgO has a significant influence on MgO content in the precipitate.The preparation of La(OH)_(3)by active MgO provides a potential way for an eco-friendly preparation method of rare earth.展开更多
Aluminum hydroxide adjuvant exhibits a poorly crystalline boehmite(PCB)structure,which demonstrates instability during prolonged storage.In the present study,we systematically investigated the quality alterations of t...Aluminum hydroxide adjuvant exhibits a poorly crystalline boehmite(PCB)structure,which demonstrates instability during prolonged storage.In the present study,we systematically investigated the quality alterations of the adjuvant stored at roo m temperature by analyzing its crystal structure,particle size distribution,electron microscopic characteristics,pH,isoelectric point(pI),and adsorption capacity.These assessments aimed to ensure the effectiveness and safety of vaccine production.Three batches of adjuvants were stored at room temperature for 15 months,and their changes were monitored using X-ray diffraction patterns,transmission electron microscopy(TEM),pH measurements,pI determination,and adsorption capacity analysis.X-ray diffraction revealed that the crystalline phases of aluminum hydroxide initially exhibited a PCB structure,which became progressively more ordered during storage.Notably,after 12 months,a new diffraction peak emerged at 18.2°2θ,with its intensity increasing over time.This corresponded to the formation of highly crystalline gibbsite and bayerite,which compromised the stability of the adjuvant.Furthermore,the pH and pI values decreased during storage,reflecting a decline in the chemical stability of the adjuvant.Comprising nanoparticles with a mean diameter of 130 nm,the adjuvant maintained a high surface area and excellent adsorption capacity.The adsorption rate at 8 mg BSA/mg Al3+consistently exceeded 97%,with no statistically significant differences observed between the adsorption capacities at 1 and 15 months(P>0.05).This indicated that the nanoparticle aluminum hydroxide adjuvant sustained high adsorption efficiency throughout the storage period,underscoring its reliability as a vaccine adsorbent.However,in the later stages of storage,the emergence of highly crystalline gibbsite and bayerite,coupled with declines in pH and pI,negatively impacted the adjuvant’s stability.Based on these findings,we recommended that aluminum hydroxide adjuvants should not be stored at room temperature for longer than 12 months to preserve their quality and efficacy.展开更多
Rationally design the morphology and structure of electroactive nanomaterials is an effective approach to enhance the performance of aqueous batteries.Herein,we co-engineered the hollow architecture and interlayer spa...Rationally design the morphology and structure of electroactive nanomaterials is an effective approach to enhance the performance of aqueous batteries.Herein,we co-engineered the hollow architecture and interlayer spacing of layered double hydroxides(LDH)to achieve high electrochemical activity.The hierarchical hollow LDH was prepared from bimetallic zeolitic imidazolate frameworks(ZIF)by a facile cation exchange strategy.Zn and Cu elements were selected as the second metals incorporated in Co-ZIF.The characteristics of the corresponding derivatives were studied.Besides,the transformation mechanism of CoZn-ZIF into nanosheet-assembled hollow Co Zn Ni LDH(denoted as CoZnNi-OH)was systematically investigated.Importantly,the interlayer spacing of CoZnNi-OH expands due to Zn^(2+)incorporation.The prepared CoZnNi-OH offers large surface area,exposed active sites,and rapid mass transfer/diffusion rate,which lead to a significant enhancement in the specific capacitance,rate performance,and cycle stability of CoZnNi-OH electrode.In addition,the aqueous alkaline CoZnNi-OH//Zn showed a maximum energy density/power density of 0.924 m Wh/cm^(2),8.479 m W/cm^(2).This work not only raises an insightful strategy for regulating the morphology and interlayer spacing of LDH,but also provides a reference of designing hollow nickel-based nanomaterials for aqueous batteries.展开更多
Zinc-nitrate battery could produce electrical power,remove pollutant nitrate and obtain value-added ammonia,where the cathodic reaction of converting nitrate to ammonia is sluggish and complex due to the involvement o...Zinc-nitrate battery could produce electrical power,remove pollutant nitrate and obtain value-added ammonia,where the cathodic reaction of converting nitrate to ammonia is sluggish and complex due to the involvement of multi-electron transfer.Thus,highly efficient catalysts for nitrate reduction reaction(NO_(3)RR)are greatly needed.In this work,we report a high entropy hydroxide(HE-OH)as an excellent NO3RR catalyst,which could achieve high NH_(3)Faradaic efficiencies(e.g.,nearly 100%at-0.3 V versus reversible hydrogen electrode)and high yield rates(e.g.,30.4 mg h^(-1)cm^(-2)at-0.4 V).Moreover,HE-OH could also deliver a current density of 10 mA/cm^(2) at an overpotential of 260 mV for oxygen evolution reaction.The assembled zinc-nitrate battery using HE-OH as the cathode demonstrates a high power density(e.g.,3.62 mW/cm^(2)),rechargeability and stability.展开更多
Aqueous hybrid-ion batteries(AHBs)are a promising class of energy storage devices characterized by low cost,high safety,and high energy density.However,aqueous Cu-Al hybrid-ion batteries face challenges such as sluggi...Aqueous hybrid-ion batteries(AHBs)are a promising class of energy storage devices characterized by low cost,high safety,and high energy density.However,aqueous Cu-Al hybrid-ion batteries face challenges such as sluggish reaction kinetics and severe structural collapse of cathode materials,which limit their practical application.Here,a high-performance aqueous Cu-Al hybrid-ion battery is developed using aluminum pre-inserted Cu_(9)S_(5)(Al-Cu_(9)S_(5))as the cathode material,derived from CuAl-layered double hydroxide(CuAl-LDH).The Al^(3+)pre-intercalation strategy narrows the band gap,enhancing electron transport and improving electrochemical kinetics.The battery exhibits excellent rate performance(463 and 408 mA h g^(-1)at current densities of 500 and 1000 mA g^(-1),respectively)and good cycle stability(with a capacity retention ratio of 81% after 300 cycles at a current density of 1000 mA g^(-1)).Its performance surpasses that of most reported Al-ion batteries.Ex situ characterization and density functional theory(DFT)calculations reveal that the pre-intercalated Al^(3+)in Al-Cu9S5participates in the reversible embedding/removal of Al ions during charge/discharge processes.These findings provide valuable insights for designing pre-intercalated cathodes in aqueous Cu-Al hybrid-ion batteries with stable cycle life.展开更多
Layered double hydroxides(LDHs)are potential cathode materials for aqueous magnesium-ion batteries(AMIBs).However,the low capacity and sluggish kinetics significantly limit their electrochemical performance in AMIBs.H...Layered double hydroxides(LDHs)are potential cathode materials for aqueous magnesium-ion batteries(AMIBs).However,the low capacity and sluggish kinetics significantly limit their electrochemical performance in AMIBs.Herein,we find that oxygen vacancies can significantly boost the capacity,electrochemical kinetics,and structure stability of LDHs.The corresponding structure-performance relationship and energy storage mechanism are elaborated through exhaustive in/ex-situ experimental characterizations and density functional theory(DFT)calculations.Specially,in-situ Raman and DFT calculations reveal that oxygen vacancies elevate orbital energy of O 2p and electron density of O atoms,thereby enhancing the orbital hybridization of O 2p with Ni/Co 3d.This facilitates electron transfer between O and adjacent Ni/Co atoms and improves the covalency of Ni–O and Co–O bonds,which activates Ni/Co atoms to release more capacity and stabilizes the Ov-NiCo-LDH structure.Moreover,the distribution of relaxation times(DRT)and molecular dynamics(MD)simulations disclose that the enhanced d-p orbital hybridization optimizes the electronic structure of Ov-NiCo-LDH,which distinctly reduces the diffusion energy barriers of Mg^(2+)and improves the charge transfer kinetics of Ov-NiCo-LDH.Consequently,the assembled Ov-NiCo-LDH//active carbon(AC)and Ov-NiCo-LDH//perylenediimide(PTCDI)AMIBs can both deliver high specific discharge capacity(182.7 and 59.4 mAh g^(−1)at 0.5 A g^(−1),respectively)and long-term cycling stability(85.4%and 89.0%of capacity retentions after 2500 and 2400 cycles at 1.0 A g^(−1),respectively).In addition,the practical prospects for Ov-NiCo-LDH-based AMIBs have been demonstrated in different application scenarios.This work not only provides an effective strategy for obtaining high-performance cathodes of AMIBs,but also fundamentally elucidates the inherent mechanisms.展开更多
Noble metal-loaded layered hydroxides exhibit high efficiency in electrocatalyzing water splitting.However,their widespread use as bifunctional electrocatalysts is hindered by low metal loading,inefficient yield,and c...Noble metal-loaded layered hydroxides exhibit high efficiency in electrocatalyzing water splitting.However,their widespread use as bifunctional electrocatalysts is hindered by low metal loading,inefficient yield,and complex synthesis processes.In this work,platinum atoms were anchored onto nickel-iron layered double hydroxide/carbon nanotube(LDH/CNT)hybrid electrocatalysts by using a straightforward milling technique with K_(2)Pt Cl_(6)·6H_(2)O as the Pt source.By adjusting the Pt-to-Fe ratio to 1/2 and 1/10,excellent electrocatalysts—Pt_(1/6)-Ni_(2/3)Fe_(1/3)-LDH/CNT and Pt_(1/30)-Ni_(2/3)Fe_(1/3)-LDH/CNT—were achieved with superior performance in hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),outperforming the corresponding commercial Pt/C(20 wt%)and Ru O_(2)electrocatalysts.The enhanced electrochemical performance is attributed to the modification of Pt's electronic structure,which exhibits electron-rich states for HER and electrondeficient states for OER,significantly boosting Pt's electrochemical activity.Furthermore,the simple milling technology for controlling Pt loading offers a promising approach for scaling up the production of electrocatalysts.展开更多
Amorphous two-dimensional transition metal oxide/(oxy)hydroxide(2D TMO/TMHO)nanomaterials(NMs)have the properties of both 2D and amorphous materials,displaying outstanding physicochemical qualities.Therefore,they demo...Amorphous two-dimensional transition metal oxide/(oxy)hydroxide(2D TMO/TMHO)nanomaterials(NMs)have the properties of both 2D and amorphous materials,displaying outstanding physicochemical qualities.Therefore,they demonstrate considerable promise for use in electrocatalytic water splitting applications.Here,the primary amorphization strategies for achieving the 2D TMO/TMHO NMs are comprehensively reviewed,including low-temperature reaction,rapid reaction,exchange/doping effect,ligand modulation,and interfacial energy confinement.By integrating these strategies with various physicochemical synthesis methods,it is feasible to control the amorphization of TMO/TMHO NMs while maintaining the distinctive benefits of their 2D structures.Furthermore,it delves into the structural advantages of amorphous 2D TMO/TMHO NMs in electrocatalytic water splitting,particularly emphasizing recent advancements in enhancing their electrocatalytic performance through interface engineering.The challenges and potential future directions for the precise synthesis and practical application of amorphous 2D TMO/TMHO NMs are also provided.This review aims to establish a theoretical foundation and offer experimental instructions for developing effective and enduring electrocatalysts for water splitting.展开更多
Developing an efficient electrocatalyst for superior electrochemical water splitting(EWS)is crucial for achieving comprehensive hydrogen production.A heterostructured electrocatalyst,free of noble metals,Ti_(3)C_(2)MX...Developing an efficient electrocatalyst for superior electrochemical water splitting(EWS)is crucial for achieving comprehensive hydrogen production.A heterostructured electrocatalyst,free of noble metals,Ti_(3)C_(2)MXene nanosheet-integrated cobalt-doped nickel hydroxide(NHCoMX)composite was synthesized via a hydrothermal method.The abundant pores in the Ti_(3)C_(2)MXene nanosheet(MX)-integrated microarchitecture increased the number of active sites and facilitated charge transfer,thus enhancing electrocatalysis.Specifically,the MXenhanced charge transfer considerably transformed the microelectronic structure of cobalt-doped Ni(OH)2(NHCo),which promoted its hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).Hence,as an EWS catalyst,NHCoMX exhibited an exceptional electrocatalytic activity,demonstrating OER and HER overpotentials of 310 mV and 73 mV,respectively,with low Tafel slopes of 65 mV dec^(-1)and 85 mV dec^(-1),respectively;it exhibited a current density of 10 mV cm^(-2)in 1.0 mol L^(-1)KOH,representing the closest efficiency to the noble state-of-the-art RuO2 and Pt/C catalyst.Furthermore,the developed electrocatalyst improved the activities of both HER and OER,leading to an overall EWS current density of 10 mA cm^(-2)at 1.72 V in an alkaline electrolyte with two electrodes.This study describes an efficient heterostructured NHCoMX composite electrocatalyst.It is significantly comparable to the noble state-of-the-art electrocatalysts and can be extended to fabricate resourceful catalysts for large-scale EWS applications.展开更多
Carbon-based materials exhibit excellent dielectric absorption properties,among which graphene has received particular attention in research of electromagnetic wave absorbing materials because of its high electrical c...Carbon-based materials exhibit excellent dielectric absorption properties,among which graphene has received particular attention in research of electromagnetic wave absorbing materials because of its high electrical conductivity and unique large-area,thin-layer two-dimensional structural features.However,the electromagnetic absorption performance of the material is hindered from further improvement due to its single component composition.It is influenced by the conductive network of graphene,making it challenging to achieve a balance in impedance matching and electromagnetic loss,thereby restricting its broader application.To address these challenges,we developed a series of nickel hydroxide-modified graphene composites.Through a structural composite design,we optimized overall impedance matching,introduced diverse loss mechanisms to enhance electromagnetic loss performance,and utilized a secondary reaction control method to precisely regulate the deposition of nickel hydroxide on the graphene surface,thereby achieving regulate of the composite material's electromagnetic parameters within a defined range.Under low sample filling ratios and a thin sample thickness of 1.8 mm,the effective absorption bandwidth reaches 6.5 GHz,demonstrating excellent electromagnetic absorption performance.This study provides a controllable design approach for modulating material electromagnetic parameters by influencing the reaction process.It also offers a design method for composites with an outstanding electromagnetic loss mechanism.展开更多
Novel and promising chloride ion batteries(CIBs)that can operate at room temperature have attracted great attentions,due to the sustainable chloride-containing resources and high theoretical energy density.To achieve ...Novel and promising chloride ion batteries(CIBs)that can operate at room temperature have attracted great attentions,due to the sustainable chloride-containing resources and high theoretical energy density.To achieve the superior electrochemical properties of CIBs,the structure design of electrode materials is essential.Herein,2D NiAl-layered double hydroxide(NiAl-LDH)nanoarrays derived from Al2O3 are in-situ grafted to graphene(G)by atomic layer deposition(ALD)and hydrothermal method.The achieved NiAl-LDH@G hybrids with 2D NiAl-LDH arrays grown perpendicularly on graphene surface,can efficiently prevent the stacking of LDHs and enlarge specific surface area to provide more active sites.The NiAl-LDH@G cathode exhibits a maximum discharge capacity of 223.3 mA h g^(-1)and an excellent reversible capacity of 107 mA h g^(-1)over 500 cycles at 100 mA g^(-1)with a high coulombic efficiency around 96%,whereas pure NiAl-LDH has a discharge capacity of only 48.8 mA h g^(-1)and a coulombic efficiency(CE)of about 78%.More importantly,the NiAl-LDH@G electrode has a stable voltage at 1.9 V and an outstanding discharge capacity of higher than 72 mA h g^(-1)after 120 days.Additionally,XRD,XPS,and EDS have been employed to unveil the electrochemical reaction and Cl-storage mechanism of the NiAlLDH@G cathode in CIBs.This work opens a facile and reasonable way for improving electrochemical performance at anion-type rechargeable batteries in terms of cathode material design and mechanism interpretation.展开更多
CoFe bimetallic hydroxides(CoFe BMHs)find wide applications as excellent catalysts in the field of water splitting.However,no study has systematically investigated the influence of the morphologies of CoFe BMHs on cat...CoFe bimetallic hydroxides(CoFe BMHs)find wide applications as excellent catalysts in the field of water splitting.However,no study has systematically investigated the influence of the morphologies of CoFe BMHs on catalyst performance.In this study,CoFe BMH nanoflowers(CoFe BMH NFs),CoFe BMH nanosheets(CoFe BMH NSHs),CoFe BMH nanorods(CoFe BMH NRs),and CoFe BMH nanospheres(CoFe BMH NSPs)were prepared on nickel foam via a hydrothermal method.CoFe BMH NSHs exhibited the most beneficial catalytic activity.At a current density of 100 mA·cm^(-2),its overpotential for oxygen evolution reaction(OER)was 282 mV,and the overall water splitting voltage was 2.05 V.The double-layer charging capacitance(Cdl)value of CoFe BMH NSHs was the largest in CoFe BMHs,which proves that CoFe BMH NSHs have the largest active area.Furthermore,the active site in the OER process was metal oxyhydroxide(MOOH)through in situ Raman characterization,and the generation of the active substance was an irreversible process.This work provides important insights into the design of catalyst morphologies and offers valuable guidelines for the enhancement of the performance of other catalysts.展开更多
High-entropy materials(HEMs),which are typically composed of five or more elements in near-equimolar ratios with concentrations ranging from 5%to 35%,have distinct elemental compositions and geometric properties that ...High-entropy materials(HEMs),which are typically composed of five or more elements in near-equimolar ratios with concentrations ranging from 5%to 35%,have distinct elemental compositions and geometric properties that allow for the development of advanced electrocatalysts for renewable energy conversion systems.The highentropy effect,crystal dislocations,cocktail effect,and slow diffusion in high-entropy layered double hydroxides(HE-LDHs)and amorphous materials(HE-AMs)have all been shown to boost electrocatalytic water oxidation performance significantly.These materials exhibit remarkable activity and stability in both alkaline and acidic conditions.HE-AMs,in particular,benefit from a variety of defects,including coordinatively unsaturated sites and loosely connected atoms,which are critical to their improved catalytic capabilities.HEMs engineering and precise nanostructure control can address the low intrinsic activity,restricted active sites,and poor conductivity of binary and ternary amorphous and LDH catalysts.This study discusses current advances in HE-LDHs and HE-AMs for water electrolysis,including synthesis methods,structural features,active site identification by DFT calculations,and their applications in water electrocatalysis.The presentation also covers potential problems and future directions for developing these materials in energy conversion device systems.展开更多
Layered double hydroxides(LDHs)have emerged as a promising class of photocatalysts with remarkable properties for diverse energy and environmental-related applications.This review offers insights into recent advances ...Layered double hydroxides(LDHs)have emerged as a promising class of photocatalysts with remarkable properties for diverse energy and environmental-related applications.This review offers insights into recent advances in LDH-based photocatalysts,focusing on their synthesis methods,structural properties,and photocatalytic performance.The unique structure of LDHs,characterized by positively charged metal hydroxide layers and intercalated anions,presents opportunities for tailoring their properties to enhance photocatalytic performance.The mechanisms for pollutant degradation,water splitting,and CO_(2) reduction are discussed,along with strategies to enhance the efficacy and stability of LDH-based photocatalysts.The photocatalytic mechanisms of LDHs for various reactions,including pollutant degradation,water splitting,and CO_(2) reduction,are discussed.Additionally,strategies for enriching the efficacy and stability of LDH-based photocatalysts are explored.This review underscores the significant potential of LDHs as versatile and efficient photocatalysts for addressing current environmental and energy challenges.展开更多
Electrically driven water splitting is an efficient method for green hydrogen production;however,its practical application is substantially constrained by the kinetically sluggish anodic oxygen evolution reaction(OER)...Electrically driven water splitting is an efficient method for green hydrogen production;however,its practical application is substantially constrained by the kinetically sluggish anodic oxygen evolution reaction(OER).Ruthenium(Ru)and its oxides are widely recognized as highly active OER catalysts.Although Ru is significantly cheaper than iridium(Ir),further reducing its content remains desirable.Herein,atomically dispersed Ru is doped into iron-nickel layered double hydroxides(Ru-FeNi-LDH)to decrease the Ru usage.We found that the Ru doping limit is roughly 9 wt%,and the Ru doping content significantly alters the OER kinetics-note that the high Ru concentration remarkably damages the Ru-FeNi-LDH structure and leads to agglomeration formation.By optimizing the Ru doping content to 3.3 wt%,the Ru-FeNi-LDH presents a low overpotential of 230 mV to reach a current density of 10 mA cm^(-2) in 1 M KOH,which is far better than the reference FeNi-LDH(280 mV)and RuO_(2)(350 mV).In the overall water splitting test,the current density of 10 mA cm^(-2) can be reached at a low voltage of 1.52 V,with stable operation for 80 h.Interestingly,Ru and Fe form an asymmetric Ru-Fe dipole,which is likely doped together into the LDH because the content of Fe instead of Ni is dependent on Ru content in experimental results.The electron-deficient feature of the Ru-Fe dipole thus facilitates the OER process.This work demonstrates a dual-transition metal synergy,providing a design strategy for OER and related catalysts.展开更多
Magnesium alloys are nontoxic and promising as orthopedic metallic implants,but preparing a biocompatible Mg(OH)_(2)layer with high corrosion protection ability remains challenging.It is generally believed that the Mg...Magnesium alloys are nontoxic and promising as orthopedic metallic implants,but preparing a biocompatible Mg(OH)_(2)layer with high corrosion protection ability remains challenging.It is generally believed that the Mg(OH)_(2)layer,especially that formed in a natural condition,cannot provide desirable corrosion resistance in the community of corrosion and protection.Here,several Mg(OH)_(2)coatings were prepared by changing the pH values of sodium hydroxide solutions.These coatings were composed of innumerable nanoplatelets with different orientations and showed distinguished capability in corrosion resistance.The nanoplatelets were well-oriented with their ab-planes parallel to,instead of perpendicular to,the magnesium alloy surface by raising the pH value to 14.0.This specific orientation resulted in the optimal coating showing long-term corrosion protection in both in vitro and in vivo environments and good osteogenic capability.These finds manifest that the environment-friendly Mg(OH)_(2)coating can also provide comparable and better corrosion protection than many traditional chemical conversion films(such as phosphate,and fluoride).展开更多
Modulating metal-organic framework’s(MOF)crystallinity and size using a polymer,in conjunction with a high surface area of layered double hydroxide,yields an effective strategy for concurrently enhancing the electroc...Modulating metal-organic framework’s(MOF)crystallinity and size using a polymer,in conjunction with a high surface area of layered double hydroxide,yields an effective strategy for concurrently enhancing the electrochemical and photocatalytic performance.In this study,we present the development of an optimized nanocomposite,denoted as 0.5PVP/ZIF-67,developed on AZ31 magnesium alloy,serving as an efficient and durable multifunctional coating.This novel strategy aims to enhance the overall performance of the porous coating through the integration of microarc oxidation(MAO),ZnFe LDH backbone,and ZIF-67 formation facilitated by the addition of polyvinylpyrrolidone(PVP),resulting in a three-dimensional,highly efficient,and multifunctional material.The incorporation of 0.5 g of PVP proved to be effective in the size modulation of ZIF-67,which formed a corrosion-resistant top layer,improving the total polarization resistance(R_(p)=8.20×10^(8)).The dual functionality exhibited by this hybrid architecture positions it as a promising candidate for mitigating environmental pollution,degrading 97.93%of Rhodamine B dye in 45 min.Moreover,the sample displayed exceptional degradation efficiency(96.17%)after 5 cycles.This study illuminates the potential of nanocomposites as electrochemically stable and photocatalytically active materials,laying the foundation for the advancements of next-generation multifunctional frameworks.展开更多
Cobalt-based layered double hydroxides(LDHs)are highly sought after by researchers due to their low-cost,high efficiency and stability for oxygen evolution reaction(OER)in water electrolysis.The OER performance of the...Cobalt-based layered double hydroxides(LDHs)are highly sought after by researchers due to their low-cost,high efficiency and stability for oxygen evolution reaction(OER)in water electrolysis.The OER performance of these LDHs is closely related to their morphology and electronic structure.However,there is a lack of theory on how to control reaction conditions to regulate the morphologies.In this paper,the growth mechanism of LDH prepared in different solvents is thoroughly studied.Consequently,the Co/Ni-LDHs exhibiting a 3D hierarchical flower-like structure were synthesized with normal alcohol as a solvent,meanwhile,the thickness of the LDHs can be controlled by the molecular weight of the normal alcohol.By adjusting the suitable Co/Ni ratio and solvent,the Co/Ni0.050-LDH-Me was synthesized and exhibited excellent OER performance.At 10 mA cm^(-2),the overpotential of Co/Ni0.050-LDH-Me is 307 mV,and the Tafel slope is 76.5 mV dec^(-1).展开更多
Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation.Nevertheless,the direct electrolysis of seawater encounters significant challenges due to poor anodic stability cau...Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation.Nevertheless,the direct electrolysis of seawater encounters significant challenges due to poor anodic stability caused by detrimental chlorine chemistry.Herein,we present our recent discovery that the incorporation of Ce into Ni Fe layered double hydroxide nanosheet array on Ni foam(Ce-Ni Fe LDH/NF)emerges as a robust electrocatalyst for seawater oxidation.During the seawater oxidation process,CeO_(2)is generated,effectively repelling Cl^(-)and inhibiting the formation of Cl O-,resulting in a notable enhancement in the oxidation activity and stability of alkaline seawater.The prepared Ce-Ni Fe LDH/NF requires only overpotential of 390 m V to achieve the current density of 1 A cm^(-2),while maintaining long-term stability for 500 h,outperforming the performance of Ni Fe LDH/NF(430 m V,150 h)by a significant margin.This study highlights the effectiveness of a Ce-doping strategy in augmenting the activity and stability of materials based on Ni Fe LDH in seawater electrolysis for oxygen evolution.展开更多
基金support from the National Natural Science Foundation of China(grant number 52075544)Innovation Funds of Jihua Laboratory(X220971UZ230)+1 种基金Basic and Applied Basic Research Foundation of Guangdong Province(2022A1515110649)Funds from Research Platforms of Guangdong Higher Education Institutes(2022ZDJS038).
文摘Efficient lubrication of magnesium alloys is a highly challenging topic in the field of tribology.In this study,magnesium silicate hydroxide(MSH)nanotubes with serpentine structures were synthesized.The tribological behavior of AZ91D magnesium alloy rubbed against GCr15 steel was studied under lubricating oil with surface-modified MSH nanotubes as additives.The effects of the concentration,applied load,and reciprocating frequency on the friction and wear of the AZ91D alloy were studied using an SRV-4 sliding wear tester.Results show a decrease of 18.7–68.5%in friction coefficient,and a reduction of 19.4–54.3%in wear volume of magnesium alloy can be achieved by applying the synthetic serpentine additive under different conditions.A suspension containing 0.3 wt.%MSH was most efficient in reducing wear and friction.High frequency and medium load were more conducive to improving the tribological properties of magnesium alloys.A series of beneficial physical and chemical processes occurring at the AZ91D alloy/steel interface can be used to explain friction and wear reduction based on the characterization of the morphology,chemical composition,chemical state,microstructure,and nanomechanical properties of the worn surface.The synthetic MSH,with serpentine structure and nanotube morphology,possesses excellent adsorbability,high chemical activity,and good self-lubrication and catalytic activity.Therefore,physical polishing,tribochemical reactions,and physicalchemical depositions can occur easily on the sliding contacts.A dense tribolayer with a complex composition and composite structure was formed on the worn surface.Its high hardness,good toughness and plasticity,and prominent lubricity resulted in the improvement of friction and wear,making the synthetic MSH a promising efficient oil additive for magnesium alloys under boundary and mixed lubrication.
基金the National Key Research and Development Program of China(2022YFB3504503)the National Natural Science Foundation of China(52274355)the Gansu Province Science and Technology Major Special Project,China(22ZD6GD061).
文摘Precipitation is often used for the preparation of La(OH)_(3)with precipitants of liquid alkali and ammonia.To solve the problems of high cost and wastewater pollution caused by common precipitants,the active MgO synthesized by pyrolysis was used as the precipitant to prepare La(OH)_(3).The species distribution of LaCl_(3)and LaCl_(3)-MgCl_(2)mixed system solution was calculated,and the kinetic analysis of the precipi-tation process was carried out to confirm the key factors influencing the precipitation of La(OH)_(3).The results show that La(OH)_(3)with D_(50)of 5.57μm,a specific surface area of 25.70 m^(2)/g,a rod-like shape,and MgO content of 0.044 wt%,was successfully prepared by adding active MgO.The precipitation ratio of La reaches 99.92%.The La(OH)_(3)precipitation is controlled by the diffusion process.The activity of MgO has a significant influence on MgO content in the precipitate.The preparation of La(OH)_(3)by active MgO provides a potential way for an eco-friendly preparation method of rare earth.
文摘Aluminum hydroxide adjuvant exhibits a poorly crystalline boehmite(PCB)structure,which demonstrates instability during prolonged storage.In the present study,we systematically investigated the quality alterations of the adjuvant stored at roo m temperature by analyzing its crystal structure,particle size distribution,electron microscopic characteristics,pH,isoelectric point(pI),and adsorption capacity.These assessments aimed to ensure the effectiveness and safety of vaccine production.Three batches of adjuvants were stored at room temperature for 15 months,and their changes were monitored using X-ray diffraction patterns,transmission electron microscopy(TEM),pH measurements,pI determination,and adsorption capacity analysis.X-ray diffraction revealed that the crystalline phases of aluminum hydroxide initially exhibited a PCB structure,which became progressively more ordered during storage.Notably,after 12 months,a new diffraction peak emerged at 18.2°2θ,with its intensity increasing over time.This corresponded to the formation of highly crystalline gibbsite and bayerite,which compromised the stability of the adjuvant.Furthermore,the pH and pI values decreased during storage,reflecting a decline in the chemical stability of the adjuvant.Comprising nanoparticles with a mean diameter of 130 nm,the adjuvant maintained a high surface area and excellent adsorption capacity.The adsorption rate at 8 mg BSA/mg Al3+consistently exceeded 97%,with no statistically significant differences observed between the adsorption capacities at 1 and 15 months(P>0.05).This indicated that the nanoparticle aluminum hydroxide adjuvant sustained high adsorption efficiency throughout the storage period,underscoring its reliability as a vaccine adsorbent.However,in the later stages of storage,the emergence of highly crystalline gibbsite and bayerite,coupled with declines in pH and pI,negatively impacted the adjuvant’s stability.Based on these findings,we recommended that aluminum hydroxide adjuvants should not be stored at room temperature for longer than 12 months to preserve their quality and efficacy.
基金supported by the National Natural Science Foundation of China(Nos.52371240,U1904215)Natural Science Foundation of Jiangsu Province(No.BK20200044)Changjiang scholars’program of the Ministry of Education(No.Q2018270)。
文摘Rationally design the morphology and structure of electroactive nanomaterials is an effective approach to enhance the performance of aqueous batteries.Herein,we co-engineered the hollow architecture and interlayer spacing of layered double hydroxides(LDH)to achieve high electrochemical activity.The hierarchical hollow LDH was prepared from bimetallic zeolitic imidazolate frameworks(ZIF)by a facile cation exchange strategy.Zn and Cu elements were selected as the second metals incorporated in Co-ZIF.The characteristics of the corresponding derivatives were studied.Besides,the transformation mechanism of CoZn-ZIF into nanosheet-assembled hollow Co Zn Ni LDH(denoted as CoZnNi-OH)was systematically investigated.Importantly,the interlayer spacing of CoZnNi-OH expands due to Zn^(2+)incorporation.The prepared CoZnNi-OH offers large surface area,exposed active sites,and rapid mass transfer/diffusion rate,which lead to a significant enhancement in the specific capacitance,rate performance,and cycle stability of CoZnNi-OH electrode.In addition,the aqueous alkaline CoZnNi-OH//Zn showed a maximum energy density/power density of 0.924 m Wh/cm^(2),8.479 m W/cm^(2).This work not only raises an insightful strategy for regulating the morphology and interlayer spacing of LDH,but also provides a reference of designing hollow nickel-based nanomaterials for aqueous batteries.
基金financially supported by the National Natural Science Foundation of China(Nos.22209040 and 22202063)。
文摘Zinc-nitrate battery could produce electrical power,remove pollutant nitrate and obtain value-added ammonia,where the cathodic reaction of converting nitrate to ammonia is sluggish and complex due to the involvement of multi-electron transfer.Thus,highly efficient catalysts for nitrate reduction reaction(NO_(3)RR)are greatly needed.In this work,we report a high entropy hydroxide(HE-OH)as an excellent NO3RR catalyst,which could achieve high NH_(3)Faradaic efficiencies(e.g.,nearly 100%at-0.3 V versus reversible hydrogen electrode)and high yield rates(e.g.,30.4 mg h^(-1)cm^(-2)at-0.4 V).Moreover,HE-OH could also deliver a current density of 10 mA/cm^(2) at an overpotential of 260 mV for oxygen evolution reaction.The assembled zinc-nitrate battery using HE-OH as the cathode demonstrates a high power density(e.g.,3.62 mW/cm^(2)),rechargeability and stability.
基金supported by the National Natural Science Foundation of China(Nos.22278020 and 2177060378)the Fundamental Research Funds for the Central Universities(Nos.12060093063 and XK1803-05)the Program for Changjiang Scholars and Innovative Research Teams in University(No.IRT1205)。
文摘Aqueous hybrid-ion batteries(AHBs)are a promising class of energy storage devices characterized by low cost,high safety,and high energy density.However,aqueous Cu-Al hybrid-ion batteries face challenges such as sluggish reaction kinetics and severe structural collapse of cathode materials,which limit their practical application.Here,a high-performance aqueous Cu-Al hybrid-ion battery is developed using aluminum pre-inserted Cu_(9)S_(5)(Al-Cu_(9)S_(5))as the cathode material,derived from CuAl-layered double hydroxide(CuAl-LDH).The Al^(3+)pre-intercalation strategy narrows the band gap,enhancing electron transport and improving electrochemical kinetics.The battery exhibits excellent rate performance(463 and 408 mA h g^(-1)at current densities of 500 and 1000 mA g^(-1),respectively)and good cycle stability(with a capacity retention ratio of 81% after 300 cycles at a current density of 1000 mA g^(-1)).Its performance surpasses that of most reported Al-ion batteries.Ex situ characterization and density functional theory(DFT)calculations reveal that the pre-intercalated Al^(3+)in Al-Cu9S5participates in the reversible embedding/removal of Al ions during charge/discharge processes.These findings provide valuable insights for designing pre-intercalated cathodes in aqueous Cu-Al hybrid-ion batteries with stable cycle life.
基金financial support of the National Natural Science Foundation of China (22379063)
文摘Layered double hydroxides(LDHs)are potential cathode materials for aqueous magnesium-ion batteries(AMIBs).However,the low capacity and sluggish kinetics significantly limit their electrochemical performance in AMIBs.Herein,we find that oxygen vacancies can significantly boost the capacity,electrochemical kinetics,and structure stability of LDHs.The corresponding structure-performance relationship and energy storage mechanism are elaborated through exhaustive in/ex-situ experimental characterizations and density functional theory(DFT)calculations.Specially,in-situ Raman and DFT calculations reveal that oxygen vacancies elevate orbital energy of O 2p and electron density of O atoms,thereby enhancing the orbital hybridization of O 2p with Ni/Co 3d.This facilitates electron transfer between O and adjacent Ni/Co atoms and improves the covalency of Ni–O and Co–O bonds,which activates Ni/Co atoms to release more capacity and stabilizes the Ov-NiCo-LDH structure.Moreover,the distribution of relaxation times(DRT)and molecular dynamics(MD)simulations disclose that the enhanced d-p orbital hybridization optimizes the electronic structure of Ov-NiCo-LDH,which distinctly reduces the diffusion energy barriers of Mg^(2+)and improves the charge transfer kinetics of Ov-NiCo-LDH.Consequently,the assembled Ov-NiCo-LDH//active carbon(AC)and Ov-NiCo-LDH//perylenediimide(PTCDI)AMIBs can both deliver high specific discharge capacity(182.7 and 59.4 mAh g^(−1)at 0.5 A g^(−1),respectively)and long-term cycling stability(85.4%and 89.0%of capacity retentions after 2500 and 2400 cycles at 1.0 A g^(−1),respectively).In addition,the practical prospects for Ov-NiCo-LDH-based AMIBs have been demonstrated in different application scenarios.This work not only provides an effective strategy for obtaining high-performance cathodes of AMIBs,but also fundamentally elucidates the inherent mechanisms.
基金supported by the Natural Science Foundation of Henan(242300421230)the Young Teacher Fundamental Research Cultivation Program of Zhengzhou University(JC23557030)the National Natural Science Foundation of China(U21A20281 and 22208322)。
文摘Noble metal-loaded layered hydroxides exhibit high efficiency in electrocatalyzing water splitting.However,their widespread use as bifunctional electrocatalysts is hindered by low metal loading,inefficient yield,and complex synthesis processes.In this work,platinum atoms were anchored onto nickel-iron layered double hydroxide/carbon nanotube(LDH/CNT)hybrid electrocatalysts by using a straightforward milling technique with K_(2)Pt Cl_(6)·6H_(2)O as the Pt source.By adjusting the Pt-to-Fe ratio to 1/2 and 1/10,excellent electrocatalysts—Pt_(1/6)-Ni_(2/3)Fe_(1/3)-LDH/CNT and Pt_(1/30)-Ni_(2/3)Fe_(1/3)-LDH/CNT—were achieved with superior performance in hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),outperforming the corresponding commercial Pt/C(20 wt%)and Ru O_(2)electrocatalysts.The enhanced electrochemical performance is attributed to the modification of Pt's electronic structure,which exhibits electron-rich states for HER and electrondeficient states for OER,significantly boosting Pt's electrochemical activity.Furthermore,the simple milling technology for controlling Pt loading offers a promising approach for scaling up the production of electrocatalysts.
基金supported by the National Key Research and Development Program of China(No.2018YFA0703700)the National Natural Science Foundation of China(No.12034002)the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities,No.FRF-IDRY-23-033)。
文摘Amorphous two-dimensional transition metal oxide/(oxy)hydroxide(2D TMO/TMHO)nanomaterials(NMs)have the properties of both 2D and amorphous materials,displaying outstanding physicochemical qualities.Therefore,they demonstrate considerable promise for use in electrocatalytic water splitting applications.Here,the primary amorphization strategies for achieving the 2D TMO/TMHO NMs are comprehensively reviewed,including low-temperature reaction,rapid reaction,exchange/doping effect,ligand modulation,and interfacial energy confinement.By integrating these strategies with various physicochemical synthesis methods,it is feasible to control the amorphization of TMO/TMHO NMs while maintaining the distinctive benefits of their 2D structures.Furthermore,it delves into the structural advantages of amorphous 2D TMO/TMHO NMs in electrocatalytic water splitting,particularly emphasizing recent advancements in enhancing their electrocatalytic performance through interface engineering.The challenges and potential future directions for the precise synthesis and practical application of amorphous 2D TMO/TMHO NMs are also provided.This review aims to establish a theoretical foundation and offer experimental instructions for developing effective and enduring electrocatalysts for water splitting.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF),funded by the Ministry of Education(NRF-2018R1A6A1A03024962)the Ministry of Science and ICT(NRF-2020R1A2C2100746).
文摘Developing an efficient electrocatalyst for superior electrochemical water splitting(EWS)is crucial for achieving comprehensive hydrogen production.A heterostructured electrocatalyst,free of noble metals,Ti_(3)C_(2)MXene nanosheet-integrated cobalt-doped nickel hydroxide(NHCoMX)composite was synthesized via a hydrothermal method.The abundant pores in the Ti_(3)C_(2)MXene nanosheet(MX)-integrated microarchitecture increased the number of active sites and facilitated charge transfer,thus enhancing electrocatalysis.Specifically,the MXenhanced charge transfer considerably transformed the microelectronic structure of cobalt-doped Ni(OH)2(NHCo),which promoted its hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).Hence,as an EWS catalyst,NHCoMX exhibited an exceptional electrocatalytic activity,demonstrating OER and HER overpotentials of 310 mV and 73 mV,respectively,with low Tafel slopes of 65 mV dec^(-1)and 85 mV dec^(-1),respectively;it exhibited a current density of 10 mV cm^(-2)in 1.0 mol L^(-1)KOH,representing the closest efficiency to the noble state-of-the-art RuO2 and Pt/C catalyst.Furthermore,the developed electrocatalyst improved the activities of both HER and OER,leading to an overall EWS current density of 10 mA cm^(-2)at 1.72 V in an alkaline electrolyte with two electrodes.This study describes an efficient heterostructured NHCoMX composite electrocatalyst.It is significantly comparable to the noble state-of-the-art electrocatalysts and can be extended to fabricate resourceful catalysts for large-scale EWS applications.
基金supported by the Research Funds of the State Key Laboratory for Marine Corrosion and Protection(No.JS220903).
文摘Carbon-based materials exhibit excellent dielectric absorption properties,among which graphene has received particular attention in research of electromagnetic wave absorbing materials because of its high electrical conductivity and unique large-area,thin-layer two-dimensional structural features.However,the electromagnetic absorption performance of the material is hindered from further improvement due to its single component composition.It is influenced by the conductive network of graphene,making it challenging to achieve a balance in impedance matching and electromagnetic loss,thereby restricting its broader application.To address these challenges,we developed a series of nickel hydroxide-modified graphene composites.Through a structural composite design,we optimized overall impedance matching,introduced diverse loss mechanisms to enhance electromagnetic loss performance,and utilized a secondary reaction control method to precisely regulate the deposition of nickel hydroxide on the graphene surface,thereby achieving regulate of the composite material's electromagnetic parameters within a defined range.Under low sample filling ratios and a thin sample thickness of 1.8 mm,the effective absorption bandwidth reaches 6.5 GHz,demonstrating excellent electromagnetic absorption performance.This study provides a controllable design approach for modulating material electromagnetic parameters by influencing the reaction process.It also offers a design method for composites with an outstanding electromagnetic loss mechanism.
基金supported by the National Natural Science Foundation of China(Grant Nos.22278101,22068010,22168016,and 52365044)the Natural Science Foundation of Hainan Province(Grant Nos.2019RC142 and 519QN176)the Finance Science and Technology Project of Hainan Province(Grant No.ZDYF2020009).
文摘Novel and promising chloride ion batteries(CIBs)that can operate at room temperature have attracted great attentions,due to the sustainable chloride-containing resources and high theoretical energy density.To achieve the superior electrochemical properties of CIBs,the structure design of electrode materials is essential.Herein,2D NiAl-layered double hydroxide(NiAl-LDH)nanoarrays derived from Al2O3 are in-situ grafted to graphene(G)by atomic layer deposition(ALD)and hydrothermal method.The achieved NiAl-LDH@G hybrids with 2D NiAl-LDH arrays grown perpendicularly on graphene surface,can efficiently prevent the stacking of LDHs and enlarge specific surface area to provide more active sites.The NiAl-LDH@G cathode exhibits a maximum discharge capacity of 223.3 mA h g^(-1)and an excellent reversible capacity of 107 mA h g^(-1)over 500 cycles at 100 mA g^(-1)with a high coulombic efficiency around 96%,whereas pure NiAl-LDH has a discharge capacity of only 48.8 mA h g^(-1)and a coulombic efficiency(CE)of about 78%.More importantly,the NiAl-LDH@G electrode has a stable voltage at 1.9 V and an outstanding discharge capacity of higher than 72 mA h g^(-1)after 120 days.Additionally,XRD,XPS,and EDS have been employed to unveil the electrochemical reaction and Cl-storage mechanism of the NiAlLDH@G cathode in CIBs.This work opens a facile and reasonable way for improving electrochemical performance at anion-type rechargeable batteries in terms of cathode material design and mechanism interpretation.
基金supported by the National Science Fund for Distinguished Young Scholars(No.52025041)the National Natural Science Foundation of China(Nos.52474319,52250091,U2341267,and 52450003)+1 种基金the Fundamental Research Funds for the Central Universities(No.FRF-TP-20-02C2)supported by the Interdisciplinary Research Project for Young Teachers of USTB,China(Fundamental Research Funds for the Central Universities)(No.FRF-IDRY-GD23-003).
文摘CoFe bimetallic hydroxides(CoFe BMHs)find wide applications as excellent catalysts in the field of water splitting.However,no study has systematically investigated the influence of the morphologies of CoFe BMHs on catalyst performance.In this study,CoFe BMH nanoflowers(CoFe BMH NFs),CoFe BMH nanosheets(CoFe BMH NSHs),CoFe BMH nanorods(CoFe BMH NRs),and CoFe BMH nanospheres(CoFe BMH NSPs)were prepared on nickel foam via a hydrothermal method.CoFe BMH NSHs exhibited the most beneficial catalytic activity.At a current density of 100 mA·cm^(-2),its overpotential for oxygen evolution reaction(OER)was 282 mV,and the overall water splitting voltage was 2.05 V.The double-layer charging capacitance(Cdl)value of CoFe BMH NSHs was the largest in CoFe BMHs,which proves that CoFe BMH NSHs have the largest active area.Furthermore,the active site in the OER process was metal oxyhydroxide(MOOH)through in situ Raman characterization,and the generation of the active substance was an irreversible process.This work provides important insights into the design of catalyst morphologies and offers valuable guidelines for the enhancement of the performance of other catalysts.
基金supported by the Innovative Research Group Project of the National Natural Science Foundation of China(No.52021004)the Funds for Chongqing Talents Plan(No.CQYC2021059563)+1 种基金the Fundamental Research Funds for the Central Universities(No.2021CDJQY-027)the National Natural Science Foundation of China(No.52206089).
文摘High-entropy materials(HEMs),which are typically composed of five or more elements in near-equimolar ratios with concentrations ranging from 5%to 35%,have distinct elemental compositions and geometric properties that allow for the development of advanced electrocatalysts for renewable energy conversion systems.The highentropy effect,crystal dislocations,cocktail effect,and slow diffusion in high-entropy layered double hydroxides(HE-LDHs)and amorphous materials(HE-AMs)have all been shown to boost electrocatalytic water oxidation performance significantly.These materials exhibit remarkable activity and stability in both alkaline and acidic conditions.HE-AMs,in particular,benefit from a variety of defects,including coordinatively unsaturated sites and loosely connected atoms,which are critical to their improved catalytic capabilities.HEMs engineering and precise nanostructure control can address the low intrinsic activity,restricted active sites,and poor conductivity of binary and ternary amorphous and LDH catalysts.This study discusses current advances in HE-LDHs and HE-AMs for water electrolysis,including synthesis methods,structural features,active site identification by DFT calculations,and their applications in water electrocatalysis.The presentation also covers potential problems and future directions for developing these materials in energy conversion device systems.
基金supported by Karpagam Academy of Higher Education,India(No.KAHE/R-Acad/A1/Seed Money/024/2981)。
文摘Layered double hydroxides(LDHs)have emerged as a promising class of photocatalysts with remarkable properties for diverse energy and environmental-related applications.This review offers insights into recent advances in LDH-based photocatalysts,focusing on their synthesis methods,structural properties,and photocatalytic performance.The unique structure of LDHs,characterized by positively charged metal hydroxide layers and intercalated anions,presents opportunities for tailoring their properties to enhance photocatalytic performance.The mechanisms for pollutant degradation,water splitting,and CO_(2) reduction are discussed,along with strategies to enhance the efficacy and stability of LDH-based photocatalysts.The photocatalytic mechanisms of LDHs for various reactions,including pollutant degradation,water splitting,and CO_(2) reduction,are discussed.Additionally,strategies for enriching the efficacy and stability of LDH-based photocatalysts are explored.This review underscores the significant potential of LDHs as versatile and efficient photocatalysts for addressing current environmental and energy challenges.
基金supported by Guangdong Basic and Applied Basic Research Foundation(2022B1515120079)Tertiary Education Scientific research project of Guangzhou Municipal Education Bureau(2024312194)+1 种基金the Science and Technology Projects in Guangzhou(2024A03J0308)the Outstanding Youth Project of Natural Science Foundation of Guangdong Province(2022B1515020020).
文摘Electrically driven water splitting is an efficient method for green hydrogen production;however,its practical application is substantially constrained by the kinetically sluggish anodic oxygen evolution reaction(OER).Ruthenium(Ru)and its oxides are widely recognized as highly active OER catalysts.Although Ru is significantly cheaper than iridium(Ir),further reducing its content remains desirable.Herein,atomically dispersed Ru is doped into iron-nickel layered double hydroxides(Ru-FeNi-LDH)to decrease the Ru usage.We found that the Ru doping limit is roughly 9 wt%,and the Ru doping content significantly alters the OER kinetics-note that the high Ru concentration remarkably damages the Ru-FeNi-LDH structure and leads to agglomeration formation.By optimizing the Ru doping content to 3.3 wt%,the Ru-FeNi-LDH presents a low overpotential of 230 mV to reach a current density of 10 mA cm^(-2) in 1 M KOH,which is far better than the reference FeNi-LDH(280 mV)and RuO_(2)(350 mV).In the overall water splitting test,the current density of 10 mA cm^(-2) can be reached at a low voltage of 1.52 V,with stable operation for 80 h.Interestingly,Ru and Fe form an asymmetric Ru-Fe dipole,which is likely doped together into the LDH because the content of Fe instead of Ni is dependent on Ru content in experimental results.The electron-deficient feature of the Ru-Fe dipole thus facilitates the OER process.This work demonstrates a dual-transition metal synergy,providing a design strategy for OER and related catalysts.
基金supported by the National Natural Science Foundation of China(NSFC,52271073)the Sichuan Science and Technology Program(2024NSFJQ0034)+3 种基金the Central Government Guided Special Program(No.2021ZYD0049)the Young Elite Scientists Sponsorship Program by CAST(YESS,2018QNRC001)the GDPH Supporting Fund for Talent Program(KY0120220137)the Scientific and Technological Projects of Guangzhou,China(202002030283).
文摘Magnesium alloys are nontoxic and promising as orthopedic metallic implants,but preparing a biocompatible Mg(OH)_(2)layer with high corrosion protection ability remains challenging.It is generally believed that the Mg(OH)_(2)layer,especially that formed in a natural condition,cannot provide desirable corrosion resistance in the community of corrosion and protection.Here,several Mg(OH)_(2)coatings were prepared by changing the pH values of sodium hydroxide solutions.These coatings were composed of innumerable nanoplatelets with different orientations and showed distinguished capability in corrosion resistance.The nanoplatelets were well-oriented with their ab-planes parallel to,instead of perpendicular to,the magnesium alloy surface by raising the pH value to 14.0.This specific orientation resulted in the optimal coating showing long-term corrosion protection in both in vitro and in vivo environments and good osteogenic capability.These finds manifest that the environment-friendly Mg(OH)_(2)coating can also provide comparable and better corrosion protection than many traditional chemical conversion films(such as phosphate,and fluoride).
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(No.2022R1A2C1006743).
文摘Modulating metal-organic framework’s(MOF)crystallinity and size using a polymer,in conjunction with a high surface area of layered double hydroxide,yields an effective strategy for concurrently enhancing the electrochemical and photocatalytic performance.In this study,we present the development of an optimized nanocomposite,denoted as 0.5PVP/ZIF-67,developed on AZ31 magnesium alloy,serving as an efficient and durable multifunctional coating.This novel strategy aims to enhance the overall performance of the porous coating through the integration of microarc oxidation(MAO),ZnFe LDH backbone,and ZIF-67 formation facilitated by the addition of polyvinylpyrrolidone(PVP),resulting in a three-dimensional,highly efficient,and multifunctional material.The incorporation of 0.5 g of PVP proved to be effective in the size modulation of ZIF-67,which formed a corrosion-resistant top layer,improving the total polarization resistance(R_(p)=8.20×10^(8)).The dual functionality exhibited by this hybrid architecture positions it as a promising candidate for mitigating environmental pollution,degrading 97.93%of Rhodamine B dye in 45 min.Moreover,the sample displayed exceptional degradation efficiency(96.17%)after 5 cycles.This study illuminates the potential of nanocomposites as electrochemically stable and photocatalytically active materials,laying the foundation for the advancements of next-generation multifunctional frameworks.
基金supported by the National Natural Science Foundation of China(52002111)the Natural Science Foundation of Hebei Province(E2024208054,B2022208006)Science Foundation of University of Hebei Province(JZX2024025).
文摘Cobalt-based layered double hydroxides(LDHs)are highly sought after by researchers due to their low-cost,high efficiency and stability for oxygen evolution reaction(OER)in water electrolysis.The OER performance of these LDHs is closely related to their morphology and electronic structure.However,there is a lack of theory on how to control reaction conditions to regulate the morphologies.In this paper,the growth mechanism of LDH prepared in different solvents is thoroughly studied.Consequently,the Co/Ni-LDHs exhibiting a 3D hierarchical flower-like structure were synthesized with normal alcohol as a solvent,meanwhile,the thickness of the LDHs can be controlled by the molecular weight of the normal alcohol.By adjusting the suitable Co/Ni ratio and solvent,the Co/Ni0.050-LDH-Me was synthesized and exhibited excellent OER performance.At 10 mA cm^(-2),the overpotential of Co/Ni0.050-LDH-Me is 307 mV,and the Tafel slope is 76.5 mV dec^(-1).
基金support from the Free Exploration Project of Frontier Technology for Laoshan Laboratory(No.16-02)the National Natural Science Foundation of China(Nos.22072015 and 21927811)。
文摘Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation.Nevertheless,the direct electrolysis of seawater encounters significant challenges due to poor anodic stability caused by detrimental chlorine chemistry.Herein,we present our recent discovery that the incorporation of Ce into Ni Fe layered double hydroxide nanosheet array on Ni foam(Ce-Ni Fe LDH/NF)emerges as a robust electrocatalyst for seawater oxidation.During the seawater oxidation process,CeO_(2)is generated,effectively repelling Cl^(-)and inhibiting the formation of Cl O-,resulting in a notable enhancement in the oxidation activity and stability of alkaline seawater.The prepared Ce-Ni Fe LDH/NF requires only overpotential of 390 m V to achieve the current density of 1 A cm^(-2),while maintaining long-term stability for 500 h,outperforming the performance of Ni Fe LDH/NF(430 m V,150 h)by a significant margin.This study highlights the effectiveness of a Ce-doping strategy in augmenting the activity and stability of materials based on Ni Fe LDH in seawater electrolysis for oxygen evolution.
