Light weight and mechanically strong α-chitin aerogels were fabricated using the sol-gel/self-assembly method from α-chitin in different aqueous alkali hydroxide(KOH, Na OH and Li OH)/urea solutions. All of the α-c...Light weight and mechanically strong α-chitin aerogels were fabricated using the sol-gel/self-assembly method from α-chitin in different aqueous alkali hydroxide(KOH, Na OH and Li OH)/urea solutions. All of the α-chitin solutions exhibited temperature-induced rapid gelation behavior. 13 C nuclear magnetic resonance(NMR) spectra revealed that the aqueous alkali hydroxide/urea solutions are non-derivatizing solvents for α-chitin. Fourier transform infrared(FT-IR), X-ray diffraction(XRD) and cross-polarization magic angle spinning(CP/MAS) 13 C NMR confirmed that α-chitin has a stable aggregate structure after undergoing dissolution and regeneration. Subsequently, nanostructured α-chitin aerogels were fabricated by regeneration from the chitin solutions in ethanol and then freeze-drying from t-Bu OH. These α-chitin aerogels exhibited high porosity(87% to 94%), low density(0.09 to 0.19 g/cm^3), high specific surface area(419 to 535 m^2/g) and large pore volume(2.7 to 3.8 cm^3/g). Moreover, the α-chitin aerogels exhibited good mechanical properties under compression and tension models. In vitro studies showed that m BMSCs cultured on chitin hydrogels have good biocompatibility. These nanostructured α-chitin aerogels may be useful for various applications, such as catalyst supports, carbon aerogel precursors and biomedical materials.展开更多
The urea oxidization reaction(UOR)is an important anodic reaction in electro-catalytic energy conversion.However,the sluggish reaction kinetics and complex catalyst transformation in electrocatalysis require activity ...The urea oxidization reaction(UOR)is an important anodic reaction in electro-catalytic energy conversion.However,the sluggish reaction kinetics and complex catalyst transformation in electrocatalysis require activity improvement and better mechanistic understanding of the state-of-the-art Ni(OH)_(2) catalyst.Herein,by utilizing low-temperature argon(Ar)plasma processing,tooth-wheel Ni(OH)_(2) nanosheets self-supported on Ni foam(Ni(OH)_(2)-Ar)are demonstrated to have improved UOR activity compared to conventional Ni(OH)_(2).The theoretical assessment confirms that the edge has a smaller cation vacancy formation energy than the basal plane,consequently explaining the structural formation.Operando and quasi-operando methods are employed to investigate the dynamic evolution of the Ni(OH)_(2) film in UOR.The crucial dehydrogenation products of Ni(OH)_(5)O^(-)intermediates are identified to be stable on the etched edge and explain the enhanced UOR in the low potential region.In addition,the dynamic active sites are monitored to elucidate the reaction mechanism in different potential ranges.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
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
Combining urea oxidation reaction(UOR) with hydrogen evolution reaction(HER) is an effective method for energy saving and highly efficient electrocatalytic hydrogen production. Herein, molybdenumincorporated cobalt ca...Combining urea oxidation reaction(UOR) with hydrogen evolution reaction(HER) is an effective method for energy saving and highly efficient electrocatalytic hydrogen production. Herein, molybdenumincorporated cobalt carbonate hydroxide nanoarrays(CoxMoyCH) are designed and synthesized as a bifunctional catalyst towards UOR and HER. Benefiting from the Mo doping, the dispersed nanoarray structure and redistributed electron density, the CoxMoyCH catalyst display outstanding catalytic performance and durability for both HER and UOR, affording the overpotential of 82 m V for HER and delivering a low potential of the 1.33 V for UOR(vs. reversible hydrogen electrode, RHE) to attain a current density of 10 m A cm^(-2), respectively. Remarkably, when CoxMoyCH was applied as bifunctional catalyst in a twoelectrode electrolyzer, a working voltage of 1.40 V is needed in urea-assisted water electrolysis at10 m A cm^(-2) and without apparent decline for 40 h, outperforming the working voltage of 1.51 V in conventional water electrolysis.展开更多
Fine nickel powders with a narrow particle size distribution were prepared by reducing nickel hydroxide in aqueous solution.The formation and reduction pathways of nickel powder were analyzed,as well as the effects of...Fine nickel powders with a narrow particle size distribution were prepared by reducing nickel hydroxide in aqueous solution.The formation and reduction pathways of nickel powder were analyzed,as well as the effects of the molar ratio of hydrazine hydrate to nickel hydroxide,hydrazine concentration,and the dosage of surfactant PEG6000 on particle size,surface morphology,and dispersion.Results reveal that the nickel particle nucleation occurs on the nickel hydroxide surface,and the nickel hydroxide gradually dissolves during the reaction.With the increase in molar ratio of hydrazine hydrate to nickel hydroxide,the nickel particle size is initially decreased and then increased.Higher hydrazine hydrate concentrations result in smaller particle sizes.A small amount of PEG6000 surfactant can improve dispersion of nickel particles,but a higher amount of PEG6000 surfactant results in the maintenance of the morphology of nickel hydroxide.Adjusting the surfactant dosage can control the average particle size between 1-2μm.展开更多
Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)...Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.展开更多
The sluggish kinetics of the oxygen evolution reaction(OER)process impedes the exploration of green hydrogen via water splitting.Herein,we design and synthesize vanadium-doped CoSn(OH)_(6)perovskite hydroxide catalyst...The sluggish kinetics of the oxygen evolution reaction(OER)process impedes the exploration of green hydrogen via water splitting.Herein,we design and synthesize vanadium-doped CoSn(OH)_(6)perovskite hydroxide catalysts by Fe^(3+)etching during the hydrothermal and chemical deposition process.The as-prepared CoVSn(OH)_(6)@CoVSnFe(OH)_(x)-4 catalyst exhibits a lowoverpotential of 225 mV at 10 mA·cm^(-2)with a Tafel slope of 30.47 mV·dec^(-1).An overall water splitting electrolyzer(CoVSn(OH)_(6)@CoVSnFe(OH)_(x)-4‖Pt/C)is constructed,delivering a voltage of 1.48 V at a current density of10 mA·cm^(-2)with excellent durability.The dynamic phase evolution during the OER process is revealed by in situ Raman and XPS measurement,which represents that the introduced V and Fe ions facilitate the formation of active CoOOH as well as modify the electronic structure of the catalyst.Density functional theory(DFT)calculations further evidence that V and Fe introduction optimize the adsorption energies of oxygen intermediates*OH and*O,respectively,thereby enabling a synergistic optimization of the multi-step OER process and advancing electrocatalytic performance.展开更多
Electrocatalysis has emerged as a sustainable approach for the selective oxidation of fatty alcohols to fatty acids,circumventing the environmental concerns associated with conventional routes.However,the low aqueous ...Electrocatalysis has emerged as a sustainable approach for the selective oxidation of fatty alcohols to fatty acids,circumventing the environmental concerns associated with conventional routes.However,the low aqueous solubility of hydrophobic fatty alcohols presents a major challenge.While nickel hydroxide(Ni(OH)_(2))serves as a cost-effective catalyst for alcohol oxidation,its hydrophilic nature limits substrate accessibility and mass transport,causing sluggish kinetics and competing oxygen evolution.Herein,we propose a hydrophobic interface engineering strategy via co-electrodeposition of Ni(OH)_(2)with polytetrafluoroethylene(PTFE),fabricating the composite electrode(ED-Ni(OH)_(2)-PTFE).The optimized electrode achieves 95%Faradaic efficiency for octanoic acid at 1.5 V vs.RHE,with a production rate 2–3 times higher than pristine Ni(OH)_(2).Mechanistic studies combining in situ Raman spectroscopy,fluorescence imaging,and coarse-grained molecular dynamics simulations reveal that PTFE selectively enriches octanol at the electrode-electrolyte interface by modulating interfacial hydrophobicity.A continuous-flow microreactor integrating anodic octanol oxidation with cathodic hydrogen evolution reduces cell voltage by~100 m V,achieving simultaneous fatty acid and hydrogen production.This work highlights the critical role of hydrophobic interfacial microenvironment design in organic electrosynthesis,offering a promising strategy for upgrading fatty alcohols under mild conditions.展开更多
The oxygen evolution reaction(OER)is regarded as the bottleneck of electrolytic water splitting.Thus,developing robust earth-abundant electrocatalysts for efficient OER has received a great deal of attention and it is...The oxygen evolution reaction(OER)is regarded as the bottleneck of electrolytic water splitting.Thus,developing robust earth-abundant electrocatalysts for efficient OER has received a great deal of attention and it is an ongoing scientific challenge.Herein,hierarchical hollow nanorods assembled with ultrathin mesoporous cobalt silicate hydroxide nanosheets(denoted as CoSi)were successfully fabricated,using the silica nanotube derived from halloysite as a sacrificial template,via a simple hydrothermal method.The resulting cobalt silicate hydroxide nanosheets stack with thicknesses∼10 nm,as confirmed by transmis-sion electron microscopy.The elaborated nanoarchitecture possesses a high specific surface area(SSA)al-lowing good exposure to the cobalt active centers exhibiting superior catalytic activity vs analogs synthe-sized using sodium silicate.Among all as-prepared CoSi samples,those synthesized at 150℃(CoSi-150)exhibited the minimum overpotential of∼347 mV at a current density of 10 mA cm^(-2).In addition,CoSi-150 also exhibited superior performance against typical cobalt-based catalysts,and its surface hydroxyl groups were beneficial for the enhancement of OER performance.Furthermore,the CoSi-150 showed ex-cellent durability and stability after the 105 s chronopotentiometry test in 1 M KOH.This design concept provides a new strategy for the low-cost preparation of high-quality cobalt water splitting electrocata-lysts.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
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
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
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
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
The aluminum hydroxide adjuvant possesses a poorly crystalline boehmite (PCB) structure, the stability of which is significantly affected by storage conditions. In the present study, we conducted a comprehensive inves...The aluminum hydroxide adjuvant possesses a poorly crystalline boehmite (PCB) structure, the stability of which is significantly affected by storage conditions. In the present study, we conducted a comprehensive investigation into the structural and quality alterations of aluminum hydroxide adjuvants under varying temperature conditions over time. Three batches of the adjuvant were stored at 2–8℃, 18–25℃, and 37℃, respectively, for 6 months. Key parameters, including X-ray diffraction patterns, pH, isoelectric point (pI), adsorption capacity, and average particle size, were analyzed to assess the impact of storage temperatures. X-ray diffraction analysis confirmed the PCB structure of the aluminum hydroxide adjuvant. Notably, after 1 month of storage at 37℃, new diffraction peaks emerged at 18.2 °2θ, with their intensity increasing progressively over time. Concurrently, the largest decreases in pI and pH were observed, measuring 0.78 and 1.33, respectively. In contrast, adjuvants stored at 2–8℃ for 6 months exhibited only faint diffraction peaks at 18.2 °2θ, indicating minor structural changes. Under these conditions, the reductions in pI and pH were comparatively smaller, at 0.43 and 0.80, respectively. The average particle size of the adjuvants remained within 110–140 nm across all storage conditions. Additionally, the aluminum hydroxide adjuvant consistently demonstrated a high protein adsorption capacity, approximately 8 mg BSA/mg Al^(3+), with no statistically significant differences in adsorption rates observed among the different temperature conditions (P > 0.05). These findings highlighted the remarkable adsorption efficiency of nanoparticle aluminum hydroxide adjuvants throughout storage, reinforcing their potential as superior vaccine adsorbents. However, elevated storage temperatures were shown to accelerate structural aging, promoting the formation of highly crystalline phases such as gibbsite or bayerite, which could compromise the stability and quality of the adjuvant.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
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
基金supported by the National Natural Science Foundation of China (21422405, 51373125)the Major Program of National Natural Science Foundation of China (21334005)+1 种基金the facility support of the Natural Science Foundation of Hubei Provincethe Fundamental Research Funds for the Central Universities
文摘Light weight and mechanically strong α-chitin aerogels were fabricated using the sol-gel/self-assembly method from α-chitin in different aqueous alkali hydroxide(KOH, Na OH and Li OH)/urea solutions. All of the α-chitin solutions exhibited temperature-induced rapid gelation behavior. 13 C nuclear magnetic resonance(NMR) spectra revealed that the aqueous alkali hydroxide/urea solutions are non-derivatizing solvents for α-chitin. Fourier transform infrared(FT-IR), X-ray diffraction(XRD) and cross-polarization magic angle spinning(CP/MAS) 13 C NMR confirmed that α-chitin has a stable aggregate structure after undergoing dissolution and regeneration. Subsequently, nanostructured α-chitin aerogels were fabricated by regeneration from the chitin solutions in ethanol and then freeze-drying from t-Bu OH. These α-chitin aerogels exhibited high porosity(87% to 94%), low density(0.09 to 0.19 g/cm^3), high specific surface area(419 to 535 m^2/g) and large pore volume(2.7 to 3.8 cm^3/g). Moreover, the α-chitin aerogels exhibited good mechanical properties under compression and tension models. In vitro studies showed that m BMSCs cultured on chitin hydrogels have good biocompatibility. These nanostructured α-chitin aerogels may be useful for various applications, such as catalyst supports, carbon aerogel precursors and biomedical materials.
基金the financial support from City University of Hong Kong Strategic Research Grant(SRG)(7005505)the National Natural Science Foundation of China(51601136 and 51604202)。
文摘The urea oxidization reaction(UOR)is an important anodic reaction in electro-catalytic energy conversion.However,the sluggish reaction kinetics and complex catalyst transformation in electrocatalysis require activity improvement and better mechanistic understanding of the state-of-the-art Ni(OH)_(2) catalyst.Herein,by utilizing low-temperature argon(Ar)plasma processing,tooth-wheel Ni(OH)_(2) nanosheets self-supported on Ni foam(Ni(OH)_(2)-Ar)are demonstrated to have improved UOR activity compared to conventional Ni(OH)_(2).The theoretical assessment confirms that the edge has a smaller cation vacancy formation energy than the basal plane,consequently explaining the structural formation.Operando and quasi-operando methods are employed to investigate the dynamic evolution of the Ni(OH)_(2) film in UOR.The crucial dehydrogenation products of Ni(OH)_(5)O^(-)intermediates are identified to be stable on the etched edge and explain the enhanced UOR in the low potential region.In addition,the dynamic active sites are monitored to elucidate the reaction mechanism in different potential ranges.
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.
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financially supported by the National Natural Science Foundation of China(52025013,22121005)the 111 Project(B12015)+1 种基金Haihe Laboratory of Sustainable Chemical Transformationsthe Fundamental Research Funds for the Central Universities。
文摘Combining urea oxidation reaction(UOR) with hydrogen evolution reaction(HER) is an effective method for energy saving and highly efficient electrocatalytic hydrogen production. Herein, molybdenumincorporated cobalt carbonate hydroxide nanoarrays(CoxMoyCH) are designed and synthesized as a bifunctional catalyst towards UOR and HER. Benefiting from the Mo doping, the dispersed nanoarray structure and redistributed electron density, the CoxMoyCH catalyst display outstanding catalytic performance and durability for both HER and UOR, affording the overpotential of 82 m V for HER and delivering a low potential of the 1.33 V for UOR(vs. reversible hydrogen electrode, RHE) to attain a current density of 10 m A cm^(-2), respectively. Remarkably, when CoxMoyCH was applied as bifunctional catalyst in a twoelectrode electrolyzer, a working voltage of 1.40 V is needed in urea-assisted water electrolysis at10 m A cm^(-2) and without apparent decline for 40 h, outperforming the working voltage of 1.51 V in conventional water electrolysis.
基金National Natural Science Foundation of China(51704257,52174350)Hunan Provincial Science and Technology Innovation Program(2024AQ2039)。
文摘Fine nickel powders with a narrow particle size distribution were prepared by reducing nickel hydroxide in aqueous solution.The formation and reduction pathways of nickel powder were analyzed,as well as the effects of the molar ratio of hydrazine hydrate to nickel hydroxide,hydrazine concentration,and the dosage of surfactant PEG6000 on particle size,surface morphology,and dispersion.Results reveal that the nickel particle nucleation occurs on the nickel hydroxide surface,and the nickel hydroxide gradually dissolves during the reaction.With the increase in molar ratio of hydrazine hydrate to nickel hydroxide,the nickel particle size is initially decreased and then increased.Higher hydrazine hydrate concentrations result in smaller particle sizes.A small amount of PEG6000 surfactant can improve dispersion of nickel particles,but a higher amount of PEG6000 surfactant results in the maintenance of the morphology of nickel hydroxide.Adjusting the surfactant dosage can control the average particle size between 1-2μm.
基金supported by the Research Grants Council(26206115,16304821 and 16309418)the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(SMSEGL20SC01)+2 种基金the Innovation and Technology Commission(grant no.ITC-CNERC14EG03)of the Hong Kong Special Administrative Regionthe Hong Kong Postdoctoral Fellowship Scheme(HKUST PDFS2021-4S12 and HKUST PDFS2021-6S08)the support from the Shenzhen fundamental research funding(JCYJ20210324115809026,20200925154115001,JCYJ20200109141216566)。
文摘Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.
基金financially supported by Yunnan Major Scientific and Technological Projects(No.202202AG050017-02)Yunnan Fundamental Research Projects(No.202101BE070001-017)the National Natural Science Foundation of China(Nos.52101258 and 52272202)
文摘The sluggish kinetics of the oxygen evolution reaction(OER)process impedes the exploration of green hydrogen via water splitting.Herein,we design and synthesize vanadium-doped CoSn(OH)_(6)perovskite hydroxide catalysts by Fe^(3+)etching during the hydrothermal and chemical deposition process.The as-prepared CoVSn(OH)_(6)@CoVSnFe(OH)_(x)-4 catalyst exhibits a lowoverpotential of 225 mV at 10 mA·cm^(-2)with a Tafel slope of 30.47 mV·dec^(-1).An overall water splitting electrolyzer(CoVSn(OH)_(6)@CoVSnFe(OH)_(x)-4‖Pt/C)is constructed,delivering a voltage of 1.48 V at a current density of10 mA·cm^(-2)with excellent durability.The dynamic phase evolution during the OER process is revealed by in situ Raman and XPS measurement,which represents that the introduced V and Fe ions facilitate the formation of active CoOOH as well as modify the electronic structure of the catalyst.Density functional theory(DFT)calculations further evidence that V and Fe introduction optimize the adsorption energies of oxygen intermediates*OH and*O,respectively,thereby enabling a synergistic optimization of the multi-step OER process and advancing electrocatalytic performance.
基金Financial supports from the National Natural Science Foundation(No.21991104 and No.22,278,235)。
文摘Electrocatalysis has emerged as a sustainable approach for the selective oxidation of fatty alcohols to fatty acids,circumventing the environmental concerns associated with conventional routes.However,the low aqueous solubility of hydrophobic fatty alcohols presents a major challenge.While nickel hydroxide(Ni(OH)_(2))serves as a cost-effective catalyst for alcohol oxidation,its hydrophilic nature limits substrate accessibility and mass transport,causing sluggish kinetics and competing oxygen evolution.Herein,we propose a hydrophobic interface engineering strategy via co-electrodeposition of Ni(OH)_(2)with polytetrafluoroethylene(PTFE),fabricating the composite electrode(ED-Ni(OH)_(2)-PTFE).The optimized electrode achieves 95%Faradaic efficiency for octanoic acid at 1.5 V vs.RHE,with a production rate 2–3 times higher than pristine Ni(OH)_(2).Mechanistic studies combining in situ Raman spectroscopy,fluorescence imaging,and coarse-grained molecular dynamics simulations reveal that PTFE selectively enriches octanol at the electrode-electrolyte interface by modulating interfacial hydrophobicity.A continuous-flow microreactor integrating anodic octanol oxidation with cathodic hydrogen evolution reduces cell voltage by~100 m V,achieving simultaneous fatty acid and hydrogen production.This work highlights the critical role of hydrophobic interfacial microenvironment design in organic electrosynthesis,offering a promising strategy for upgrading fatty alcohols under mild conditions.
基金supported by the Central Government Guiding Local Science and Technology Development Fund Projects(No.236Z4108G)China Scholarship Council,the National Natu-ral Science Foundation of China(No.51874115)+2 种基金the Open Project of State Key Laboratory of Environment-friendly Energy Materials(No.22kfhg09)the Open Project of Key Laboratory of Solid Waste Treatment and Resource Recycle of Ministry of Education(No.22kfgk01)the Youth Talent Support Program of Hebei Province,the Giant Plan Innovation Team Project of Hebei Province,and the Excellent Young Scientist Foundation of Hebei province,China(No.E2018202241).
文摘The oxygen evolution reaction(OER)is regarded as the bottleneck of electrolytic water splitting.Thus,developing robust earth-abundant electrocatalysts for efficient OER has received a great deal of attention and it is an ongoing scientific challenge.Herein,hierarchical hollow nanorods assembled with ultrathin mesoporous cobalt silicate hydroxide nanosheets(denoted as CoSi)were successfully fabricated,using the silica nanotube derived from halloysite as a sacrificial template,via a simple hydrothermal method.The resulting cobalt silicate hydroxide nanosheets stack with thicknesses∼10 nm,as confirmed by transmis-sion electron microscopy.The elaborated nanoarchitecture possesses a high specific surface area(SSA)al-lowing good exposure to the cobalt active centers exhibiting superior catalytic activity vs analogs synthe-sized using sodium silicate.Among all as-prepared CoSi samples,those synthesized at 150℃(CoSi-150)exhibited the minimum overpotential of∼347 mV at a current density of 10 mA cm^(-2).In addition,CoSi-150 also exhibited superior performance against typical cobalt-based catalysts,and its surface hydroxyl groups were beneficial for the enhancement of OER performance.Furthermore,the CoSi-150 showed ex-cellent durability and stability after the 105 s chronopotentiometry test in 1 M KOH.This design concept provides a new strategy for the low-cost preparation of high-quality cobalt water splitting electrocata-lysts.
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 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 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 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 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.
文摘The aluminum hydroxide adjuvant possesses a poorly crystalline boehmite (PCB) structure, the stability of which is significantly affected by storage conditions. In the present study, we conducted a comprehensive investigation into the structural and quality alterations of aluminum hydroxide adjuvants under varying temperature conditions over time. Three batches of the adjuvant were stored at 2–8℃, 18–25℃, and 37℃, respectively, for 6 months. Key parameters, including X-ray diffraction patterns, pH, isoelectric point (pI), adsorption capacity, and average particle size, were analyzed to assess the impact of storage temperatures. X-ray diffraction analysis confirmed the PCB structure of the aluminum hydroxide adjuvant. Notably, after 1 month of storage at 37℃, new diffraction peaks emerged at 18.2 °2θ, with their intensity increasing progressively over time. Concurrently, the largest decreases in pI and pH were observed, measuring 0.78 and 1.33, respectively. In contrast, adjuvants stored at 2–8℃ for 6 months exhibited only faint diffraction peaks at 18.2 °2θ, indicating minor structural changes. Under these conditions, the reductions in pI and pH were comparatively smaller, at 0.43 and 0.80, respectively. The average particle size of the adjuvants remained within 110–140 nm across all storage conditions. Additionally, the aluminum hydroxide adjuvant consistently demonstrated a high protein adsorption capacity, approximately 8 mg BSA/mg Al^(3+), with no statistically significant differences in adsorption rates observed among the different temperature conditions (P > 0.05). These findings highlighted the remarkable adsorption efficiency of nanoparticle aluminum hydroxide adjuvants throughout storage, reinforcing their potential as superior vaccine adsorbents. However, elevated storage temperatures were shown to accelerate structural aging, promoting the formation of highly crystalline phases such as gibbsite or bayerite, which could compromise the stability and quality of the adjuvant.
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 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.
