In this work,a facile chelation-mediated route was developed to fabricate ultrathin cobalt(oxy)hydroxides(CoOOH)nanosheets on hematite photoanode(Fe_(2)O_(3)).The route contains two steps of the adsorption of[Co-EDTA]...In this work,a facile chelation-mediated route was developed to fabricate ultrathin cobalt(oxy)hydroxides(CoOOH)nanosheets on hematite photoanode(Fe_(2)O_(3)).The route contains two steps of the adsorption of[Co-EDTA]^(2-)species on Fe_(2)O_(3) nanorod array followed by the hydrolysis in alkaline solution.The resulting CoOOH/Fe_(2)O_(3) exhibits a remarkably improved photocurrent density of 2.10 mA cm^(-2) at 1.23 V vs.RHE,which is ca.2.8 times that of bare Fe_(2)O_(3).In addition,a negative shift of onset potential ca.200 mV is achieved.The structural characterizations reveal the chelate EDTA plays important roles that enhance the adsorption of Co species and the formation of contact between CoOOH and Fe_(2)O_(3).(Photo)electrochemical analysis suggests,besides providing active sites for water oxidation,CoOOH at large extent promotes the charge separation and the charge transfer via passivating surface states and suppressing charge recombination.It also found CoOOH possesses some oxygen vacancies,which could act as trapping centers for photogenerated holes and facilitate the charge separation.Intensity modulated photocurrent spectroscopy(IMPS)shows that,under low applied potential the water oxidation mainly occurs on CoOOH,while under high applied potential the water oxidation could occur on both CoOOH and Fe_(2)O_(3).The findings not only provide an efficient strategy for designing ultrathin(oxy)hydroxides on semiconductors for PEC applications but also put forward a new insight on the role of CoOOH during water oxidation.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
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
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
Beginning from the industrial revolution,non-renewable fossil fuels have powered the population growth and economic expansion.However,the overdependence of such energy sources leads to serious eco-crisis and energy se...Beginning from the industrial revolution,non-renewable fossil fuels have powered the population growth and economic expansion.However,the overdependence of such energy sources leads to serious eco-crisis and energy security issues.As shown in Fig.1,the emissions of CO_(2) greenhouse gas are rising year by year because of the significant amount consumption of fossil energy[1].Searching sustainable energy technologies to achieve carbon neutrality has thus become an urgent task for the future of human society[2].As the most abundant and inexhaustible energy source,sunlight has brought dawn to the opportunities for a sustainable society.Owing to the diurnal and seasonal cycles,the solar energy has the intermittent character,which limits its applications.展开更多
The synthesis of calcium formate by Ca(OH)_2 carbonylation was studied in a semi-batch stirred tank.The reaction mechanism was analyzed theoretically and the rate of each step was compared.The influence ofreaction con...The synthesis of calcium formate by Ca(OH)_2 carbonylation was studied in a semi-batch stirred tank.The reaction mechanism was analyzed theoretically and the rate of each step was compared.The influence ofreaction conditions on the formation of calcium formate was investigated.The results indicate that the rate-controlling step is the reaction between dissolved CO and dissolved Ca(OH)_2,and the gaseous diffusion resistance can be eliminated when the stirring speed reached 1000 r/min.Furthermore,the reaction kinetics was studied at a stirring speed of 1000 r/min,temperature of 423–453 K,pressure of 2.0–3.5 MPa and different initial concentrations of Ca(OH)_2.An effective method was proposed to measure the reaction rate of CO.A mathematical model was developed using the dual-film theory,and the parameters were obtained using regression of experimental data.The reaction rates calculated using the kinetics model were compared with experimental data.The results show that the deviations are within ±10%,proving that the established model is valid and can provide a basis for industrial amplification.展开更多
Electrochemical CO_(2)reduction into energy-carrying compounds,such as formate,is of great importance for carbon neutrality,which however suffers from high electrical energy input and liquid products crossover.Herein,...Electrochemical CO_(2)reduction into energy-carrying compounds,such as formate,is of great importance for carbon neutrality,which however suffers from high electrical energy input and liquid products crossover.Herein,we fabricated self-supported ultrathin NiCo layered double hydroxides(LDHs)electrodes as anode for methanol electrooxidation to achieve a high formate production rate(5.89 mmol h^(-1)cm^(-2))coupled with CO_(2)electro-reduction at the cathode.A total formate faradic efficiency of both anode for methanol oxidation and cathode for CO_(2)reduction can reach up to 188%driven by a low cell potential of only 2.06 V at 100 mA cm^(-2)in membrane-electrode assembly(MEA).Physical characterizations demonstrated that Ni^(3+)species,formed on the electrochemical oxidation of Ni-containing hydroxide,acted as catalytically active species for the oxidation of methanol to formate.Furthermore,DFT calculations revealed that ultrathin LDHs were beneficial for the formation of Ni^(3+)in hydroxides and introducing oxygen vacancy in NiCo-LDH could decrease the energy barrier of the rate-determining step for methanol oxidation.This work presents a promising approach for fabricating advanced electrodes towards electrocatalytic reactions.展开更多
ZnO/NiO/ZnAl2O4 mixed-metal oxides were successfully synthesized through a hydrotalcite-like precursor route, in which appropriate amounts of metal salts solutions were mixed to obtain a new series of ZnNiAl layered d...ZnO/NiO/ZnAl2O4 mixed-metal oxides were successfully synthesized through a hydrotalcite-like precursor route, in which appropriate amounts of metal salts solutions were mixed to obtain a new series of ZnNiAl layered double hydroxides（LDHs） as precursors, followed by calcination under different temperatures. The as-obtained samples were characterized by SEM, HRTEM, TEM, XRD, BET, TG-DTA, and UV-Vis spectra techniques. The photocatalytic activities of the samples were evaluated by degradation of methyl orange（MO） under the simulated sunlight irradiation. The effects of Zn/Ni/Al mole ratio and calcination temperature on the composition, morphology and photocatalytic activity of the samples were investigated in detail. The results indicated that compared with ZnNiAl-LDHs, the mixed-metal oxide showed superior photocatalytic performance for the degradation of MO. A maximum of 97.3% photocatalytic decoloration rate within 60 min was achieved from the LDH with the Zn/Ni/Al mole ratio of 2：1：1 and the calcination temperature of 500 ℃, which much exceeded that of Degussa P25 under the same conditions. The possible mechanism of photocatalytic degradation over ZnO/NiO/ZnAl2O4 was discussed.展开更多
Electrocatalytic glucose oxidation to high-value chemicals provides a sustainable route for biomass valorization.NiCo-based catalysts have emerged as promising candidates for glucose oxidation reaction owing to the in...Electrocatalytic glucose oxidation to high-value chemicals provides a sustainable route for biomass valorization.NiCo-based catalysts have emerged as promising candidates for glucose oxidation reaction owing to the intrinsic activity of Ni and Co catalytic centers.However,the dynamic evolution and atomic-scale synergy between these centers remain elusive.Herein,we fabricated NiCo_(2)O_(4)nanosheets supported on nickel foam,where Ni preferentially occupies tetrahedral sites to regulate the electronic configuration of octahedral Co.Experimental and theoretical results demonstrate that the incorporation of tetrahedral Ni induces low-to-intermediate spin transition in octahedral Co,thereby optimizing eg orbital occupancy and stabilizing active sites.This spin-state engineering establishes Ni-Co synergistic catalytic centers for the selective oxidation of glucose to formate(FA).At higher potential(≥1.4 V vs.RHE),octahedral Co undergoes reconstruction into excessive active CoOOH and CoO_(2)species,resulting in glucose overoxidation to CO_(2)and intensified competitive oxygen evolution.In contrast,at lower potentials(<1.4 V vs.RHE),tetrahedral Ni facilitates electron delocalization across the Ni–O–Co lattice,thereby stabilizing octahedral Co for glucose adsorption and oxidation.Subsequently,a coupled electrocatalytic system was constructed,achieving 80.7%FA yield with 91.3%Faradaic efficiency(FE)at NiCo_(2)O_(4)anode and H2 evolution rate of 696μmol h^(−1)with 99.9%FE at Pt cathode for 2 h under 1.35 V vs.RHE.This work provides a deep insight into spin-state regulation of the catalytic center,offering valuable guidance for rational catalyst design.展开更多
For many two-dimensional(2D)materials,low coordination edges and corner sites offer greatly enhanced catalytic performance compared to basal sites,motivating the search for new synthetic approaches towards ultrathin a...For many two-dimensional(2D)materials,low coordination edges and corner sites offer greatly enhanced catalytic performance compared to basal sites,motivating the search for new synthetic approaches towards ultrathin and ultrafine 2D nanomaterials with high specific surface areas.To date,the synthesis of catalysts that are both ultrathin(monolayer)and ultrafine(lateral size<10nm)has proven extremely challenging.Herein,using a facile ultrasonic exfoliation procedure,we describe the successful synthesis of ultrafine ZnCo-LDH nanosheets(denoted as ZnCo-UF)with a size^3.5 nm and thickness^0.5 nm.The single layer ZnCo-UF nanosheets possess an abundance of oxygen vacancies(Vo)and unsaturated coordination s让es,thereby affording outstanding electrocatalytic water oxidation performance.DFT calculations confirmed that Vo on the surface of ZnCo-UF enhanced H20 adsorption via increasing the electropositivity of the nanosheets.展开更多
The oxidative energy storage behaviors of a designed novel system comprising a nickel hydroxide film electrode and an oxygen-reducing platinum cathode were investigated by various electrochemical techniques. The struc...The oxidative energy storage behaviors of a designed novel system comprising a nickel hydroxide film electrode and an oxygen-reducing platinum cathode were investigated by various electrochemical techniques. The structure and morphology of samples were characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD） analysis. It is found that the oxidative energy storage in the Ni（OH）2 electrodes can be obviously enhanced in the coupling system containing the cathode electrolytes with higher oxygen content or lower pH value. The results of the oxidation-discharge cycle tests show that the Ni（OH）2 film electrode oxidized in the coupling system with 1.0 mol/L Na2SO4 （pH=2） as cathode electrolyte for 600 s presents discharge capacities of 79.0 mC/cm2 at the first cycle and 97.9 mC/cm2 at the 12th cycle, suggesting the excellent reversibility of the investigated oxidative energy storage and conversion system.展开更多
A series of rare earth hydroxide and oxide nanoparticles have been prepared by precipitation method with alcohol as the dispersive and protective reagent. Transmission electron microscope （TEM） images indicate that ...A series of rare earth hydroxide and oxide nanoparticles have been prepared by precipitation method with alcohol as the dispersive and protective reagent. Transmission electron microscope （TEM） images indicate that the particles are spherical in shape and smaller than 100 nm in size. The crystallite sizes of cubic Ln2O3 have lanthanide shrinking effect, while average crystal lattice distortion rates possess lanthanide swelling effect. The diffraction peak intensity of heavy rare earth oxide nanometer powders is remarkably stronger than that of light rare earth oxide nanometer powders. The variation of diffraction intensity with atomic number presents an inverted W type, forming a double peak structure. Fourier transform infrared （FTIR） spectrums reveal that Ln2O3 nanopowders have higher surface activity than that of ordinary Ln2O3 powders. The UV-vis spectra show that Ln-O bond of these particles is slightly blue-shifted, and its absorption intensity decreases.展开更多
Extracting B2O3 from calcined boron mud(CBM) was studied. The effect of factors such as reaction temperature and NaO H-to-CBM mass ratio on B2O3 extraction efficiency was investigated. The results show that increasing...Extracting B2O3 from calcined boron mud(CBM) was studied. The effect of factors such as reaction temperature and NaO H-to-CBM mass ratio on B2O3 extraction efficiency was investigated. The results show that increasing reaction temperature and NaO H-to-CBM mass ratio increases B2O3 extraction efficiency. There are two stages for the B2O3 extracting process: 0–20 min is the first stage, which is rapid; 20–50 min is the second stage, which is slower than the first stage. The overall extracting process follows the shrinking core model, and the first and second stages are determined to obey the surface chemical reaction model and the diffusion through the products layer model,respectively. The activation energies of the first and second stages are calculated to be 41.74 and 15.43 kJ·mol-1,respectively. The B2O3 extracting kinetics equations of the first and second stages are also obtained.展开更多
To further enhance the corrosion resistance of the porous micro-arc oxidation(MAO) ceramic layers on AZ31 magnesium alloy, superhydrophobic Mg-Al layered double hydroxide(LDH) coating was fabricated on MAO-coated AZ31...To further enhance the corrosion resistance of the porous micro-arc oxidation(MAO) ceramic layers on AZ31 magnesium alloy, superhydrophobic Mg-Al layered double hydroxide(LDH) coating was fabricated on MAO-coated AZ31 alloy by using in-situ growth method followed by surface modification with stearic acid. The characteristics of different coatings were investigated by XRD, SEM and EDS. The effect of the hydrothermal treatment time on the formation of the LDH coatings was studied. The results demonstrated that the micro-pores and cracks of MAO coating were gradually sealed via in-situ growing LDH with prolonging hydrothermal treating time. Electrochemical measurement displayed that the lowest corrosion current density, the most positive corrosion potential and the highest impedance modulus were observed for superhydrophobic LDH/MAO coating compared with those of MAO coating and LDH/MAO coating. Immersion experiment proved that the superhydrophobic LDH/MAO coating with the active anti-corrosion capability significantly enhanced the long-term corrosion protection for MAO coated alloy.展开更多
Catalytic oxidation is regarded as one of the most promising strategies for volatile organic compounds(VOCs)purification.Mixed metal oxides(MMOs),after topological transformation using layered double hydroxides(LDHs)a...Catalytic oxidation is regarded as one of the most promising strategies for volatile organic compounds(VOCs)purification.Mixed metal oxides(MMOs),after topological transformation using layered double hydroxides(LDHs)as precursors,are extensively used as catalysts for VOCs oxidation due to their uniformity advantage.This review summarizes the developments in the LDH-derived VOCs heterogeneous catalytic oxidation over the last 10 years.Particularly,it addresses the VOCs abatement performance over MMO,noble metal/MMO,core-shell structured MMO,and integral MMO film catalysts originating from LDHs.Moreover,it highlights the water vapor effect and oxidation mechanism.This review indicates that LDH-based catalysts are a category of important VOCs oxidation materials.展开更多
An efcient and simple in-situ growth strategy has been discovered for the preparation of highly reproducible and continuous symbiotic ZIF-8-based anticorrosion coating by using graphene oxide(GO)/Mg AlNO3layered doubl...An efcient and simple in-situ growth strategy has been discovered for the preparation of highly reproducible and continuous symbiotic ZIF-8-based anticorrosion coating by using graphene oxide(GO)/Mg AlNO3layered double hydroxides(G/LDHs) buffer layer as a new type of connecting carrier based on micro-arc oxide(MAO) coating of AZ31 magnesium alloy. The components of ZIF-8 were adsorbed and bounded to the surface of the G/LDHs buffer layer-modified substrates to promote the nucleation of ZIF-8,thus growing a phase-pure, uniform, and good symbiosis ZIF-8 membrane. ZIF-8 particles with different growth times compensate for the grain boundary defects of the G/LDHs coating precursor buffer layer to different degrees. The prepared ZIF-8-based coating has excellent stability and corrosion resistance. The results demonstrate that the G/LDHs buffer layer provides a new channel for the MOF-modified MAO substrate of AZ31 magnesium alloy. It also proves that it is feasible to build high-performance anticorrosive coatings with MOF materials.展开更多
Paired electrolysis of waste feedstocks holds an energy-efficient alternative for chemical production;however,the sluggish anodic oxidation limited the total efficiency under larger current density.Herein,we construct...Paired electrolysis of waste feedstocks holds an energy-efficient alternative for chemical production;however,the sluggish anodic oxidation limited the total efficiency under larger current density.Herein,we constructed ultralow-coordinated Ni species with Ni–O coordination number of∼3 via a hydrothermal synthesis-sulfidation-annealing process and electrochemical activation and demonstrated the vital role in accelerating the proton deintercalation and reactive oxygen intermediate·OH formation during electro-reforming polyethylene terephthalate hydrolysate(POR).The target catalyst NiCoSx/NF afforded a high formate productivity of 7.4 mmol cm^(−2)h^(−1)at∼600 mA cm^(−2)with a formate Faradic efficiency(FE_(formate))of 92.4%in POR and maintained a FE_(formate)of∼90%for 100 h at 2 A in a membrane electrode assembly electrolyzer.Coupling POR on NiCoSx/NF with carbon dioxide reduction reaction on oxygen vacancies enriched Vo-BiSnO reached effective concurrent formate production with 172.7%of FE_(formate)at 500 mA cm^(−2)and long-term stability.Such excellent performance shows the great prospect of electrocatalyst design by regulating the local metal environment.展开更多
The surface oxide layer of grain-oriented electrical steels was investigated by scanning electron microscopy.The formation mechanism and the influence on the glass film of the surface oxide layer were analyzed by the ...The surface oxide layer of grain-oriented electrical steels was investigated by scanning electron microscopy.The formation mechanism and the influence on the glass film of the surface oxide layer were analyzed by the calculation of thermodynamics and kinetics.The surface oxide layer with 2.3μm in thickness is mainly composed of SiO_(2),a small amount of FeO and Fe_(2)SiO_(4).During the formation of surface oxide layer,the restriction factor was the diffusion of O in the oxide layer.At the initial stage of the decarburization annealing,FeO would be formed on the surface layer.SiO_(2) and silicate particles rapidly nucleated,grew and formed a granular oxide layer in the subsurface.As the oxidation layer thickens,the nucleation of new particles decreases,and the growth of oxide particles would be dominant.A lamellar oxide layer was formed between the surface oxide layer and the steel matrix,and eventually formed a typical three-layer structure.During the high temperature annealing,MgO mainly reacted with SiO_(2) and Fe_(2)SiO_(4) in the surface oxide layer to form Mg2SiO_(4) and Fe_(2)SiO_(4) would respond first,thus forming the glass film with average thickness of 4.87μm.展开更多
In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal salts.The cation exchange resinsupported iron and magnesium oxide...In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal salts.The cation exchange resinsupported iron and magnesium oxides/hydroxides composite(FeMg/CER)was synthesized and introduced as a new and potential adsorbent for selective removal of nitrate ion in the water environment.Characteristics of FeMg/CER were determined by techniques such as Fouriertransform infrared spectroscopy,scanning electron microscopy,and Xray diffraction.The results showed that FeMg/CER material had a high nitrate adsorption capacity of 200 mg NO_(3)^()·g^(1)with a fast equilibrium adsorption time of 30 min at pH 5.In addition,it had good durability of at least 10 times of regeneration,which could be applied to practical water and wastewater treatment.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
基金supported by the National Natural Science Foundation of China(51502078)the Major Project of Science and Technology,Education Department of Henan Province(19A150019 and 19A150018)+2 种基金the Science and Technology Research Project of Henan Province(192102310490 and 182102410090)the program for Science&Technology Innovation Team in Universities of Henan Province(19IRTSTHN029)supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,Chemical Sciences,Geosciences,and Biosciences Division,Catalysis Science program。
文摘In this work,a facile chelation-mediated route was developed to fabricate ultrathin cobalt(oxy)hydroxides(CoOOH)nanosheets on hematite photoanode(Fe_(2)O_(3)).The route contains two steps of the adsorption of[Co-EDTA]^(2-)species on Fe_(2)O_(3) nanorod array followed by the hydrolysis in alkaline solution.The resulting CoOOH/Fe_(2)O_(3) exhibits a remarkably improved photocurrent density of 2.10 mA cm^(-2) at 1.23 V vs.RHE,which is ca.2.8 times that of bare Fe_(2)O_(3).In addition,a negative shift of onset potential ca.200 mV is achieved.The structural characterizations reveal the chelate EDTA plays important roles that enhance the adsorption of Co species and the formation of contact between CoOOH and Fe_(2)O_(3).(Photo)electrochemical analysis suggests,besides providing active sites for water oxidation,CoOOH at large extent promotes the charge separation and the charge transfer via passivating surface states and suppressing charge recombination.It also found CoOOH possesses some oxygen vacancies,which could act as trapping centers for photogenerated holes and facilitate the charge separation.Intensity modulated photocurrent spectroscopy(IMPS)shows that,under low applied potential the water oxidation mainly occurs on CoOOH,while under high applied potential the water oxidation could occur on both CoOOH and Fe_(2)O_(3).The findings not only provide an efficient strategy for designing ultrathin(oxy)hydroxides on semiconductors for PEC applications but also put forward a new insight on the role of CoOOH during water oxidation.
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 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 National Natural Science Foundation of China(No.52202321)the Starting Research Funds of Hefei University of Technology.
文摘Beginning from the industrial revolution,non-renewable fossil fuels have powered the population growth and economic expansion.However,the overdependence of such energy sources leads to serious eco-crisis and energy security issues.As shown in Fig.1,the emissions of CO_(2) greenhouse gas are rising year by year because of the significant amount consumption of fossil energy[1].Searching sustainable energy technologies to achieve carbon neutrality has thus become an urgent task for the future of human society[2].As the most abundant and inexhaustible energy source,sunlight has brought dawn to the opportunities for a sustainable society.Owing to the diurnal and seasonal cycles,the solar energy has the intermittent character,which limits its applications.
基金supported by the National High-Tech Research and Development Program of China ("863" Program, No.2012AA06A113)
文摘The synthesis of calcium formate by Ca(OH)_2 carbonylation was studied in a semi-batch stirred tank.The reaction mechanism was analyzed theoretically and the rate of each step was compared.The influence ofreaction conditions on the formation of calcium formate was investigated.The results indicate that the rate-controlling step is the reaction between dissolved CO and dissolved Ca(OH)_2,and the gaseous diffusion resistance can be eliminated when the stirring speed reached 1000 r/min.Furthermore,the reaction kinetics was studied at a stirring speed of 1000 r/min,temperature of 423–453 K,pressure of 2.0–3.5 MPa and different initial concentrations of Ca(OH)_2.An effective method was proposed to measure the reaction rate of CO.A mathematical model was developed using the dual-film theory,and the parameters were obtained using regression of experimental data.The reaction rates calculated using the kinetics model were compared with experimental data.The results show that the deviations are within ±10%,proving that the established model is valid and can provide a basis for industrial amplification.
基金the financial support from the National Nature Science Foundation of China(22078232 and 21938008)the Haihe Laboratory of Sustainable Chemical Transformations for financial support。
文摘Electrochemical CO_(2)reduction into energy-carrying compounds,such as formate,is of great importance for carbon neutrality,which however suffers from high electrical energy input and liquid products crossover.Herein,we fabricated self-supported ultrathin NiCo layered double hydroxides(LDHs)electrodes as anode for methanol electrooxidation to achieve a high formate production rate(5.89 mmol h^(-1)cm^(-2))coupled with CO_(2)electro-reduction at the cathode.A total formate faradic efficiency of both anode for methanol oxidation and cathode for CO_(2)reduction can reach up to 188%driven by a low cell potential of only 2.06 V at 100 mA cm^(-2)in membrane-electrode assembly(MEA).Physical characterizations demonstrated that Ni^(3+)species,formed on the electrochemical oxidation of Ni-containing hydroxide,acted as catalytically active species for the oxidation of methanol to formate.Furthermore,DFT calculations revealed that ultrathin LDHs were beneficial for the formation of Ni^(3+)in hydroxides and introducing oxygen vacancy in NiCo-LDH could decrease the energy barrier of the rate-determining step for methanol oxidation.This work presents a promising approach for fabricating advanced electrodes towards electrocatalytic reactions.
基金Project(21306041)supported by the National Natural Science Young Foundation of ChinaProject(21271071)supported by the National Natural Science Foundation of ChinaProject(15A076)supported by the Scientific Research Foundation of Hunan Provincial Education Department of China
文摘ZnO/NiO/ZnAl2O4 mixed-metal oxides were successfully synthesized through a hydrotalcite-like precursor route, in which appropriate amounts of metal salts solutions were mixed to obtain a new series of ZnNiAl layered double hydroxides（LDHs） as precursors, followed by calcination under different temperatures. The as-obtained samples were characterized by SEM, HRTEM, TEM, XRD, BET, TG-DTA, and UV-Vis spectra techniques. The photocatalytic activities of the samples were evaluated by degradation of methyl orange（MO） under the simulated sunlight irradiation. The effects of Zn/Ni/Al mole ratio and calcination temperature on the composition, morphology and photocatalytic activity of the samples were investigated in detail. The results indicated that compared with ZnNiAl-LDHs, the mixed-metal oxide showed superior photocatalytic performance for the degradation of MO. A maximum of 97.3% photocatalytic decoloration rate within 60 min was achieved from the LDH with the Zn/Ni/Al mole ratio of 2：1：1 and the calcination temperature of 500 ℃, which much exceeded that of Degussa P25 under the same conditions. The possible mechanism of photocatalytic degradation over ZnO/NiO/ZnAl2O4 was discussed.
基金financially supported by the National Natural Science Foundation of China (22472199)Chinese Universities Scientific Fund (15055009)Central University Guided Funds for Building World-Class Universities (Disciplines) and Advancing Characteristic Development
文摘Electrocatalytic glucose oxidation to high-value chemicals provides a sustainable route for biomass valorization.NiCo-based catalysts have emerged as promising candidates for glucose oxidation reaction owing to the intrinsic activity of Ni and Co catalytic centers.However,the dynamic evolution and atomic-scale synergy between these centers remain elusive.Herein,we fabricated NiCo_(2)O_(4)nanosheets supported on nickel foam,where Ni preferentially occupies tetrahedral sites to regulate the electronic configuration of octahedral Co.Experimental and theoretical results demonstrate that the incorporation of tetrahedral Ni induces low-to-intermediate spin transition in octahedral Co,thereby optimizing eg orbital occupancy and stabilizing active sites.This spin-state engineering establishes Ni-Co synergistic catalytic centers for the selective oxidation of glucose to formate(FA).At higher potential(≥1.4 V vs.RHE),octahedral Co undergoes reconstruction into excessive active CoOOH and CoO_(2)species,resulting in glucose overoxidation to CO_(2)and intensified competitive oxygen evolution.In contrast,at lower potentials(<1.4 V vs.RHE),tetrahedral Ni facilitates electron delocalization across the Ni–O–Co lattice,thereby stabilizing octahedral Co for glucose adsorption and oxidation.Subsequently,a coupled electrocatalytic system was constructed,achieving 80.7%FA yield with 91.3%Faradaic efficiency(FE)at NiCo_(2)O_(4)anode and H2 evolution rate of 696μmol h^(−1)with 99.9%FE at Pt cathode for 2 h under 1.35 V vs.RHE.This work provides a deep insight into spin-state regulation of the catalytic center,offering valuable guidance for rational catalyst design.
基金financial support from the National Key R&D Program of China (Grant Nos.: 2017YFA0206904, 2017YFA0206900, and 2016YFB0600901)the National Program on Key Basic Research Project (Grant No.: 2014CB239402)+6 种基金the National Natural Science Foundation of China (Grant Nos.: 51772305, 51572270, U1662118, 31671489, U1332205, and 21701131)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.: XDB17000000)the Royal Society Newton Advanced Fellowship (Grant No.: NA170422)the Young Elite Scientist Sponsorship Program by CAST (Grant No.: YESS20160137)the Youth Innovation Promotion Association of the CASthe Fund of Xi’an University of Science and Technology (Grant No.:2018QDJ014)funding support from the Energy Education Trust of New Zealand
文摘For many two-dimensional(2D)materials,low coordination edges and corner sites offer greatly enhanced catalytic performance compared to basal sites,motivating the search for new synthetic approaches towards ultrathin and ultrafine 2D nanomaterials with high specific surface areas.To date,the synthesis of catalysts that are both ultrathin(monolayer)and ultrafine(lateral size<10nm)has proven extremely challenging.Herein,using a facile ultrasonic exfoliation procedure,we describe the successful synthesis of ultrafine ZnCo-LDH nanosheets(denoted as ZnCo-UF)with a size^3.5 nm and thickness^0.5 nm.The single layer ZnCo-UF nanosheets possess an abundance of oxygen vacancies(Vo)and unsaturated coordination s让es,thereby affording outstanding electrocatalytic water oxidation performance.DFT calculations confirmed that Vo on the surface of ZnCo-UF enhanced H20 adsorption via increasing the electropositivity of the nanosheets.
基金Projects (50972128,51174176) supported by the National Natural Science Foundation of China
文摘The oxidative energy storage behaviors of a designed novel system comprising a nickel hydroxide film electrode and an oxygen-reducing platinum cathode were investigated by various electrochemical techniques. The structure and morphology of samples were characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD） analysis. It is found that the oxidative energy storage in the Ni（OH）2 electrodes can be obviously enhanced in the coupling system containing the cathode electrolytes with higher oxygen content or lower pH value. The results of the oxidation-discharge cycle tests show that the Ni（OH）2 film electrode oxidized in the coupling system with 1.0 mol/L Na2SO4 （pH=2） as cathode electrolyte for 600 s presents discharge capacities of 79.0 mC/cm2 at the first cycle and 97.9 mC/cm2 at the 12th cycle, suggesting the excellent reversibility of the investigated oxidative energy storage and conversion system.
文摘A series of rare earth hydroxide and oxide nanoparticles have been prepared by precipitation method with alcohol as the dispersive and protective reagent. Transmission electron microscope （TEM） images indicate that the particles are spherical in shape and smaller than 100 nm in size. The crystallite sizes of cubic Ln2O3 have lanthanide shrinking effect, while average crystal lattice distortion rates possess lanthanide swelling effect. The diffraction peak intensity of heavy rare earth oxide nanometer powders is remarkably stronger than that of light rare earth oxide nanometer powders. The variation of diffraction intensity with atomic number presents an inverted W type, forming a double peak structure. Fourier transform infrared （FTIR） spectrums reveal that Ln2O3 nanopowders have higher surface activity than that of ordinary Ln2O3 powders. The UV-vis spectra show that Ln-O bond of these particles is slightly blue-shifted, and its absorption intensity decreases.
基金financially supported by the National Natural Science Foundation of China(No.51204037)
文摘Extracting B2O3 from calcined boron mud(CBM) was studied. The effect of factors such as reaction temperature and NaO H-to-CBM mass ratio on B2O3 extraction efficiency was investigated. The results show that increasing reaction temperature and NaO H-to-CBM mass ratio increases B2O3 extraction efficiency. There are two stages for the B2O3 extracting process: 0–20 min is the first stage, which is rapid; 20–50 min is the second stage, which is slower than the first stage. The overall extracting process follows the shrinking core model, and the first and second stages are determined to obey the surface chemical reaction model and the diffusion through the products layer model,respectively. The activation energies of the first and second stages are calculated to be 41.74 and 15.43 kJ·mol-1,respectively. The B2O3 extracting kinetics equations of the first and second stages are also obtained.
基金Project(17JS083) supported by the Key Laboratory Program of Shaanxi Education Department,ChinaProject(2016JZ018) supported by the Key Program of Natural Science Research of Shaanxi Province,ChinaProject(51701162) supported by the National Natural Science Foundation of China
文摘To further enhance the corrosion resistance of the porous micro-arc oxidation(MAO) ceramic layers on AZ31 magnesium alloy, superhydrophobic Mg-Al layered double hydroxide(LDH) coating was fabricated on MAO-coated AZ31 alloy by using in-situ growth method followed by surface modification with stearic acid. The characteristics of different coatings were investigated by XRD, SEM and EDS. The effect of the hydrothermal treatment time on the formation of the LDH coatings was studied. The results demonstrated that the micro-pores and cracks of MAO coating were gradually sealed via in-situ growing LDH with prolonging hydrothermal treating time. Electrochemical measurement displayed that the lowest corrosion current density, the most positive corrosion potential and the highest impedance modulus were observed for superhydrophobic LDH/MAO coating compared with those of MAO coating and LDH/MAO coating. Immersion experiment proved that the superhydrophobic LDH/MAO coating with the active anti-corrosion capability significantly enhanced the long-term corrosion protection for MAO coated alloy.
基金supported by the National Key R&D Program of China(2017YFC0211503,2016YFC0207100)the Strategic Priority Research Program(A)of the Chinese Academy of Sciences(XDA23030300)+2 种基金the National Natural Science Foundation of China(21401200,51672273)the Open Research Fund of State Key Laboratory of Multi-phase Complex Systems(MPCS-2017-D-06)the Young Talent Project of the Center for Excellence in Regional Atmospheric Environment,CAS(CERAE201805)~~
文摘Catalytic oxidation is regarded as one of the most promising strategies for volatile organic compounds(VOCs)purification.Mixed metal oxides(MMOs),after topological transformation using layered double hydroxides(LDHs)as precursors,are extensively used as catalysts for VOCs oxidation due to their uniformity advantage.This review summarizes the developments in the LDH-derived VOCs heterogeneous catalytic oxidation over the last 10 years.Particularly,it addresses the VOCs abatement performance over MMO,noble metal/MMO,core-shell structured MMO,and integral MMO film catalysts originating from LDHs.Moreover,it highlights the water vapor effect and oxidation mechanism.This review indicates that LDH-based catalysts are a category of important VOCs oxidation materials.
基金financially supported by the National Natural Science Foundation of China (Nos.51971040,52171101)the Natural Science Foundation of Chongqing (No.cstc2021jcyj-msxm X0613)+1 种基金the National Natural Science Foundation of China (Nos.52001036,51971044)the Independent Research Project of State Key Laboratory of Mechanical Transmissions (No.SKLMT-ZZKT-2021M11)。
文摘An efcient and simple in-situ growth strategy has been discovered for the preparation of highly reproducible and continuous symbiotic ZIF-8-based anticorrosion coating by using graphene oxide(GO)/Mg AlNO3layered double hydroxides(G/LDHs) buffer layer as a new type of connecting carrier based on micro-arc oxide(MAO) coating of AZ31 magnesium alloy. The components of ZIF-8 were adsorbed and bounded to the surface of the G/LDHs buffer layer-modified substrates to promote the nucleation of ZIF-8,thus growing a phase-pure, uniform, and good symbiosis ZIF-8 membrane. ZIF-8 particles with different growth times compensate for the grain boundary defects of the G/LDHs coating precursor buffer layer to different degrees. The prepared ZIF-8-based coating has excellent stability and corrosion resistance. The results demonstrate that the G/LDHs buffer layer provides a new channel for the MOF-modified MAO substrate of AZ31 magnesium alloy. It also proves that it is feasible to build high-performance anticorrosive coatings with MOF materials.
基金We highly thank the funding from the National Natural Science Foundation of China(grants 22222806,22178162,22072065,and 22408170)the Distinguished Youth Foundation of Jiangsu Province(BK20220053)+2 种基金the National Key Research and Development Program of China(2024YFE0206900)the Six Talent Peaks Project in Jiangsu Province(grant JNHB-035)Agency for Science,Technology and Research(A*STAR)through Low Carbon Energy Research Finding Initiative(LCERFI01-0033|U2102d2006).
文摘Paired electrolysis of waste feedstocks holds an energy-efficient alternative for chemical production;however,the sluggish anodic oxidation limited the total efficiency under larger current density.Herein,we constructed ultralow-coordinated Ni species with Ni–O coordination number of∼3 via a hydrothermal synthesis-sulfidation-annealing process and electrochemical activation and demonstrated the vital role in accelerating the proton deintercalation and reactive oxygen intermediate·OH formation during electro-reforming polyethylene terephthalate hydrolysate(POR).The target catalyst NiCoSx/NF afforded a high formate productivity of 7.4 mmol cm^(−2)h^(−1)at∼600 mA cm^(−2)with a formate Faradic efficiency(FE_(formate))of 92.4%in POR and maintained a FE_(formate)of∼90%for 100 h at 2 A in a membrane electrode assembly electrolyzer.Coupling POR on NiCoSx/NF with carbon dioxide reduction reaction on oxygen vacancies enriched Vo-BiSnO reached effective concurrent formate production with 172.7%of FE_(formate)at 500 mA cm^(−2)and long-term stability.Such excellent performance shows the great prospect of electrocatalyst design by regulating the local metal environment.
基金Financial supports from National Key Research and Development Program(No.2016YFB0300305)National Natural Science Foundation of China(No.51804003)are gratefully acknowledged.
文摘The surface oxide layer of grain-oriented electrical steels was investigated by scanning electron microscopy.The formation mechanism and the influence on the glass film of the surface oxide layer were analyzed by the calculation of thermodynamics and kinetics.The surface oxide layer with 2.3μm in thickness is mainly composed of SiO_(2),a small amount of FeO and Fe_(2)SiO_(4).During the formation of surface oxide layer,the restriction factor was the diffusion of O in the oxide layer.At the initial stage of the decarburization annealing,FeO would be formed on the surface layer.SiO_(2) and silicate particles rapidly nucleated,grew and formed a granular oxide layer in the subsurface.As the oxidation layer thickens,the nucleation of new particles decreases,and the growth of oxide particles would be dominant.A lamellar oxide layer was formed between the surface oxide layer and the steel matrix,and eventually formed a typical three-layer structure.During the high temperature annealing,MgO mainly reacted with SiO_(2) and Fe_(2)SiO_(4) in the surface oxide layer to form Mg2SiO_(4) and Fe_(2)SiO_(4) would respond first,thus forming the glass film with average thickness of 4.87μm.
基金Vietnam National University-Ho Chi Minh City under grant number A2020-16-01.
文摘In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal salts.The cation exchange resinsupported iron and magnesium oxides/hydroxides composite(FeMg/CER)was synthesized and introduced as a new and potential adsorbent for selective removal of nitrate ion in the water environment.Characteristics of FeMg/CER were determined by techniques such as Fouriertransform infrared spectroscopy,scanning electron microscopy,and Xray diffraction.The results showed that FeMg/CER material had a high nitrate adsorption capacity of 200 mg NO_(3)^()·g^(1)with a fast equilibrium adsorption time of 30 min at pH 5.In addition,it had good durability of at least 10 times of regeneration,which could be applied to practical water and wastewater treatment.
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.
