Seawater electrolysis holds significant importance for advancing clean energy conversion.NiFe-based catalysts exhibit outstanding performance in the oxygen evolution reaction(OER)under alkaline conditions.However,the ...Seawater electrolysis holds significant importance for advancing clean energy conversion.NiFe-based catalysts exhibit outstanding performance in the oxygen evolution reaction(OER)under alkaline conditions.However,the instability of the Fe active center leads to leakage issues,hindering further development in the field of seawater electrolysis.Here,we adopt an element doping engineering strategy to enhance the OER activity of Ni-Fe oxyhydroxides and greatly stabilize the Fe sites by meticulously optimizing the d-band centers.Among the selected metals(Al,Ce,Co,Cr,Cu,Mn,Sn,Zn and Zr),Mn doping is the most effective as confirmed by both theoretical calculations and experimental verifications.The NiFeMn-OOH/NF formed in situ from the corresponding metal-organic framework requires only 217 mV to achieve a current density of 10 mA·cm^(–2) in alkaline seawater,and exhibits exceptional stability.Theoretical calculations uncover that the Fe sites exhibit better balance of adsorption-desorption kinetics for OER intermediates than Ni sites and Ni-Fe dual-sites,while Mn sites with the polyvalent nature modulate the d-band center closer to Fermi level,facilitate the transfer of electrons across the catalyst surface,thus accelerating the reaction kinetics.This work is of considerable significance for achieving efficient and sustainable seawater electrolysis.展开更多
First-row(3 d)transition metal oxyhydroxides have attracted increasing attention due to their various advantages.Although investigating the oxidation mechanism and processing such materials into hierarchical architect...First-row(3 d)transition metal oxyhydroxides have attracted increasing attention due to their various advantages.Although investigating the oxidation mechanism and processing such materials into hierarchical architectures are greatly desired for their further development,it remains unclear how the oxidation state change occurs,and efforts to produce hierarchical oxyhydroxides in compliance with high ecological and economic standards have progressed slowly.Here,we describe a facile one-step coprecipitation route for the preparation of hierarchical CoOOH,NiOOH and MnOOH,which involves the diffusion of NH_(3)originating from ammonium hydroxide solution into an aqueous solution containing metal ion salts and K_(2)S_(2)O_(8).Comprehensive characterizations by scanning electron microscope,transmission electron microscopy,X-ray diffraction analysis,X-ray photoelectron spectroscopy,ultraviolet-visible spectroscopy and in situ p H measurement demonstrated that K_(2)S_(2)O_(8)induces the oxidation state change of metal ion species after the start of hydrolysis.Meanwhile,it was found that,benefiting from the OH–concentration gradient created by the NH_(3)diffusion method and the suitable growth environment provided by the presence of K_(2)S_(2)O_(8)(high nucleation rate and secondary nucleation),the formation of hierarchical oxyhydroxide structures can be realized in aqueous solution at ambient temperature without the use of heat energy and additional structure-directing agents.The hierarchical CoOOH structures are performed as the electrocatalysts for the oxygen evolution reaction in alkaline media,which exhibit good activity with an overpotential of 320 m V at 10 m A cm^(-2)and a low Tafel slope of 59.6 m V dec^(–1),outperforming many congeneric electrocatalysts.Overall,our study not only provides important insights to understand the formation mechanism of hierarchical oxyhydroxides,but also opens up new opportunities for the preparation of hierarchical oxyhydroxides via a facile,green and low-cost method.展开更多
BACKGROUND Hyperphosphatemia(HP)is a common complication in an advanced stage of chronic kidney disease(CKD)and is associated with cardiovascular issues,metabolic bone abnormalities and worsening of secondary hyperpar...BACKGROUND Hyperphosphatemia(HP)is a common complication in an advanced stage of chronic kidney disease(CKD)and is associated with cardiovascular issues,metabolic bone abnormalities and worsening of secondary hyperparathyroidism.Most patients on dialysis require phosphate binders to control HP.Sucroferric oxyhydroxide(SO)(Dynulta^(TM))is a calcium-free,polynuclear iron(III)based oral phosphate binder,for the treatment of HP.In this phase IV,open-label,singlearm,multi-center,12-week,SOLO CKD study evaluated efficacy and safety of Dynulta^(TM)in Indian CKD patients undergoing hemodialysis.AIM To investigate the efficacy,safety and tolerability of SO Chewable Tablet(Dynulta^(TM))in patients with CKD on hemodialysis.METHODS Hyperphosphatemic patients on hemodialysis and fulfilling eligibility criteria were included in the study for at least 12 weeks and received SO 1500 mg chewable tablet per day.The key endpoint was change in mean serum phosphorus levels after 12 weeks.Data were analysed using analysis of variance,Paired test,Wilcoxon test,and post-hoc comparisons,with P<0.05 considered statistically significant,using Graph Pad software.RESULTS A total of 114 patients were enrolled and 94 patients completed the study.The mean±SD serum phosphorous level was reduced from 7.62 mg/dL±2.02 mg/dL at baseline to 5.13 mg/dL±1.88 mg/dL after 12 weeks of treatment.At each follow-up visit,the reduction in mean serum phosphorous levels was statistically significant(P value<0.05)compared to baseline,confirming the efficacy of SO.A total of 33.33%of patients experienced adverse events(AEs).The most frequently reported AEs were pyrexia,nasopharyngitis and headache,which were considered unlikely to be related to the study drug treatment.No serious AEs was reported during the study period and no patients discontinued treatment due to AEs.CONCLUSION This first real-world study in Indian CKD patients on hemodialysis shows SO as a safe,and effective monotherapy for HP,though its small sample size limits generalizability.展开更多
The mineralogical and micromorphological characteristics of Si-Fe-Mn oxyhydroxides from the dacite-hosted PACMANUS hydrothermal field were analyzed.The samples are poorly crystallized Si-Fe-Mn oxyhydroxides with minor...The mineralogical and micromorphological characteristics of Si-Fe-Mn oxyhydroxides from the dacite-hosted PACMANUS hydrothermal field were analyzed.The samples are poorly crystallized Si-Fe-Mn oxyhydroxides with minor birnessite, todorokite, nontronite, goethite, and opal-A.There are some microtextures which are rather like fossil microbes such as the filamentous silica and the hollow pipes.Flakes of nontronite crystals are found either forming a honeycomb texture or distrib- uted on the surface of the hollow pipes.Nontronite is the product precipitated from low-temperature hydrothermal fluids, and microbes may play a role in its formation.Si-Fe-Mn oxyhydroxides have two kinds of nuclei: Si-Mn nuclei and Si nuclei, both enveloped by the similar Si-Fe outer layer, existing in the rod-shaped oxyhydroxide and spheroidal oxyhydroxide, respectively.In the Si-Mn nuclei, the concentration of SiO2 is between 39.32 wt% and 86.31 wt%, and MnO concentration is between 4.97 wt% and 27.01 wt%, but Fe2O3 concentration is very low (0.54 wt%-3.43 wt%).In the Si nucleus the concentration of SiO2 is 90.17 wt%, but concentration of MnO and Fe2O3 are low, with 0.06 wt% and 3.47 wt%, respectively.The formation of the Si-Mn nucleus is closely related to microbes, whereas the Si nucleus is of inorganic origin.展开更多
This paper investigated the effects of five kinds of Au surfaces terminated with and without functional groups on the crystallization of ferric oxides/oxyhydroxides in the suspension condition. Self-assembled monolaye...This paper investigated the effects of five kinds of Au surfaces terminated with and without functional groups on the crystallization of ferric oxides/oxyhydroxides in the suspension condition. Self-assembled monolayers （SAMs） were used to create hydroxyl （-OH）, carboxyl （-COOH）, amine （-NH2） and methyl （-CH3） functionalized surfaces, which proved to be of the same surface density. The immersion time of substrates in the Fe（OH）3 suspension was divided into two time portions. During the first period of 2 h, few ferric oxide/oxyhydroxide was deposited except that E-Fe203 was detected on -NH2 surface. Crystallization for 10h evidenced more kinds of iron compounds on the functional surfaces. Goethite and maghemite were noticed on four functional surfaces, and maghemite also grew on Au surface. Deposition of ^-Fe203 was found on -OH surface, while the growth of orthorhombic and hexagon FeOOH were indicated on -NH2 surface. Considering the wide existence of iron compounds in nature, our investigation is a precedent work to the study of iron biomineralization in the suspension area.展开更多
Synthesized iron oxyhydroxide was applied for the adsorptive removal of As(V)and As(III)from the aquas media.Additionally,this investigation highlighted the synergistic effect of calcium carbonate in conjunction with ...Synthesized iron oxyhydroxide was applied for the adsorptive removal of As(V)and As(III)from the aquas media.Additionally,this investigation highlighted the synergistic effect of calcium carbonate in conjunction with iron oxyhydroxide,resulting in enhanced removal efficiency.The experiment was conducted under various conditions:concentration,dosage,pH,agitation,and temperature.Material characterizations such as Brunauer Emmett Teller,X-ray diffraction,scanning electron microscopy,and Fourier transform infrared spectroscopy were implied to understand adsorption mechanisms.The Langmuir model revealed optimal concentrations for As(V)=500μg/L at pH-5 and As(III)=200μg/L at pH-7,resulting in 95%and 93%adsorption efficiencies,respectively.Maximum adsorption capacities“qm”were found to be 1266.943μg/g for As(V)and 1080.241μg/g for As(III).Freundlich model demonstrated favorable adsorption by indicating“n>1”such as As(V)=2.542 and As(III)=2.707;similarly,the speciation factor“RL<1”for both species as As(V)=0.1 and As(III)=0.5,respectively.The kinetic study presented a pseudo-second-order model as best fitted,indicating throughout chemisorption processes for removing As(V)and As(III).Furthermore,incorporating calcium carbonate presented a significant leap in the removal efficiency,indicating As(V)from 95%to 98%and As(III)from 93%to 96%,respectively.Our findings offer profound motivation for developing effective and sustainable solutions to tackle arsenic contamination,underscoring the exceptional promise of iron oxyhydroxide in conjunction with calcium carbonate to achieve maximum removal efficiency.展开更多
In this article,we report a 3D NiFe phosphite oxyhydroxide plastic electrode using high-resolution digital light processing(DLP)3D-printing technology via induced chemical deposition method.The as-prepared 3D plastic ...In this article,we report a 3D NiFe phosphite oxyhydroxide plastic electrode using high-resolution digital light processing(DLP)3D-printing technology via induced chemical deposition method.The as-prepared 3D plastic electrode exhibits no template requirement,freedom design,low-cost,robust,anticorrosion,lightweight,and micro-nano porous characteristics.It can be drawn to the conclusion that highly oriented open-porous 3D geometry structure will be beneficial for improving surface catalytic active area,wetting performance,and reaction–diffusion dynamics of plastic electrodes for oxygen evolution reaction(OER)catalysis process.Density functional theory(DFT)calculation interprets the origin of high activity of NiFe(PO_(3))O(OH)and demonstrates that the implantation of the–PO_(3)can effectively bind the 3d orbital of Ni in NiFe(PO_(3))O(OH),lead to the weak adsorption of intermediate,make electron more active to improve the conductivity,thereby lowing the transform free energy of*O to*OOH.The water oxidization performance of as-prepared 3D NiFe(PO_(3))O(OH)hollow tubular(HT)lattice plastic electrode has almost reached the state-of-the-art level compared with the as-reported large-current-density catalysts or 3D additive manufactured plastic/metal-based electrodes,especially for high current OER electrodes.This work breaks through the bottleneck that plagues the performance improvement of low-cost high-current electrodes.展开更多
During the chemical weathering of the uranium mill tailings,released uranium could be immobilized by the newly formed secondary minerals such as oxyhydroxides.A deeper understanding of the interaction between uranium ...During the chemical weathering of the uranium mill tailings,released uranium could be immobilized by the newly formed secondary minerals such as oxyhydroxides.A deeper understanding of the interaction between uranium and common oxyhydroxides under environmental conditions is necessary.In this work,uranium sorption behaviors on Al-,Mn-and Fe-oxyhydroxide minerals(boehmite,manganite,goethite,and lepidocrocite)were investigated by batch experiments.Results showed that the uranium sorption on Al-oxyhydroxide behaved significantly differently from the other three minerals.The sorption edge of the Mn-and Fe-oxyhydroxides located around pH 5,while the sorption edge of boehmite shifted about 1.5 pH unit to near neutral.The sorption isotherms of uranium on manganite,goethite and lepidocrocite at pH 5.0 could be well fitted by the Langmuir model.Instead of surface complexation,sorption on boehmite happened mainly by uranium-bearing carbonates and hydroxides precipitation as illustrated by the characterization results.Both carbonate and phosphate strongly affected the uranium sorption behavior.The removal efficiency of uranium by boehmite exceeded 98%after three sorption-desorption cycles,indicating it may be a potential material for uranium removal and recovery.展开更多
Sluggish reaction kinetics of oxygen evolution reaction(OER), resulting from multistep proton-coupled electron transfer and spin constriction, limits overall efficiency for most reported catalysts. Herein, using model...Sluggish reaction kinetics of oxygen evolution reaction(OER), resulting from multistep proton-coupled electron transfer and spin constriction, limits overall efficiency for most reported catalysts. Herein, using modeled ZnFe_(2-x)Ni_xO_(4)(0 ≤ x ≤ 0.4) spinel oxides, we aim to develop better OER electrocatalyst through combining the construction of ferromagnetic(FM) ordering channels and generation of highly active reconstructed species. The number of symmetry-breaking Fe–O–Ni structure links to the formation of FM ordering electron transfer channels. Meanwhile, as the number of Ni^(3+)increases, more ligand holes are formed, beneficial for redirecting surface reconstruction. The electro-activated ZnFe_(1.6)Ni_(0.4)O_(4) shows the highest specific activity, which is 13 and 2.5 times higher than that of ZnFe_(2)O_(4) and unactivated ZnFe_(1.6)Ni_(0.4)O_(4), and even superior to the benchmark IrO_(2) under the overpotential of 350 mV. Applying external magnetic field can make electron spin more aligned, and the activity can be further improved to 39 times of ZnFe_(2)O_(4). We propose that intriguing FM exchange-field interaction at FM/paramagnetic interfaces can penetrate FM ordering channels into reconstructed oxyhydroxide layers, thereby activating oxyhydroxide layers as spin-filter to accelerate spin-selective electron transfer. This work provides a new guideline to develop highly efficient spintronic catalysts for water oxidation and other spin-forbidden reactions.展开更多
An efficient and economical oxygen evolution reaction(OER)catalyst is critical to the widespread application of solar energy to fuel conversion.Among many potential OER catalysts,the metal oxyhydroxides,especially FeO...An efficient and economical oxygen evolution reaction(OER)catalyst is critical to the widespread application of solar energy to fuel conversion.Among many potential OER catalysts,the metal oxyhydroxides,especially FeOOH,show promising OER reactivity.In the present work,we performed a DFT+U study of the OER mechanism on theγ‐FeOOH(010)surface.In particular,we established the chemical potential of the OH?and hole pair and included the OH?anion in the reaction pathway,accounting to the alkaline conditions of anodic OER process.We then analyzed the OER pathways on the surface with OH‐,O‐and Fe‐terminations.On the surface with OH‐and O‐terminations,the O2molecule could form from either OH reacting with the surface oxygen species(-OH*and-O*)or the combination of two surface oxygen species.On the Fe‐terminated surface,O2can only form by adsorbing OH on the Fe sites first.The potential‐limiting step of the oxygen evolution with different surface terminations was determined by following the free‐energy change of the elementary steps along each pathway.Our results show that oxygen formation requires recreating the surface Fe sites,and consequently,the condition that favors the partially exposed Fe sites will promote oxygen formation.展开更多
The iron rust phases formed on low alloy steels containing different quantities of Cr element have been characterized using EPMA, Raman spectroscopy, TEM, optical microscopy etc. The ion selective properties of synthe...The iron rust phases formed on low alloy steels containing different quantities of Cr element have been characterized using EPMA, Raman spectroscopy, TEM, optical microscopy etc. The ion selective properties of synthesized rust films with the same phase constituent as the atmospheric corrosion products were investigated using self-made apparatus. The results showed that corrosion loss of steels exposed in marine atmosphere decreased rapidly as the Cr content of the steel was increased. Cr-containing steels were covered by a uniform compacted rust layer composed of fine particles with an average diameter of several nanometers. Inner rust layer of Cr-containing steel (2 mass fraction) was composed of a-CrxFe1-xOOH, with Cr content of about 5 mass fraction. Such rust layer showed cation selective property, and could depress the penetration of Cl- to contact substrate steel directly.展开更多
Y2O3 nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently there are many studies focusing on controlling the size and morphology of Y2O3 in order to obtain better materials per...Y2O3 nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently there are many studies focusing on controlling the size and morphology of Y2O3 in order to obtain better materials performance. In present study, yttrium oxyhydroxide precursor was synthesized via a facile solvothermal process through the dissolution-re-crystallization mechanism of Y2O3 raw powders in the ethylenediamine solvent, then nanosized yttrium oxide crystal was prepared from the precursor through post heat treatment process. The effects of solvothermal treatment temperature, holding time, solvent kinds and post heat treatment parameters on crystalline structure, grain shape and size of nanocrystal were investigated by XRD, TEM and TGA-DTA measurements. TEM images reveal that the morphology of product after post heat treatment at 460℃for 12 h is rice-like nanocrystal. XRD shows that this product is pure cubic Y2O3 cphase. Present study reveals that high purity Y2O3 with rice-like morphology can be easily prepared with average size around 30 nm under suitable post heat treatment parameters. In addition, the effects of solvents such as water and ethanol etc. on the crystal structure and morphology were also investigated. It is suggested that dissolution-recrystallization process may be the main mechanism for the formation of nano-sized YOOH precursors under solvothermal reaction condition, and the ethylenediamine solvent is likely to play an important role in controlling the transformation process of yttria precursors to the Y2O3 nanocrystal.展开更多
Cylindrical nickel metal hydride （Ni-MH） battery with high specific volume capacity was prepared by using the oxyhydroxide Ni（OH）2 and AB5 type hydrogen storage alloy and adjusting the designing parameters of posi...Cylindrical nickel metal hydride （Ni-MH） battery with high specific volume capacity was prepared by using the oxyhydroxide Ni（OH）2 and AB5 type hydrogen storage alloy and adjusting the designing parameters of positive and negative electrodes. The oxyhydroxide Ni（OH）2 was synthesized by oxidizing spherical β-Ni（OH）2 with chemical method. The X-ray diffraction （XRD） patterns and the Fourier transform infrared （PT-IR） spectra indicated that 7-NiOOH was formed on the oxyhydroxide Ni（OH）2 powders, and some H2O molecules were inserted into their crystal lattice spacing. The battery capacity could not be improved when the oxyhydroxide Ni（OH）2 sample was directly used as the positive active materials. However, based on the conductance and residual capacity of the oxyhydroxide Ni（OH）2 powders, AA size Ni-MH battery with 2560 mA.h capacity and 407 W·h·L^-1 specific volume energy at 0.2C was obtained by using the commercial spherical β-Ni（OH）2 and AB5-type hydrogen-storage alloy powders as the active materials when 10% mass amount of the oxyhydroxide Ni（OH）2 with 2.50 valence was added to the positive active materials and subsequently the battery designing parameters were adjusted as well. The as-prepared battery showed 70% initial capacity after 80 cycles at 0.5C. The possibility for adjusting the capacity ratio of positive and negative electrodes from 1 ： 1.35 to 1 ： 1.22 was demonstrated preliminarily. It is considered the as-prepared battery can meet the requirement of some special portable electrical instruments.展开更多
Nanostructured iron oxyhydroxide（Fe OOH） thin films have been synthesized using an electrodeposition method on a nickel foam（NF） substrate and effect of air annealing temperature on the catalytic performance is st...Nanostructured iron oxyhydroxide（Fe OOH） thin films have been synthesized using an electrodeposition method on a nickel foam（NF） substrate and effect of air annealing temperature on the catalytic performance is studied. The as-deposited and annealed thin films were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）, field emission scanning electron microscopy（FE-SEM） and linear sweep voltammetry（LSV） to determine their structural, morphological, compositional and electrochemical properties, respectively. The as-deposited nanostructured amorphous Fe OOH thin film is converted into a polycrystalline Fe;O;with hematite crystal structure at a high temperature. The Fe OOH thin film acts as an efficient electrocatalyst for the oxygen evolution reaction（OER） in an alkaline 1 M KOH electrolyte. The film annealed at 200 °C shows high catalytic activity with an onset overpotential of 240 m V with a smaller Tafel slope of 48 m V/dec. Additionally, it needs an overpotential of 290 mV to the drive the current density of 10 m A/cm;and shows good stability in the 1 M KOH electrolyte solution.展开更多
Rational design of low‐cost and efficient electrocatalysts for ethanol oxidation reaction(EOR)is imperative for electrocatalytic ethanol fuel cells.In this work,we developed a copper‐doped nickel oxyhydroxide(Cu‐do...Rational design of low‐cost and efficient electrocatalysts for ethanol oxidation reaction(EOR)is imperative for electrocatalytic ethanol fuel cells.In this work,we developed a copper‐doped nickel oxyhydroxide(Cu‐doped NiOOH)catalyst via in situ electrochemical reconstruction of a NiCu alloy.The introduction of Cu dopants increases the specific surface area and more defect sites,as well as forms high‐valence Ni sites.The Cu‐doped NiOOH electrocatalyst exhibited an excellent EOR performance with a peak current density of 227 mA·cm^(–2)at 1.72 V versus reversible hydrogen electrode,high Faradic efficiencies for acetate production(>98%),and excellent electrochemical stability.Our work suggests an attractive route of designing non‐noble metal based electrocatalysts for ethanol oxidation.展开更多
Europium oxyhydroxide crystals were synthesized by the flux method. The as-grown crystals were transparent and had a plate-like shape with natural flat surfaces. The powder XRD data were refined by assuming a monoclin...Europium oxyhydroxide crystals were synthesized by the flux method. The as-grown crystals were transparent and had a plate-like shape with natural flat surfaces. The powder XRD data were refined by assuming a monoclinic structure of the space group P21/m and lattice parameters of a=0.4346 nm, b=0.3744 nm, c=0.6107 nm, and β=108.62°. The magnetic susceptibility of the EuOOH crystals exhibited typical Van Vleck temperature-independent paramagnetism below 120 K. The calculated susceptibility, based on Van Vleck＇s theory, agreed with the experimental data to some extent, with the coupling constant λ=458±10 K. The experimental results were in close agreement with the results calculated using a modified formula with λ=505±2 K and a constant term C=4.6×10^-4 emu/（mol·Oe）.展开更多
Water splitting has received more and more attention because of its huge potential to generate clean and renewable energy.The highly active and durable oxygen evolution reaction(OER)catalysts play a decisive factor in...Water splitting has received more and more attention because of its huge potential to generate clean and renewable energy.The highly active and durable oxygen evolution reaction(OER)catalysts play a decisive factor in achieving efficient water splitting.The identification of authentic active origin under the service conditions can prompt a more reasonable design of catalysts together with well-confined micro-/nano-structures to boost the efficiency of water splitting.Herein,Fe,Co,and Ni ternary transition metal dichalcogenide(FCND)nanorod arrays on Ni foam are purposely designed as an active and stable low-cost OER pre-catalyst for the electrolysis of water in alkaline media.The optimized FCND catalyst demonstrated a lower overpotential than the binary and unary counterparts,and a 27-fold rise in kinetic current density at the overpotential of 300 m V compared to the nickel dichalcogenide counterpart.Raman spectra and other structural characterizations at different potentials reveal that the in-situ surface self-reconstruction from FCND to ternary transition metal oxyhydroxides(FCNOH)on catalyst surfaces initiated at about 1.5 V,which is identified as the origin of OER activity.The surface selfreconstruction towards FCNOH also enables excellent stability,without fading upon the test for 50 h.展开更多
Developing high-performing oxygen evolution reaction(OER)electrocatalysts under high-current operation conditions is critical for future commercial applications of alkaline water electrolysis for clean energy generati...Developing high-performing oxygen evolution reaction(OER)electrocatalysts under high-current operation conditions is critical for future commercial applications of alkaline water electrolysis for clean energy generation.Herein,we prepared a three-dimensional(3D)bimetallic oxyhydroxide hybrid grown on a Ni foam(NiFeOOH/NF)prepared by immersing Ni foam(NF)into Fe(NO_(3))_(3) solution.In this unique 3D structure,the NiFeOOH/NF hybrid was composed of crystalline Ni(OH)_(2) and amorphous FeOOH evenly grown on the NF surface.As a bimetallic oxyhydroxide electrocatalyst,the NiFeOOH/NF hybrid exhibited excellent catalytic activity,surpassing not only the other reported Ni–Fe based electrocatalysts,but also the commercial Ir/C catalyst.In situ electrochemical Raman spectroscopy demonstrated the active FeOOH and NiOOH phases involved in the OER process.Profiting from the synergy of Fe and Ni catalytic sites,the NiFeOOH/NF hybrid delivered an outstanding OER performance under challenging industrial conditions in a 10.0 mol·L^(-1) KOH electrolyte at 80℃,requiring potentials as small as 1.47 and 1.51 V to achieve the super-high catalytic current densities of 100 and 500mA∙cm^(-2),respectively.展开更多
Crystals of co-doped gadolinium oxyhydroxide （GdOOH）, Gd0.98Eu0.02-xTbxOOH and Gd1-y-zDyyBizOOH, were synthesized by a flux method. The color coordinates in the Commission Internationale de I＇Eelairage （CIE） chro...Crystals of co-doped gadolinium oxyhydroxide （GdOOH）, Gd0.98Eu0.02-xTbxOOH and Gd1-y-zDyyBizOOH, were synthesized by a flux method. The color coordinates in the Commission Internationale de I＇Eelairage （CIE） chromaticity diagram of Gd0.98Eu0.02-xTbxOOH, obtained under 254 nm irradiation, shifted along a straight line with the changing values ofx to include the yellow region. The CIE coordinates of Dy^3＋ doped in GdOOH were located in the yellow region, while the emission intensity of Dy^3＋ under 286 nm irradiation increased by more than 40 times when co-doped with Bi^3＋.展开更多
Metal oxyhydroxides(MOOH)generated from irreversible reconstructions of transition metal compounds are intrinsic active species for oxygen evolution reaction,whose activities are still constrained by sluggish deproton...Metal oxyhydroxides(MOOH)generated from irreversible reconstructions of transition metal compounds are intrinsic active species for oxygen evolution reaction,whose activities are still constrained by sluggish deprotonation kinetics and inherent adsorption energy scaling relations.Herein,we construct a tunable proton acceptor(TPA)on oxyhydroxides by in-situ reconstruction of metal oxoacids such as NiC2O4to accelerate deprotonation and break adsorption energy scaling relations during OER.The modified C_(2)O_(4)^(2-)as a TPA can easily extract H of*OH(forming*HC2O4intermediate)and then promote deprotonation by the transmitted hydrogen bond with*OOH along conjugated(H...)O=C-O(-H)chain.As a result,Ni OOH-C2O4shows non-concerted proton-electron transfer and improved deprotonation rate,and delivers a good OER activity(270 mV@10 mA cm-2).The conjugate acidity coefficient(pKa)of the modified oxoacid group can be a descriptor for TPA selection.This TPA strategy can be universally applied to Co-,Fe-,and Ni-based oxyhydroxides to facilitate OER efficiency.展开更多
文摘Seawater electrolysis holds significant importance for advancing clean energy conversion.NiFe-based catalysts exhibit outstanding performance in the oxygen evolution reaction(OER)under alkaline conditions.However,the instability of the Fe active center leads to leakage issues,hindering further development in the field of seawater electrolysis.Here,we adopt an element doping engineering strategy to enhance the OER activity of Ni-Fe oxyhydroxides and greatly stabilize the Fe sites by meticulously optimizing the d-band centers.Among the selected metals(Al,Ce,Co,Cr,Cu,Mn,Sn,Zn and Zr),Mn doping is the most effective as confirmed by both theoretical calculations and experimental verifications.The NiFeMn-OOH/NF formed in situ from the corresponding metal-organic framework requires only 217 mV to achieve a current density of 10 mA·cm^(–2) in alkaline seawater,and exhibits exceptional stability.Theoretical calculations uncover that the Fe sites exhibit better balance of adsorption-desorption kinetics for OER intermediates than Ni sites and Ni-Fe dual-sites,while Mn sites with the polyvalent nature modulate the d-band center closer to Fermi level,facilitate the transfer of electrons across the catalyst surface,thus accelerating the reaction kinetics.This work is of considerable significance for achieving efficient and sustainable seawater electrolysis.
基金funded by the Deutsche Forschungsgemeinschaft DFG and the Sino-German Center for Research Promotion(Grants GZ 1351 and CO 194/19-1)funded by a Chinese Scholarship Council stipend。
文摘First-row(3 d)transition metal oxyhydroxides have attracted increasing attention due to their various advantages.Although investigating the oxidation mechanism and processing such materials into hierarchical architectures are greatly desired for their further development,it remains unclear how the oxidation state change occurs,and efforts to produce hierarchical oxyhydroxides in compliance with high ecological and economic standards have progressed slowly.Here,we describe a facile one-step coprecipitation route for the preparation of hierarchical CoOOH,NiOOH and MnOOH,which involves the diffusion of NH_(3)originating from ammonium hydroxide solution into an aqueous solution containing metal ion salts and K_(2)S_(2)O_(8).Comprehensive characterizations by scanning electron microscope,transmission electron microscopy,X-ray diffraction analysis,X-ray photoelectron spectroscopy,ultraviolet-visible spectroscopy and in situ p H measurement demonstrated that K_(2)S_(2)O_(8)induces the oxidation state change of metal ion species after the start of hydrolysis.Meanwhile,it was found that,benefiting from the OH–concentration gradient created by the NH_(3)diffusion method and the suitable growth environment provided by the presence of K_(2)S_(2)O_(8)(high nucleation rate and secondary nucleation),the formation of hierarchical oxyhydroxide structures can be realized in aqueous solution at ambient temperature without the use of heat energy and additional structure-directing agents.The hierarchical CoOOH structures are performed as the electrocatalysts for the oxygen evolution reaction in alkaline media,which exhibit good activity with an overpotential of 320 m V at 10 m A cm^(-2)and a low Tafel slope of 59.6 m V dec^(–1),outperforming many congeneric electrocatalysts.Overall,our study not only provides important insights to understand the formation mechanism of hierarchical oxyhydroxides,but also opens up new opportunities for the preparation of hierarchical oxyhydroxides via a facile,green and low-cost method.
文摘BACKGROUND Hyperphosphatemia(HP)is a common complication in an advanced stage of chronic kidney disease(CKD)and is associated with cardiovascular issues,metabolic bone abnormalities and worsening of secondary hyperparathyroidism.Most patients on dialysis require phosphate binders to control HP.Sucroferric oxyhydroxide(SO)(Dynulta^(TM))is a calcium-free,polynuclear iron(III)based oral phosphate binder,for the treatment of HP.In this phase IV,open-label,singlearm,multi-center,12-week,SOLO CKD study evaluated efficacy and safety of Dynulta^(TM)in Indian CKD patients undergoing hemodialysis.AIM To investigate the efficacy,safety and tolerability of SO Chewable Tablet(Dynulta^(TM))in patients with CKD on hemodialysis.METHODS Hyperphosphatemic patients on hemodialysis and fulfilling eligibility criteria were included in the study for at least 12 weeks and received SO 1500 mg chewable tablet per day.The key endpoint was change in mean serum phosphorus levels after 12 weeks.Data were analysed using analysis of variance,Paired test,Wilcoxon test,and post-hoc comparisons,with P<0.05 considered statistically significant,using Graph Pad software.RESULTS A total of 114 patients were enrolled and 94 patients completed the study.The mean±SD serum phosphorous level was reduced from 7.62 mg/dL±2.02 mg/dL at baseline to 5.13 mg/dL±1.88 mg/dL after 12 weeks of treatment.At each follow-up visit,the reduction in mean serum phosphorous levels was statistically significant(P value<0.05)compared to baseline,confirming the efficacy of SO.A total of 33.33%of patients experienced adverse events(AEs).The most frequently reported AEs were pyrexia,nasopharyngitis and headache,which were considered unlikely to be related to the study drug treatment.No serious AEs was reported during the study period and no patients discontinued treatment due to AEs.CONCLUSION This first real-world study in Indian CKD patients on hemodialysis shows SO as a safe,and effective monotherapy for HP,though its small sample size limits generalizability.
基金supported by National Natural Science Foundation of China(Grant No.40830849)National Key Basic Research Program of China(Grant No.2013CB429700)+1 种基金Shandong Province Natural Science Foundation of China for Distin-guished Young Scholars(Grant No.JQ200913)the Pilot Project of Knowledge Innovation Project,Chinese Academy of Sciences(Grant No.KZCX2-YW-211)
文摘The mineralogical and micromorphological characteristics of Si-Fe-Mn oxyhydroxides from the dacite-hosted PACMANUS hydrothermal field were analyzed.The samples are poorly crystallized Si-Fe-Mn oxyhydroxides with minor birnessite, todorokite, nontronite, goethite, and opal-A.There are some microtextures which are rather like fossil microbes such as the filamentous silica and the hollow pipes.Flakes of nontronite crystals are found either forming a honeycomb texture or distrib- uted on the surface of the hollow pipes.Nontronite is the product precipitated from low-temperature hydrothermal fluids, and microbes may play a role in its formation.Si-Fe-Mn oxyhydroxides have two kinds of nuclei: Si-Mn nuclei and Si nuclei, both enveloped by the similar Si-Fe outer layer, existing in the rod-shaped oxyhydroxide and spheroidal oxyhydroxide, respectively.In the Si-Mn nuclei, the concentration of SiO2 is between 39.32 wt% and 86.31 wt%, and MnO concentration is between 4.97 wt% and 27.01 wt%, but Fe2O3 concentration is very low (0.54 wt%-3.43 wt%).In the Si nucleus the concentration of SiO2 is 90.17 wt%, but concentration of MnO and Fe2O3 are low, with 0.06 wt% and 3.47 wt%, respectively.The formation of the Si-Mn nucleus is closely related to microbes, whereas the Si nucleus is of inorganic origin.
文摘This paper investigated the effects of five kinds of Au surfaces terminated with and without functional groups on the crystallization of ferric oxides/oxyhydroxides in the suspension condition. Self-assembled monolayers （SAMs） were used to create hydroxyl （-OH）, carboxyl （-COOH）, amine （-NH2） and methyl （-CH3） functionalized surfaces, which proved to be of the same surface density. The immersion time of substrates in the Fe（OH）3 suspension was divided into two time portions. During the first period of 2 h, few ferric oxide/oxyhydroxide was deposited except that E-Fe203 was detected on -NH2 surface. Crystallization for 10h evidenced more kinds of iron compounds on the functional surfaces. Goethite and maghemite were noticed on four functional surfaces, and maghemite also grew on Au surface. Deposition of ^-Fe203 was found on -OH surface, while the growth of orthorhombic and hexagon FeOOH were indicated on -NH2 surface. Considering the wide existence of iron compounds in nature, our investigation is a precedent work to the study of iron biomineralization in the suspension area.
基金funded by the National Natural Science Foundation of China(Nos.42177078 and 42020104005).
文摘Synthesized iron oxyhydroxide was applied for the adsorptive removal of As(V)and As(III)from the aquas media.Additionally,this investigation highlighted the synergistic effect of calcium carbonate in conjunction with iron oxyhydroxide,resulting in enhanced removal efficiency.The experiment was conducted under various conditions:concentration,dosage,pH,agitation,and temperature.Material characterizations such as Brunauer Emmett Teller,X-ray diffraction,scanning electron microscopy,and Fourier transform infrared spectroscopy were implied to understand adsorption mechanisms.The Langmuir model revealed optimal concentrations for As(V)=500μg/L at pH-5 and As(III)=200μg/L at pH-7,resulting in 95%and 93%adsorption efficiencies,respectively.Maximum adsorption capacities“qm”were found to be 1266.943μg/g for As(V)and 1080.241μg/g for As(III).Freundlich model demonstrated favorable adsorption by indicating“n>1”such as As(V)=2.542 and As(III)=2.707;similarly,the speciation factor“RL<1”for both species as As(V)=0.1 and As(III)=0.5,respectively.The kinetic study presented a pseudo-second-order model as best fitted,indicating throughout chemisorption processes for removing As(V)and As(III).Furthermore,incorporating calcium carbonate presented a significant leap in the removal efficiency,indicating As(V)from 95%to 98%and As(III)from 93%to 96%,respectively.Our findings offer profound motivation for developing effective and sustainable solutions to tackle arsenic contamination,underscoring the exceptional promise of iron oxyhydroxide in conjunction with calcium carbonate to achieve maximum removal efficiency.
基金the National Natural Science Foundation of China(52001173&52100190)the Jiangsu Specially-Appointed Professor Program,Natural Science Foundation of Jiangsu Province(BK20200970&BK20210834)+2 种基金General Project of Natural Science Research in Jiangsu Colleges and Universities(20KJB530011&20KJB430046)Research Fund of Nantong University(03083054)National College Students'innovation and entrepreneurship training program(202110304019Z)for financial support.
文摘In this article,we report a 3D NiFe phosphite oxyhydroxide plastic electrode using high-resolution digital light processing(DLP)3D-printing technology via induced chemical deposition method.The as-prepared 3D plastic electrode exhibits no template requirement,freedom design,low-cost,robust,anticorrosion,lightweight,and micro-nano porous characteristics.It can be drawn to the conclusion that highly oriented open-porous 3D geometry structure will be beneficial for improving surface catalytic active area,wetting performance,and reaction–diffusion dynamics of plastic electrodes for oxygen evolution reaction(OER)catalysis process.Density functional theory(DFT)calculation interprets the origin of high activity of NiFe(PO_(3))O(OH)and demonstrates that the implantation of the–PO_(3)can effectively bind the 3d orbital of Ni in NiFe(PO_(3))O(OH),lead to the weak adsorption of intermediate,make electron more active to improve the conductivity,thereby lowing the transform free energy of*O to*OOH.The water oxidization performance of as-prepared 3D NiFe(PO_(3))O(OH)hollow tubular(HT)lattice plastic electrode has almost reached the state-of-the-art level compared with the as-reported large-current-density catalysts or 3D additive manufactured plastic/metal-based electrodes,especially for high current OER electrodes.This work breaks through the bottleneck that plagues the performance improvement of low-cost high-current electrodes.
基金National Natural Science Foundation of China(NSFC,No.11475008)。
文摘During the chemical weathering of the uranium mill tailings,released uranium could be immobilized by the newly formed secondary minerals such as oxyhydroxides.A deeper understanding of the interaction between uranium and common oxyhydroxides under environmental conditions is necessary.In this work,uranium sorption behaviors on Al-,Mn-and Fe-oxyhydroxide minerals(boehmite,manganite,goethite,and lepidocrocite)were investigated by batch experiments.Results showed that the uranium sorption on Al-oxyhydroxide behaved significantly differently from the other three minerals.The sorption edge of the Mn-and Fe-oxyhydroxides located around pH 5,while the sorption edge of boehmite shifted about 1.5 pH unit to near neutral.The sorption isotherms of uranium on manganite,goethite and lepidocrocite at pH 5.0 could be well fitted by the Langmuir model.Instead of surface complexation,sorption on boehmite happened mainly by uranium-bearing carbonates and hydroxides precipitation as illustrated by the characterization results.Both carbonate and phosphate strongly affected the uranium sorption behavior.The removal efficiency of uranium by boehmite exceeded 98%after three sorption-desorption cycles,indicating it may be a potential material for uranium removal and recovery.
基金supported by the National Key R&D Program of China (2020YFA0710000)the National Natural Science Foundation of China (22278307, 22008170, 21978200, 22161142002, and 22121004)+2 种基金the Applied Basic Research Program of Qinghai Province (2023-ZJ-701)the Haihe Laboratory of Sustainable Chemical Transformationsthe Tianjin Research Innovation Project for Postgraduate Students (2022BKYZ035)。
文摘Sluggish reaction kinetics of oxygen evolution reaction(OER), resulting from multistep proton-coupled electron transfer and spin constriction, limits overall efficiency for most reported catalysts. Herein, using modeled ZnFe_(2-x)Ni_xO_(4)(0 ≤ x ≤ 0.4) spinel oxides, we aim to develop better OER electrocatalyst through combining the construction of ferromagnetic(FM) ordering channels and generation of highly active reconstructed species. The number of symmetry-breaking Fe–O–Ni structure links to the formation of FM ordering electron transfer channels. Meanwhile, as the number of Ni^(3+)increases, more ligand holes are formed, beneficial for redirecting surface reconstruction. The electro-activated ZnFe_(1.6)Ni_(0.4)O_(4) shows the highest specific activity, which is 13 and 2.5 times higher than that of ZnFe_(2)O_(4) and unactivated ZnFe_(1.6)Ni_(0.4)O_(4), and even superior to the benchmark IrO_(2) under the overpotential of 350 mV. Applying external magnetic field can make electron spin more aligned, and the activity can be further improved to 39 times of ZnFe_(2)O_(4). We propose that intriguing FM exchange-field interaction at FM/paramagnetic interfaces can penetrate FM ordering channels into reconstructed oxyhydroxide layers, thereby activating oxyhydroxide layers as spin-filter to accelerate spin-selective electron transfer. This work provides a new guideline to develop highly efficient spintronic catalysts for water oxidation and other spin-forbidden reactions.
基金supported by the Chemical,Biological,Environmental,and Transport Systems(CBET)program of US National Science Foundation(CBET-1438440)~~
文摘An efficient and economical oxygen evolution reaction(OER)catalyst is critical to the widespread application of solar energy to fuel conversion.Among many potential OER catalysts,the metal oxyhydroxides,especially FeOOH,show promising OER reactivity.In the present work,we performed a DFT+U study of the OER mechanism on theγ‐FeOOH(010)surface.In particular,we established the chemical potential of the OH?and hole pair and included the OH?anion in the reaction pathway,accounting to the alkaline conditions of anodic OER process.We then analyzed the OER pathways on the surface with OH‐,O‐and Fe‐terminations.On the surface with OH‐and O‐terminations,the O2molecule could form from either OH reacting with the surface oxygen species(-OH*and-O*)or the combination of two surface oxygen species.On the Fe‐terminated surface,O2can only form by adsorbing OH on the Fe sites first.The potential‐limiting step of the oxygen evolution with different surface terminations was determined by following the free‐energy change of the elementary steps along each pathway.Our results show that oxygen formation requires recreating the surface Fe sites,and consequently,the condition that favors the partially exposed Fe sites will promote oxygen formation.
基金This research were supported by the Science and Technology Society of Shanghai, China Appreciation is expressed to Y.F.Zhu of the Instrumental Analysis Center of Shanghai JiaoTong University for the use of Raman Spectroscope.
文摘The iron rust phases formed on low alloy steels containing different quantities of Cr element have been characterized using EPMA, Raman spectroscopy, TEM, optical microscopy etc. The ion selective properties of synthesized rust films with the same phase constituent as the atmospheric corrosion products were investigated using self-made apparatus. The results showed that corrosion loss of steels exposed in marine atmosphere decreased rapidly as the Cr content of the steel was increased. Cr-containing steels were covered by a uniform compacted rust layer composed of fine particles with an average diameter of several nanometers. Inner rust layer of Cr-containing steel (2 mass fraction) was composed of a-CrxFe1-xOOH, with Cr content of about 5 mass fraction. Such rust layer showed cation selective property, and could depress the penetration of Cl- to contact substrate steel directly.
基金Project supported by SRF for ROCS, SEM (2003-14) and Science and Technology Department of Zhejiang Province (2003C11027)
文摘Y2O3 nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently there are many studies focusing on controlling the size and morphology of Y2O3 in order to obtain better materials performance. In present study, yttrium oxyhydroxide precursor was synthesized via a facile solvothermal process through the dissolution-re-crystallization mechanism of Y2O3 raw powders in the ethylenediamine solvent, then nanosized yttrium oxide crystal was prepared from the precursor through post heat treatment process. The effects of solvothermal treatment temperature, holding time, solvent kinds and post heat treatment parameters on crystalline structure, grain shape and size of nanocrystal were investigated by XRD, TEM and TGA-DTA measurements. TEM images reveal that the morphology of product after post heat treatment at 460℃for 12 h is rice-like nanocrystal. XRD shows that this product is pure cubic Y2O3 cphase. Present study reveals that high purity Y2O3 with rice-like morphology can be easily prepared with average size around 30 nm under suitable post heat treatment parameters. In addition, the effects of solvents such as water and ethanol etc. on the crystal structure and morphology were also investigated. It is suggested that dissolution-recrystallization process may be the main mechanism for the formation of nano-sized YOOH precursors under solvothermal reaction condition, and the ethylenediamine solvent is likely to play an important role in controlling the transformation process of yttria precursors to the Y2O3 nanocrystal.
基金Supported by the Natural Science Foundation of Department of Education （05Z008） and the Science and Technology Projects of Guangdong Province （2007B030101007）.
文摘Cylindrical nickel metal hydride （Ni-MH） battery with high specific volume capacity was prepared by using the oxyhydroxide Ni（OH）2 and AB5 type hydrogen storage alloy and adjusting the designing parameters of positive and negative electrodes. The oxyhydroxide Ni（OH）2 was synthesized by oxidizing spherical β-Ni（OH）2 with chemical method. The X-ray diffraction （XRD） patterns and the Fourier transform infrared （PT-IR） spectra indicated that 7-NiOOH was formed on the oxyhydroxide Ni（OH）2 powders, and some H2O molecules were inserted into their crystal lattice spacing. The battery capacity could not be improved when the oxyhydroxide Ni（OH）2 sample was directly used as the positive active materials. However, based on the conductance and residual capacity of the oxyhydroxide Ni（OH）2 powders, AA size Ni-MH battery with 2560 mA.h capacity and 407 W·h·L^-1 specific volume energy at 0.2C was obtained by using the commercial spherical β-Ni（OH）2 and AB5-type hydrogen-storage alloy powders as the active materials when 10% mass amount of the oxyhydroxide Ni（OH）2 with 2.50 valence was added to the positive active materials and subsequently the battery designing parameters were adjusted as well. The as-prepared battery showed 70% initial capacity after 80 cycles at 0.5C. The possibility for adjusting the capacity ratio of positive and negative electrodes from 1 ： 1.35 to 1 ： 1.22 was demonstrated preliminarily. It is considered the as-prepared battery can meet the requirement of some special portable electrical instruments.
基金supported by the Human Resources Development program(no.20124010203180) of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)Grant funded by the Korea government Ministry of Trade,Industry and Energysupported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science,ICT and Future Planning(NRF-2015R1A2A2A01006856)
文摘Nanostructured iron oxyhydroxide（Fe OOH） thin films have been synthesized using an electrodeposition method on a nickel foam（NF） substrate and effect of air annealing temperature on the catalytic performance is studied. The as-deposited and annealed thin films were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）, field emission scanning electron microscopy（FE-SEM） and linear sweep voltammetry（LSV） to determine their structural, morphological, compositional and electrochemical properties, respectively. The as-deposited nanostructured amorphous Fe OOH thin film is converted into a polycrystalline Fe;O;with hematite crystal structure at a high temperature. The Fe OOH thin film acts as an efficient electrocatalyst for the oxygen evolution reaction（OER） in an alkaline 1 M KOH electrolyte. The film annealed at 200 °C shows high catalytic activity with an onset overpotential of 240 m V with a smaller Tafel slope of 48 m V/dec. Additionally, it needs an overpotential of 290 mV to the drive the current density of 10 m A/cm;and shows good stability in the 1 M KOH electrolyte solution.
文摘Rational design of low‐cost and efficient electrocatalysts for ethanol oxidation reaction(EOR)is imperative for electrocatalytic ethanol fuel cells.In this work,we developed a copper‐doped nickel oxyhydroxide(Cu‐doped NiOOH)catalyst via in situ electrochemical reconstruction of a NiCu alloy.The introduction of Cu dopants increases the specific surface area and more defect sites,as well as forms high‐valence Ni sites.The Cu‐doped NiOOH electrocatalyst exhibited an excellent EOR performance with a peak current density of 227 mA·cm^(–2)at 1.72 V versus reversible hydrogen electrode,high Faradic efficiencies for acetate production(>98%),and excellent electrochemical stability.Our work suggests an attractive route of designing non‐noble metal based electrocatalysts for ethanol oxidation.
基金Project supported by Japan Society for the Promotion of Science(JSPS)KAKENHI Grants(21560696,24560827)
文摘Europium oxyhydroxide crystals were synthesized by the flux method. The as-grown crystals were transparent and had a plate-like shape with natural flat surfaces. The powder XRD data were refined by assuming a monoclinic structure of the space group P21/m and lattice parameters of a=0.4346 nm, b=0.3744 nm, c=0.6107 nm, and β=108.62°. The magnetic susceptibility of the EuOOH crystals exhibited typical Van Vleck temperature-independent paramagnetism below 120 K. The calculated susceptibility, based on Van Vleck＇s theory, agreed with the experimental data to some extent, with the coupling constant λ=458±10 K. The experimental results were in close agreement with the results calculated using a modified formula with λ=505±2 K and a constant term C=4.6×10^-4 emu/（mol·Oe）.
基金the financial support from the National Natural Science Foundation of China(21673171)the kind support for the academic research by the Ministry of Education Singapore(Tier 1,R284-000-193-114)for research conducted in the National University of Singapore.Q.C.thanks support from the China Scholarship Council(CSC)。
文摘Water splitting has received more and more attention because of its huge potential to generate clean and renewable energy.The highly active and durable oxygen evolution reaction(OER)catalysts play a decisive factor in achieving efficient water splitting.The identification of authentic active origin under the service conditions can prompt a more reasonable design of catalysts together with well-confined micro-/nano-structures to boost the efficiency of water splitting.Herein,Fe,Co,and Ni ternary transition metal dichalcogenide(FCND)nanorod arrays on Ni foam are purposely designed as an active and stable low-cost OER pre-catalyst for the electrolysis of water in alkaline media.The optimized FCND catalyst demonstrated a lower overpotential than the binary and unary counterparts,and a 27-fold rise in kinetic current density at the overpotential of 300 m V compared to the nickel dichalcogenide counterpart.Raman spectra and other structural characterizations at different potentials reveal that the in-situ surface self-reconstruction from FCND to ternary transition metal oxyhydroxides(FCNOH)on catalyst surfaces initiated at about 1.5 V,which is identified as the origin of OER activity.The surface selfreconstruction towards FCNOH also enables excellent stability,without fading upon the test for 50 h.
基金Y.Hou expresses appreciation for the assistance of the National Natural Science Foundation of China(21922811,21878270,and 21961160742)the Zhejiang Provincial Natural Science Foundation of China(LR19B060002)+2 种基金the Fundamental Research Funds for the Central Universities(2020XZZX002-09)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2019R01006)the Startup Foundation for Hundred-Talent Program of Zhejiang University.K.Ostrikov acknowledges partial assistance from the Australian Research Council.
文摘Developing high-performing oxygen evolution reaction(OER)electrocatalysts under high-current operation conditions is critical for future commercial applications of alkaline water electrolysis for clean energy generation.Herein,we prepared a three-dimensional(3D)bimetallic oxyhydroxide hybrid grown on a Ni foam(NiFeOOH/NF)prepared by immersing Ni foam(NF)into Fe(NO_(3))_(3) solution.In this unique 3D structure,the NiFeOOH/NF hybrid was composed of crystalline Ni(OH)_(2) and amorphous FeOOH evenly grown on the NF surface.As a bimetallic oxyhydroxide electrocatalyst,the NiFeOOH/NF hybrid exhibited excellent catalytic activity,surpassing not only the other reported Ni–Fe based electrocatalysts,but also the commercial Ir/C catalyst.In situ electrochemical Raman spectroscopy demonstrated the active FeOOH and NiOOH phases involved in the OER process.Profiting from the synergy of Fe and Ni catalytic sites,the NiFeOOH/NF hybrid delivered an outstanding OER performance under challenging industrial conditions in a 10.0 mol·L^(-1) KOH electrolyte at 80℃,requiring potentials as small as 1.47 and 1.51 V to achieve the super-high catalytic current densities of 100 and 500mA∙cm^(-2),respectively.
基金Project supported by JSPS KAKENHI(21560696,24560827)
文摘Crystals of co-doped gadolinium oxyhydroxide （GdOOH）, Gd0.98Eu0.02-xTbxOOH and Gd1-y-zDyyBizOOH, were synthesized by a flux method. The color coordinates in the Commission Internationale de I＇Eelairage （CIE） chromaticity diagram of Gd0.98Eu0.02-xTbxOOH, obtained under 254 nm irradiation, shifted along a straight line with the changing values ofx to include the yellow region. The CIE coordinates of Dy^3＋ doped in GdOOH were located in the yellow region, while the emission intensity of Dy^3＋ under 286 nm irradiation increased by more than 40 times when co-doped with Bi^3＋.
基金the support from the National Key R&D Program of China(2020YFA0710000)the National Natural Science Foundation of China(22278307,22222808,21978200)the Haihe Laboratory of Sustainable Chemical Transformations。
文摘Metal oxyhydroxides(MOOH)generated from irreversible reconstructions of transition metal compounds are intrinsic active species for oxygen evolution reaction,whose activities are still constrained by sluggish deprotonation kinetics and inherent adsorption energy scaling relations.Herein,we construct a tunable proton acceptor(TPA)on oxyhydroxides by in-situ reconstruction of metal oxoacids such as NiC2O4to accelerate deprotonation and break adsorption energy scaling relations during OER.The modified C_(2)O_(4)^(2-)as a TPA can easily extract H of*OH(forming*HC2O4intermediate)and then promote deprotonation by the transmitted hydrogen bond with*OOH along conjugated(H...)O=C-O(-H)chain.As a result,Ni OOH-C2O4shows non-concerted proton-electron transfer and improved deprotonation rate,and delivers a good OER activity(270 mV@10 mA cm-2).The conjugate acidity coefficient(pKa)of the modified oxoacid group can be a descriptor for TPA selection.This TPA strategy can be universally applied to Co-,Fe-,and Ni-based oxyhydroxides to facilitate OER efficiency.
