Oxygen evolution reaction(OER)is the core electrode reaction in energy-related technologies,such as electrolytic water,electrocatalytic carbon dioxide reduction,rechargeable metal-air batteries,and renewable fuel cell...Oxygen evolution reaction(OER)is the core electrode reaction in energy-related technologies,such as electrolytic water,electrocatalytic carbon dioxide reduction,rechargeable metal-air batteries,and renewable fuel cells.Development of well-stocked,cost-effective,and high-performance OER electrocatalysts is the key to the improvement of energy efficiency and the large-scale commercial implementation of these technologies.Multicomponent transition metal oxides and(oxy)hydroxides are the most promising OER catalysts due to their low cost,adjustable structure,high electrocatalytic activity,and outstanding durability.In this review,a brief overview about the mechanisms of OER is first offered,accompanied with the theory and calculation criteria.Then,the latest advances in the rational design of the related OER electrocatalysts and the modulation of the electronic structure of active sites are comprehensively summarized.Specifically,various strategies(including element doping,defect engineering,and fabrication of binderless catalysts)used to improve the OER performance are detailedly discussed,emphasizing the structure–function relationships.Finally,the challenges and perspectives on this promising field are proposed.展开更多
Efficient and robust noble-metal-free bifunctional electrocatalysts for overall water splitting(OWS)is of great importance to realize the large-scale hydrogen production.Herein,we report the growth of undoped and Cr-d...Efficient and robust noble-metal-free bifunctional electrocatalysts for overall water splitting(OWS)is of great importance to realize the large-scale hydrogen production.Herein,we report the growth of undoped and Cr-doped NiCo2O4(Cr-NiCo2O4)nanoneedles(NNs)on nickel foam(NF)as bifunctional electrocatalysts for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).We demonstrate that Cr-doping significantly improves activity for HER and OER by increasing the conductivity of NNs and allowing more active sites on NNs electrochemically accessible.When amorphous FeOOH is electrodeposited on the surface of Cr-NiCo2O4 NNs,the resulting FeOOH/Cr-NiCo2O4/NF exhibits itself as an excellent bifunctional catalyst for OWS.In the two-electrode cell where FeOOH/Cr-NiCo2O4/NF is used both as cathode and anode for OWS,a cell voltage of only 1.65 V is required to achieve an electrolysis current density of 100 mA·cm^−2.In addition,the catalyst shows a very high stability for OWS,the two-electrode cell can operate at a consist current density of 20 mA·cm^−2 for 10 h OWS with the cell voltage being stable at ca.1.60 V.These results demonstrate that FeOOH/Cr-NiCo2O4/NF possesses an OWS performance superior to most of transition-metal based bifunctional electrocatalysts working in alkaline medium.The excellent bifunctional activity and stability of FeOOH/Cr-NiCo2O4/NF are attributed to the following reasons:(i)The NN structure provides a large specific surface area;(ii)the high conductivity of Cr-NiCo2O4 enables more active centers on the far-end part of NNs to be electrochemically reached;(iii)the deposition of FeOOH supplies additional active sites for OWS.展开更多
Highly active,durable and inexpensive oxygen evolution reaction(OER)catalysts are crucial for achieving practical and high-efficiency water splitting.Herein,hierarchical interconnected NixCo1−xOOH nanosheet arrays sup...Highly active,durable and inexpensive oxygen evolution reaction(OER)catalysts are crucial for achieving practical and high-efficiency water splitting.Herein,hierarchical interconnected NixCo1−xOOH nanosheet arrays supported on TiO2/Ti substrate have been fabricated through a facile photodeposition method.Compared with pristine NiOOH,the obtained NixCo1−xOOH nanosheet arrays possess larger exposed electrochemical active surface area,faster transfer and collection of electrons and stronger electronic interaction,showing a low overpotential of 350 mV at a current density of 10 mA·cm−2 and a small Tafel slope of 41 mV·dec−1 in basic solutions,with the OER performance superior to pristine NiOOH and most Ni-based catalysts.Furthermore,the NixCo1−xOOH electrode demonstrates excellent stability at the current density of 10 mA·cm−2 for 24 hours,which is attributed to the structural maintenance caused by the good adhesion of the catalyst and the substrate.Our study provides an alternative approach for the rational design of highly active and promising OER electrocatalysts.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
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
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
Developing highly efficient and low-cost electrocatalysts towards oxygen evolution reaction(OER)is essential for practical application in water electrolyzers and rechargeable metal-air batteries.Although Fe-based oxyh...Developing highly efficient and low-cost electrocatalysts towards oxygen evolution reaction(OER)is essential for practical application in water electrolyzers and rechargeable metal-air batteries.Although Fe-based oxyhydroxides are regarded as state-of-the-art non-noble OER electrocatalysts,the origin of performance enhancement derived from Fe doping remains a hot topic of considerable discussion.Herein,we demonstrate that in situ generated Fe vacancies in the pristine CoFeOOH catalyst through a pre-conversion process during alkaline OER result from dynamic Fe dissolution,identifying the origin of Fe-vacancy-induced enhanced OER kinetics.Density functional theory(DFT)calculations and experimental results including X-ray absorption fine-structure spectroscopy,in situ UV-Vis spectroscopy,and in situ Raman spectroscopy reveal that the Fe vacancies could significantly promote the d-band center and valence states of adjacent Co sites,alter the active site from Fe atom to Co atom,accelerate the formation of high-valent active Co^(4+)species,and reduce the energy barrier of the potential-determining step,thereby contribute to the significantly enhanced OER performance.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
Nickel iron(hydroxyl)hydroxide with unique layered structure and controllable composition is widely regarded as typical oxygen evolution reaction(OER)catalysts.Recently,developing top-down approaches to realize the fa...Nickel iron(hydroxyl)hydroxide with unique layered structure and controllable composition is widely regarded as typical oxygen evolution reaction(OER)catalysts.Recently,developing top-down approaches to realize the facile preparation of transition metal hydroxide catalyst has received wide attention.Based on the natural microorganism corrosion behavior,this work demonstrates the external magnetic field-assisted microbial corrosion strategy to construct advanced transition metal hydroxide OER catalyst,and the prepared biofilm electrode presents superior OER performance in the existence of magnetic field,which needs an overpotential of 287 mV at 100 mA cm^(-2).Experimental and theoretical calculations show the applied magnetic field can accelerate sulfate reducing bacteria(SRB)corrosion and chemical corrosion.The additional magnetic field can promote SRB corrosion to produce FeS,which can facilitate the optimization of O intermediate desorption from the NiOOH catalyst during OER process,reducing the reaction energy barrier for O→OOH.The synergistic effect between the nickel-iron oxyhydroxides originated from the accelerated chemical corrosion and FeS produced from the accelerated SRB corrosion interprets the improved OER activity.This work explores the influence of magnetic field on the construction of advanced OER materials,which can provide an effective magnetic field-assisted corrosion engineering strategy,and promote the development of multidisciplinary fields of physics,biology,and emerging energy conversion technologies.展开更多
Ferric oxyhydroxide loaded anion exchanger （FOAE） hybrid adsorbent was prepared by loading nanosized ferric oxyhydroxide （FO） on anion exchanger resin for the removal of phosphate from wastewater. TEM and XRD anal...Ferric oxyhydroxide loaded anion exchanger （FOAE） hybrid adsorbent was prepared by loading nanosized ferric oxyhydroxide （FO） on anion exchanger resin for the removal of phosphate from wastewater. TEM and XRD analysis confirmed the existence of FO on FOAE. After FO loading, the adsorption capacity of the hybrid adsorbent increased from 38.70 to 51.52mg.g-1. Adsorption processes for both FOAE and anion resin were better fit to the pseudo first order model. Batch adsorption experiments revealed that higher temperature （313K）, higher initial phosphate concentration （50 mg.L-1） and lower solution pH （pH value of 2） would be more propitious to phosphate adsorption. Competition effect of coexisting anions on phosphate removal can be concluded as sulfate 〉 nitrate 〉 chloride. Freundlich isotherm model can describe the adsorption of phosphate on FOAE more accurately, which indicated the heterogeneous adsorption occurred on the inner-surface of FOAE.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
Designing efficient and stable electrocatalysts to improve the oxygen evolution reaction(OER)with slow reaction kinetics is essential to improve hydrogen production from electrochemical water splitting.This research h...Designing efficient and stable electrocatalysts to improve the oxygen evolution reaction(OER)with slow reaction kinetics is essential to improve hydrogen production from electrochemical water splitting.This research has prepared a series of FeOOH/Ni(HCO_(3))_(2)heterostructured materials(denoted as FeOOH_(x)/Ni(HCO_(3))_(2))by a one-pot solvothermal method.The OER performance of the catalysts was maximized by finely tuning the content of different components,heterogeneous interfaces,and electronic structures.Specifically,the obtained FeOOH0.60/Ni(HCO_(3))_(2)heterostructured nanosheets had the lowest overpotential of 216 mV at a current density of 10 mA·cm^(−2)and were stable at a high current density of 100 mA·cm^(−2)for more than 96 h.The excellent OER activity and stability were still maintained in alkaline natural seawater(1 M KOH+seawater).When FeOOH0.60/Ni(HCO_(3))_(2)was used as the anode for water splitting,the electrolyzer provided a current density of 10 mA·cm^(−2)at a very low cell voltage of 1.51 V(1.56 V at 1 M KOH+seawater)and exhibited superior stability.The outstanding OER performance is ascribed to the synergistic effect of FeOOH and Ni(HCO_(3))_(2)upon heterostructure formation,as well as the altered electronic structure between the heterogeneous interfaces and the suitable hierarchical nanosheet morphology facilitating many active sites.This work provides a promising direction for improving the electrocatalytic activity of nickel-based catalysts in seawater splitting,which has important implications for both hydrogen economy and environmental remediation.展开更多
Eu3+-doped gadolinium oxyhydroxide Gd1-xEuxOOH crystals were synthesized by the flux method. The X-ray diffraction data for the crystals were well refined assuming a monoclinic structure with the P21/m space group. Gd...Eu3+-doped gadolinium oxyhydroxide Gd1-xEuxOOH crystals were synthesized by the flux method. The X-ray diffraction data for the crystals were well refined assuming a monoclinic structure with the P21/m space group. Gd1-xEuxOOH (x ≤ 0.2) crystals showed strong red emission, and the highest fluorescence quantum yield (Φf) was 0.27, obtained for x = 0.10. Φf decreased rapidly as the Eu3+ content x increased above 0.2, owing to concentration quenching. Analysis with a percolation model indicated three-dimensional energy transfer between the Eu3+ ions.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
本文利用一种简单的化学配体控制氧化方法,将NiFeCoAlOOH纳米颗粒负载在钛掺杂的纳米多孔赤铁矿光阳极上(Ti-PH),并将其用于光电催化水分解、由于NiFeCoAlOOH能够帮助提升Ti-PH光阳极的析氧反应动力学并且降低表面电荷转移电阻,修饰后...本文利用一种简单的化学配体控制氧化方法,将NiFeCoAlOOH纳米颗粒负载在钛掺杂的纳米多孔赤铁矿光阳极上(Ti-PH),并将其用于光电催化水分解、由于NiFeCoAlOOH能够帮助提升Ti-PH光阳极的析氧反应动力学并且降低表面电荷转移电阻,修饰后的光阳极相对于1.23 V us.RHE时具有2.46 mA/cm^(2)的光电流密度,并且与Ti-PH或空白赤铁矿光阳极相比具有更好的稳定性.此外,对比钛掺杂的纳米多孔赤铁矿光阳极,NiFeCoAlOOH修饰后的光电流的起始电位负移了~60 mV.这项工作为设计高性能、稳定、廉价的光电化学电池提供了一种具有潜力的催化剂修饰方法.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
Developing cost-effective and facile methods to synthesize efficient and stable electrocatalysts for large-scale water splitting is highly desirable but remains a significant challenge.In this study,a facile ambient t...Developing cost-effective and facile methods to synthesize efficient and stable electrocatalysts for large-scale water splitting is highly desirable but remains a significant challenge.In this study,a facile ambient temperature synthesis of hierarchical nickel-iron(oxy)hydroxides nanosheets on iron foam(FF-FN)with both superhydrophilicity and superaerophobicity is reported.Specifically,the as-fabricated FF-FN electrode demonstrates extraordinary oxygen evolution reaction(OER)activity with an ultralow overpotential of 195 mV at 10 mA cm^(-2)and a small Tafel slope of 34 mV dec^(-1)in alkaline media.Further theoretical investigation indicates that the involved lattice oxygen in nickel-iron-based-oxyhydroxide during electrochemical self-reconstruction can significantly reduce the OER reaction overpotential via the dominated lattice oxygen mechanism.The rechargeable Zn-air battery assembled by directly using the as-prepared FF-FN as cathode displays remarkable cycling performance.It is believed that this work affords an economical approach to steer commercial Fe foam into robust electrocatalysts for sustainable energy conversion and storage systems.展开更多
Cobalt oxyhydroxide(CoOOH)has been turned out to be a high-efficiency catalyst for peroxymonosulfate(PMS)activation.In this study,CoOOH was loaded on bismuth oxide(Bi_(2)O_(3))using a facile chemical precipitation pro...Cobalt oxyhydroxide(CoOOH)has been turned out to be a high-efficiency catalyst for peroxymonosulfate(PMS)activation.In this study,CoOOH was loaded on bismuth oxide(Bi_(2)O_(3))using a facile chemical precipitation process to improve its catalytic activity and stability.The result showed that the catalytic performance on the 2,4-dichlorophenol(2,4-DCP)degradation was significantly enhanced with only 11 wt%Bi_(2)O_(3)loading.The degradation rate in the CoOOH@Bi_(2)O_(3)/PMS system(0.2011 min−1)was nearly 6.0 times higher than that in the CoOOH/PMS system(0.0337 min−1).Furthermore,CoOOH@Bi_(2)O_(3)displayed better stability with less Co ions leaching(16.4%lower than CoOOH)in the PMS system.These phenomena were attributed to the Bi_(2)O_(3)loading which significantly increased the conductivity and specific surface area of the CoOOH@Bi_(2)O_(3)composite.Faster electron transfer facilitated the redox reaction of Co(III)/Co(II)and thus was more favorable for reactive oxygen species(ROS)generation.Meanwhile,larger specific surface area furnished more active sites for PMS activation.More importantly,there were both non-radical(^(1)O_(2))and radicals(SO_(4)^(−)•,O_(2)^(−)•,and OH•)in the CoOOH@Bi_(2)O_(3)/PMS system and^(1)O_(2)was the dominant one.In general,this study provided a simple and practical strategy to enhance the catalytic activity and stability of cobalt oxyhydroxide in the PMS system.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
The adsorbent, iron oxy-hydroxide coated brick, was used in the present work for removal of iron(II) from aqueous solutions. The adsorption performances of this composite were significantly improved when brick pellets...The adsorbent, iron oxy-hydroxide coated brick, was used in the present work for removal of iron(II) from aqueous solutions. The adsorption performances of this composite were significantly improved when brick pellets (as a support material) were pre-treated in a 6 M HCl solution at 90°C for 6 hours, when compared to untreated ones and those pre-washed in a 1M HCl solution at RT for 1 day. This phenomenon was attributed to larger surface areas measured for modified brick by BET, thus enabling a better FeOOH deposition. The ability of this new composite to better adsorb Fe2+ ions from synthetic solutions was evidenced from fixed-bed column experiments: data were compared to those obtained from raw brick and iron oxides - coated sand columns. The adsorption mechanism followed better pseudosecond-order reaction kinetics, suggesting a chemisorption process, and the rate constant increased with a temperature increase, revealing the endothermic nature of Fe(II) adsorption. Furthermore, the equilibrium data fitted the Langmuir isotherm model with a maximum monolayer sorption capacity Qmax = 0.669 mg/g and a Langmuir constant KL = 0.659 L/mg at room temperature. The activation energy (Ea) of Fe(II) adsorption and the changes in entropy (ΔS), enthalpy (ΔH) and free energy (ΔG) of activation were determined, with values suggesting the involvement of an activated chemical adsorption and an associative mechanism.展开更多
基金supported by the National Natural Science Foundation of China(No.22075099)the Natural Science Foundation of Jilin Province(No.20220101051JC)the Education Department of Jilin Province(No.JJKH20220967KJ).
文摘Oxygen evolution reaction(OER)is the core electrode reaction in energy-related technologies,such as electrolytic water,electrocatalytic carbon dioxide reduction,rechargeable metal-air batteries,and renewable fuel cells.Development of well-stocked,cost-effective,and high-performance OER electrocatalysts is the key to the improvement of energy efficiency and the large-scale commercial implementation of these technologies.Multicomponent transition metal oxides and(oxy)hydroxides are the most promising OER catalysts due to their low cost,adjustable structure,high electrocatalytic activity,and outstanding durability.In this review,a brief overview about the mechanisms of OER is first offered,accompanied with the theory and calculation criteria.Then,the latest advances in the rational design of the related OER electrocatalysts and the modulation of the electronic structure of active sites are comprehensively summarized.Specifically,various strategies(including element doping,defect engineering,and fabrication of binderless catalysts)used to improve the OER performance are detailedly discussed,emphasizing the structure–function relationships.Finally,the challenges and perspectives on this promising field are proposed.
基金We gratefully acknowledge the financial support of this work by the National Natural Science Foundation of China(Nos.51872015 and 51672017).
文摘Efficient and robust noble-metal-free bifunctional electrocatalysts for overall water splitting(OWS)is of great importance to realize the large-scale hydrogen production.Herein,we report the growth of undoped and Cr-doped NiCo2O4(Cr-NiCo2O4)nanoneedles(NNs)on nickel foam(NF)as bifunctional electrocatalysts for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).We demonstrate that Cr-doping significantly improves activity for HER and OER by increasing the conductivity of NNs and allowing more active sites on NNs electrochemically accessible.When amorphous FeOOH is electrodeposited on the surface of Cr-NiCo2O4 NNs,the resulting FeOOH/Cr-NiCo2O4/NF exhibits itself as an excellent bifunctional catalyst for OWS.In the two-electrode cell where FeOOH/Cr-NiCo2O4/NF is used both as cathode and anode for OWS,a cell voltage of only 1.65 V is required to achieve an electrolysis current density of 100 mA·cm^−2.In addition,the catalyst shows a very high stability for OWS,the two-electrode cell can operate at a consist current density of 20 mA·cm^−2 for 10 h OWS with the cell voltage being stable at ca.1.60 V.These results demonstrate that FeOOH/Cr-NiCo2O4/NF possesses an OWS performance superior to most of transition-metal based bifunctional electrocatalysts working in alkaline medium.The excellent bifunctional activity and stability of FeOOH/Cr-NiCo2O4/NF are attributed to the following reasons:(i)The NN structure provides a large specific surface area;(ii)the high conductivity of Cr-NiCo2O4 enables more active centers on the far-end part of NNs to be electrochemically reached;(iii)the deposition of FeOOH supplies additional active sites for OWS.
基金supported by the National Natural Science Foundation of China(No.21373182)the Zhejiang Provincial Natural Science Foundation of China(No.LY17B030004).
文摘Highly active,durable and inexpensive oxygen evolution reaction(OER)catalysts are crucial for achieving practical and high-efficiency water splitting.Herein,hierarchical interconnected NixCo1−xOOH nanosheet arrays supported on TiO2/Ti substrate have been fabricated through a facile photodeposition method.Compared with pristine NiOOH,the obtained NixCo1−xOOH nanosheet arrays possess larger exposed electrochemical active surface area,faster transfer and collection of electrons and stronger electronic interaction,showing a low overpotential of 350 mV at a current density of 10 mA·cm−2 and a small Tafel slope of 41 mV·dec−1 in basic solutions,with the OER performance superior to pristine NiOOH and most Ni-based catalysts.Furthermore,the NixCo1−xOOH electrode demonstrates excellent stability at the current density of 10 mA·cm−2 for 24 hours,which is attributed to the structural maintenance caused by the good adhesion of the catalyst and the substrate.Our study provides an alternative approach for the rational design of highly active and promising OER electrocatalysts.
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.
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supported by the National Natural Science Foundation of China(22272121,21972107)the Fundamental Research Funds for the Central Universities(2042022kf1179).
文摘Developing highly efficient and low-cost electrocatalysts towards oxygen evolution reaction(OER)is essential for practical application in water electrolyzers and rechargeable metal-air batteries.Although Fe-based oxyhydroxides are regarded as state-of-the-art non-noble OER electrocatalysts,the origin of performance enhancement derived from Fe doping remains a hot topic of considerable discussion.Herein,we demonstrate that in situ generated Fe vacancies in the pristine CoFeOOH catalyst through a pre-conversion process during alkaline OER result from dynamic Fe dissolution,identifying the origin of Fe-vacancy-induced enhanced OER kinetics.Density functional theory(DFT)calculations and experimental results including X-ray absorption fine-structure spectroscopy,in situ UV-Vis spectroscopy,and in situ Raman spectroscopy reveal that the Fe vacancies could significantly promote the d-band center and valence states of adjacent Co sites,alter the active site from Fe atom to Co atom,accelerate the formation of high-valent active Co^(4+)species,and reduce the energy barrier of the potential-determining step,thereby contribute to the significantly enhanced OER performance.
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supported by the Innovation and Entrepreneurship Training Program Funded by Wuhan Institute of Technology(202210490007)The National Natural Science Foundation of China(22102125)the Natural Science Foundation of Hubei Province(2023AFB620)are also acknowledged.
文摘Nickel iron(hydroxyl)hydroxide with unique layered structure and controllable composition is widely regarded as typical oxygen evolution reaction(OER)catalysts.Recently,developing top-down approaches to realize the facile preparation of transition metal hydroxide catalyst has received wide attention.Based on the natural microorganism corrosion behavior,this work demonstrates the external magnetic field-assisted microbial corrosion strategy to construct advanced transition metal hydroxide OER catalyst,and the prepared biofilm electrode presents superior OER performance in the existence of magnetic field,which needs an overpotential of 287 mV at 100 mA cm^(-2).Experimental and theoretical calculations show the applied magnetic field can accelerate sulfate reducing bacteria(SRB)corrosion and chemical corrosion.The additional magnetic field can promote SRB corrosion to produce FeS,which can facilitate the optimization of O intermediate desorption from the NiOOH catalyst during OER process,reducing the reaction energy barrier for O→OOH.The synergistic effect between the nickel-iron oxyhydroxides originated from the accelerated chemical corrosion and FeS produced from the accelerated SRB corrosion interprets the improved OER activity.This work explores the influence of magnetic field on the construction of advanced OER materials,which can provide an effective magnetic field-assisted corrosion engineering strategy,and promote the development of multidisciplinary fields of physics,biology,and emerging energy conversion technologies.
基金This research was supported by the National Natural Science Foundation of China （Grant No. 51208352）, the Tianjin Research Program of Application Foundation and Advanced Technology （No.13JCQNJC09100）, and Open Project of State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology （No. QA201209）.
文摘Ferric oxyhydroxide loaded anion exchanger （FOAE） hybrid adsorbent was prepared by loading nanosized ferric oxyhydroxide （FO） on anion exchanger resin for the removal of phosphate from wastewater. TEM and XRD analysis confirmed the existence of FO on FOAE. After FO loading, the adsorption capacity of the hybrid adsorbent increased from 38.70 to 51.52mg.g-1. Adsorption processes for both FOAE and anion resin were better fit to the pseudo first order model. Batch adsorption experiments revealed that higher temperature （313K）, higher initial phosphate concentration （50 mg.L-1） and lower solution pH （pH value of 2） would be more propitious to phosphate adsorption. Competition effect of coexisting anions on phosphate removal can be concluded as sulfate 〉 nitrate 〉 chloride. Freundlich isotherm model can describe the adsorption of phosphate on FOAE more accurately, which indicated the heterogeneous adsorption occurred on the inner-surface of FOAE.
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.
基金supported by the Tianjin Science and Technology Support Key Projects(No.20JCYBJC01420).
文摘Designing efficient and stable electrocatalysts to improve the oxygen evolution reaction(OER)with slow reaction kinetics is essential to improve hydrogen production from electrochemical water splitting.This research has prepared a series of FeOOH/Ni(HCO_(3))_(2)heterostructured materials(denoted as FeOOH_(x)/Ni(HCO_(3))_(2))by a one-pot solvothermal method.The OER performance of the catalysts was maximized by finely tuning the content of different components,heterogeneous interfaces,and electronic structures.Specifically,the obtained FeOOH0.60/Ni(HCO_(3))_(2)heterostructured nanosheets had the lowest overpotential of 216 mV at a current density of 10 mA·cm^(−2)and were stable at a high current density of 100 mA·cm^(−2)for more than 96 h.The excellent OER activity and stability were still maintained in alkaline natural seawater(1 M KOH+seawater).When FeOOH0.60/Ni(HCO_(3))_(2)was used as the anode for water splitting,the electrolyzer provided a current density of 10 mA·cm^(−2)at a very low cell voltage of 1.51 V(1.56 V at 1 M KOH+seawater)and exhibited superior stability.The outstanding OER performance is ascribed to the synergistic effect of FeOOH and Ni(HCO_(3))_(2)upon heterostructure formation,as well as the altered electronic structure between the heterogeneous interfaces and the suitable hierarchical nanosheet morphology facilitating many active sites.This work provides a promising direction for improving the electrocatalytic activity of nickel-based catalysts in seawater splitting,which has important implications for both hydrogen economy and environmental remediation.
文摘Eu3+-doped gadolinium oxyhydroxide Gd1-xEuxOOH crystals were synthesized by the flux method. The X-ray diffraction data for the crystals were well refined assuming a monoclinic structure with the P21/m space group. Gd1-xEuxOOH (x ≤ 0.2) crystals showed strong red emission, and the highest fluorescence quantum yield (Φf) was 0.27, obtained for x = 0.10. Φf decreased rapidly as the Eu3+ content x increased above 0.2, owing to concentration quenching. Analysis with a percolation model indicated three-dimensional energy transfer between the Eu3+ ions.
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supported by the National Key Research and Development Program of China(No.2017YFA0402800)the National Natural Science Foundation of China(No.51772285 and No.21971229)the Fundamental Research Funds for the Central Universities,and CAS Belt and Road Scholarship for International Students.
文摘本文利用一种简单的化学配体控制氧化方法,将NiFeCoAlOOH纳米颗粒负载在钛掺杂的纳米多孔赤铁矿光阳极上(Ti-PH),并将其用于光电催化水分解、由于NiFeCoAlOOH能够帮助提升Ti-PH光阳极的析氧反应动力学并且降低表面电荷转移电阻,修饰后的光阳极相对于1.23 V us.RHE时具有2.46 mA/cm^(2)的光电流密度,并且与Ti-PH或空白赤铁矿光阳极相比具有更好的稳定性.此外,对比钛掺杂的纳米多孔赤铁矿光阳极,NiFeCoAlOOH修饰后的光电流的起始电位负移了~60 mV.这项工作为设计高性能、稳定、廉价的光电化学电池提供了一种具有潜力的催化剂修饰方法.
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sponsored by the Guangdong-Hong Kong-Macao Joint Laboratory(grant no.2019B121205001)Macao Science and Technology Development Fund(FDCT)for funding(project no.0098/2020/A2)+2 种基金the support of the National Natural Science Foundation of China(Grant No.52104309)Natural Science Foundation of Hubei Province(2021CFB011)“Macao Young Scholars Program,”China(AM2020004).
文摘Developing cost-effective and facile methods to synthesize efficient and stable electrocatalysts for large-scale water splitting is highly desirable but remains a significant challenge.In this study,a facile ambient temperature synthesis of hierarchical nickel-iron(oxy)hydroxides nanosheets on iron foam(FF-FN)with both superhydrophilicity and superaerophobicity is reported.Specifically,the as-fabricated FF-FN electrode demonstrates extraordinary oxygen evolution reaction(OER)activity with an ultralow overpotential of 195 mV at 10 mA cm^(-2)and a small Tafel slope of 34 mV dec^(-1)in alkaline media.Further theoretical investigation indicates that the involved lattice oxygen in nickel-iron-based-oxyhydroxide during electrochemical self-reconstruction can significantly reduce the OER reaction overpotential via the dominated lattice oxygen mechanism.The rechargeable Zn-air battery assembled by directly using the as-prepared FF-FN as cathode displays remarkable cycling performance.It is believed that this work affords an economical approach to steer commercial Fe foam into robust electrocatalysts for sustainable energy conversion and storage systems.
基金The present work was funded by the Natural Science Foundation of Jilin Provincial Science&Technology Department(Grant No.20180101081JC,20200403034SFthe Science and Technology Project of the Education Department of Jilin Province(Grant No.JJKH20190125KJ).Besides,we would thank to the supervision of Professor Wei Feng from Jilin University for this work.
文摘Cobalt oxyhydroxide(CoOOH)has been turned out to be a high-efficiency catalyst for peroxymonosulfate(PMS)activation.In this study,CoOOH was loaded on bismuth oxide(Bi_(2)O_(3))using a facile chemical precipitation process to improve its catalytic activity and stability.The result showed that the catalytic performance on the 2,4-dichlorophenol(2,4-DCP)degradation was significantly enhanced with only 11 wt%Bi_(2)O_(3)loading.The degradation rate in the CoOOH@Bi_(2)O_(3)/PMS system(0.2011 min−1)was nearly 6.0 times higher than that in the CoOOH/PMS system(0.0337 min−1).Furthermore,CoOOH@Bi_(2)O_(3)displayed better stability with less Co ions leaching(16.4%lower than CoOOH)in the PMS system.These phenomena were attributed to the Bi_(2)O_(3)loading which significantly increased the conductivity and specific surface area of the CoOOH@Bi_(2)O_(3)composite.Faster electron transfer facilitated the redox reaction of Co(III)/Co(II)and thus was more favorable for reactive oxygen species(ROS)generation.Meanwhile,larger specific surface area furnished more active sites for PMS activation.More importantly,there were both non-radical(^(1)O_(2))and radicals(SO_(4)^(−)•,O_(2)^(−)•,and OH•)in the CoOOH@Bi_(2)O_(3)/PMS system and^(1)O_(2)was the dominant one.In general,this study provided a simple and practical strategy to enhance the catalytic activity and stability of cobalt oxyhydroxide in the PMS system.
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＋.
文摘The adsorbent, iron oxy-hydroxide coated brick, was used in the present work for removal of iron(II) from aqueous solutions. The adsorption performances of this composite were significantly improved when brick pellets (as a support material) were pre-treated in a 6 M HCl solution at 90°C for 6 hours, when compared to untreated ones and those pre-washed in a 1M HCl solution at RT for 1 day. This phenomenon was attributed to larger surface areas measured for modified brick by BET, thus enabling a better FeOOH deposition. The ability of this new composite to better adsorb Fe2+ ions from synthetic solutions was evidenced from fixed-bed column experiments: data were compared to those obtained from raw brick and iron oxides - coated sand columns. The adsorption mechanism followed better pseudosecond-order reaction kinetics, suggesting a chemisorption process, and the rate constant increased with a temperature increase, revealing the endothermic nature of Fe(II) adsorption. Furthermore, the equilibrium data fitted the Langmuir isotherm model with a maximum monolayer sorption capacity Qmax = 0.669 mg/g and a Langmuir constant KL = 0.659 L/mg at room temperature. The activation energy (Ea) of Fe(II) adsorption and the changes in entropy (ΔS), enthalpy (ΔH) and free energy (ΔG) of activation were determined, with values suggesting the involvement of an activated chemical adsorption and an associative mechanism.
