Post-Synthetic and In Situ Vacancy Repairing of Iron Hexacyanoferrate Toward Highly Stable Cathodes for Sodium-Ion Batteries

Iron hexacyanoferrate(FeHCF)is a promising cathode material for sodium-ion batteries.However,FeHCF always suffers from a poor cycling stability,which is closely related to the abundant vacancy defects in its framework.Herein,post-synthetic and in-situ vacancy repairing strategies are proposed for the synthesis of highquality FeHCF in a highly concentrated Na_(4)Fe(CN)_(6) solution.Both the post-synthetic and in-situ vacancy repaired FeHCF products(FeHCF-P and FeHCF-I)show the significant decrease in the number of vacancy defects and the reinforced structure,which can suppress the side reactions and activate the capacity from low-spin Fe in FeHCF.In particular,FeHCF-P delivers a reversible discharge capacity of 131 mAh g^(−1) at 1 C and remains 109 mAh g^(−1) after 500 cycles,with a capacity retention of 83%.FeHCF-I can deliver a high discharge capacity of 158.5 mAh g^(−1) at 1 C.Even at 10 C,the FeHCF-I electrode still maintains a discharge specific capacity of 103 mAh g^(−1) and retains 75% after 800 cycles.This work provides a new vacancy repairing strategy for the solution synthesis of high-quality FeHCF.

In-Situ Microscopic FTIR Spectroelectrochemistry of Ascorbic Acid in Poly(ethylene glycol)/LiClO_4 Electrolyte Paste and in the Presence of Dispersed Cobalt Hexacyanoferrate Microcrystalline Powder

In-situ microscopic FTIR spectroelectrochemical technique(MFTIRs) was applied to studying the electrochemical oxidation of ascorbic acid(AA) in poly(ethylene glycol)(PEG) paste at a 100 μm diameter Pt disk electrode. Using this technique, the catalytic ability of cobalt hexacyanoferrate(CoHCF) microcrystalline toward AA oxidation was also studied. It was found that the dispersed CoHCF powder in the PEG paste can generate well shaped thin layer cyclic voltammetric waves with the peak height proportional to the scan rate, corresponding to the Fe centered redox reactions. This oxidation step catalyzed the AA oxidation. Also, this pasted CoHCF powder generated well resolved in situ MFTIRs spectra, by which a chemical interaction between CC bond of AA ring and CoHCF lattice was revealed. A corresponding surface docking mechanism for the catalytic reaction has been proposed.

H_(2)S在Cr(111)面上吸附与解离的第一性原理研究

采用了第一性原理研究了H_(2)S在Cr(111)面的吸附解离过程,利用吸附能、吸附构型和偏态密度图(PDOS)研究了H_(2)S及其解离产物在Cr(111)面上的吸附情况,都偏向倾斜吸附在Cr(111)面.同时研究了HS/H和S/H共吸附情况,得到共吸附物质在Cr(111)面上有明显的相互作用.最后使用线性同步和二次同步变换方法确定了解离反应的过渡态,了解到第一、二步解离的活化能分别为1.65 eV、0.82 eV,H_(2)S分子在Cr(111)面上的解离过程是放热反应,反应能为-2.90 eV.

High Fe^(LS)(C)electrochemical activity of an iron hexacyanoferrate cathode boosts superior sodium ion storage

Sodium iron hexacyanoferrate(FeHCF)is one of the most promising cathode materials for sodium-ion batteries(SIBs)due to its low cost theoretical capacity.However,the low electrochemical activity of Fe^(LS)(C)in FeHCF drags down its practical capacity and potential plateau.Herein,FeHCF with high Fe^(LS)(C)electrochemical activity(C-FeHCF)is synthesized via a facile citric acid-assisted solvothermal method.As the cathode of SIBs,C-FeHCF shows superior cycling stability(ca.87.3%capacity retention for 1000 cycles at 10 C)and outstanding rate performance(ca.68.5%capacity retention at 50 C).Importantly,the contribution of Fe^(LS)(C)to the whole capacity was quantitatively analyzed via combining dQ/dV and discharge curve for the first time,and the index reaches 44.53%for C-FeHCF,close to the theoretical value.In-situ X-ray diffraction proves the structure stability of C-FeHCF during charge-discharge process,ensuring its superior cycling performance.Furthermore,the application feasibility of the C-FeHCF cathode in quasi-solid SIBs is also evaluated.The quasi-solid SIBs with the C-FeHCF cathode exhibit excellent electrochemical performance,delivering an initial discharge capacity of 106.5 mAh g^(−1) at 5 C and high capacity retention of 89.8%over 1200 cycles.This work opens new insights into the design and development of advanced cathode materials for SIBs and the beyond.

Electrochemically switched ion exchange performances of capillary deposited nickel hexacyanoferrate thin films

Thin films of capillary deposited nickel hexacyanoferrate(NiHCF) were investigated as electrochemically switched ion exchange(ESIX) materials. The films were generated on platinum and graphite substrates based on the ternary reagent diagram. In 1 mol/L KNO3 solution, cyclic voltammetry(CV) combined with energy-dispersive X-ray spectroscopy(EDS) was used to determine the influence of experimental conditions on the electroactivity of the NiHCF thin film on Pt substrates. The ion selectivity, ion-exchange capacity and the regenerability of NiHCF films on Pt and graphite substrates were investigated. The experiment results show that the NiHCF thin films from Ni2+-poor growth conditions have double peaks CV curves and contain relatively larger amount of potassium; while those from Ni2+-rich growth conditions are single peak CV curves and contain relatively smaller amount of potassium. It is demonstrated that the NiHCF thin films of capillary chemical deposition have good ESIX performances.

Enhanced stability and rate performance of zinc-doped cobalt hexacyanoferrate (CoZnHCF) by the limited crystal growth and reduced distortion

Cobalt hexacyanoferrate (CoHCF) is a potential cathode for aqueous Na-ion batteries due to its high theoretical specific capacity (170 m Ah g^(-1));however,its lower rate capability and cyclability limit its applications.Structural distortion at a weak N-coordinated crystal field during cycling disintegrates Co,yielding an irreversible reaction.Different Zn amounts ranging 0–1 were added to the Co site to suppress the structural irreversibility of CoHCF,yielding Co_(1-x)Zn_(x)HCF powder;this Zn (x≤0.09) addition reduced the powder’s dimension because the lower four coordination of Zn–N,not the six coordination of Co–N,limits the powder growth.Simultaneously,a small lattice parameter and interaxial angle (~90°) are obtained,implying that a narrower Co_(1-x)Zn_(x)HCF inner structure is formed to accommodate Na ions.Moreover,the electronic conductivity of Co_(1-x)Zn_(x)HCF gradually increased within 0–0.09 range.A smaller particle size with a high surface area leads to a near-surface-limited redox process,similar to a capacitive reaction.Both the surface-limited reaction and electronic conductivity enhances the reversibility due to the smaller charge transfer resistance at the electrode/electrolyte interface caused by Zn addition.Replacing redox-active Co with non-active Zn amount of 0.07 (Co_(1-x)Zn_(x)HCF) slightly reduces the specific capacity from 127 to 119 mAh g^(-1)at 0.1 A g^(-1)due to the shrunken Co charging sites.Rate performance is enhanced by compromising the capacity and reduced distortion,resulting in 81%retention at a 20-times-faster charging rate.Notably,the Co_(1-x)Zn_(x)HCF sample exhibited the good stability while preserving 74%of the initial capacity at 0.5 A g^(-1)after 200 cycles.

Molecular dynamics simulation of ion selectivity traits of nickel hexacyanoferrate thin films

The ion selectivity of nickel hexacyanoferrate thin film to alkali cations in ESIX (electrochemically switched ion exchange) processes was investigated using molecular dynamics(MD) techniques; water and cation (Na+ and Cs+) intercalation, configuration, and dynamics in reduced nickel hexacyanoferrate structures with different cation combinations were studied and compared with the experimental results. In the simulations, water was represented by an extended simple point-charge(SPC/E) model, and all other atomic interactions were represented by a universal force field(UFF). The potential energies of various cations combination (Cs+ and Na+) in reduced i-NiHCF and 1 mol/L Cs/NaCl mixed solution were obtained. In most cases, the total potential energy of the solid is reduced when water is intercalated into the various reduced NiHCF structures. Combining the solid and the solution simulation results, it is shown that the solid composition of 3Cs+/1Na+ is the stablest structure form (NaCs3Ni4[Fe(CN)6]3) over a range of solution compositions.

Characterization of porous cobalt hexacyanoferrate and activated carbon electrodes under dynamic polarization conditions in a sodium-ion pseudocapacitor

We report here the activated carbon and cobalt hexacyanoferrate composite,which is applied as the electrode materials in symmetric supercapacitors containing a 1.0 M Na_(2)SO_(4) aqueous electrolyte.This novel material combines high specific surface area and electrochemical stability of activated carbon with the redox properties of cobalt hexacyanoferrate,resulting in maximum specific capacitance of 329 F g^(-1) with large voltage working window of 2.0 V.Electrochemical studies indicated that cobalt hexacyanoferrate introduces important pseudocapacitive properties accounting for the overall charge-storage process,especially when I<0.5 A g^(-1).At lower gravimetric currents(e.g.,0.05 A g^(-1))and up to 1.0 V,the presence of cobalt hexacyanoferrate improves the specific energy for more than 300%.In addition,to better understanding the energy storage process we also provided a careful investigation of the electrode materials under dynamic polarization conditions using the in situ Raman spectroscopy and synchrotron light Xray diffraction techniques.Interesting complementary findings were obtained in these studies.We believe that this novel electrode material is promising for applications regarding the energy-storage process in pseudocapacitors with long lifespan properties.

Thermal Decomposition of Potassium Titanium Hexacyanoferrate(Ⅱ) Loaded with Cesium in a Fixed Bed Calciner

The thermal decomposition of potassium titanium hexacyanoferrate（ Ⅱ ） （KTiFC） loaded with cesium （referred to as Used Exchanger,or UE） was-studied at different flow rate of air in a fixed bed calciner. The calcina t ign processconsisted of four stages：ambient temperature- 180℃ （stageⅠ ）, 180-250℃（stage Ⅱ）, 250-400℃ （stage Ⅲ）, and constant 400℃ （stage Ⅳ）.The most intense reaction occurred in stage .Ⅱ. The rate of thermal decomposition was controlled, depending on the O2 flux, by O2 or CN concentration in ditterent stages. Results from differential thermal analysis （DTA） showed that the calcination reaction of the anhydrous UE was exothermic, with an approximate heat output of 4.6kJ·g^-1, which was so large to cause the possible agglomeration of calcined residues. The agglomeration could be avoided by enhancing heat transfer and controlling the O2 flux. It was found that there was no cyanides in the calcined residues and no CN-bearing gases such as HCN and （CN）2 in the off-gas. It seemed that the catalytic oxidation furnace behind the fixed bed calciner could be cancelled.

OH^(*)对Ni(111)上甲烷部分氧化成CO影响的理论计算

为促进我国能源结构转型和缓解能源短缺压力,将储量丰富的天然气(甲烷)部分氧化成合成气具有重要的现实意义。该过程常用的催化剂为Ni基催化剂,其存在易积炭失活的问题。深入研究Ni基催化剂表面的催化机理有助于解决该问题。基于密度泛函理论的第一性原理计算方法,确定了甲烷部分氧化中相关物种在Ni(111)上最有利的吸附构型,并通过二聚体方法搜索了反应过程中各基元反应的过渡态,分析了Ni(111)上甲烷部分氧化生成CO的整个过程。结果表明,CH^(*)在Ni(111)上的吸附能为6.98 eV,CH2^(*)脱氢生成CH^(*)的活化能为0.28 eV,远低于CH^(*)脱氢的活化能(1.29 eV),说明CH^(*)可在Ni表面大量存在,并且其变化可影响整个反应途径。在甲烷部分氧化生成CO的整个过程中,OH^(*)氧化CH^(*)生成CO^(*)时的活化能为1.48 eV,较C^(*)被O^(*)直接氧化生成CO的活化能(1.59 eV)低0.11 eV,因此形成OH^(*)更有利于CO的生成。在CH^(*)被OH^(*)氧化生成CO^(*)的过程中,经历了CHOH^(*)→COH^(*)→CO^(*)的转化过程,整个转化过程的活化能为0.91 eV;而CHOH^(*)→CHO^(*)→CO^(*)的转化过程的活化能为0.73 eV,因此CHOH^(*)更倾向于脱氢生成CHO^(*)进而生成CO^(*),甲烷部分氧化生成CO^(*)的最佳反应路径为CH_4^(*)→CH_3^(*)→CH_(2)^(*)→CH^(*)+OH^(*)→CHOH^(*)→CHO^(*)→CO^(*)。

Electrochemical oxidation of polyethylene glycol in electroplating solution using paraffin composite copper hexacyanoferrate modified (PCCHM) anode

Electrochemical oxidation of polyethylene glycol(PEG) in an acidic(pH 0.18 to 0.42) and high ionic strength electroplating solution was investigated. The electroplating solution is a major source of wastewater in the printing wiring board industry. A paraffin composite copper hexacyanoferrate modified(PCCHM) electrode was used as the anode and a bare graphite electrode was used as the cathode. The changes in PEG and total organic carbon(TOC) concentrations during the course of the reaction were monitored. The efficiency of the PCCHM anode was compared with bare graphite anode and it was found that the former showed significant electrocatalytic property for PEG and TOC removal. Chlorides present in the solution were found to contribute significantly in the overall organic removal process. Short chain organic compounds like acetic acid, oxalic acid, formic acid and ethylene glycol formed during electrolysis were identified by HPLC method. Anode surface area and applied current density were found to influence the electro-oxidation process, in which the former was found to be dominating. Investigations of the kinetics for the present electrochemical reaction suggested that the two stage first-order kinetic model provides a much better representation of the overall mechanism of the process if compared to the generalized kinetic model.

Low-strain binary hexacyanoferrate nanocuboids with concentration-gradient structure towards fast and durable energy storage

The exploration of low-strain and high-performance electrode is a crucial issue for aqueous potassiumion battery(AKIB).Herein,a novel potassium mediated iron/manganese binary hexacyanoferrate nanocuboid,i.e.,K_(x)Fe_(y)Mn_(1-y)[Fe(CN)_(6)]·nH_(2)O(KFeMnHCF)nanocuboid,with the concentration-gradient(CG)structure is designed as a high-performance cathode for AKIB.Internal the CG-KFeMnHCF nanocuboids,the manganese content gradually decreases from the interior to the surface and the iron content changes reverse,resulting in the concentration-gradient structure.Both experimental and finite element simulation(FEA)results demonstrate the lower internal stress and better mechanical characteristics of CG structured nanocuboid than the homogenous structured one upon ion intercalation/deintercalation processes.Meanwhile,the electrochemical testing and theoretical calculation(DFT)results disclose the substitution of Fe to Mn in the KMnHCF crystal results in the enhanced electronic conductivity,potassium migration and electrochemical kinetics.Taken both advantages from the well-designed architecture and optimized crystal structure,the CG-KFeMnHCF achieves the superior rate capability and ultrahigh stability in aqueous potassium ion system.In particular,the CG-KFe_(0.31)Mn_(0.69)HCF achieves the best comprehensive properties among all the samples.The full AKIBs based on CG-KFe_(0.31)Mn_(0.69)HCF cathode achieves the high energy density(83 Wh kg^(-1)),superior power density,high capacity retention(83%)over high-rate long-term cycles,good adaptation to a wide temperature range(-20 to 40℃)and high reliability even under outside deformations.Therefore,this work not only provides a new clue to design the highperformance cathode,but also promotes the applications of AKIBs for diverse electronics and wide working environments.

Antifungal Potential of Transition Metal Hexacyanoferrates against Fungal Diseases of Mushroom

Ferrocyanides of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) were synthesized and characterized by IR spectra, magnetic susceptibility, thermal gravimetric analysis, elemental analysis and X ray diffraction studies. Antimicrobial potential of these complexes have been evaluated. Antifungal screening of these complexes has been carried out against Mycogone perniciosa and Verticillium fungicola causing wet and dry bubble diseases of button mushroom respectively. Nickel ferrocyanide has been found to be most effective against Mycogone perniciosa with 60% inhibitory effect while cadmium ferrocyanide has exhibited significant potential of 85% against Verticillium fungicola.

Electrochemical Properties of Modified Carbon Paste with Copper Hexacyanoferrate Film on Nitric Oxide Reduction

Copper hexacyanoferate film was prepared electrochemically on carbon paste electrode and was tested for detection of nitric (II) oxide in comparison with unmodified electrodes. Modified electrode could be operated under physiological conditions (pH 7.5, 0.1 M phosphate buffer), with an operating potential of ﹣400 mV (vs. Ag/AgCl) in hydrodynamic amperometry. The amperometric response of the electrode showed good linearity up to 250 μM with a detection limit (3σ) of 8.32 μM. The relative standard deviation for the repeatability of measurements for 100 μM nitric (II) oxide was 4.1% (n = 10 measurements) and the corresponding reproducibility was 14% (n = 5 electrodes). The effect of investigated interferences (nitrite and nitrate ion) was not fatal and could be eliminated using the standard addition method. The modified electrode also seems promising to detect NO in car exhaust fumes.

辣椒新品种遵椒111的选育

遵椒111是以核质互作雄性不育系ZHS7为母本、自交系cqw-b2为父本杂交选育而成的干鲜兼用朝天椒杂交1代新品种。该品种中熟,在贵州省春季露地栽培全生育期186 d。植株生长势强,株型紧凑,平均株高70.40 cm,株幅75.63 cm,果实单生向上,果面光滑,果实指形,单株挂果数125.7个,果实纵径7.15 cm、横径1.68 cm,果肉厚度0.18 cm,单果质量5.76 g,青熟果绿色,老熟果红色。果实辣味中等、商品性好,鲜果辣椒素含量(w,后同)171 mg·kg^(-1),维生素C含量156 mg·100 g^(-1)。平均667 m^(2)鲜椒产量1574.32 kg。田间表现高抗青枯病,抗黄瓜花叶病毒(cucumber mosaic virus,CMV)、烟草花叶病毒(tobacco mosaic virus,TMV)、炭疽病和疫病;适宜在贵州省及相似生态地区进行保护地栽培。2023年通过农业农村部非主要农作物品种登记。

精细化在“111”产品质量提升中的应用

在内蒙古某“CO_(2)+O_(2)”地浸铀矿山引入精细化管理模式,对影响产品质量的吸附、淋洗、酸化沉淀等工序进行精细管理。淋洗剂配制由“沉降母液+碳酸氢钠+盐酸+氯化钠”优化为“沉降母液+碳酸氢钠+清水”,维持淋洗剂pH为9.5~10.0,降低了系统氯离子积累;提升淋洗合格液中铀质量峰值浓度,并将其维持在80~130 g/L;自动控制酸化过程的盐酸添加量,精准控制pH在4.5~4.6,进一步降低合格液中的碳铀比;调整淋洗合格液的流量,保持淋洗合格液平均铀质量浓度为30~70 g/L,降低合格液铀质量浓度对产品质量的影响;控制浆体沉淀时间,提升浆体压滤效果。优化生产参数后,产品水分降低了8.50%,铀含量提升了2.88%,产品质量整体提升。

Wafer-scale 30°twisted bilayer graphene epitaxially grown on Cu_(0.75)Ni_(0.25)(111)

Twisted bilayer graphene(TBG) has been extensively studied because of its novel physical properties and potential application in electronic devices.Here we report the synthesis and characterization of 300 TBG naturally grown on Cu_(0.75)Ni_(0.25)(111) film and investigate the electronic structure by angle-resolved photoemission spectroscopy.Compared with other substrates,our TBG with a wafer scale is acquired with a shorter growth time.The Fermi velocity and energy gap of Dirac cones of TBG are comparable with those of a monolayer on Cu_(0.85)Ni_(0.15)(111).The signature of moré lattices has not been observed in either the low-energy electron diffraction patterns or the Fermi surface map within experimental resolution,possibly due to different Cu and Ni contents in the substrates enhancing the different couplings between the substrate and the first/second layers and hindering the formation of a quasiperiodic structure.

ZnO/Vo-(111)Cu_(2)O/NiF光催化材料协同PMS氧化高效去除盐酸环丙沙星

针对盐酸环丙沙星(CIP-HCl)的难降解性,本实验成功合成了以泡沫镍为基底的光催化异质结ZnO/Vo-(111)Cu_(2)O/NiF,该复合材料具有良好的光响应强度,电化学阻抗较小;通过光照产生的能量激活PMS,使其生成具有强氧化性的活性物质SO_(4)^(·-);利用光催化协同PMS氧化共同参与盐酸环丙沙星的高效降解,在20 min内降解效率高达97.5%。

In-situ FTIR Spectroelectrochemical Study of Chromium Hexacyanoferrate on Glassy Carbon Electrode

Chromium hexacyanoferrate (CrHCF) modified grassy carbon electrode (GC) in different electrolytes was studied by cyclic voltammetry and in situ FTIR spectroelectrochemistry. The results indicate that the behavior of CrHCF firm can be understood in term of two structures: Cr1/3Cr(III)Fe(II)(CN), and MCr(III)Fe(II)(CN)(6). Besides,the film exists in amorphous state: the outer layer is porous film, while the inner layer is relatively compact. According to the electrochemical reaction of CrHCF, the lattice can contract and expand with the cations' diffusion.

Localized-states quantum confinement induced by roughness in CdMnTe/CdTe heterostructures grown on Si(111) substrates

This work shows that despite a lattice mismatch of almost 20%, CdMnTe/CdTe/CdMnTe heterostructures grown directly on Si(111) have surprisingly good optical emission properties. The investigated structures were grown by molecular beam epitaxy and characterized by scanning transmission electron microscopy, macro-and micro-photoluminescence. Low temperature macro-photoluminescence experiments indicate three emission bands which depend on the CdTe layer thickness and have different confinement characteristics. Temperature measurements reveal that the lower energy emission band (at 1.48 eV)is associated to defects and bound exciton states, while the main emission at 1.61 eV has a weak 2D character and the higher energy one at 1.71 eV has a well-defined (zero-dimensional, 0D) 0D nature. Micro-photoluminescence measurements show the existence of sharp and strongly circularly polarized (up to 40%) emission lines which can be related to the presence of Mn in the heterostructure. This result opens the possibility of producing photon sources with the typical spin control of the diluted magnetic semiconductors using the low-cost silicon technology.