Electropolymerization of aniline in KOH solution and properties of the polymer are studied by using in situ reflex ellipsometry, cyclic voltammetry and fluorescence spectroscopic method. The change patterns of ellipso...Electropolymerization of aniline in KOH solution and properties of the polymer are studied by using in situ reflex ellipsometry, cyclic voltammetry and fluorescence spectroscopic method. The change patterns of ellipsometric parameters and the thickness of film in the process of electropolymerization are investigated. The complex refractive indices and the fluorescence spectra of PAN indicate that the PAN is a new kind of luminous material.展开更多
This study was done to evaluate the nugget zone(NZ)corrosion behavior of dissimilar copper/brass joints welded by friction stir lap welding(FSLW)in a solution of 0.015 mol/L borax(pH 9.3).To this end,dissimilar copper...This study was done to evaluate the nugget zone(NZ)corrosion behavior of dissimilar copper/brass joints welded by friction stir lap welding(FSLW)in a solution of 0.015 mol/L borax(pH 9.3).To this end,dissimilar copper/brass plates were welded with two dissimilar heat inputs(low and high)during the welding procedure.The high and low heat inputs were conducted with 710 r/min,16 mm/min and 450 r/min,25 mm/min,respectively.Using open circuit potential(OCP)measurements,electrochemical impedance spectroscopy(EIS)and Tafel polarization tests,the electrochemical behavior of the specimens in borate buffer solution was assessed.With the help of scanning electron microscope(SEM),the morphology of welded specimen surfaces was examined after immersion in the test solution.According to the results,the NZ grain size and resistance improvement reduced due to the nugget zone corrosion with a decreased heat input.The results obtained from Tafel polarization and EIS indicated the improved corrosion behavior of the welded specimen NZ with a decrease in the heat input during the welding process unlike the copper and brass metals.Furthermore,an increased heat input during the welding process shows a reduction in the conditions for forming the passive films with higher protection behavior.展开更多
Nickel(Ni)-based materials act as one of the most promising candidates as platinum-group-metal-free(PGM-free)electrocatalysts for hydrogen oxidation reaction(HOR)in alkaline solution.Nevertheless,the electrocatalytic ...Nickel(Ni)-based materials act as one of the most promising candidates as platinum-group-metal-free(PGM-free)electrocatalysts for hydrogen oxidation reaction(HOR)in alkaline solution.Nevertheless,the electrocatalytic activity of pure Ni is significantly limited due to the sluggish kinetics under alkaline condition.To accelerate the kinetics,constructing heterostructures and nitride structures have been developed as two representative strategies.Here,we combined the two methods and presented a facile synthesis of the sheet-like Ni_(3)N/MoO_(2)in-plane heterostructures for enhanced HOR in alkaline electrolytes.Relative to Ni or Ni_(3)N,the Ni_(3)N/MoO_(2)in-plane heterostructures exhibited a significantly increased mass activity by 8.6-fold or 4.4-fold,respectively.Mechanistic studies revealed that the enhanced activity of Ni_(3)N/MoO_(2)could be attributed to the weakened hydrogen adsorption and strengthened hydroxyl adsorption.This work provides a facile approach to design high-efficiency catalysts for hydrogen-oxidation catalysis and beyond.展开更多
The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studie...The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studied. Cathodicpolarization curves showed the electrocatalytic activity of Ni/C electrode prepared byMVS method was higher than that of the one prepared by conventional method.展开更多
The corrosion-wear behavior of a nanocrystalline Fe_（88）Si_（12） alloy disc coupled with a Si_3N_4 ball was investigated in acid（pH 3） and alkaline（pH 9） aqueous solutions. The dry wear was also measured for re...The corrosion-wear behavior of a nanocrystalline Fe_（88）Si_（12） alloy disc coupled with a Si_3N_4 ball was investigated in acid（pH 3） and alkaline（pH 9） aqueous solutions. The dry wear was also measured for reference. The average friction coefficient of Fe_（88）Si_（12） alloy in the pH 9 solution was approximately 0.2, which was lower than those observed for Fe_（88）Si_（12） alloy in the pH 3 solution and in the case of dry wear. The fluctuation of the friction coefficient of samples subjected to the pH 9 solution also showed similar characteristics. The wear rate in the pH 9 solution slightly increased with increasing applied load. The wear rate was approximately one order of magnitude less than that in the pH 3 solution and was far lower than that in the case of dry wear, especially at high applied load. The wear traces of Fe_（88）Si_（12） alloy under different wear conditions were examined and analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The results indicated that the tribo-chemical reactions that involve oxidation of the worn surface and hydrolysis of the Si_3N_4 ball in the acid solution were restricted in the pH 9 aqueous solution. Thus, water lubrication can effectively improve the wear resistance of nanocrystalline Fe_（88）Si_（12） alloy in the pH 9 aqueous solution.展开更多
Since the application in fuel cell,the electrochemical adsorption of hydroxyl has received considerable attention in recent years.While most research mainly focus on the room temperature,in this paper,the electrochemi...Since the application in fuel cell,the electrochemical adsorption of hydroxyl has received considerable attention in recent years.While most research mainly focus on the room temperature,in this paper,the electrochemical adsorption of hydroxyl in alkaline solution at high temperature was investigated.An unusual oxidation peak was observed at-0.27 V,suggesting new behavior of hydroxyl adsorption occurred.As is known two kinds of cation hydrated clusters exist in alkaline solution,(H_(2)O)_(x-1)M^(+)-H_(2)O-O_(ad)H and(H_(2)O)_xM^(+)-O_(ad)H.For K^(+)and Cs^(+),the cluster shows unstable structure due to the weak interaction between hydrated cation and OH^(-)especially at high temperature.However,For Li^(+),Na^(+)the cluster structure would be stable,as the interaction force between the hydrated cation and OH^(-)is so strong.It was revealed that the unusual oxidation peak has some relationship with the(H_(2)O)_(x-1)M^(+)-H_(2)O-O_(ad)H cluster(K^(+)and Cs^(+))absorbed at Pt electrode surface.When the temperature was raised,(H_(2)O)_(x-1)M^(+)-H_(2)O-and-O_(ad)H was disconnected,then the O_(ad)H absorbed at Pt surface got oxidated.Based on the SEM observation,it was showed the unusual electrochemical oxidation reaction would generate platinum oxides,blocking the reactive sites at Pt electrode surface,thus reducing the electrochemical reactivity of Pt electrode.Accordingly,parameters of alkaline concentration and temperature were systematically studied,it was found that increase temperature or alkaline concentration was in favor of the unusual oxidation reaction.This study provides more understanding of hydroxyl adsorption behavior at Pt electrode surface for the high temperature water solution environment.展开更多
The effect of pH value and different kinds of anions on the corrosion behavior of Cu/Al casting-rolled clad plates in the alkaline solution was evaluated by means of scanning electron microscopy(SEM),energy dispersive...The effect of pH value and different kinds of anions on the corrosion behavior of Cu/Al casting-rolled clad plates in the alkaline solution was evaluated by means of scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),weight loss analysis,3D confocal laser scanning microscopy(CLSM)and electrochemical test.Results show the corrosion mainly occurs on the aluminum side.The corrosion resistance of the Cu/Al decreases as the pH value increases.When pH≥12,the dissolution of the film layer is faster than the passivation process.The addition of Cl^(-)ions reduces the corrosion resistance of the Cu/Al clad plates,which leads to pitting corrosion.The higher the concentration of Cl^(-)ions,the more prone the pitting to occur.The addition of SO_(4)^(2-)ions causes the denudation of the samples.The corrosion resistance of the Cu/Al is better in the alkaline solution containing NO_(3)^(-)ions than that in the solution containing Cl^(-)ions or SO_(4)^(2-)ions.When adding SO_(4)^(2-),NO^(3)^(-)and Cl^(-)to the pure alkaline solution,the corrosion resistance of the Cu/Al clad plates decreases.展开更多
The stress corrosion cracking(SCC)performance of the sealed Alloy 690 plugs was investigated in 350℃deoxygenated concentrated alkaline solution.Sealing was used to expose only the inner surface of the plug,preventing...The stress corrosion cracking(SCC)performance of the sealed Alloy 690 plugs was investigated in 350℃deoxygenated concentrated alkaline solution.Sealing was used to expose only the inner surface of the plug,preventing direct contact between the tube sheet and the concentrated alkaline solution.After exposure for 1000 h,several intergranular cracks were observed on the inner wall of the plugs.Stress corrosion cracks primarily appear in some regions on the inner wall,which are highly deformed and advanced along the random grain boundary.The internal oxide layer formed in the high-temperature alkaline solution was not dense;it comprised a composite oxide with multiple layers.The outermost layer consisted of Fe-Cr-Ni oxide particles,and beneath it was an uneven Ni-rich layer,followed by a thin Cr-rich layer closest to the matrix.High kernel average misorientation in the heavily deformed region and a lack of chromium carbide contributed to crack initiation and propagation of Alloy 690 plug in hot concentrated alkaline solutions.展开更多
In this study,a cleaner method for separation and recovery of V/W/Na in waste selective catalytic reduction(SCR)catalyst alkaline leaching solution was proposed.The method involved membrane electrolysis followed by io...In this study,a cleaner method for separation and recovery of V/W/Na in waste selective catalytic reduction(SCR)catalyst alkaline leaching solution was proposed.The method involved membrane electrolysis followed by ion morphology pretreatme nt and solvent extraction.An acidic V(Ⅴ)/W(Ⅵ)solution was obtained using the me mbrane electrolysis method without adding any other chemical reagents.In addition,Na was recovered in the form of NaOH by product,avoiding the generation of Na containing wastewater.The electrolysis parameters were investigated,the lowest power consumption of 3063 kW·h·t^(-1)NaOH was obtained at a current density of 125 A·m^(-2)and an initial NaOH concentration of 2 mol·L^(-1).After electrolysis,oxalic acid was added to the acidic V/W containing solution,converting V(Ⅴ)negative ion to V(Ⅳ)positive ion.Since W(Ⅵ)ion state remained in negative form,the generation of heteropolyacid ions(W_(x)V_(y)O_(z)^(n-))was prevented.It was found that under the condition of oxalic acid addition/theoretical consumption 1.2 and reaction temperature 75℃,100%V(Ⅴ)was co nverted to V(Ⅳ4).Using 10%N263+10%noctanol+80%sulfonated kerosene as extractant,the highest W(Ⅵ)/V(Ⅳ)separation coefficient of 7559.76was obtained at pH=1.8,O:A ratio=1:1 and extraction time 15 min.With 2 mol·L^(-1)NaOH as stripping reagent,the W stripping efficiency reached 98.50%at O:A ratio=2:1 after 4-stages of stripping.The enrichment of V remained in the solution was realized using P204 as extractant and 20%(mass)H_(2)SO_(4)as stripping reagent.The parameters of extraction/stripping process were investigated,using 10%P204+10%TBP+80%sulfonated kerosene as extractant,the V extraction efficiency reached 97.50%at O:A ratio=1:2after 4 stages of extraction.Using 20%H_(2)SO_(4)as the stripping reagent,the V stripping efficiency was 98.30%at an O:A ratio of 4:1 after five stage s of stripping.After the entire process,a high-purity VOSO_(4)and Na_(2)WO_(4)product solutions were obtained with V/W recovery efficiency 95.84%/98.50%,separately.This study examined a more effective and cleaner method for separating V/W/Na in Na_(2)WO_(4)/NaVO_(3)solution,which may serve as a reference for the separation and recovery of V/W/Na in waste SCR catalysts.展开更多
The selective recovery of lead from the zinc oxide dust using an alkaline Na2EDTA solution was investigated. The effects of temperature, leaching time, Na2EDTA concentration and initial NaOH concentration on the leach...The selective recovery of lead from the zinc oxide dust using an alkaline Na2EDTA solution was investigated. The effects of temperature, leaching time, Na2EDTA concentration and initial NaOH concentration on the leaching rates of lead and zinc were studied. The following optimized leaching conditions were obtained： liquid-to-solid ratio 5：1 mL/g, stirring speed 650 r/min, Na2EDTA concentration 0.12 mol/L, initial NaOH concentration 0.5 mol/L, leaching temperature 70 ℃, leaching time 120 min. Under the optimized conditions, the average leaching rates of lead, zinc, fluoride and chloride are 89.92%, 0.94%, 62.84% and 90.02%, respectively. The filtrate was used to electrowin lead powders. The average current efficiency of electrowinning is about 93% and lead content is higher than 98% under the conditions of temperature of 60 ℃, current density of 200 A/m2, H3PO4 concentration of 1.5 g/L, and lead ion concentration of above 5 g/L. The consumption of Na2EDTA and the direct current are about respectively 0.218 kg and 0.958 kW·h for per kilogram of lead powder.展开更多
Potentiodynamic polarization tests and slow strain rate test（SSRT） in combination with fracture morphology observations were conducted to investigate the stress corrosion cracking（SCC） behavior of 7003 aluminum al...Potentiodynamic polarization tests and slow strain rate test（SSRT） in combination with fracture morphology observations were conducted to investigate the stress corrosion cracking（SCC） behavior of 7003 aluminum alloy（AA7003） in acid and alkaline chloride solutions under various applied potentials（Ea）. The results show that AA7003 is to a certain extent susceptible to SCC via anodic dissolution（AD） at open-circuit potential（OCP） and is highly susceptible to hydrogen embrittlement（HE） at high negative Ea in the solutions with p H levels of 4 and 11. The susceptibility increases with negative shift in the potential when Ea is less than-1000 m V vs. SCE. However, the susceptibility distinctly decreases because of the inhibition of AD when Ea is equal to-1000 m V vs. SCE. In addition, the SCC susceptibility of AA7003 in the acid chloride solution is higher than that in the alkaline solution at each potential. Moreover, the effect of hydrogen on SCC increases with increasing hydrogen ion concentration.展开更多
Beyond 45 nm, due to the superior CMP performance requirements with the metal gate of aluminum in the advanced CMOS process, a novel alkaline slurry for an aluminum gate CMP with poly-amine alkali slurry is investigat...Beyond 45 nm, due to the superior CMP performance requirements with the metal gate of aluminum in the advanced CMOS process, a novel alkaline slurry for an aluminum gate CMP with poly-amine alkali slurry is investigated. The aluminum gate CMP under alkaline conditions has two steps： stock polishing and fine polishing. A controllable removal rate, the uniformity of aluminum gate and low corrosion are the key challenges for the alkaline polishing slurry of the aluminum gate CMP. This work utilizes the complexation-soluble function of FA/O II and the preference adsorption mechanism of FA/O I nonionic surfactant to improve the uniformity of the surface chemistry function with the electrochemical corrosion research, such as OCP-TIME curves, Tafel curves and AC impedance. The result is that the stock polishing slurry （with SiO2 abrasive） contains 1 wt.% H2O2,0.5 wt.% FA/O II and 1.0 wt.% FA/O I nonionic surfactant. For a fine polishing process, 1.5 wt.% H2O2, 0.4 wt.% FA/O II and 2.0 wt.% FA/O I nonionic surfactant are added. The polishing experiments show that the removal rates are 3000 ±50 A/min and 1600 ± 60 A/dmin, respectively. The surface roughnesses are 2.05 ± 0.128 nm and 1.59 ± 0.081 nm, respectively. A combination of the functions of FA/O II and FA/O I nonionic surfactant obtains a controllable removal rate and a better surface roughness in alkaline solution.展开更多
Underpotential deposition(UPD) of Cu on an Au electrode followed by redox replacement reaction(RRR) of CuUPD with a Pt source(H2PtCl6 or K2PtCl4) yielded Au-supported Pt adlayers(for short,Pt(CuUPD-Pt4+)n/Au for H2PtC...Underpotential deposition(UPD) of Cu on an Au electrode followed by redox replacement reaction(RRR) of CuUPD with a Pt source(H2PtCl6 or K2PtCl4) yielded Au-supported Pt adlayers(for short,Pt(CuUPD-Pt4+)n/Au for H2PtCl6,or Pt(CuUPD-Pt2+)n/Au for K2PtCl4,where n denotes the number of UPD-redox replacement cycles).The electrochemical quartz crystal microbalance(EQCM) technique was used for the first time to quantitatively study the fabricated electrodes and estimate their mass-normalized specific electrocatalytic activity(SECA) for methanol oxidation in alkaline solution.In comparison with Pt(CuUPD-Pt2+)n/Au,Pt(CuUPD-Pt4+)n/Au exhibited a higher electrocatalytic activity,and the maximum SECA was obtained to be as high as 35.7 mA ?g?1 at Pt(CuUPD-Pt4+)3/Au.The layer-by-layer architecture of Pt atoms on Au is briefly discussed based on the EQCM-revealed redox replacement efficiency,and the calculated distribution percentages of bare Au sites agree with the experimental results deduced from the charge under the AuOx-reduction peaks.The EQCM is highly recommended as an efficient technique to quantitatively examine various electrode-supported catalyst adlayers,and the highly efficient catalyst adlayers of noble metals are promising in electrocatalysis relevant to biological,energy and environmental sciences and technologies.展开更多
The effects of additives on the surface and cross-sectional morphologies of zinc deposits on iron substrate from alkalinezincate solution were characterized by scanning electron microscope(SEM).The cathodic reaction m...The effects of additives on the surface and cross-sectional morphologies of zinc deposits on iron substrate from alkalinezincate solution were characterized by scanning electron microscope(SEM).The cathodic reaction mechanisms under variousconcentrations of additives were investigated using cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS)techniques.It is found that with increasing the additive A content in the bath solution,the nucleation overpotential(NOP)value isobviously increased and the inhibition effect is strengthened.This may be mainly due to the adsorption of additive A on the cathodicelectrode surface,which can cover the active sites and block the discharge reduction.The results of EIS analysis indicate that therate-determining step of zinc electrodeposition process is changed from mixed control step into electrochemical reduction step in thepresence of additive A.However,any quantity of additive B has little effect on the NOP value and the inhibition effect is not obvious.Furthermore,addition of additive A and additive B at the same time displays the strongest inhibition effect and shows a strongsynergism because of their co-adsorption on the cathodic electrode surface.展开更多
The solid-phase extraction（SPE） technique applied to the extraction of organic compound was creatively used as the extraction of inorganic gold in the paper.Two types of techniques were proposed and explored,namely ...The solid-phase extraction（SPE） technique applied to the extraction of organic compound was creatively used as the extraction of inorganic gold in the paper.Two types of techniques were proposed and explored,namely the SPE and the liquid–liquid extraction（LLE） of the quaternary ammonium surfactant [cetytrimethyl ammonium bromide（CTMAB）,cetyl pyridine bromide（CPB）,benzyl dimethyl dodecyl ammonium chloride（BDMDAC）,and dodecyl trimethyl ammonium chloride（DTMAC）].The surfactant could react with Au（CN）2^- to form the ionic complex,and the compound could be extracted by SPE column of reversed-phase bonded silica gel.Hence,a new method of SPE was proposed to extract gold with these features of the high selectivity,the reliability,and the simplicity.The experimental result shows that the recovery rate of gold is more than 98 %,and the solid-phase extraction column is not easily damaged and it can be repeatedly used.The new method can be used as the extraction process of gold from alkaline cyanide solution as well.Besides,the paper also puts forward a new process of gold extraction.展开更多
Solvent extraction based on ionic liquids is generally considered to be an environmentally benign and effective technology for gold(Ⅰ)recovery.The aim of this work is to study gold(Ⅰ)extraction from aurocyanide solu...Solvent extraction based on ionic liquids is generally considered to be an environmentally benign and effective technology for gold(Ⅰ)recovery.The aim of this work is to study gold(Ⅰ)extraction from aurocyanide solution using fluorine-free ionic liquids[A336][SCN],[A336][MTBA]and[A336][Mal].Various factors that affect gold(Ⅰ)extraction(including concentration of ionic liquids,equilibrium pH,concentration of the modifier tributyl phosphate(TBP),reaction time and initial concentration of gold in an aqueous solution)were studied and optimized.The results indicate that the three Aliquat336-based ionic liquids all exhibit excellent behaviors for gold(Ⅰ)extraction.More than 99.8%of gold(Ⅰ)can be extracted from the aqueous phase into the ionic liquid phase.The gold-loaded ionic liquids were characterized using infrared spectroscopy and mass spectrometry to study the extraction mechanism of gold(Ⅰ).The results revealed that extraction of gold(Ⅰ)into the ionic liquid phase was based on an exchange reaction between the anion Au(CN)2-in aqueous solution and the anion SCN-in ionic liquid[A336][SCN].The logarithmic relationship between distribution coefficient and TBP concentration indicates that two TBP molecules are involved in the formation of the extracted complex.The extracted complex was determined to be A336^(+)·Au(CN)_(2)^(-)·2 TBP.In addition,the gold(Ⅰ)-loaded ionic liquids can be efficiently stripped using NH4 SCN,2-methylthiobenzoic acid and methyl maltol.The results establish that Aliquat 336-based ionic liquids have potential application prospects in gold(Ⅰ)recovery from cyanide solutions.展开更多
Polarographic characteristics of Te(Ⅳ)-alkaline dye were investiga- ted at mercury electrode in acidic solution.It was found that the mechanism of the electrode process depended on the concentration of Te(Ⅳ).
The exploration of stable and highly efficient alkaline hydrogen evolution reaction(HER)electrocatalysts is imperative for alkaline water splitting.Herein,Se-doped NiCoP with hierarchical nanoarray structures directly...The exploration of stable and highly efficient alkaline hydrogen evolution reaction(HER)electrocatalysts is imperative for alkaline water splitting.Herein,Se-doped NiCoP with hierarchical nanoarray structures directly grown on carbon cloth(Se-NiCoP/CC)was prepared by hydrothermal reaction and phosphorization/selenization process.The experimental results reveal that Se doping could increase the electrochemical active sites and alter the electronic structure of NiCoP.The optimized Se-NiCoP/CC electrode exhibits outstanding HER activity in alkaline electrolyte,which only needs a low overpotential of 79 mV at the current density of 10 mA/cm^(2).When serving as anode and cathode electrode simultaneously,the Se-NiCoP/CC electrodes achieve current density of 50 mA/cm^(2) at a low voltage of only 1.62 V.This work provides a feasible way to rationally design high active HER electrocatalysts.展开更多
Passivation kinetics of two Mg-RE alloys,such as Mg-Nd-Gd-Zn-Zr(EV31A),and Mg-Y-Nd-Gd-Zr(WE43C)were investigated in two different heat treated conditions(solution treated and overaged)in 0.01-1.0 M NaOH solutions unde...Passivation kinetics of two Mg-RE alloys,such as Mg-Nd-Gd-Zn-Zr(EV31A),and Mg-Y-Nd-Gd-Zr(WE43C)were investigated in two different heat treated conditions(solution treated and overaged)in 0.01-1.0 M NaOH solutions under potentiostatic conditions.Negative reaction order was observed in dilute NaOH which transitioned to positive values as the passivation time increased and in the 1 M NaOH as well.The passive layers showed platelet morphology and the size of the platelets decreased with increase in the NaOH concentration.The hydrogen evolution reaction(HER)kinetics was not improved on the passive layer covered surface of the Mg-RE alloys in contrast to the improvements reported on the hydroxide covered pure magnesium.The electrochemical impedance increased with increase in the NaOH concentration in the solution treated condition of both Mg-RE alloys,whereas the overaged EV31A alloy showed a reverse trend.The passive layer of EV31A showed almost 100%higher charge carrier density than the film formed on the WE43C in the overaged condition.A better passivation behavior was observed in the solution treated condition than that in the overaged condition which could be attributed to the uniform distribution of the RE elements in the solution treated specimens.The WE43C alloy revealed better corrosion resistance in the alkaline solution than the EV31A alloy.展开更多
Crystalline engineering and heterostructure have attracted much attention as effective strategies to improve the electrocatalytic activity for hydrogen evolution reaction(HER).In this study,a new heterostructure catal...Crystalline engineering and heterostructure have attracted much attention as effective strategies to improve the electrocatalytic activity for hydrogen evolution reaction(HER).In this study,a new heterostructure catalyst(Ru/RuS_(2)@N-rGO)with low crystallinity was fabricated by a simple and low-temperature method for HER in alkaline solution,applying the Na_(2)SO_(4)as S source and polypyrrole as N source.Optimizing through the controllable crystalline engineering and composition ratio of Ru and RuS_(2),the Ru/RuS_(2)@N-rGO heterocatalyst at the calcining 500°C revealed highly efficient HER activity with overpotential 18 mV at a current density 10 mA/cm^(2)and remarkable stability for 24 h in 1.0 mol/L KOH.This work provides a facile and effective method in designing advanced electrocatalysts for HER in the alkaline electrolytes by synergistically structural and component modulations.展开更多
文摘Electropolymerization of aniline in KOH solution and properties of the polymer are studied by using in situ reflex ellipsometry, cyclic voltammetry and fluorescence spectroscopic method. The change patterns of ellipsometric parameters and the thickness of film in the process of electropolymerization are investigated. The complex refractive indices and the fluorescence spectra of PAN indicate that the PAN is a new kind of luminous material.
文摘This study was done to evaluate the nugget zone(NZ)corrosion behavior of dissimilar copper/brass joints welded by friction stir lap welding(FSLW)in a solution of 0.015 mol/L borax(pH 9.3).To this end,dissimilar copper/brass plates were welded with two dissimilar heat inputs(low and high)during the welding procedure.The high and low heat inputs were conducted with 710 r/min,16 mm/min and 450 r/min,25 mm/min,respectively.Using open circuit potential(OCP)measurements,electrochemical impedance spectroscopy(EIS)and Tafel polarization tests,the electrochemical behavior of the specimens in borate buffer solution was assessed.With the help of scanning electron microscope(SEM),the morphology of welded specimen surfaces was examined after immersion in the test solution.According to the results,the NZ grain size and resistance improvement reduced due to the nugget zone corrosion with a decreased heat input.The results obtained from Tafel polarization and EIS indicated the improved corrosion behavior of the welded specimen NZ with a decrease in the heat input during the welding process unlike the copper and brass metals.Furthermore,an increased heat input during the welding process shows a reduction in the conditions for forming the passive films with higher protection behavior.
文摘Nickel(Ni)-based materials act as one of the most promising candidates as platinum-group-metal-free(PGM-free)electrocatalysts for hydrogen oxidation reaction(HOR)in alkaline solution.Nevertheless,the electrocatalytic activity of pure Ni is significantly limited due to the sluggish kinetics under alkaline condition.To accelerate the kinetics,constructing heterostructures and nitride structures have been developed as two representative strategies.Here,we combined the two methods and presented a facile synthesis of the sheet-like Ni_(3)N/MoO_(2)in-plane heterostructures for enhanced HOR in alkaline electrolytes.Relative to Ni or Ni_(3)N,the Ni_(3)N/MoO_(2)in-plane heterostructures exhibited a significantly increased mass activity by 8.6-fold or 4.4-fold,respectively.Mechanistic studies revealed that the enhanced activity of Ni_(3)N/MoO_(2)could be attributed to the weakened hydrogen adsorption and strengthened hydroxyl adsorption.This work provides a facile approach to design high-efficiency catalysts for hydrogen-oxidation catalysis and beyond.
文摘The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studied. Cathodicpolarization curves showed the electrocatalytic activity of Ni/C electrode prepared byMVS method was higher than that of the one prepared by conventional method.
基金supported by the National Natural Science Foundation of China(No.51201172)
文摘The corrosion-wear behavior of a nanocrystalline Fe_（88）Si_（12） alloy disc coupled with a Si_3N_4 ball was investigated in acid（pH 3） and alkaline（pH 9） aqueous solutions. The dry wear was also measured for reference. The average friction coefficient of Fe_（88）Si_（12） alloy in the pH 9 solution was approximately 0.2, which was lower than those observed for Fe_（88）Si_（12） alloy in the pH 3 solution and in the case of dry wear. The fluctuation of the friction coefficient of samples subjected to the pH 9 solution also showed similar characteristics. The wear rate in the pH 9 solution slightly increased with increasing applied load. The wear rate was approximately one order of magnitude less than that in the pH 3 solution and was far lower than that in the case of dry wear, especially at high applied load. The wear traces of Fe_（88）Si_（12） alloy under different wear conditions were examined and analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The results indicated that the tribo-chemical reactions that involve oxidation of the worn surface and hydrolysis of the Si_3N_4 ball in the acid solution were restricted in the pH 9 aqueous solution. Thus, water lubrication can effectively improve the wear resistance of nanocrystalline Fe_（88）Si_（12） alloy in the pH 9 aqueous solution.
基金the National Key Research and Development Program of China(2020YFC1909703)S&T Program of Hebei Province(21284402Z)+1 种基金Fangchenggang Key Research and Development(AB20014008)Lvliang Key Research and Development Program(2020GXZDYF7)。
文摘Since the application in fuel cell,the electrochemical adsorption of hydroxyl has received considerable attention in recent years.While most research mainly focus on the room temperature,in this paper,the electrochemical adsorption of hydroxyl in alkaline solution at high temperature was investigated.An unusual oxidation peak was observed at-0.27 V,suggesting new behavior of hydroxyl adsorption occurred.As is known two kinds of cation hydrated clusters exist in alkaline solution,(H_(2)O)_(x-1)M^(+)-H_(2)O-O_(ad)H and(H_(2)O)_xM^(+)-O_(ad)H.For K^(+)and Cs^(+),the cluster shows unstable structure due to the weak interaction between hydrated cation and OH^(-)especially at high temperature.However,For Li^(+),Na^(+)the cluster structure would be stable,as the interaction force between the hydrated cation and OH^(-)is so strong.It was revealed that the unusual oxidation peak has some relationship with the(H_(2)O)_(x-1)M^(+)-H_(2)O-O_(ad)H cluster(K^(+)and Cs^(+))absorbed at Pt electrode surface.When the temperature was raised,(H_(2)O)_(x-1)M^(+)-H_(2)O-and-O_(ad)H was disconnected,then the O_(ad)H absorbed at Pt surface got oxidated.Based on the SEM observation,it was showed the unusual electrochemical oxidation reaction would generate platinum oxides,blocking the reactive sites at Pt electrode surface,thus reducing the electrochemical reactivity of Pt electrode.Accordingly,parameters of alkaline concentration and temperature were systematically studied,it was found that increase temperature or alkaline concentration was in favor of the unusual oxidation reaction.This study provides more understanding of hydroxyl adsorption behavior at Pt electrode surface for the high temperature water solution environment.
基金financially supported by the National Natural Science Foundation of China(No.52001216)。
文摘The effect of pH value and different kinds of anions on the corrosion behavior of Cu/Al casting-rolled clad plates in the alkaline solution was evaluated by means of scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),weight loss analysis,3D confocal laser scanning microscopy(CLSM)and electrochemical test.Results show the corrosion mainly occurs on the aluminum side.The corrosion resistance of the Cu/Al decreases as the pH value increases.When pH≥12,the dissolution of the film layer is faster than the passivation process.The addition of Cl^(-)ions reduces the corrosion resistance of the Cu/Al clad plates,which leads to pitting corrosion.The higher the concentration of Cl^(-)ions,the more prone the pitting to occur.The addition of SO_(4)^(2-)ions causes the denudation of the samples.The corrosion resistance of the Cu/Al is better in the alkaline solution containing NO_(3)^(-)ions than that in the solution containing Cl^(-)ions or SO_(4)^(2-)ions.When adding SO_(4)^(2-),NO^(3)^(-)and Cl^(-)to the pure alkaline solution,the corrosion resistance of the Cu/Al clad plates decreases.
基金financially supported by the National Science and Technology Major Project(2019YFB1900904)the National Natural Science Foundation of China(52271060 and 51771107)Independent Research and Development Project of State Key Laboratory of Advanced Special Steel(SKLASS)Shanghai University(2022-Z00)
文摘The stress corrosion cracking(SCC)performance of the sealed Alloy 690 plugs was investigated in 350℃deoxygenated concentrated alkaline solution.Sealing was used to expose only the inner surface of the plug,preventing direct contact between the tube sheet and the concentrated alkaline solution.After exposure for 1000 h,several intergranular cracks were observed on the inner wall of the plugs.Stress corrosion cracks primarily appear in some regions on the inner wall,which are highly deformed and advanced along the random grain boundary.The internal oxide layer formed in the high-temperature alkaline solution was not dense;it comprised a composite oxide with multiple layers.The outermost layer consisted of Fe-Cr-Ni oxide particles,and beneath it was an uneven Ni-rich layer,followed by a thin Cr-rich layer closest to the matrix.High kernel average misorientation in the heavily deformed region and a lack of chromium carbide contributed to crack initiation and propagation of Alloy 690 plug in hot concentrated alkaline solutions.
基金the support the National Natural Science Foundation of China(5210440)S&T Program of Hebei(23311501D)Program of HBIS Group under HG2023222。
文摘In this study,a cleaner method for separation and recovery of V/W/Na in waste selective catalytic reduction(SCR)catalyst alkaline leaching solution was proposed.The method involved membrane electrolysis followed by ion morphology pretreatme nt and solvent extraction.An acidic V(Ⅴ)/W(Ⅵ)solution was obtained using the me mbrane electrolysis method without adding any other chemical reagents.In addition,Na was recovered in the form of NaOH by product,avoiding the generation of Na containing wastewater.The electrolysis parameters were investigated,the lowest power consumption of 3063 kW·h·t^(-1)NaOH was obtained at a current density of 125 A·m^(-2)and an initial NaOH concentration of 2 mol·L^(-1).After electrolysis,oxalic acid was added to the acidic V/W containing solution,converting V(Ⅴ)negative ion to V(Ⅳ)positive ion.Since W(Ⅵ)ion state remained in negative form,the generation of heteropolyacid ions(W_(x)V_(y)O_(z)^(n-))was prevented.It was found that under the condition of oxalic acid addition/theoretical consumption 1.2 and reaction temperature 75℃,100%V(Ⅴ)was co nverted to V(Ⅳ4).Using 10%N263+10%noctanol+80%sulfonated kerosene as extractant,the highest W(Ⅵ)/V(Ⅳ)separation coefficient of 7559.76was obtained at pH=1.8,O:A ratio=1:1 and extraction time 15 min.With 2 mol·L^(-1)NaOH as stripping reagent,the W stripping efficiency reached 98.50%at O:A ratio=2:1 after 4-stages of stripping.The enrichment of V remained in the solution was realized using P204 as extractant and 20%(mass)H_(2)SO_(4)as stripping reagent.The parameters of extraction/stripping process were investigated,using 10%P204+10%TBP+80%sulfonated kerosene as extractant,the V extraction efficiency reached 97.50%at O:A ratio=1:2after 4 stages of extraction.Using 20%H_(2)SO_(4)as the stripping reagent,the V stripping efficiency was 98.30%at an O:A ratio of 4:1 after five stage s of stripping.After the entire process,a high-purity VOSO_(4)and Na_(2)WO_(4)product solutions were obtained with V/W recovery efficiency 95.84%/98.50%,separately.This study examined a more effective and cleaner method for separating V/W/Na in Na_(2)WO_(4)/NaVO_(3)solution,which may serve as a reference for the separation and recovery of V/W/Na in waste SCR catalysts.
基金Project (50974138) supported by the National Natural Science Foundation of ChinaProject (2010ssxt158) supported by Graduate Student Innovation Foundation of Central South University,China
文摘The selective recovery of lead from the zinc oxide dust using an alkaline Na2EDTA solution was investigated. The effects of temperature, leaching time, Na2EDTA concentration and initial NaOH concentration on the leaching rates of lead and zinc were studied. The following optimized leaching conditions were obtained： liquid-to-solid ratio 5：1 mL/g, stirring speed 650 r/min, Na2EDTA concentration 0.12 mol/L, initial NaOH concentration 0.5 mol/L, leaching temperature 70 ℃, leaching time 120 min. Under the optimized conditions, the average leaching rates of lead, zinc, fluoride and chloride are 89.92%, 0.94%, 62.84% and 90.02%, respectively. The filtrate was used to electrowin lead powders. The average current efficiency of electrowinning is about 93% and lead content is higher than 98% under the conditions of temperature of 60 ℃, current density of 200 A/m2, H3PO4 concentration of 1.5 g/L, and lead ion concentration of above 5 g/L. The consumption of Na2EDTA and the direct current are about respectively 0.218 kg and 0.958 kW·h for per kilogram of lead powder.
基金financially supported by the National Natural Science Foundation of China(No.51371039)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),Jiangsu Province,China
文摘Potentiodynamic polarization tests and slow strain rate test（SSRT） in combination with fracture morphology observations were conducted to investigate the stress corrosion cracking（SCC） behavior of 7003 aluminum alloy（AA7003） in acid and alkaline chloride solutions under various applied potentials（Ea）. The results show that AA7003 is to a certain extent susceptible to SCC via anodic dissolution（AD） at open-circuit potential（OCP） and is highly susceptible to hydrogen embrittlement（HE） at high negative Ea in the solutions with p H levels of 4 and 11. The susceptibility increases with negative shift in the potential when Ea is less than-1000 m V vs. SCE. However, the susceptibility distinctly decreases because of the inhibition of AD when Ea is equal to-1000 m V vs. SCE. In addition, the SCC susceptibility of AA7003 in the acid chloride solution is higher than that in the alkaline solution at each potential. Moreover, the effect of hydrogen on SCC increases with increasing hydrogen ion concentration.
文摘Beyond 45 nm, due to the superior CMP performance requirements with the metal gate of aluminum in the advanced CMOS process, a novel alkaline slurry for an aluminum gate CMP with poly-amine alkali slurry is investigated. The aluminum gate CMP under alkaline conditions has two steps： stock polishing and fine polishing. A controllable removal rate, the uniformity of aluminum gate and low corrosion are the key challenges for the alkaline polishing slurry of the aluminum gate CMP. This work utilizes the complexation-soluble function of FA/O II and the preference adsorption mechanism of FA/O I nonionic surfactant to improve the uniformity of the surface chemistry function with the electrochemical corrosion research, such as OCP-TIME curves, Tafel curves and AC impedance. The result is that the stock polishing slurry （with SiO2 abrasive） contains 1 wt.% H2O2,0.5 wt.% FA/O II and 1.0 wt.% FA/O I nonionic surfactant. For a fine polishing process, 1.5 wt.% H2O2, 0.4 wt.% FA/O II and 2.0 wt.% FA/O I nonionic surfactant are added. The polishing experiments show that the removal rates are 3000 ±50 A/min and 1600 ± 60 A/dmin, respectively. The surface roughnesses are 2.05 ± 0.128 nm and 1.59 ± 0.081 nm, respectively. A combination of the functions of FA/O II and FA/O I nonionic surfactant obtains a controllable removal rate and a better surface roughness in alkaline solution.
基金supported by the National Natural Science Foundation of China (20675029 & 90713018)the State Special Scientific Project on Water Treatment (2009ZX07212-001-06)
文摘Underpotential deposition(UPD) of Cu on an Au electrode followed by redox replacement reaction(RRR) of CuUPD with a Pt source(H2PtCl6 or K2PtCl4) yielded Au-supported Pt adlayers(for short,Pt(CuUPD-Pt4+)n/Au for H2PtCl6,or Pt(CuUPD-Pt2+)n/Au for K2PtCl4,where n denotes the number of UPD-redox replacement cycles).The electrochemical quartz crystal microbalance(EQCM) technique was used for the first time to quantitatively study the fabricated electrodes and estimate their mass-normalized specific electrocatalytic activity(SECA) for methanol oxidation in alkaline solution.In comparison with Pt(CuUPD-Pt2+)n/Au,Pt(CuUPD-Pt4+)n/Au exhibited a higher electrocatalytic activity,and the maximum SECA was obtained to be as high as 35.7 mA ?g?1 at Pt(CuUPD-Pt4+)3/Au.The layer-by-layer architecture of Pt atoms on Au is briefly discussed based on the EQCM-revealed redox replacement efficiency,and the calculated distribution percentages of bare Au sites agree with the experimental results deduced from the charge under the AuOx-reduction peaks.The EQCM is highly recommended as an efficient technique to quantitatively examine various electrode-supported catalyst adlayers,and the highly efficient catalyst adlayers of noble metals are promising in electrocatalysis relevant to biological,energy and environmental sciences and technologies.
基金Project(2014CB643401)supported by the National Basic Research Program of ChinaProjects(51134007,51404299)supported by the National Natural Science Foundation of China
文摘The effects of additives on the surface and cross-sectional morphologies of zinc deposits on iron substrate from alkalinezincate solution were characterized by scanning electron microscope(SEM).The cathodic reaction mechanisms under variousconcentrations of additives were investigated using cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS)techniques.It is found that with increasing the additive A content in the bath solution,the nucleation overpotential(NOP)value isobviously increased and the inhibition effect is strengthened.This may be mainly due to the adsorption of additive A on the cathodicelectrode surface,which can cover the active sites and block the discharge reduction.The results of EIS analysis indicate that therate-determining step of zinc electrodeposition process is changed from mixed control step into electrochemical reduction step in thepresence of additive A.However,any quantity of additive B has little effect on the NOP value and the inhibition effect is not obvious.Furthermore,addition of additive A and additive B at the same time displays the strongest inhibition effect and shows a strongsynergism because of their co-adsorption on the cathodic electrode surface.
基金financially supported by the National Natural Science Foundation of China (No.20471051.)
文摘The solid-phase extraction（SPE） technique applied to the extraction of organic compound was creatively used as the extraction of inorganic gold in the paper.Two types of techniques were proposed and explored,namely the SPE and the liquid–liquid extraction（LLE） of the quaternary ammonium surfactant [cetytrimethyl ammonium bromide（CTMAB）,cetyl pyridine bromide（CPB）,benzyl dimethyl dodecyl ammonium chloride（BDMDAC）,and dodecyl trimethyl ammonium chloride（DTMAC）].The surfactant could react with Au（CN）2^- to form the ionic complex,and the compound could be extracted by SPE column of reversed-phase bonded silica gel.Hence,a new method of SPE was proposed to extract gold with these features of the high selectivity,the reliability,and the simplicity.The experimental result shows that the recovery rate of gold is more than 98 %,and the solid-phase extraction column is not easily damaged and it can be repeatedly used.The new method can be used as the extraction process of gold from alkaline cyanide solution as well.Besides,the paper also puts forward a new process of gold extraction.
基金the National Natural Science Foundation of China(No.51464044)the Natural Science Foundation of Yunnan Province(No.2018FB014)the Free Exploration Fund for Academician of Yunnan Province(No.2019HA005)。
文摘Solvent extraction based on ionic liquids is generally considered to be an environmentally benign and effective technology for gold(Ⅰ)recovery.The aim of this work is to study gold(Ⅰ)extraction from aurocyanide solution using fluorine-free ionic liquids[A336][SCN],[A336][MTBA]and[A336][Mal].Various factors that affect gold(Ⅰ)extraction(including concentration of ionic liquids,equilibrium pH,concentration of the modifier tributyl phosphate(TBP),reaction time and initial concentration of gold in an aqueous solution)were studied and optimized.The results indicate that the three Aliquat336-based ionic liquids all exhibit excellent behaviors for gold(Ⅰ)extraction.More than 99.8%of gold(Ⅰ)can be extracted from the aqueous phase into the ionic liquid phase.The gold-loaded ionic liquids were characterized using infrared spectroscopy and mass spectrometry to study the extraction mechanism of gold(Ⅰ).The results revealed that extraction of gold(Ⅰ)into the ionic liquid phase was based on an exchange reaction between the anion Au(CN)2-in aqueous solution and the anion SCN-in ionic liquid[A336][SCN].The logarithmic relationship between distribution coefficient and TBP concentration indicates that two TBP molecules are involved in the formation of the extracted complex.The extracted complex was determined to be A336^(+)·Au(CN)_(2)^(-)·2 TBP.In addition,the gold(Ⅰ)-loaded ionic liquids can be efficiently stripped using NH4 SCN,2-methylthiobenzoic acid and methyl maltol.The results establish that Aliquat 336-based ionic liquids have potential application prospects in gold(Ⅰ)recovery from cyanide solutions.
基金Project Supported by National Natural Scientific Foundation of China
文摘Polarographic characteristics of Te(Ⅳ)-alkaline dye were investiga- ted at mercury electrode in acidic solution.It was found that the mechanism of the electrode process depended on the concentration of Te(Ⅳ).
基金Projects(51772086,51872087,51971089)supported by the National Natural Science Foundation of ChinaProject(2018TP1037-202102)supported by Open Fund of Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion,China+1 种基金Project supported by Student National SIT Innovation Program,ChinaProject(2020CB1007)supported by Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy,China。
文摘The exploration of stable and highly efficient alkaline hydrogen evolution reaction(HER)electrocatalysts is imperative for alkaline water splitting.Herein,Se-doped NiCoP with hierarchical nanoarray structures directly grown on carbon cloth(Se-NiCoP/CC)was prepared by hydrothermal reaction and phosphorization/selenization process.The experimental results reveal that Se doping could increase the electrochemical active sites and alter the electronic structure of NiCoP.The optimized Se-NiCoP/CC electrode exhibits outstanding HER activity in alkaline electrolyte,which only needs a low overpotential of 79 mV at the current density of 10 mA/cm^(2).When serving as anode and cathode electrode simultaneously,the Se-NiCoP/CC electrodes achieve current density of 50 mA/cm^(2) at a low voltage of only 1.62 V.This work provides a feasible way to rationally design high active HER electrocatalysts.
基金The support provided by the U.S. Nuclear Regulatory Commission through a faculty development grant NRC-HQ-84-15-G-0025 is gratefully acknowledged. J. Ninlachart acknowledges the support by Royal Thai Navy.
文摘Passivation kinetics of two Mg-RE alloys,such as Mg-Nd-Gd-Zn-Zr(EV31A),and Mg-Y-Nd-Gd-Zr(WE43C)were investigated in two different heat treated conditions(solution treated and overaged)in 0.01-1.0 M NaOH solutions under potentiostatic conditions.Negative reaction order was observed in dilute NaOH which transitioned to positive values as the passivation time increased and in the 1 M NaOH as well.The passive layers showed platelet morphology and the size of the platelets decreased with increase in the NaOH concentration.The hydrogen evolution reaction(HER)kinetics was not improved on the passive layer covered surface of the Mg-RE alloys in contrast to the improvements reported on the hydroxide covered pure magnesium.The electrochemical impedance increased with increase in the NaOH concentration in the solution treated condition of both Mg-RE alloys,whereas the overaged EV31A alloy showed a reverse trend.The passive layer of EV31A showed almost 100%higher charge carrier density than the film formed on the WE43C in the overaged condition.A better passivation behavior was observed in the solution treated condition than that in the overaged condition which could be attributed to the uniform distribution of the RE elements in the solution treated specimens.The WE43C alloy revealed better corrosion resistance in the alkaline solution than the EV31A alloy.
基金supported by National Natural Science Foundation of China(Nos.21773184 and 21671158)Key Science and Technology Project of Henan(No.202102210238)+1 种基金Natural Science Foundation of Henan(No.212300410339)Cultivation Program for Young Backbone Teachers in Henan University of Technology(Nos.21420108 and 21420073).
文摘Crystalline engineering and heterostructure have attracted much attention as effective strategies to improve the electrocatalytic activity for hydrogen evolution reaction(HER).In this study,a new heterostructure catalyst(Ru/RuS_(2)@N-rGO)with low crystallinity was fabricated by a simple and low-temperature method for HER in alkaline solution,applying the Na_(2)SO_(4)as S source and polypyrrole as N source.Optimizing through the controllable crystalline engineering and composition ratio of Ru and RuS_(2),the Ru/RuS_(2)@N-rGO heterocatalyst at the calcining 500°C revealed highly efficient HER activity with overpotential 18 mV at a current density 10 mA/cm^(2)and remarkable stability for 24 h in 1.0 mol/L KOH.This work provides a facile and effective method in designing advanced electrocatalysts for HER in the alkaline electrolytes by synergistically structural and component modulations.
