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Adsorption and corrosion inhibition behavior of imidazole on cobalt electrodes studied by SERS and electrochemical methods

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Science china chemistry 2005年第6期48卷 497-503页

作者： GU Wei1, LIU Guokun2. REN Bin2. WU Deyin2. GU Renao1 & TIAN Zhongqun2.1. Department of chemistry, College of chemistry and {2. engineering, Suzhou university, Suzhou 2.5006, china 2. State Key Laboratory for Physical chemistry of Solid Surfaces and Department of chemistry, College of chemistry and {2. engineering, Xiamen university, Xiamen 361005, china 1. Department of chemistry College of Chemistry and Chemical Engineering Suzhou University 215006 Suzhou China 2. State Key Laboratory for Physical chemistry of Solid Surfaces and Department of chemistry College of Chemistry and Chemical Engineering Xiamen University 361005 Xiamen China

The interaction of imidazole with Co electrodes in an electrochemical system was studied by surface-enhanced Raman scattering (SERS) and electrochemical methods. The SER spectra of Co in an imidazole solution as a function of the applied potential were analyzed and the assignment of the Raman bands was made. It was found that there were three kinds of sur-face species on the Co surface in different potential regions and they were interchangeable de-pending on the potential. In a relatively negative potential region (?1.2.to ?0.9 V), imidazole was adsorbed on the surface and its orientation might change from a vertical configuration via the N-end of the pyridine ring to a tilted configuration via the C2.N3 double bond. In a more positive potential region (?0.8 to ?0.7 V), the SERS signal from the adsorbed imidazole weakened and finally disappeared, meanwhile the signal from the Co and imidazole complex strengthened gradually. At the open circuit potential (?0.6 V), we detected very strong bands from the Co ox-ides. By comparing the Tafel curves of the Co electrode in the solution without and with imidazole, we found that imidazole has a marked effect on the corrosion inhibition of the Co electrode. This result demonstrates that we may be able to reveal the complicated interaction of surface species with metal surface at the molecular level by combining the SERS and electrochemical methods.

关键词： cobalt, imidazole, inhibition, surface-enhanced Raman spectroscopy, Tafel plot.

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A thin-layer spectroelectrochemical study of 3,3',5,5'-tetramethylbenzidine at SnO_2.F film optically transparent electrode

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Science china chemistry 2004年第4期47卷 267-275页

作者： JIAO Kui1, YANG Tao2.& NIU Shuyan1,2.1. College of chemistry and Molecular engineering, Qingdao {2. of Science and Technology, Qingdao 2.6042. china 2. College of chemistry and chemical engineering, Ocean {2. of china, Qingdao 2.6003, china Correspondence should be addressed to Jiao Kui 1. College of chemistry and Molecular engineering Qingdao University of Science and Technology 266042 Qingdao China 2. College of chemistry and chemical {2. Ocean University of China 266003 Qingdao China

The electrooxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) is dependent on the pH value of Britton-Robinson (B-R) buffer solution. In this work, the electrooxidation behavior of TMB was investigated with a SnO2.F film optically transparent thin-layer spectroelectrochemical cell. TMB underwent one two-electron electrooxidation process in the pH range from 2.0 to chemical reaction to yield an azo compound. Several spectroelectrochemical techniques, such as thin-layer cyclic voltammetry, thin-layer cyclic voltabsorptometry, thin-layer potential-controlled electrolysis absorptometry, thin-layer single-potential-step chronoabsorptometry, thin-layer dou-ble-potential-step chronoabsorptometry, thin-layer single-potential-step open-circuit relaxation chronoabsorptometry, were applied to this investigation. The formal potential E0’ and the electron transfer number corresponding to the electrooxidation of TMB in B-R buffer solution, and the reaction rate constant of the subsequent chemical reaction were determined.

关键词： 3,3′,5,5′-tetramethylbenzidine tin oxide film optically transparent electrode thin-layer spectroelectro-chemistry electrooxidation

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Voltammmetric Determination of Uric Acid in the Presence of Ascorbates Using Overoxidized Polypyrrole Film Coated Glassy Carbon Electrodes

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chemical Research in Chinese Universities 1997年第3期13卷 207-214页

作者： KANG Tian-fang , SHEN Guo-li, YU Ru-qin (Department of chemistry and chemical {2.,hunan university, changsha, , 410082.

The voltammetric behaviour of uric acid at overoxidized polypyrrole (OPPY ) film-coated glassy carbon (GC ) electrodes was investigaied. The chemically modi- fied electrodes exhilbited an excellent permselectivity for uric acid of undissociated form in an acidic medium. The current response sensitivity of uric acid at the modi- fied electrodes was markedly increased by properly anodizing activation of underly- ing electrodes and overoxidizing treatment of polypyrrole film. The voltammetric response of uric acid at the chemically modified electrode was linearly related to itinvestigatedtion in the range of 4. 0 ×10-7 -8. 0 ×10-5 mol/L in pH 5 buffer solu- tions. Ascorbic acid in less than 150-fold excess did not interfere with the voltam- metric determination of uric acid. The proposed procedure was utilized to determine uric acicl in human urine and serum samples without any pretreatment.

关键词： Voltammetry . Uric acid Overoxidized polypyrrole film modified elec- trode

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Study on Enhancement in Gibbsite Precipitation of Bayer Process under 33 kHz Ultrasound

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Journal of Materials Science & Technology 2003年第6期19卷 607-610页

作者： Jihua ZHAO and Qiyuan CHENCollege of chemistry and chemical {2., Central South university, changsha 410083, chinaCollege of chemistry and chemical {2., Lanzhou university, Lanzhou 730000, china Cent S Univ Coll Chem & Chem Engn Changsha 410083 Peoples R China Lanzhou Univ Coll Chem & Chem Engn Lanzhou 730000 Peoples R China

The enhancement of gibbsite precipitation in Bayer process by 33 kHz ultrasound has been studied. From orthome-thod experiment, the optimized operating parameters of treatment under 33 kHz ultrasonic cleaner have obtained. Compared with crystallization of AI(OH)3 without treatment of ultrasound, the precipitation time is reduced by 15 h when the precipitation ratio is 45%. From the results of grain size distribution and SEM photographs of gibbsite, it is found that secondary nucleation and agglomeration could be enhanced under 33 kHz ultrasound. The products are same from comparison of X-ray powder diffraction, but the Raman spectrum of sodium aluminate solution under 33 kHz ultrasound is different from that without ultrasound.

关键词： Ultrasound Aluminium trihydroxide Precipitation

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Preparation of 5N high purified indium by the method of chemical purification-electrolysis

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Rare Metals 2002年第2期21卷 137-141页

作者： ZENG Dongming, ZHOU Zhihua, SHU Wangen, LIU Younian, and HU AipingCollege of chemistry and chemical {2., Central South university, changsha 410083, china College of chemistry and chemical {2. Central South University Changsha 410083

The application of indium requires high purity indium as material.5N high purity indium had been prepared by the method of acombination of chemically smelting and electrolysis. Smelting timewas 10 min, the abstraction rate of cadmium was 80/100-90/100 whenused solution of I_2.KI and glycerine to smelt indium. 4N metalindium was used as anode, high purity indium as cathode, In-2.SO_4)_3-H_2.O_4 system as electrolyte, and In content is 100 g/L, pH2.3 and current density 80-100 a/m^2.

关键词： high-purify indium preparation chemical purifying

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Hydroisomerization of n-heptane over bimetal-bearing H_3PW_(12.O_(40) catalysts supported on dealuminated USY zeolite

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Science china chemistry 2008年第2期51卷 120-127页

作者： WEI RuiPing1,2. GU YanBo1 & WANG Jun1 1 State Key Laboratory of Materials-Oriented chemical engineering, College of {2. and chemical engineering, Nanjing Uni- versity of Technology, Nanjing 2.0009, china 2.College of {2. and chemical engineering, Southeast university, Nanjing 2.1189, china State Key Laboratory of Materials-Oriented chemical engineering College of Chemistry and Chemical EngineeringNanjing University of TechnologyNanjing 210009China College of chemistry and chemical {2. Southeast UniversityNanjing 211189China

The bimetal-bearing (CePt or LaPt) 12.tungstophosphoric acid (H3PW12.40 (PW)) catalysts supported on dealuminated USY zeolite (DUSY) were prepared by impregnation and characterized by XRD, BET, IR, and H2.chemisorption. Their catalytic activities were tested in the hydroisomerization of n-heptane with a continuous atmospheric fixed-bed reactor. After the steam treatment combined with the acid leaching, as well as the supporting with PW and the bimetals, the DUSY support retains the Y zeolite porosity and the PW well keeps its Keggin structure in catalysts. The doping of Ce into the catalysts enhances the dispersion of Pt on the catalyst surface. The Pt-bearing PW catalysts doped with Ce or La, especially Ce, exhibit much higher catalytic activity and selectivity than the catalysts without dopants at lowered reaction temperatures. At the optimal reaction conditions, i.e., the reaction temperature of 2.0℃ and WHSV of 1.4 h1, the catalyst with a Pt loading of 0.4%, PW loading of 10% and a molar ratio of Ce to Pt of 15:1 shows a conversion of n-heptane of 70.3% with a high selectivity for isomerization products of 94.1%.

关键词： hydroisomerization of n-heptane bimetal catalyst heteropoly acid USY platinum

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Long-chain tetraalkyltin compounds as neutral carriers for nitrite-selective PVC membrane electrodes

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Chinese Journal of chemistry 1988年第3期6卷 215-222页

作者： WANG Ke-Min YU Ru-Qin*, Department of chemistry and chemical {2., hunan university, changsha Department of chemistry and chemical {2. Hunan University Changsha

The nitrite-selective PVC membrane electrodes prepared with lipophilic long-chain tetraal-kyltin compounds as neutral carrier show selectivity patterns significantly different from those obtainedwith classical anion-exchangers. The potentiometric selectivity coefficient for nitrite ion with respectto nitrate ion has been improved by about four orders of magnitude. The linear response range ofthe electrode based on tetralauryltin （TLT） is from 1×10-1M down to 2.10-5M with a detectionlimit of 5×10-6M. The Nernstian response of the electrode in the medium of pH≥7 graduallychanges to a doubled super-Nernstian response when the solution turns slightly acidic. The changeof the response slope has a closely relation with the stepwise complex-formation equilibrium of thecarrier with the anion involved, which was experimentally studied by using ultraviolet *** explanation of the anomalous response behavior as well as the curve form of the potential-pHplot is given.

关键词： TLT PVC

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Fluorescent nanoparticles for chemical and biological sensing

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Science china chemistry 2011年第8期54卷 1157-1176页

作者： LIU JianBo, YANG XiaoHai, HE XiaoXiao, WANG KeMin, WANG Qing, GUO QiuPing, SHI Hui, HUANG Jin & HUO XiQin State Key Laboratory of Chemo/Biosensing and Chemometrics College of chemistry and chemical {2., Institute of Biology, hunan university Key Laboratory for Bio-Nanotechnology and Molecule {2. of hunan Province, changsha 410082. china 1. State Key Laboratory of Chemo/Biosensing and Chemometrics College of chemistry and chemical {2. Institute of Biology Hunan University Key Laboratory for Bio-Nanotechnology and Molecule engineering of hunan Province Changsha 410082 China

Fluorescent nanoparticles (NPs), including quantum dots (QDs), dye-doped NPs, and rare earth-based NPs, etc., have been a major focus of research and development during the past decade. The impetus behind such endeavors can be attributed to their unique chemical and optical properties, such as bright fluorescence, high photostability, large Stocks shift and flexible processability. The introduction of fluorescent NPs into analytical chemistry has opened up new venues for fluorescent analysis. In this review, we focus on the developments and analytical applications of fluorescent NPs in the chemical and biological sensing of pH, ions, organic compounds, small biological molecules, nucleic acids, proteins, virus and bacteria. The review also points out the in vitro and in vivo imaging application of fluorescent NPs at the cell and body levels. Meanwhile, the ad- vantages of NPs brought field of sensing and signal transductions are also discussed.

关键词： fluorescence sensing quantum dots dye-doped nanoparticles rare earth-based nanoparticles

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Drag reduction of flow boiling with polymer additives

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Journal of Central South university of Technology 2001年第2期8卷 143-146页

作者： QIU Yun ren 1,CHEN Wei ping 2.SI Qin 3 (1.College of chemistry and chemical {2., Central South university, changsha 410083, china 2.Editorial Office of Journal of Central South university, changsha 410083, china 3.College of chemical E 1. College of chemistry and chemical {2. Central South University 410083 Changsha China 2. Editorial Office of Journal of Central South university 410083 Changsha China 3. College of chemical engineering Tianjin University 300072 Tianjin China

The drag reducing effect of polymer additive aqueous solution was investigated in flow boiling, and the polymer additives were two kinds of polyacrylamide (PAM) with relative molecular mass about 2.56×10 6 and 8.55×10 6. The frictional pressure drop was calculated according to the measured total pressure drop. The results show that the flow drag of flow boiling is reduced by adding a small amount of PAM to water when heat flux is in the range of 15.1 kW·m -2.to 47.0 kW·m -2., when the mass fraction of PAM is higher than 2.0×10 -5 , the drag reducing effect is obvious. Drag reducing effect of PAM, whose relative molecular mass is 8.55×10 6, is slightly better than that of 2.56×10 6 at the same mass fraction, and the greater the flow rate of the additive solution, the better the effect of the drag reduction.

关键词： polymer additive flow boiling drag reduction pressure drop

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Size effect of fullerene cages and encaged clusters in M3N@C2.

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Science china chemistry 2009年第5期52卷 584-589页

作者： GAN LiHua School of chemistry and chemical {2., Southwest university, Chongqing 400715, china School of chemistry and chemical {2. Southwest University Chongqing 400715 China

Based on the calculated findings that the sizes of encaged clusters determine the structures and the stability of C80-based trimetallic nitride fullerenes (TNFs), more extensive density functional theory calculations were performed on M3N@C68, M3N@C78 and M3N@C80 (M=Sc, Y and La). The calculated results demonstrated that the structures and stability undergo a transition with the increasing of the sizes of the cages and clusters. Sc3N is planar inside the three considered cages, Y3N is slightly pyramidal inside C68-6140 and C78-5 and planar inside I h C80-7, however, La3N is pyramidal inside all the three cages. Those cages with pyramidal clusters inside deformed considerably, compared with their parent cages. In these cases, the bonding of metallic atoms toward the cages does not play an impor-tant role, and the encaged cluster tends to be located inside the cages with the largest M-M and M-C distances so that the strain energy can be released mostly. These calculations revealed the size effect of fullerene cages and encaged clusters, and can explain the position priority of M3N inside fullerene cages and the differences in yield of M3N@C2..

关键词： trimetallic nitride fullerenes (TNFs) density functional theory (DFT) size effect stability

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