武汉大学电化学陈胜利PPT学习教案

1、会计学1 武汉大学电化学陈胜利武汉大学电化学陈胜利 1. A. J. Bard, L. R. Faulkner著， 邵元华等译，电化学方法原理和应用， 2005年， 化学工业出版社 2. 李荻 主编 电化学原理（1999年）北京航天航空大学出版设社 第1页/共31页 1.绪论（电化学科学概述） 2.电化学界面的电荷迁移过程 3.电化学界面的稳态传质过程 4.电化学界面的暂态传质过程 5.复杂电极反应动力学 6.电化学界面的基本性质 7.电化学催化 8.复习总结 9.考试 第2页/共31页 1.What does electrochemistry deal with ? 2.The featur

2、es of electrochemical processes and reactions; 3.The philosophy and strategies in electrochemical studies 4.A historical view of electrochemical science 第3页/共31页 nThe laws (principles) and the technologies concerning the conversion between chemical energy and electrical energy nInterrelation between

3、 chemical phenomena (chemical reactions, chemical changes, etc.) and electric phenomena (charge, current, potential, electric field, etc.) nThe phenomena, processes and reactions occurring at interface between an electronic conductor (electrode) and an ionic conductor (electrolyte) . 第4页/共31页 lElect

4、ronic conductors（Metals、 Semiconductors); lIonic conductors (electrolyte solutions, solid electrolyte, ionic liquid, melted salts); ionic conductor + - electronic conductor electronic conductor V A InterfaceInterface ElectrodeElectrode How does the current flow at the interface between types of cond

5、uctors ? Ionic conductors alone can not constitute a closed circuit to conduct current. 第5页/共31页 H2 + O2 H2O + H (Q) H2 2H+ + 2e- 4e- + O2 + 4H+ 2H2O H2 + O2 H2O + G (W) e- H+ Chemical energy Heat Chemical energy Work Electrons act as reactant or product 第6页/共31页 Fe2O3 + C + H (Q) Fe + CO2 C + 2O2-

6、CO2 + 4e- Fe2O3 + 6e- 2Fe + 3O2- e- Fe2O3 + C + G (W) Fe + CO2 Heat Chemical energy Work Chemical energy 第7页/共31页 Electrode electrolyte How to control the reaction direction and rate? 第8页/共31页 A schematic view of electrode reaction at solid/solution interfaces Potential shifts negatively Oz + e Rz-1

7、 The electrode potential control the Feimi level of electrode, which determine the direction and the rate of charge transfer LUMO HOMO - Rz- 1 Oz - Rz- 1 Oz E r EF EF E r e Equilibrium LUMO HOMO 第9页/共31页 lTo serve as electron reservoir (sources, sink) lTo provide and modulate the driving force of re

8、action (potential ) lTo collect and conduct the reaction current lCatalyst Rz- 1 Oz E r e LUMO HOMO 第10页/共31页 Ei Electrochemica l reactions What ? - The reaction stoichiometry Why? - The reaction thermodynamics How? - The reaction mechanism and kinetics (rates) 第11页/共31页 )( )/( )/( :DensityCurrent 2

9、 2 Secondsdt cmCoulombsdQ cmAmperesj dt dN cmondmolv)sec/( :rateReaction 2 nF Q N nF i v O + ne- R 第12页/共31页 Working electrode Potential control or monitor Current control or monitor Auxiliary electrode Reference electrode Schematic three-electrode cell used in electrochemical studies 第13页/共31页 Pt C

10、H+=1mol.l-1 H 2 H 2 H2 2H+ + 2e- 第14页/共31页 Metal wire KCl solution Hg2Cl2 Hg Pt wire Hg2Cl2 + 2e- 2Hg + 2Cl- 第15页/共31页 Possible processes involved in an electrode reaction Oad O Rad R O* R* ne Ob Rb Mass transpor t Mass transport Preceding Chemical reactions Following Chemical reactions Electrode Ch

11、arge transfer Adsorption Desorption Mass transport play a key role in electrochemical processes Reaction layer Mass transport layer Interface 第16页/共31页 第17页/共31页 ? ? transportmass of rate - reaction electrode of rate - 0 0 0 mk mk m k For a reaction consisting of a series of sequential steps or proc

12、esses, all steps will proceed with the same rate which the lowest step can reach. The kinetics of the overall reaction is determined by the kinetics of rds and the thermodynamics of the other steps. 第18页/共31页 t i 0 r R everse tim e t i 0 f 第19页/共31页 第20页/共31页 CcompactCdiffuse iRsolution 第21页/共31页 E

13、dsC R t s e R E i t= RsCd i = 0.37 i0 s R E i 0 1. Potential step tt d sRC C q iREEE dt dq i 第22页/共31页 i )( d s C t RiE s iRE 0 2. Current step tt 第23页/共31页 E vC d 1. Potential sweep t E Scan rate: v i 第24页/共31页 第25页/共31页 第26页/共31页 Charge formation & transfer Electrochemical reactions Energy conversion formation