INORGANIC ELECTROCHEMISTRY
Academic year and teacher
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- Versione italiana
- Academic year
- 2015/2016
- Teacher
- STEFANO CARAMORI
- Credits
- 6
- Didactic period
- Secondo Semestre
- SSD
- CHIM/03
Training objectives
- Knowledges: understanding the structure of the electrified interface and the fundamentals of electrochemical kinetics and thermodynamics. Electronic properties of conductor and semiconductors, elements of microscopic theories for the the heterogeneous charge transfer between molecules and extendend solids. Understanding of the current voltage characteristic of semiconductor/electrolye junctions based on space charge and diffusive transport models.
Abilities: calculating the open circuit potential of a galvanic cell and to evaluate the potential determining chemical variables.
Ability to proposing a kinetic model for a multi-stage electrochemical reaction and to extract diagnostic criteria within reasonable approximations.
Manipulation of Fermi-Dirac distribution to obtain thermodynamically relevant quantities for the description of the energetics of the semiconductor-electrolyte interface.
Ability to describe the architecture and use of simple photoelectrochemical cells for carry out energy conversion processes
Prerequisites
- Fundamentals of electrostatics (Gauss Theorem, Poisson equation)
Elements of Chemical thermodynamics and Kinetics Course programme
- The course is divided into three main sections. 1) Cell thermodynamics and structure of the electrified interface (ca. 20 hours): thermodynamics of electrochemical cells. Volta (outer) and dipolar potential. Galvani Potential. Electrochemical potential and its application to the description of cell thermodynamics. Examples of electrochemical cells involving homogenous and heterogeneous equilibria. Liquid joint potentials and their minimization. Membrane potentials and their exploitation in electroanalytical chemistry. The glass electrode.
The structure of the electrified interface. Gibbs Duhem equation for the interfaces. Lippmann Equation. Electrocapillary curve. The Helmholtz Perrin model of the electrified interface and comparison with the experiment. The Gouy-Chapman model and modification according to Stern and Grahame. Description of the capacitive behavior of an ideally unpolarizable interface (mercury electrode). Structure of the interface in the constant capacitance region and in presence of contact adsorption. Inner Helmholtz Plane.
2) Electrochemical kinetics (ca.16 hours): Butler-Volmer equation. Microscopic theories of the charge transfer. Marcus-Gerischer Equation. Some quantum-mechanical aspects of heterogenous charge transfer processes.
Multi-stage electrochemical processes. Steady state, rate determining step, adsorbed intermediates. Consequences of the kinetic model on the Tafel slope and its significance as a diagnostic tool for verifying mechanistic hypothesis. Electrocatalysis.
3) Semiconductor electrochemistry and photoelectrochemistry (ca.12 hours). n and p-type semiconductor. Formation of space charge region. Consequences on the J-V characteristics in the dark and under illumination Mott-Schottky equation. Generation, transport and recombination of charge carriers under illumination. Diffusion length of charge carriers. Charge transfer kinetics in the presence of built in potential. Gärtner model and relevant limiting cases. Nanostructured electrodes. Chemical capacitance. Models of porous photoelectrodes in the presence of charge generation and transport.
Technological aspects of electrochemical and photoelectrochemical processes for energy conversion, storage and environmental remediation. Didactic methods
- 48 hours of lectures in the classroom mostly hand writing at the blackboard. Lessons are complemented by slides reporting experimental correlations and results.
Learning assessment procedures
- The oral examination will allow to verify the knowledge of the students about the structure of the electrified interface, the fundamental of kinetic and electron transfer models used in electrochemistry and the properties of the semiconductor/electrolyte junction. The student should show the following abilities: ability to use relationships between electric variables and thermodynamic functions in order to predict equilibrium cell and membrane potentials of different kinds of galvanic cells. Ability to use kinetic equations based on the high field approximation to describe multi-step electrochemical reactions and obtain mechanistic diagnostic criteria. The student must be able to deduct the current/voltage relationships in schottky barriers and describe the architecture and functioning of photoelectrochemical cell for solar energy conversion.
The student will be allowed to choose a preferred topic to initiate the discussion of his oral Reference texts
- J.O'M. Bockris A. Reddy "Modern Electrochemistry"
N. Sato "Electrochemistry at Metal and Semiconductor Electrodes"
A.J. Bard, L. Faulkner "Electrochemical Methods, Fundamentals and Applications"
Gileadi, "Electrochemical Kinetics for Chemists, Engineers and Material Scientists"
Slides are available to the students.
