The Current's Language: A Narrative Review of Electroanalytical Chemistry, from Faraday's Decomposition to Impedance Spectroscopy
Electroanalytical chemistry reads chemistry through the electrode: the family of methods—polarography, cyclic voltammetry, and impedance spectroscopy—that make the current's response to a programmed potential a quantitative and mechanistic language. This article presents a narrative review of the primary literature that built that language, from Faraday's 1834 electrical decomposition and Nernst's 1889 electromotive activity, through Heyrovský and Shikata's 1925 polarograph and Ilkovič's 1934 diffusion-current equation, Randles's 1948 cathode-ray polarography and Ševčík's 1948 triangular-wave analysis, Nicholson and Shain's 1964 theory of stationary electrode polarography, whose cyclic voltammetry's peaks became the field's fingerprints, Kolthoff and Lingane's 1952 Polarography and Delahay's 1954 instrumental methods, Bard and Faulkner's 2001 Electrochemical Methods, the codifying textbook, and the impedance line of Epelboin, Keddam, and Takenouchi's 1972 reaction models and Orazem and Tribollet's 2008 Electrochemical Impedance Spectroscopy. The synthesis is organized around three themes: the thermodynamic and polarographic foundation, in which the electrode's equilibrium and diffusion currents were formalized; the voltammetric settlement, in which the sweep's peaks acquired their theory and their diagnostic power; and the impedance extension, in which the frequency domain separated the interface's processes. It is concluded that electroanalysis's century is the electrode's conversion into an instrument—its current a language whose grammar the corpus wrote.