voltammogram

A voltammogram is a plot of current versus applied potential obtained during voltammetric electrochemical measurements. It records the electric current response of a solution to controlled changes in the potential of a working electrode in the presence of a supporting electrolyte. As the potential is swept, oxidation and/or reduction of analyte species generates Faradaic current, typically accompanied by smaller non-Faradaic (capacitive) currents.

Interpreting a voltammogram involves relating features to the redox behavior of species in solution. For a simple reversible redox couple, the voltammogram shows oxidation and reduction peaks whose potentials approximate the formal redox potential, and whose peak currents scale with concentration and diffusion coefficients. The separation of peak potentials provides information about electron-transfer kinetics; broader, shifted, or suppressed peaks indicate slower kinetics or irreversibility. The area under peaks relates to the number of electrons transferred. Mass transport, electrode surface state, and convection influence peak shapes, while a supporting electrolyte minimizes ion migration effects.

Common voltammetric techniques produce different voltammograms. Cyclic voltammetry involves sweeping the potential forward and backward to yield a characteristic loop. Linear sweep voltammetry uses a single directional sweep. Differential pulse voltammetry and square wave voltammetry employ pulsed potentials to enhance sensitivity and resolution.

Applications of voltammograms span qualitative identification of redox-active species, quantitative concentration analysis, investigation of reaction mechanisms and kinetics, sensor development, corrosion studies, and energy storage research.