Comparison of fast electron transfer kinetics at platinum, gold, glassy carbon and diamond electrodes using Fourier-transformed AC voltammetry and scanning electrochemical microscopy

摘要: Heterogeneous electron transfer (ET) processes at electrode/electrolyte interfaces are of fundamental and applied importance extensively studied by a range electrochemical techniques, all which have various attributes but also limitations. The present study focuses on the one-electron oxidation tetrathiafulvalene (TTF) reduction tetracyanoquinodimethane (TCNQ) in acetonitrile solution two powerful techniques: Fourier-transformed large amplitude alternating current voltammetry (FTACV); scanning microscopy (SECM), both supported detailed theoretical models. At conventional Pt, Au glassy carbon (GC) electrode materials, apparent (overall) charge kinetic values determined FTACV give standard ET rate constants, k0FTACV, that fast close to reversible limit. They good agreement with highly localised k0SECM measurements SECM under conditions high mass transport rates. In contrast, impact complex heterogeneous surface polycrystalline boron doped diamond (pBDD) degenerate p-type doping results across compared overall k0FTACV measured for studied. Moreover, reduced availability carriers surface, each energy state, metal, decreases as potential becomes more negative, lower k0 pBDD than GC. measurement technique has an influence: made much higher local density FTACV, TCNQ/TCNQ˙−, negative formal potential, limited carrier > k0SECM, unusual coefficients voltammetric waveshapes from SECM. These data thus highlight understanding influence further demonstrate how kinetics differ electrodes, this case organic solvent, received less attention aqueous systems studies pBDD.