A fundamental in situ IR spectroelectrochemical study of the electrical polarization of nickel, copper and gold electrodes in the presence of the unstable tellurocyanate ion in DMSO and DMF solutions

Abstract

Subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS) studies have been performed for the first time on the interaction of the tellurocyanate ion (TeCN À ) with electrically polarised nickel (Ni), copper (Cu) and gold (Au) electrodes in dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) containing tetrabutylammonium perchlorate (TBAP) as a supporting electrolyte. In general, it was conclusively shown that the TeCN À ion decomposes at certain applied potentials on electrically polarized electrochemical cells to form elemental tellurium and cyanide (CN À ) ion. The cause of the decomposition was reasoned to be due to the presence of electrodissolved metal ions from the electrode, which destabilise the TeCN À ion through their polarising power as cations. The severity of the destabilisation was found to increase in the order Au + > Cu + > Ni 2+ , which is in general agreement with the relative polarising power of these metal ions. SNIFTIRS and IR transmission data from model solutions demonstrated that the metal complex ion speciation observed during the polarization experiments therefore arose directly from the interaction of the studied metal electrode with CN À ions released by decomposition, rather than with the TeCN À ion itself. The potential at which the electrochemical decomposition of the TeCN À ion occurred and its rate of decomposition depended on the type of metal electrode used. In general, the instability of the TeCN À ion in electrochemically polarized systems reflects its fundamental chemistry of decomposing in the presence of polarizing cations and that it may be of use as a sensor for these species in an electrochemical setting.

In Situ Electrocatalytic Infrared Spectroscopy for Dynamic Reactions

“…Due to the weak absorption signal during the experiment, different methods have been developed to performed background corrections. The most commonly used method is SNIFTIRS, which was pioneered by Pons et al at 1980s and extensively used. − Sometimes single-potential alteration FTIR spectroscopy (SPAFTIRS) is also used . Briefly, the IR spectroscopy at the reference potential ( E 0 ) and the reaction potential ( E 1 ) are collected respectively as spectrum R ( E 0 ) and R ( E 1 ).…”

Recent advances in Raman and surface enhanced Raman spectroelectrochemistry

“…UV/ Vis spectroscopy/electrochemical analysis (e.g., fluorescence spectroscopy/electrochemical analysis) can only indicate the absorption or emission spectrum information of specific functional groups, whereas more accurate molecular structure fingerprint information cannot be presented (Yu et al, 2000;Fernandez-Blanco et al, 2013). Its application in electrochemical reactions research is less extensive than the infrared spectroscopy/electrochemical analysis being developed in the same period (Kevin and Pons, 1988;Le Rille and Tadjeddine, 1999;Kavan et al, 2000;Adato et al, 2015;Alwis et al, 2015;Lardner et al, 2016). However, in situ infrared spectroscopy/electrochemical technology exhibits the defects of being easily affected by solvent (e.g., it is interfered by water absorption peaks) and less adsorbed molecular weight on electrode surface, thereby leading to the generation of weak response signals.…”