What is the origin of the reduction peaks observed at 0.32 V and 0.5 V in the CV of Pt(111) in high-concentration HClO₄ electrolyte?
Label:chem
Topic
In cyclic voltammetry studies of Pt(111) in high concentrations of HClO₄ (1 M), anomalous reduction peaks appear at 0.32 V and 0.5 V versus the reversible hydrogen electrode (RHE). These peaks have not been fully explained in previous studies.
From: "Effect of trace impurities in perchloric acid on blank voltammetry of Pt(111)", Electrochimica Acta, Volume 466, 20 October 2023, 143035
Answer
The reduction peak at 0.32 V is attributed to the reduction of nitrates to nitric oxide (NO), confirmed by in situ Fourier transform infrared spectroscopy (FTIR). The peak at 0.5 V is consistent with the desorption of sulfate ions, as demonstrated by spiking HClO₄ electrolyte with trace quantities of sulfuric acid. These peaks are indicative of the presence of nitrate and sulfate impurities in the HClO₄ solution, which significantly impact the voltammetric response of Pt(111).
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