Electrooxidation of sulfide by cobalt pentacyanonitrosylferrate film on glassy carbon electrode by cyclic voltammetry

A glassy carbon (GC) electrode was modified with cobalt pentacyanonitrosylferrate (CoPCNF) film. Cyclic voltammetry (CV) of the CoPCNF onto the GC (CoPCNF/GC) shows a redox couple (FeIII/FeII) with a standard potential (E0′) of 580 mV. The current ratio Ipa/Ipc remains almost 1, and a peak separation (ΔEp) of 106 mV is observed in 0.5 M KNO3 as the supporting electrolyte. Anodic peak currents were found to be linearly proportional to the scan rate between 10 and 200 mV s−1, indicating an adsorption-controlled process. The redox couple of the CoPCNF film presents an electrocatalytic response to sulfide in aqueous solution. The analytical curve was linear in the concentration range of 7.5 × 10−5 to 7.7 × 10−4 M with a detection limit of 4.6 × 10−5 M for sulfide ions in 0.5 M KNO3 solution.