Electrocatalytic formation of NO2− at a poly crystalline Ag surface in neutral medium

Electrocatalytic reduction of NO3− at a polycrystalline Ag electrode in the presence of KCl has been investigated. The measurements made by the stationary and hydrodynamic electrodes revealed that the Ag electrode substantially promoted the activity of the NO3− reduction through a two-electron transfer process. The electrochemical investigations suggested that the reduction process follows first order kinetics. In the bulk electrolysis experiments, the rate constants (k1; 35.1 × 10−3 min−1 and k2; 6.5 × 10−3 min−1) were estimated with respect to NO3− and NO2− reduction, respectively. The voltammetric investigations and the evaluation of rate constants (k1 > k2) established that Ag electrode is efficient in the formation of NO2− from the reduction of NO3−.

Graphical abstractCyclic voltammograms obtained at the Ag electrode in N2− saturated 0.05 M KCl solution containing 0.01 M NaNO3 in the potential scan rates of (1) 9, (2) 16, (3) 25, (4) 36, (5) 40, (6) 50, (7) 60, (8) 75, (9) 80, (10) 90, and (11) 100 mV s−1 (top to bottom).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Electrocatalytic reduction of NO3− has been accomplished in the neutral medium using a polycrystalline Ag electrode. ► The NO3− reduction reaction involves two-electron transfer reaction producing NO2− as an intermediate. The NO2− reduction rate is 5.4 times slower than that of NO3− reduction triggering NO2− as a stable product. ► The mass transfer controlled process follows first order kinetics.