Oxygen Reduction on Silver in 6.5M Caustic Soda Solution

Abstract

The cathodic reduction of oxygen in 6.5M membrane-grade caustic soda solution has been studied experimentally at a silver rotating disk electrode at 25~ The results can be approximated by the parallel mechanism for oxygen reduction with catalytic decomposition of peroxide. Further analysis of this mechanism indicates that the sequential process with catalytic decomposition of peroxide predominates over the direct 4e-process. Direct application of the sequential mechanism to the data indicates that the latter mechanism with catalytic decomposition of peroxide much more accurately reflects the experimental results. The relevant kinetic parameters are calculated on the basis of the mechanisms presented.

Silver Nanowire‐Based Catalysts for Oxygen Reduction Reaction in Alkaline Solution

“…These results are in agreement with fundamental studies by Adanuvor and White where pre-reduced silver electrode undergoes 4e À reduction and produces minimal hydrogen peroxide as an intermediate. [50] In a strongly alkaline electrolyte (6.5 M NaOH), two-wave O 2 reduction polarization curves were observed for Ag electrodes, where the first reduction wave corresponded to 4-electron reduction and the second wave to the 2e À + 2e À reduction process. [50] Figure 4c presents a comparison of polarization curves for peroxide reduction on GC electrodes covered with AgNWs of three different diameters.…”

Oxygen Reduction Reaction on Silver Catalysts in Alkaline Media: a Minireview

“…Adanuvor et al. studied the ORR on silver electrodes in 6.5 M NaOH solution and also confirmed that O 2 reduction is first order with respect to O 2 concentration . They observed two‐wave polarisation curves and performed a thorough kinetic analysis of the data.…”

“…[3] Adanuvor et al studied the ORR on silver electrodes in 6.5 M NaOH solution and also confirmed that O 2 reduction is first order with respect to O 2 concentration. [4] They observed two-wave polarisation curves and performed a thorough kinetic analysis of the data. The estimated kinetic parameters of the reaction led to the conclusion that the ORR proceeds via sequential mechanism involving catalytic decomposition of peroxide.…”

The oxygen reduction reaction at silver electrodes in high chloride media and the implications for silver nanoparticle toxicity

“…Moreover, superoxide O 2 À c and hydroxyl radicals cOH react with most biomolecules in its path including lipids, proteins, and DNA. In reactions with saturated compounds, hydroxy radicals cOH can abstract hydrogen atoms from carbonhydrogen bonds forming a stronger OH bond and radical propagation (eqn (17) and (18)). [35][36][37]41 An example is the lipid peroxidation, the product of which is harmful to membraneassociated proteins, 42 In this paper we generate a fundamental understanding of the ORR in chloride containing media including seawater to explore the possible fate of silver nanoparticles in those media.…”

“… 16 In particular, as a common oxygen reduction catalyst, the ORR on silver may involve catalytic decomposition of H 2 O 2 alongside or as an alternative to the rapid electroreduction of peroxide to water ( eqn (4)–(8) ). 17 O 2 + e − ⇌ O 2 − ˙ (RDS) O 2 − ˙ + H 2 O + e − ⇌ HO 2 − + OH − HO 2 − + H 2 O ⇌ H 2 O 2 + OH − …”