Redox Electrochemistry of Mn(II) Via Carbon Black Nanoparticle Impacts

The field of impactelectrochemistry, namely, electrochemical processesoccurring at nanoparticles during collisions with a substrate electrode,has recently been applied to the recovery of commercially importantmetals. In this study, the reduction and oxidation of solution Mn(II)were observed on carbon black particles during nanoimpacts, with theonset potentials of the reduction and oxidation processes in goodagreement with solution voltammetry. The formation of Mn(0) and MnO2 was confirmed via scanning electron microscopy/energy-dispersiveX-ray (SEM/EDX) analysis and X-ray photoelectron spectroscopy (XPS)analysis. Coverages of between 0.2 and 0.6 monolayer equivalents wereobtained for the reductive deposition of Mn, whereas for the anodicdeposition of MnO2, a more complex picture was found dueto the oxidation pathway from Mn(II) to MnO2.