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

The field of impact electrochemistry, namely, electrochemical processes occurring at nanoparticles during collisions with a substrate electrode, has recently been applied to the recovery of commercially important metals. In this study, the reduction and oxidation of solution Mn(II) were observed on carbon black particles during nanoimpacts, with the onset potentials of the reduction and oxidation processes in good agreement with solution voltammetry. The formation of Mn(0) and MnO₂ was confirmed via scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) analysis and X-ray photoelectron spectroscopy (XPS) analysis. Coverages of between 0.2 and 0.6 monolayer equivalents were obtained for the reductive deposition of Mn, whereas for the anodic deposition of MnO₂, a more complex picture was found due to the oxidation pathway from Mn(II) to MnO₂.