Highly Sensitive As³⁺ Detection Using Electrodeposited Nanostructured MnO and Phase Evolution of the Active Material...

A simple, one-step electrodeposition approach has been used to fabricate MnO on an indium-doped tin oxide substrate for highly sensitive As³⁺ detection. We report an experimental limit of detection of 1 ppb through anodic stripping voltammetry with selectivity to As³⁺ in the presence of 10 times higher concentrations of several metal ions. Additionally, we report the simultaneous phase evolution of active material occurring through multiple stripping cycles, wherein MnO/Mn₂O₃ eventually converts to Mn₃O₄ as a result of change in the oxidation states of manganese. This occurs with concomitant changes in morphology. Change in the electronic property (increased charge transfer resistance) of the material due to sensing results in an eventual decrease in sensitivity after multiple stripping cycles. In a nutshell, this paper reports stripping-voltammetry-induced change in morphology and phase of as-prepared Mn-based electrodes during As sensing.