Reversible redox transition and pseudocapacitance of molybdenum/surface molybdenum oxides

Redox transitions and superior pseudocapacitance are two typical characteristics in the electrochemical behavior of metallic Mo (with surface Mo oxides) and bulk Mo oxides; both of which were attributed to the participation of H⁺/cations. The effects of different electrolyte anions (Cl ^-, SO₄^2- and ClO₄^-) on redox transition and pseudocapacitance of thin-film 'Mo/Mo oxides' electrodes were assessed in this work through DC and AC electrochemical experiments. Voltammetric peak potentials and currents and potential-dependent pseudocapacitance were strongly dependent on the electrolyte's anion. The variations were tested at different electrolyte pH levels and using different electrolyte cations (Li⁺, Na⁺ and K⁺). The results were correlated with those obtained using a Se⁴⁺ based electrolyte. The findings reported here are expected to aid the applicability of Mo and its oxides in electrocatalysis, electrodeposition, supercapacitor, display, corrosion control and solar cells.