A high-energy-state biomimetic enzyme of oxygen-deficient MnTiO nanodiscs for sensitive electrochemical sensing of the superoxide anion.

It is of great importance to determine the superoxide anion (O2˙-), a kind of active free radical that plays important roles in catalytic and biological processes. We present here a high-energy-state biomimetic enzyme with extraordinary activity for O2˙- by inducing surface oxygen defects in MnTiO3 nanodiscs. Oxygen defects enable surface rich active Mn sites with high oxidation ability, which significantly promote the adsorption and electro-oxidation of O2˙-. The oxygen deficient MnTiO3 towards O2˙- exhibits a sensitivity of 126.48 μA μM-1 cm-2 and a detection limit of 1.54 nM, among the best performance of O2˙- sensing platforms.