Ammonium nickel phosphate on nickel foam with a Ni3+-rich surface for ultrasensitive nonenzymatic glucose sensors

We propose a new, simple and effective strategy to enhance the electro-catalytic activity by regulating the valence states of the electro-catalyst. The proportion of Ni3+/Ni2+ on the ammonium nickel phosphate/nickel foam electrode surface was increased after H2O2 solution treatment. The kinetic analysis results showed catalytic rate constants (Kcat) of Ni3+-rich surface electrode (4.028 × 106 cm3·mol−1·s−1) is bigger than the original electrode (4.928 × 105 cm3·mol−1·s−1), suggesting higher electro-catalytic activity of Ni3+-rich surface electrode. Ni3+-rich surface electrode shows an ultra high sensitivity (11,361 µA·mM−1·cm−2) in the range of 0.001-1 mM, which is much higher than the original electrode in the same linear range. And the sensitivity of 3579.9 µA·mM−1·cm−2 of Ni3+-rich surface electrode in the range of 2-4 mM is also enhanced compared with the original electrode.