A comparative study of carbon nanotube supported MFe2O4 spinels (M = Fe, Co, Mn) for amperometric determination of H2O2 at neutral pH values

Three ferrites of type MFe2O4 (where M is bivalent Fe, Co or Mn) dispersed on multi-walled carbon nanotubes (MWCNTs) were prepared by a coprecipitation method. Their electrocatalytic properties toward the reduction of H2O2 at pH 7.4 were systematically compared. Catalytic reduction rates at an applied potential of -0.4 V (vs. Ag/AgCl) and pseudo Michaelis-Menten constants show the electrocatalytic ability to follows the order Fe3O4 > CoFe2O4 > MnFe2O4. This diversity is attributed to the differences in the M(II) used and its occupancy on the lattice surface. The sensitivities are 120.98 +/- 0.15, 48.45 +/- 0.23 and 32.25 +/- 0.27 mu A cm(-2) mM(-1), and the limits of detection are 0.98, 2.59 and 5.64 mu M of H2O2 (at an S/N ratio of 3).