Electrocatalytic properties of new active ternary ferrite film anodes for O2 evolution in alkaline medium

摘要: Abstract Some ternary ferrites with molecular formula, CoFe2−xCrxO4 (0≤x≤1.0) have been synthesized at 70 °C by a precipitation method and were transformed into the film form pretreated Ni support (1.5×1.0 cm2) using an oxide-slurry painting technique. The study showed that Cr-substitution from 0.2 to 1.0 mol increased electrocatalytic activity of oxide towards oxygen evolution reaction (OER), optimum improvement in apparent being 0.8 Cr. At E=600 mV versus Hg/HgO 1 M KOH (25 °C), current density (ja) catalyst, CoFe1.2Cr0.8O4, was ∼80 times greater than observed base (i.e. CoFe2O4). OER on Cr-substituted oxides two Tafel slopes, one (b=42±1 per decade) low overpotential other (b=66±6 higher potential. order respect OH− concentration ∼1.3±0.1 for each electrocatalyst. thermodynamic parameters OER, namely, standard electrochemical enthalpy activation (ΔH°el#), (ΔH°#) entropy (ΔS°#) also determined. It values ΔH°el# ΔH°# decreased CoFe2O4 lattice; decrement, however, greatest ΔS°# largely negative varying between ∼−61 −126 J deg−1 mol−1.