Rational design of FeS2 microspheres as high-performance catalyst for electrooxidation of hydrazine

Abstract Inspired by the relatively recognized performance of transition metal sulfides in the oxidation of hydrazine, the catalytic properties of FeS2 and Fe3S4 are compared via the density functional theory calculations. Due to the different coordination numbers of iron-sulfur, the free energies of the dehydrogenation steps on FeS2 are far less than those on Fe3S4, which led to the much better catalytic performance of FeS2. Accordingly, FeS2 microspheres are rationally proposed as a more efficient electrocatalyst for hydrazine oxidation, which is then prepared by a facile one-step hydrothermal strategy. Such FeS2 microspheres show great activity for hydrazine oxidation with an onset oxidation potential of 0.22 V vs. reversible hydrogen electrode, and a peak current density of 16 mA cm−2. Meanwhile, stability and high faradaic efficiency (3.5e−/N2H4) is obtained for hydrazine oxidation to N2.