In situ growth of highly active Cu-Fe spinel materials on N-doped porous carbon spheres via an adjustable localized microenvironment

Spinel-structured oxides have attracted interest owing to their long-term stability and good catalytic activity for oxygen reduction reactions. However, the insufficient rate of electron conduction in spinel-structured oxides limits their application in electrocatalysis. In this study, we propose an in situ growth of Cu-Fe spinels on the surface of N-doped glucose-derived carbon spheres via a one-pot method by adjusting the local solution environment at high temperatures, which enhances the oxygen reduction activity of the material through a tight binding between the N-doped carbon spheres and the Cu-Fe spinels. The Cu-Fe spinel material loaded on the surface of the rough porous carbon spheres showed good oxygen reduction activity with an ORR half-wave potential of 0.83 V, a transferred electron number of 3.87, a Tafel slope of 59.8 mV dec(-1), a good long-term stability, and its half-wave potential remaining almost unchanged after 5000 CV tests.