Copper-involved highly efficient oxygen reduction reaction in both alkaline and acidic media

Oxygen reduction reaction (ORR) plays a significant role in many renewable energy storage and conversion devices. Various kinds of transition metal-based electrocatalysts were developed to promote the ORR. Among them, Cu-based catalysts were rarely studied due to their intrinsic de-active feature in bulk state, especially in acidic medium. In this work, single Cu atoms and Cu clusters-anchored nitrogen-doped porous carbons are rationally developed. As electrocatalysts for ORR, half-wave potential (E1/2) of 0.88 V and diffusion limiting current density (JL) of 5.88 mA cm−2 can be achieved in 0.1 M KOH, exceeding the most of reported non-precious catalysts and commercial Pt/C. Significantly, as-prepared catalysts exhibit the state-of-the-art performance in acidic medium among all of reported Cu-based catalysts with the E1/2 of 0.80 V and JL of 5.86 mA cm−2. Theoretical calculations indicate that the nitrogen-coordinated Cu atoms are the dominating active sites, and the neighboring Cu cluster increases the electron density of d orbitals of single-Cu-atom, which weakened the O-O interaction, thus further boost ORR performance. This work not only presents a facile strategy to fabricate efficient catalysts but also identifies the great potential of Cu based materials for ORR in both alkaline and acidic media.