Efficient bifunctional Co–N dual-doped carbon electrocatalysts for oxygen reduction and evolution reaction

The design of highly active catalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critically important. Herein, we demonstrate such remarkable bifunctional catalysts for both ORR and OER with tunable dimensional and structural properties. Three-dimensional (3D) interconnected frameworks comprising Co and N dual-doped carbon nanosheets (CNSs) and carbon nanotubes (CNTs) were fabricated, delivering a half-wave potential of 0.812 V (vs. the reversible hydrogen electrode, RHE) for ORR in alkaline media, only a little bit lower than that of the state-of-the-art commercial Pt/C (0.856 V vs. RHE). Such catalyst also displayed an OER potential of 1.582 V (vs. RHE) with an overpotential of 0.80 V between ORR and OER at the current density of 10 mA cm−2, significantly lower than that of Pt/C. We found that Co and N species synergistically played a crucial role in tuning the electrocatalytic performance. This 3D framework provided a promising bifunctional catalyst alternative for both ORR and OER.