NaCl‐Templated Porous Co/N/C Composites as Highly Active Electrocatalysts for Oxygen Electrocatalysis

In the present study, a template‐directed synthesis method was developed to fabricate a porous cobalt‐nitrogen‐carbon electrocatalyst (porous Co/N/C‐2). The new material is one example among many non‐precious metals that are promising for oxygen evolution/reduction reactions (OER/ORR), two key reactions in clean renewable energy technologies. In testing the OER activity, we found that at a current density of 10 mA cm −2 , this electrocatalyst requires only 350 mV overpotential, with a Tafel slope value of 86.58 mV dec −1 . The above electrocatalytic data are superior to most reported Co/N/C‐based catalysts, as well as comparable with those for traditional RuO 2 , which is the standard precious metal catalyst for OER application. Similarly, good results are achieved in terms of the electrocatalytic activity for the ORR. Indeed, less than 5% of H 2 O 2 is detected during the experiment, suggesting that a major portion of the reaction takes place via a highly effective (four‐electron) mechanism. The catalyst exhibits a preferential four‐electron (4e − ) reduction pathway, with an electron‐transfer number (n) of 3.92. The experimental data show excellent electrocatalytic activity, with an onset current density of 5.8 mA cm −2 and a half‐wave potential of 0.87 V versus RHE (values that we compare against traditional Pt/C samples). This work provides an accessible route to prepare low‐cost, efficient metal‐nitrogen‐carbon electrocatalysts, in view of the potential they offer in applications such as fuel cells or metal‐air batteries.