Tuning Cobalt and Nitrogen Co-Doped Carbon to Maximize Catalytic Sites on a Superabsorbent Resin for Efficient Oxygen Reduction.

The electrocatalytic performance and cost of oxygen reduction reaction (ORR) catalysts are crucial to many renewable energy conversion and storage systems/devices. Recently, transition-metal/nitrogen-doping carbon catalysts (M-N-C) have attracted tremendous attention due to their low cost and excellent catalytic activities; however, they are restricted in large-scale commercial applications by complex preparation processing. Here, a facile strategy to prepare Co-N-C catalysts has been developed. A kind of superabsorbent resin normally found in diapers, poly(acrylic acid-acrylamide), is used to adsorb a transition-metal cobalt salt and a pyrolysis strategy at 800 °C under an argon atmosphere is followed. The resin simultaneously plays a multiple role, which includes structural support, dispersing cobalt ions by coordinate bonds, and providing a carbon and nitrogen source. Attributed to the conductive carbon frameworks and abundant catalytic sites, the Co-N-C catalyst exhibits an excellent electrocatalytic performance. High onset potential (0.96 V vs. reversible hydrogen electrode, RHE), half-wave potential (0.80 V vs. RHE), and a large diffusion-limited current density (4.65 mA cm-2 ) are achieved for the ORR, which are comparable or superior to the commercial 20 % Pt/C and reported M-N-C ORR electrocatalysts. This work provides a universal dispersion technology for Co-N-C catalyst, which makes it a very promising candidate toward the ORR.