National Research Council of Canada. Energy, Mining and Environment
A simple, large-scale and green synthetic route is demonstrated for the preparation of polyquaternium derived heteroatom (N and S) co-doped hierarchically porous carbon (HPC). Our protocol allows for the simultaneous optimization of both porous structures and surface functionalities of (N and S) co-doped carbon (N-S-HPC). As a result, the obtained N-S-HPC shows a superior catalytic ORR performance to the commercial Pt/C catalyst in alkaline media, including high catalytic activity, remarkable long-term stability and strong methanol tolerance. Even in acidic media where most non-precious metal catalysts are suffered from high overpotential and low durability, our N-S-HPC exhibits an amazing ORR activity with a half-wave potential of 0.73V, and 40% enhanced limited diffusion-current density when compared to Pt/C catalyst. Particularly, when used for constructing a zinc–air battery cathode, such an N-S-HPC catalyst can give a discharge peak power density as high as 536 mW cm-2. At 1.0 V of cell voltage, a current density of 317 mA cm-2 is achieved. This performance is superior to all reported non-precious metal catalysts in literature for zinc–air batteries and significantly outperforms the state-of-the-art platinum-based catalyst.