Ultrathin two-dimensional phosphorus and nitrogen Co-doped carbon nanosheet as efficient oxygen reduction electrocatalyst

Abstract Developing metal-free electrocatalysts with high performance towards oxygen reduction reaction (ORR) is critical for the commercialization of fuel cell technologies and metal-air batteries. Herein, we develop an effective and rational strategy to synthesize an ultrathin two-dimensional (2-D) carbon nanosheet (P–NCNS) with more exposed N and P doping sites as ORR electrocatalyst. This strategy adopts ice/salt dual-template to construct an ultrathin 2-D porous carbon nanosheet using gelatin as C/N precursor, and employs red P as P dopant to achieve controllable doping of heteroatoms. Red P also acts as a pore-forming agent to create abundant porosity on 2-D carbon surface through the activation of P-containing species. The resulting carbon nanosheet exhibits an ultrathin thickness of 1–2 nm, a large specific surface area (499.5 m2 g−1) and a well-defined micro/mesoporous structure, showing more exposed and abundant N, P doping sites that are accessible to the ORR reactants. As a result, P–NCNS shows an outstanding ORR performance both in alkaline and acidic electrolyte. More attractively, P–NCNS was used as the cathode electrocatalyst for a primary zinc-air battery showing good performance and long-term stability. This strategy offers a new insight for the design and synthesis of high-performance non-precious metal electrocatalyst for ORR.