Porous 2D carbon nanosheets synthesized via organic groups triggered polymer particles exfoliation:an effective cathode catalyst for polymer electrolyte membrane fuel cells

The synthesis of two-dimensional (2D) porous carbon materials has attracted much attention due to their widespread applications. In this work, Fe/N doped hierarchical porous carbon nanosheets are developed through thermal activation step based on organic groups triggered polymer particles exfoliation. Polymer nanoparticles are exfoliated by the reaction between the phenolic hydroxyl groups and the amino groups. The gas produced from dicyandiamide then blows polymer fragments into ultrathin flexible carbon nanosheets under pyrolysis process, along with nitrogen doping. The Fe–N–C catalyst exhibits half-wave potential (E1/2) at 0.852 V (vs. RHE) in 0.1 M KOH and at 0.686 V (vs. RHE) in 0.5 M H2SO4 for oxygen reduction reaction. Additionally, the polymer electrolyte membrane fuel cell that employs the catalyst at the cathode exhibits good durability without showing significant degradation after 96 h continuous operation. Furthermore, this method can be generalized to synthesize carbon nanosheets by using various polymer precursors. This work provides a new and general strategy for preparing porous carbon or metal/carbon nanosheets, which paves the way for the mass production of effective 2D carbon materials in many important applications.