Nitrogen-doped porous activated carbon derived from cocoon silk as a highly efficient metal-free electrocatalyst for the oxygen reduction reaction

Heteroatom-doped porous carbon has attracted considerable research interest due to its effective catalytic activity towards the oxygen reduction reaction (ORR). In this study, nitrogen-doped porous activated carbon (PAC) is fabricated via a facile heat-treatment and chemical activation of cocoon silk in an inert gas atmosphere. The prepared PAC exhibits excellent ORR catalytic performances with the half-wave potential of -0.13 V and an onset potential of +0.03 V vs. Ag/AgCl, which match the Pt/C catalyst and are superior to various other reported biomass derived metal-free carbon catalysts. This catalytic proficiency is attributed to the plentiful electronegative N atoms within the carbon lattice, large surface area and high porosity. The PAC also exhibits high stability, durability and an effective tolerance effect to methanol crossover. In addition, the as-prepared PAC shows remarkable feasibility as a cathodic catalyst for microbial fuel cells (MFCs). This study provides a new approach for the synthesis of metal-free carbon nanomaterials derived from natural materials, and broadens the design for the fabrication of ORR catalysts.