Synthesis of phosphorus-doped carbon hollow spheres as efficient metal-free electrocatalysts for oxygen reduction

Phosphorus-doped carbon hollow spheres (P-CHS) have been synthesized by a hydrothermal method using glucose as a carbon source, tetraphenylphosphonium bromide as a P source and anionic surfactant sodium dodecyl sulfate as a soft template. The as-prepared P-CHS have microporous shell structure with high specific surface area of >500 m2 g−1. The electrocatalytic activity of P-CHS for oxygen reduction reaction (ORR) in alkaline media has been studied by using a rotating ring-disk electrode (RRDE) technique. The RRDE results reveal that the as-prepared P-CHS containing 1.61 at.% of P exhibits high electrocatalytic activity and superior long-term stability for the ORR. The content of P in carbon is found to have a great influence on the microstructure and therefore the ORR activity of P-CHS. The high electrocatalytic activity and durability of P-CHS for the ORR are primarily ascribed to highly active catalytic sites induced by P doping in the carbon lattice and the efficient mass transfer of reactants and products facilitated by hollow spherical structure of P-CHS during the ORR.