▎ 摘　　要

The exploitation of highly sustainable, highly efficient catalysts toward oxygen reduction reaction to replace the precious Pt is a key issue for metal air batteries. In this report, sustainable pollen derived three-dimensional porous carbon/graphene composites with Zn and N doping are developed as non-precious catalyst toward oxygen reduction reaction. The prepared Zn and N doped porous carbon/graphene composites show a hierarchical porous structure, large specific area, and high N contents. As catalyst toward oxygen reduction reaction, the prepared sample with an optimized graphene content exhibits a half-wave potential similar to 0.90 V (versus reversible hydrogen electrode), and a limited current density of 5.5 mA cm(-2) in alkaline electrolytes. Meanwhile, it manifests remarkable electrochemical stability and superior tolerance to methanol poisoning. It is found that Zn, N doping and introduction of graphene are key factors for the improved oxygen electrocatalytic capability because active sites and conductivity are strengthened. Moreover, the prepared sample also shows a good oxygen reduction activity in acid electrolyte. Density functional theory calculations demonstrate that Zn-N-4 is the major and the most active site. On the basis of the excellent performance, the prepared composites with renewable biomass sources may have a good potential as a highly efficient and durable oxygen reduction electrocatalysts.