A Thermally Decomposable Template Route to Synthesize Nitrogen-Doped Wrinkled Carbon Nanosheets as Highly Efficient and Stable Electrocatalysts for the Oxygen Reduction Reaction

摘要

We successfully developed a thermally decomposable template route to prepare wrinkled carbon nanosheets with a high level of nitrogen functional moieties by direct carbonization of biomass glucose and dicyandiamide as the renewable feedstocks. Confined pyrolysis of glucose within the interlayers of dicyandiamide-derived g-C3N4 as a thermally removable template results in the formation of two-dimensional (2D) wrinkled carbon nanosheets as well as simultaneous high-level nitrogen doping. The textural properties and nitrogen contents could be controlled by adjusting the mass ratio of glucose/dicyandiamide. Among various samples, the sample prepared with the dicyandiamide/glucose mass ratio of 7/1 has optimal activity for the electrocatalytic oxygen reduction (onset potential -0.12 V vs saturated calomel electrode (SCE); limiting current density 4.73 mA/cm(2)) in 0.1 M KOH solution, the half-wave potential of which is only 67 mV larger than that for 20 wt % Pt/C. Moreover, it demonstrates a highly efficient four-electron reaction process, as well as superior durability and tolerance to MeOH crossover to Pt/C. The excellent activity is mainly attributed to the high content of pyridinic and graphitic-N groups, highly graphitized structures, and wrinkled 2D nanostructures, efficiently promoting the increased exposure of actives sites and fast mass/electron transfer.