Single-step Synthesis of Highly Porous Nitrogen-doped Carbon by Solid–gas Mechanochemical Treatment as an Oxygen Reduction Electrocatalyst (Supporting Information)

Herein, we report a single-step mechanochemical synthesis of highly porous nitrogen-doped carbon and its electrocatalytic oxygen reduction activity. X-ray diffraction and X-ray photoelectron spectroscopy measurements revealed that solid–gas mechanochemical treatment (MT) using a planetary ball mill cleaved the C–C bonds in carbon black (CB) and simultaneously incorporated nitrogen atoms with a high proportion of quaternary N into the carbon network. MT at a milling speed of 600 rpm yielded nitrogen-doped porous carbon (N-PC) with an optimal combination of nitrogen content of 2.20 at% and surface area of 516 m2 g−1, which is 10 times larger than that of CB (51.1 m2 g−1). Owing to the high nitrogen content and large surface area, N-PC synthesized by MT at a milling speed of 600 rpm exhibited higher oxygen reduction activity than N-PC synthesized by MT at a milling speed of 800 rpm and porous carbon synthesized by MT at a milling speed of 300 rpm.

本项研究中，我们报道了一种单步机械化学合成高度多孔氮掺杂碳及其电催化氧还原活性的方法。通过X射线衍射和X射线光电子能谱的测量，揭示了使用行星式球磨机进行的固体-气体机械化学处理（MT）能够断裂碳黑（CB）中的C-C键，并同时将高比例的四价氮原子引入碳网络中。在600 rpm的研磨速度下进行的MT产生了氮掺杂多孔碳（N-PC），其氮含量为2.20 at%，比表面积为516 m2 g−1，是CB（51.1 m2 g−1）的10倍。由于氮含量高和比表面积大，在600 rpm的研磨速度下通过MT合成的N-PC展现出比在800 rpm下合成的N-PC以及在300 rpm下合成的多孔碳更高的氧还原活性。