Nitrogen-doped carbon materials as multi-task metal-free catalysts

本工作旨在通过在碳基材料中掺杂氮物种来开发无金属的多功能碳基催化剂。氮掺杂已经通过在不同条件下在氨和空气流中的热处理来进行，并且如此制备的碳材料已经应用于已知由碱和金属催化剂催化的不同有机反应。掺氮碳材料对Knoevenagel缩合反应、肼还原硝基苯反应和氧化氧杂蒽反应都具有活性。在碳表面上存在几种不同类型的氮物种，并且认为催化活性物种取决于所检查的反应。对于Knoevenagel缩合，活性和吡啶型氮物种的量之间有很好的相关性。硝基苯还原活性与碳表面存在的氮和氧物种的量相关。

The present work aims to develop metal-free multifunctional carbon-based catalysts by doping nitrogen species to parent carbon materials. The nitrogen doping has been performed by heat treatment in a stream of ammonia and air under different conditions and the carbon materials so prepared have been applied for different organic reactions that are known to be catalyzed by alkali and metal catalysts. The nitrogen-doped carbon materials were active for Knoevenagel condensation, reduction of nitrobenzene with hydrazine, and aerobic oxidation of xanthene. There were a few different types of nitrogen species on the carbon surface and catalytically active species were believed to depend on the reactions examined. For Knoevenagel condensation, there was a good correlation between the activity and the amount of pyridine-type nitrogen species. The activity for nitrobenzene reduction was correlated with the amount of nitrogen and oxygen species present on the carbon surface.