Surface Modification of CN through Oxygen-Plasma Treatment: A Simple Way toward Excellent Hydrophilicity.

We developed a universal method to prepare hydrophilic carbon nitrogen (CN) nanosheets. By treating CN nanosheets with oxygen plasma, hydroxylamine groups (N-OH) with intense protonation could be introduced on the surface; moreover, the content of N-OH groups increased linearly with the oxygen-plasma treatment time. Thanks to the excellent hydrophilicity, uniformly dispersed CN solution were prepared, which was further translated into CN paper by simple vacuum filtration. Pure CN paper with good stability, excellent hydrophilicity, and biocompatibility were proved to have excellent performance in tissue repair. Further research demonstrated that the oxygen-plasma treatment method can also introduce N-OH groups into other nitrogen-containing carbon materials (NCMs) such as N-doped graphene, N-doped carbon nanotube, and CN, which offers a new perspective on the surface modification and functionalization of these carbon nanomaterials.