Fabricating Nanodiamonds from Biomass by Direct Laser Writing under Ambient Conditions

Commercial nanodiamonds (NDs) are usually produced by detonation and chemical vapor deposition. While these methods normally require either the application of extreme temperatures/pressures or expensive and hazardous gaseous/chemical precursors, in this study, NDs were produced on paper made from nanolignin/cellulose nanofibrils (LCNF) composite film by means of direct laser writing at ambient temperature and air pressure. The generation of NDs was found to depend largely on high laser power. Graphene nanoribbons and carbon nano-onions were obtained at lower laser power as acceptable products. As cellulose nanofibrils were unsuccessfully lased in this study, the effects of diverse components of LCNFs were investigated. Results showed that a suitable cellulose content in LCNFs can accelerate laser carbonization, while an excessive oxygen content component will lead to the combustion of LCNFs in air. Moreover, it was found that a higher lignin content was essential for the formation of NDs. Individual nanolignin particles were able to be converted into NDs. However, this lasing process needed a higher-power laser than that did that from LCNF. Considering the abundance and renewability of LCNFs, the direct laser writing technique provides a simple, inexpensive, and environmentally friendly method for the synthesis of NDs and the fabrication of paper-based carbon patterns from biomass, which is both inexpensive and readily available.