Carbon quantum dots derived from rice straw doped with N and S and its nanocomposites with hydroxypropyl cellulose nanocomposite

As biomass, rice straw (RS) is often valorized as a precursor of green products. In this respect, the RS-based carbon quantum dots (CQDs) are synthesized doped with N and S during the preparation. Synergistic doping with lipoic acid and ethylenediamine can vastly increase the yield of CQD from rice straw from 6.14 % to 62.8 %, and sulfur doping plays a more important role on the surface functional groups of the quantum dots. Further assessment is achieved toward the performance of SN-CQDs-hydroxypropyl cellulose nanocomposites. The optical behavior of synthesized SN-CQDs, and the critical concentration of its liquid crystal behaviors, at which the anisotropic phase begins to emerge, is approximately 1 %. Incorporating it into HPC, especially at 5 %, provided nanocomposite films with effective liquid crystal, tensile strength, and thermal stability. This sample's texture reveals a planar structure with colors ranging from yellow to red. The synergistic effect of incorporating SN-CQDs is shown by improving the strength to ~282.1 %, and the activation energy increased from 583.6 kJ.mol−1 to 615.1 kJ/mol. HPC-SN-CQDs can be assembled into an LED device, emitting warm light, of which CIE coordinate is (0.34,0.43).