Preparation of concentration dependent nitrogen sulfur Co-doped graphene quantum dots by UV irradiation and reversible optical switch of hydroxypropyl methyl cellulose

Nitrogen and sulfur co-doped graphene quantum dots (N, S-GQDs) are prepared by using o-phenylendiamine and catechol as raw materials under UV irradiation in dimethyl sulfoxide (DMSO) solution for 2 h. The resultant N, S-GQDs show uniform size, good crystallinity and fluorescence stability. The tunable polychromatic luminescence is obtained by adjusting the concentration of N, S-GQDs. Then, N, S-GQDs/HPMC composite material is designed and synthesized, which exhibits light responsive optical switching performance owing to micro-aggregation efficacy of N, S-GQDs to transform light into heat and drive the phase transition of hydroxypropyl methyl cellulose (HPMC). Therefore, the prepared N, S-GQDs/HPMC with excellent solar modulation ability can easily switch between opaque and transparent states depending on weather condition. In the end, the thermoresponsive property of N, S-GQDs/HPMC endows it with good performance as functional materials matrix.