Nitrogen, sulphur co-doped graphene quantum dot: An excellent sensor for nitroexplosives

Study of sensing properties of nitroexplosives using luminescent carbon based quantum dots is an interesting area of research. Enhancement in sensing ability exploiting edge states and doped states in quantum dots is an elegant approach. In the present work, graphene quantum dots (GQD) are co-doped by nitrogen and sulphur to produce large number of localized energy levels near conduction band. Remarkable enhancement in fluorescence quenching effect compared to their individual doped states either by nitrogen or sulphur is observed using only 90μM solution of 2,4,6-trinitro phenol (TNP) via charge transfer among these doped states to detect trinitrophenol selectively. The detection limit has been calculated to about 19.05 ppb. The origin of this ultra high fluorescence quenching and low detection limit is the presence of electron rich edge states due to ‘N’ and ‘S’ dopants as verified by Zeta potential results.