Quantitative removal of Hg(II) as Hg(0) using carbon cloths coated graphene quantum dots and their silver nanoparticles composite and application of Hg(0) for the sensitive determination of nitrobenzene

The removal of Hg(II) by adsorption using various carbon based materials is extensively studied in the past. But, the disposal of the resulting Hg(II) adsorbed materials is the major concern. Herein, a simple and novel sustainable strategy is introduced to remediate Hg(II) as Hg(0) with the help of graphene quantum dots (GQDs) coated carbon cloth (CC) and utilize the formed Hg(0) as an sensor for nitrobenzene (NB). When GQDs coated CC (CC/GQDs) was contacted with Hg(II) of different concentration it was converted into Hg(0), which is confirmed by TEM and SEM. The reduction of Hg(II) to Hg(0) by CC/GQDs is further confirmed from the XPS spectrum obtained for Hg 4 f region at binding energies of 100 and 104 eV besides differential pulse voltammetry (DPV). The Hg(II) removed from the solution is quantified by ICP-AES. It is found that CC/GQDs completely removed 10 ppm Hg(II) within 2 h. Further, to enhance the removal efficiency, silver nanoparticles are introduced on GQDs ([email protected]). The CC/[email protected] show 3-fold higher removal efficiency than CC/GQDs. Finally, the formed product, Hg(0) is successfully used as a sensitive electrochemical sensor for NB with the limit of detection of 30 pM (S/N = 3).