▎ 摘　　要

A simple and realistic approach to the utilization of waste "black carbon particulates of petrol soot" for the fabrication of few-layer water-soluble photoluminescent graphene nanosheets (wsGNS) is described herein. Direct transformation of pollutant soot to fluorescent nanocarbons can be a promising approach for providing some economic benefits along with a clean atmosphere. Oxidation of petrol soot resulted in the isolation of the watersoluble version of graphene nanosheets (GNS). Oxidative treatment is a key step in preventing the aggregation of the GNS and rendering them water-soluble. A high degree of "selfpassivation" on wsGNS provides evidence of the tunable photoluminescent emissions over a broad range of the visible spectrum with slight extension in the near-infrared region. The photoluminescent properties of wsGNS are used here for the selective detection of hexavalent chromium ions with a detection limit of 0.51 mu M and for imaging HeLa cells.