▎ 摘　　要

So far, it is difficult to preparegraphene quantum dots (GQDs)with high quantum yield (QY), high biocompatibility, and high yieldby conventional top-down methods. We describe here a facile strategyto synthesize GQDs in NaOH/N-methylpyrrolidone (NMP)under sonication, which was subsequently passivated by saccharideto improve their stability. In the synthesis process, the GQDs werepredominantly generated through exfoliation of graphite sheets. NaOHboosted the formation of GQDs by intercalation into the layer of graphitesheets, and the yield could be effectively increased to 7.54% witha prolonged sonication time and enhanced power, which was differentfrom traditional methods. Due to the structure of the GQDs being similarto that of pristine graphene, GQDs possessed relatively high QYs,up to 19.12%. With further functionalization by hydrophilic saccharide,xylan-passivated GQDs with better stability and QY were applied forthe detection of Fe3+ in the range of 0-75 & mu;Mwith a limit of detection of 92.8 nM. Furthermore, chitosan-oligosaccharide(COS)-passivated GQDs showed good performance in cell imaging. Therefore,this work provides an efficient method to prepare GQDs and presentstheir promising application in ferroptosis after passivation.