Fe single atoms anchored on fluorine-doped ultrathin carbon nanosheets for sensitive colorimetric detection of p-phenylenediamine

Single-atom catalysts have attracted enormous research interest in the field of catalysis owing to their remarkable catalytic activity, excellent stability and outstanding atom utilization. Herein, a new single atom based on single Fe atoms on fluorine-doped (Fe-SAs@FNC) ultrathin carbon nanosheets was successfully synthesized by a polymer-assisted heating method. Experimental evidence showed that the resultant Fe-SAs@FNC with Fe-N4 sites exhibits superior peroxidase-like activity, which oxidizes the colorless 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue product in the presence of hydrogen peroxide (H2O2). Based on this, an ultrasensitive and highly selective colorimetric detection method for p-phenylenediamine (PPD) in hair dyes and PPD in hair after dyeing was established, which had a wide linear range (0.2-50 μM) and low detection limit (0.07 μM). This method shows satisfactory sensitivity and selectivity.