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–N 4 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 (H 2 O 2 ). 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.