Controllable synthesis of boron-doped Zn–N–C single-atom nanozymes for the ultrasensitive colorimetric detection of p-phenylenediamine

Single-atom catalysts with atomically dispersed M-Nx active sites have been widely used as nanozymes for colorimetric sensing due to their similar structure to natural enzymes, but they are still limited by their biological activity. Herein, controllable synthesis of B-doped Zn–N–C (ZnBNC) single-atom nanozymes (SAzymes) was designed and realized for the first time as a potent peroxidase mimetic. Based on the peroxidase-like activity of ZnBNC SAzymes, a novel colorimetric method was developed for the highly sensitive and selective detection of p-phenylenediamine (PPD) with a wide response range (0.3–10 μM) and a low detection limit (0.1 μM), which can be used as an alternative method for the detection of PPD in hair dyes and dyed hair samples.