▎ 摘　　要

A facile approach is proposed for the growth of platinum nanoparticles on graphene oxide (PtNPs/GO). The resulting PtNPs/GO hybrid has been proved to function as peroxidase mimics that can catalyze the oxidation of peroxidase substrates in the presence of hydrogen peroxide (H2O2). Kinetic studies indicate that the PtNPs/GO nanocomposite has a considerably higher affinity for both 3,3', 5,5'-tetramethyl-benzidine (TMB) and H2O2 than those of other platinum-based peroxidase mimics. Furthermore, colorimetric recognition and sensing of L-cysteine with high sensitivity and selectivity is presented based on target-induced shielding against the peroxidase-like activity of PtNPs/GO. We envision that this material will be an ideal candidate for a wide range of potential applications in the fields of biomedicine and environmental chemistry.