FePt nanoparticles-decorated graphene oxide nanosheets as enhanced peroxidase mimics for sensitive response to H2O2.

Bimetallic-based nanoparticles usually display improved catalytic performance compared to monometallic counterparts. Herein, the well-dispersed FePt nanoparticles decorated on the surface of graphene oxide (GO) nanosheets have been successfully synthesized by a simple polyol protocol method. The FePt/GO nanocomposites were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), magnetic property measurement system (MPMS), and Fourier transform infrared spectra (FT-IR), respectively. Interestingly, FePt/GO nanocomposites demonstrated the highly intrinsic peroxidase-like activity and can rapidly catalyze to oxidize the substrate 3,3',5,5'-tetramethylbenzidine (TMB) into a blue product oxidized TMB (oxTMB), in the presence of H2O2 only in 30 s observed by the naked eye. Electron spin resonance (ESR) revealed that the underlying catalytic mechanism of FePt/GO nanocomposites was attributed to the generation of hydroxyl radicals (OH) from decomposing of H2O2, due to the synergistic effect between FePt nanoparticles and GO nanosheets. Moreover, H2O2 can be detected over a wide linear detection range of 0.03-0.5 mM with a detection limit of 2.2 × 10-5 M. Based on the mimic enzyme FePt/GO, a colorimetric ultrasensitive H2O2 sensor was constructed with the help of TMB in buffer solution.