▎ 摘　　要

Fluorescence quenching of fluorescent dyes by metals, metal oxides or carbon nanomaterials is a trending technique for elemental inspection of nanoscale physical and biochemical processes. Development of graphene oxide-based fluorescence sensors has become a hot spot of research for biomedical applications owing to its profound optical, electrical and sensing properties. Chemical doping of graphene oxide leads to upgradation of its intrinsic features. Hence, it is of great interest to investigate doped counterparts of graphene oxide for credible optical and biosensing. In view of this, we herein report successful sulfur doping of graphene oxide with superb catalytic activity towards enhanced fluorescence quenching and ultrasensitive detection of hydrogen peroxide. Results evidence that sulfur doping via hydrothermal treatment greatly influences the surface chemistry, functionalities and thus the catalytic performance of graphene oxide. The high quenching efficiency of sulfur doped graphene oxide can be attributed to its capabilities of good adsorbability and high electron mobility that substantially catalyzes the decomposition of hydrogen peroxide into - OH radicals, consequently quenching the fluorescence of Rhodamine-B efficiently. Characterization tools such as XRD, SEM, FTIR, UV-Vis, XPS, RAMAN spectroscopy were used to investigate the surface chemistry and morphology and chemical composition of the prepared samples. Different parameters such as concentration of dye, amount of dopant, concentration of particles etc.; were explored for ultrasensitive detection of hydrogen peroxide. Under optimal conditions, the limit of detection (LOD) for hydrogen peroxide was as low as 100 pM with linear detection range from 1 nM to 1 mu M. Hence, based on our findings, we propose a highly desirable sensitive and selective H2O2 detection method by virtue of high binding affinity and quenching ability of SGO.