A new approach to in-situ uniform growth of Fe<inf>3</inf>O<inf>4</inf> nanoparticles over thermally exfoliated rGO sheet for the non-enzymatic and enzymatic detection of glucose

A new strategy has been adopted to synthesis agglomeration free uniformly decorated Fe3O4 nanoparticles (NPs) over reduced graphene oxide (rGO) sheets using a solid-state pyrolysis method (Fe3O4/erGO). This strategy does not require any additional capping agents. The morphology and performance of the synthesised Fe3O4/erGO were then compared with a reference catalyst prepared by the conventional chemical precipitation method (Fe3O4/rGO). It was observed that the as-prepared Fe3O4/erGO shows the presence of higher defect densities, more wrinkled nature and significantly higher reactivity towards glucose oxidation than Fe3O4/rGO. The catalyst Fe3O4/erGO modified non-enzymatic and enzymatic sensor shows about 25 and 64 times increment in current response than Fe3O4/rGO towards glucose oxidation, attributed to the higher effective electrochemical surface area (ECSA). The sensitivity of both the non-enzymatic and enzymatic sensor is calculated, taking into account both the ECSA and the geometrical surface area (GA). Both the non-enzymatic and enzymatic sensor exhibit high sensitivity, wide range linearity with a low detection limit of 4.1 µM and 2.2 µM respectively. They also show good stability over 20 cycles. It was also observed that the performance of the non-enzymatic sensor in real blood is comparable with the clinically obtained value of glucose. Additionally, the non-enzymatic sensor also shows potential for simultaneous detection of glucose and uric acid. Thus, the features of both the non-enzymatic and enzymatic Fe3O4/erGO catalyst demonstrate its potential for use as a practical electrochemical sensor.