Multifunctional graphene (RGO) wrapped Au plasmonic nanostructure: Giant enhanced photoluminescence, excellent visible-light assisted photodetection along with its application towards electrochemical non-enzymatic H2O2 and AA biosensor

Abstract: We have synthesized bare GO (S1), RGO wrapped Au nanocomposite (S2) and characterized by FESEM and Raman. Electrochemical study shows that S2 exhibits very sensitive electrochemical sensing capability towards H2O2... [ view full abstract ]

Abstract: 

We have synthesized bare GO (S1), RGO wrapped Au nanocomposite (S2) and characterized by FESEM and Raman. Electrochemical study shows that S2 exhibits very sensitive electrochemical sensing capability towards H₂O₂ and AA due to presence of a large number of catalytic sites in the sample. Enhanced PL emission is due to combined influence of FRET and SPR effect for Au nanoparticles. Moreover, upon visible light illumination, S2 exhibits an enhanced current response of switching due to production of photocurrent through inter-band 6sp transition within Au.

Introduction: 

In the past few years nano/micro sized materials have gained considerable focus due to their large scale prospective applications. Hydrogen peroxide (H2O2) is extensively used in clinical, biopharmaceuticals, environmental and industrial fields. Ascorbic acid (AA) is a powerful antioxidant, naturally occurs in citrus fruits and vegetable products. Therefore, sensitive detection of a small quantity of H2O2 or AA is of great scientific importance. We have studied PL, visible-light assisted photodetection and electrochemical sensing based on S2. 

Results and Discussion: 

The FESEM images of both samples are depicted in Fig. 1(a) and 1(b), where RGO wrap a large no of Au nanoparticles (50-70 nm). Fig. 1(c) shows Raman spectra of S1 and S2, confirms the attachment of RGO with Au. Fig. 1(d) depicts that RGO-Au is more electroactive than bare GO. So, we have measured biosensing study (H2O2 and AA) based on RGO-Au/ITO working electrode here. The value of the sensitivity obtained from the calibration curve (Fig. 2) are 280.28 µAmM-1cm-2 (in a wide range from 1µM to 0.8 mM, correlation coefficient = 0.96681 and the lowest detection limit is estimated to be 6.80 µM at S/N= 3) towards H2O2 sensing and 314.07µAmM-1cm-2 (in a wide range from 25µM to 300µM, correlation coefficient = 0.97133 and the lowest detection limit is estimated to be 6.80 µM at S/N= 3) towards AA sensing(Fig. 2). Moreover, S2 shows electrochemical switching under visible light, depicted in Figure 3. 

Conclusion: 

So we can use RGO@Au for electrochemical H2O2 and AA biosensor and visible light assisted photodetection applications purpose.