Platinum nanoparticle-decorated reduced graphene oxide nanosheets: A recyclable and highly efficient catalyst towards the reduction of para-nitrophenol and methylene blue

The present study focuses on the design and development of Pt nanoparticle (PtNPs) decorated reduced graphene oxide (RGO) nanohybrid as an efficient heterogeneous catalyst towards the reduction of p-nitrophenol (p-NP) and methylene blue (MB). The citrate reduction of chloroplatinic acid in the presence of amino-propyl trimethoxy silane (APTMS) modified graphene oxide (GO) produced RGO/PtNPs nanohybrid comprised of uniform and high-density distribution of smaller-sized PtNPs. The APTMS provide efficient nucleation points via their amino groups and thereby play a vital role in regulating the size as well as the distribution of the anchored PtNPs in the present approach. The morphological and structural characterization of RGO/PtNPs nanohybrid was done by using X-ray powder diffraction, scanning and transmission electron microscopy, Fourier transform infrared and Raman spectroscopic techniques. The homogeneous and high-density dispersion of smaller-sized PtNPs endows superior catalytic activity to RGO/PtNPs nanohybrid. The nanohybrid exhibited outstanding catalytic performance enabling rapid reduction of both p-NP and MB at ambient conditions. The estimated rate constants for p-NP and MB reduction were 15.9 x 10-3, and 187 x 10-3 s- 1 respectively, which outperform the rate constants of several previously reported metal-based GO/RGO nanocatalysts. The recycling tests showed that the nanohybrid maintained good catalytic stability even after the fifth recycle run. The RGO/PtNPs nanohybrid can be exploited for sustainable and efficient catalytic reduction of other environmental pollutants also. Further, the strategy followed in the present study to achieve homogenous and high-density distribution of Pt nanoparticles could be adopted for the anchoring of other metal/metal oxide/semiconductor nanoparticles.