In situ construction of hybrid MnO2@GO heterostructures for enhanced visible light photocatalytic, anti-inflammatory and anti-oxidant activity

Abstract

Graphene oxide with a sheet like structure is extremely attractive especially in the field of photocatalysis as it promotes charge separation and has a high surface area. In this study, visible light active MnO₂/GO nanocomposites were constructed by an in situ solution phase approach with an excellent photocatalytic response. The as-synthesised MnO₂/GO nanocomposites were systematically characterised by various spectroscopic and microscopic techniques. Morphological characterisation displayed that the MnO₂ nanoparticles are well anchored over the whole surface of the graphene oxide sheets. The photocatalytic experiments suggested that the MG_0.4 nanocomposite showed the best photocatalytic response – almost 94% of rhodamine-B (Rh-B) dye was degraded in 65 min. The higher efficiency in the photocatalytic performance of the MnO₂/GO composites is attributed to the enhanced separation of the photogenerated charge carriers in the composite. We are optimistic that our findings can unlock a new direction for the photocatalytic application of MnO₂/GO composites. The as-synthesised MnO₂/GO nanocomposites were also evaluated for antioxidant activity using an in vitro DPPH radical assay. Considerable in vitro antioxidant activities in a concentration-dependent manner were recorded. Interestingly, the nanocomposite MG_0.4 showed a more elevated scavenging efficiency than GO in DPPH tests. Furthermore, the nanocomposites were investigated for their in vitro anti-inflammatory activity using the inhibition of protein denaturation method. The protein denaturation assay shows the prominent anti-inflammatory activity of the as-synthesised materials.