Visible light induced efficient photocatalytic degradation of azo dye into nontoxic byproducts by CdSe quantum dot conjugated nano graphene oxide

Abstract

We investigated the degradation of an azo dye, Congo red (CR), under the sunlight by using the nanoconjugate of graphene oxide (nGO) and CdSe quantum dots (QD) as the nano-photocatalyst. TEM confirmed the presence of CdSe QD of 4 nm size on the surface of nGO. Our results revealed that with an optimized concentration of 0.5 g/L the synthesized catalyst was most efficient at pH 7.0 with a degradation efficiency of more than 90% for 20 ppm and 100 ppm dye within 60 min of time. The nanoconjugate, having ratio between nGO and CdSe QD (w/w) as 1:5, demonstrated highest degradation efficiency. Further, FTIR spectra of photocatalyst before and after its application confirmed the complete photodegradation of CR. Microbial time kill assay also confirmed the non-toxicity character of photo-degraded by-products. Moreover, the regeneration experiment on nanoconjugate for five cycles of photocatalysis confirmed its high reusability. Thus, our nanoconjugate can be used as effective nano material for the rapid degradation of CR dye under sunlight.