Visible-light responsive Au nanoparticle-decorated polypyrrole-carbon black/SnO2 ternary nanocomposite for ultrafast removal of insecticide imidacloprid and methylene blue

Abstract

Highly precise, determined and mind provoking steps are must for efficacious designing of smart visible-light photocatalysts. Herein, we successfully designed an ultrafast visible-light responsive photocatalyst comprising of SnO2, polypyrrole doped carbon black (PPy-C) and gold nanoparticles (Au NPs) by a simple and reliable approach. XRD, FTIR, XPS, FESEM, TEM and UV–vis spectroscopic tools were employed for comprehensive characterization of synthesized nanostructures. XPS and XRD investigations confirmed the establishment of ternary photocatalyst among SnO2, PPy-C and Au. TEM analysis showed that synthesized SnO2 material possessed irregular nanorods of 20–100 nm length and 20 nm diameter. The PPy-C polymer combination has beads or dumbbell shape morphology intertwined with SnO2 while dispersed Au NPs can be easily seen along with PPy-C and SnO2 nanostructures. The bandgap energy (Eg) for pristine SnO2, PPy-C/SnO2 and Au@PPy-C/SnO2 nanocomposite was found to be 3.55, 3.22 and 2.85 eV, respectively. The photocatalytic performance of each newly produced photocatalyst was evaluated under visible light using imidacloprid (an insecticide derivative) and methylene blue (MB) dye as target pollutants. Among different tested photocatalysts, the newly created Au@PPy-C/SnO2 trio combination was proven to be the most proficient with 93.18 % removal of imidacloprid in just 20 min and complete destruction of MB dye only in 10 min. The degradation rate constant (k) for SnO2 and Au@PPy-C/SnO2 was found to be 0.0327 and 0.1310 min−1 respectively, revealing 4 times higher proficiency of Au@PPy-C/SnO2 than bare SnO2. The effect of variation of different parameters on imidacloprid photodegradation has also been investigated like irradiation time, reaction pH, substrate concentration and catalyst concentration. Higher photocatalytic activity has been observed at low substrate concentration under acidic condition (pH: 4) with 20 minutes as an optimal time.