Biopolymer-based trimetallic nanocomposite synthesis, characterization and its application in the catalytic degradation of 4-nitrophenol

Gum kondagogu (GK), a natural biopolymer was successfully employed in the synthesis of trimetallic (AgAuPd) nanocomposites and characterized for their physicochemical properties in comparison with the monometallic nanoparticles. The UV–visible spectrum of GK-Ag nanoparticles (NPs) and GK-AuNPs showed distinctive surface plasmon peaks at 418 and 546 nm, respectively. In contrast, GK-PdNPs and the trimetallic nanoparticles did not exhibit any specific absorbance within the region of 200–800 nm. Fourier-transform infrared spectroscopy revealed that hydroxyl, acetyl, and carboxylate functional groups are responsible for the formation of GK-NPs. The scanning electron microscopy and energy dispersive X-ray analysis depicted the surface morphology and elemental composition of GK-based nanoparticles in comparison with native gum. Further, the GK-trimetallic nanocomposite was crystalline in nature with face-centered cubic geometry based on X-ray diffraction analysis and oxidation state zero as analyzed by X-ray photoelectron spectroscopy. The zeta potential (mV) for the GK-AgAuPdNPs was recorded as − 4.97 ± 1.25 when compared to native gum − 25.25 ± 2.64. The transmission electron microscopy analysis displayed the average sizes for GK-AgNPs (13 ± 4.8 nm), GK-AuNPs (8 ± 3.0 nm), GK-PdNPs (6 ± 1.1 nm), and the trimetallic GK-AgAuPdNPs (28 ± 8.1 nm). The synthesized GK-NPs exhibited enhanced catalytic efficiencies in the reduction of an anthropogenic agent 4-nitrophenol (4-NP) by NaBH 4 to 4-aminophenol with rate constants k (min −1 ) 0.180 for (GK-AgNPs), 0.158 (GK-AuNPs), 0.293 (GK-PdNPs), and 0.287 (GK-AgAuPdNPs). Our findings disclosed that GK-trimetallic NPs are more efficient catalysts in the reduction of 4-NP as compared to monometallic nanoparticles.