Bio-surfactant mediated synthesis of Au/g-C3N4 plasmonic hybrid nanocomposite for enhanced photocatalytic reduction of mono-nitrophenols

Abstract

A bio-surfactant assisted synthesis route has demonstrated in room temperature for decoration of gold nanoparticles (AuNPs) on g-C3N4 usingAverrhoa carambola leaf extract towards mono-nitrophenol reduc-tion under visible light irradiation. Biomolecules of the leaf extract and optimised reaction condition played a vital role on tuning the morphology and optoelectronic properties of AuNPs. The size of AuNPs were found to be 15 +/-& nbsp;3 nm on 2D g-C3N4 sheets by TEM and STEM-HAADF analysis. Among the designed plasmonic hybrid photocatalysts 3-wt% loaded AuNPs on g-C(3)N(4)showed 99.01% of 4-nitrophenol, 97.70% of 3-nitrophenol and 98.50% of 2-nitrophenol photoreduction. The photocatalytic efficiency of Au/g-C(3)N(4)was investigated under several parameters such as pH, initial nitrophenol concen-tration, and in presence of external inorganic anions. The mechanism of photoreduction of nitrophenol to aminophenol by Au/g-C(3)N(4)was proposed based on the intermediate obtained from GCMS analysis. The observed higher catalytic activity of plasmonic hybrid photcatalysts is due to the synergic chemistry between the conduction band of g-C3N4 and AuNP plasmonic band, which is well supported by PL, EIS, and transient photocurrent analysis. Kinetic rate constant for 3Au/g-C(3)N(4)was found to be 0.43 min(-1) at pH 3. Moreover, the rate of reaction significantly increased in presence of Cl-. ICP-OES analysis of as synthesised 3Au/g-C(3)N(4)plasmonic photocatalyst shows there was no gold leaching even after ten cycles confirming the stability and reusability of the catalyst. (C)& nbsp;2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.