Green arginine capped Hafnium oxide nanoparticles, a computationally designed framework, for electrochemical sensing of mercury (II) ion

Abstract

In this research, for the first time, novel and green arginine-capped hafnium oxide nanoparticles (L-Arg@HfO2 NPs) were developed for selective electrochemical sensing of mercuric ions (Hg2+). The Hg2+ ions are the prevailing mercury species in aqueous sources and have grievous noxious effects on the ecosystem and human health. The L-Arg@HfO2 NPs, synthesized using an environmentally friendly green hydrothermal method, exhibited spherical morphology and interaction through the guanidine group of L-Arg and carboxylic group led to biocompatibility and provide selectivity for Hg2+ sensing, as supported by the outcomes of computational studies. The outcomes of various analytical studies suggested that Arg@HfO2-NPs exhibited synergistic electrocatalytic activities in Hg2+ sensing. Primarily, the high selectivity of the L-Arg@HfO2/Au nanosystem could have arisen from the electrostatic interaction of Hg2+ ions (point charge) with the free carboxylate group (dipole) of the L-Arg. Secondarily, selective adsorption may be due to the interactions of the inherent ionic field of the HfO2 and carboxylic group of L-Arg towards the Hg2+. The toxicity and biocompatibility evaluation of developed systems was performed to project eco-system acceptability Arg@HfO2-NPs if projected for real application. On adopting optimized parameters, herein proposed sensor responded linearly to Hg2+ ions in the concentration ranging from 2 to 140 µM and exhibited a low detection limit of 152.58 nM. Additionally, L-Arg@HfO2/Au sensor exhibited reproducibility, adequate stability, reusability, better selectivity at various pH, and selectivity towards Hg2+ in the case of real water samples analysis.