Scheelite-type rare earth vanadates TVO4 (T = Ho, Y, Dy) electrocatalysts: Investigation and comparison of T site variations towards bifunctional electrochemical sensing application

Abstract

In the wake of the recent COVID-19 pandemic, antibiotics are now being used in unprecedented quantities across the globe, raising major concerns regarding pharmaceutical pollution and antimicrobial resistance (AMR). In view of the incoming tide of alarming apprehensions regarding their aftermath, it is critical to investigatecontrol strategies that can halt their spread. Rare earth vanadates notable for their fundamental and technological significance are increasingly being used as electrochemical probes for the precise quantification of various pharmaceutical compounds. However, a comprehensive study of the role of the cationic site in tailoring the response mechanism is relatively unexplored. Hence, in this work we present a facile hydrothermal synthesis route of rare earth vanadates TVO4 (T = Ho, Y, Dy) as efficient electrocatalyst for the simultaneous detection of nitrofurazone (NF) and roxarsone (RX). There appears to be a significant correlation between T site substitution, morphological and the electrochemical properties of rare earth metal based vanadates. Following a comparative study of the electrochemical activity, the three rare-earth vanadates were found to respond differently depending on their composition of T sites. The results demonstrate that Dy-based vanadate displays increased electrical conductivity and rapid charge transfer characteristics. Thus, under optimal reaction conditions DyVO4- based electrodes imparts outstanding selectivity towards the detection of NF and RX with an extensive detection window of NF = 0.01–264 µM & RX = 0.01–21 µM and 36–264 µM and low detection limit (0.002, 0.0009 µM for NF and RX, respectively). In real-time samples, the proposed sensor reveals itself to be a reliable electrode material capable of detecting residues such as NF and RX.