MXene-Supported Cu-Ag Nanohybrids for Electrochemical Nitrate and Nitrite Detection in Alkaline Media

Abstract

In this study, an electrochemical sensor based on Ti3C2Tx MXene functionalized with bimetallic Cu-Ag nanoparticles was developed for the selective and sensitive detection of nitrate and nitrite ions. Owing to the high surface area, excellent conductivity, and versatile surface chemistry of Ti3C2Tx, the sensor exhibits dual linear response ranges for nitrate (0.1-10 mM and 10-100 mM), while enabling simultaneous nitrite detection across the same concentration intervals of nitrate addition. The detection limits for nitrate were calculated as 5.2 µM and 124.0 µM, with corresponding sensitivities of 220.75 and 5.095 µA mM-1 cm-2, and for nitrite (0.1-1 mM and 1-30 mM), the detection limits calculated for nitrite were 0.031 µM and 0.211 µM with sensitivities of 898.12 and 131.35 µA mM-1 cm-2, respectively. The sensor further demonstrates remarkable selectivity against common interfering species and retains electrochemical stability over 100 cyclic voltammetry cycles. Validation through real-sample analysis in soil, lake water, and tap water yielded high recovery rates, underscoring its practical utility. Overall, this study highlights the successful deployment of MXene-based electrochemical sensing for nitrate and nitrite ions, extending the scope of MXene applications beyond conventional reduction processes.