Electrochemical detection of formic acid using transition metal aluminate (T = Cu, Co, Zn) with layered d-MXene composites.

Formic acid is widely used in food preservation, pharmaceutical formulations, and industrial processes, making accurate determination essential for quality control and safety assessment. In this study, an electrochemical sensor based on CuAl2O4, CoAl2O4, and ZnAl2O4 spinel oxides integrated with d-MXene-modified glassy carbon electrodes (GCE) developed for the selective detection of formic acid. The structural and surface characteristics of the synthesized materials were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Impedance and CV techniques were employed to evaluate the sensing performance of the modified electrodes. Among the fabricated composites, CoAl2O4/d-MXene/GCE exhibited the highest electrocatalytic activity towards formic acid. Differential pulse voltammetry revealed a broad linear detection range of 0.02-1645 μM, with a detection limit of 0.0101 μM and a quantification limit of 0.066 μM. The sensor also demonstrated excellent selectivity and satisfactory recovery in food samples, highlighting its potential for practical food analysis applications.