Hafnium doped tungsten oxide intercalated carbon matrix for electrochemical detection of perfluorooctanoic acid

Highly toxic perfluorooctanoic acid (PFOA) has been extensively used in fabricating household products, which can pose extreme harm to the human health and hygiene, thereby resulting in environmental contamination such as in water and soil. In this research, hafnium-doped tungsten oxide (Hf.WO3) modified carbon paste electrode was developed for the first time to investigate the trace level determination of PFOA via the electrochemical methods since these are cost-effective, simple, and selective for detecting the compounds at the trace level. The Hf.WO3 nanoparticles were synthesized by a hydrothermal method and characterized using XRD, TEM, EDX, and XPS to understand their structural purity and crystallinity. The prepared nanoparticles were employed to modify the base electrode by measuring voltammetric responses at Hf.WO3/CPE that was found to be more sensitive than the nascent electrode. The effect pH of electrolyte, scan rate, temperature variation, immersion time, and concentration (linearity range of 7.0 × 10-8 M to 3.0 × 10-4 M) has been studied using cyclic voltammetry (CV) and square wave voltammetric (SWV) techniques. Thermodynamic parameters such as enthalpy, entropy, and activation energy were determined by the temperature variation study. The LOD of the developed electrode was determined to be 1.83x10-8 M. The real-time application of the electrode in the determination of PFOA was examined from the spiked soil, water, spoiled vegetable, and spoiled fruit samples (%RSD ranging from 2.88 to 5.94), while interference study demonstrates the high selectivity of the electrode towards PFOA.