CNT functionalized GdCoBi ternary metal oxide nanocomposite for electrochemical detection of perfluorooctanoic acid and energy storage applications

Perfluorooctanoic acid "Forever Chemical" presents substantial ecological challenges owing to its persistence and resistance to degradation. The study introduces a novel approach by integrating ternary metal oxides-Gd2O3, Co3O4, and Bi2O3 with carbon nanotubes to develop a versatile electrode material, CNT@GdCoBi NCs, which demonstrates dual functionality as both an electrochemical sensor for PFOA and a component for energy storage devices. The electrode exhibits outstanding electrochemical sensing performance, with a detection limit for PFOA of 4.9 ppb. Interference tests reveal the electrode's high selectivity for PFOA, with a tolerance limit of <= 5 %. Practical application on various fruits, vegetables, and water samples shows an average relative standard deviation (%RSD) between 4.8 % and 5.6 %, underscoring the practical effectiveness of the CNT@GdCoBi NCs electrode. Furthermore, the CNT@GdCoBi NCs exhibit remarkable supercapacitor performance, achieving a specific capacitance of 1197 F/g at 2 A/g, which is 1.5 times higher than that of GdCoBi NCs. At a current density of 2 A/g, the symmetric supercapacitor device demonstrates a specific capacitance of 269 F/g, along with a high energy density of 52 Wh/kg at a power density of 500 W/kg. Additionally, the CNT@GdCoBi NCs electrode maintains good durability, retaining 94 % of its capacitance after 10,000 cycles.