Performance analysis of three distinct NixV2Oy single-phase nano self-assemblies for asymmetric supercapacitor fabrication and effective detection of low-concentration hazardous herbicide

Abstract

Single-phase inorganic nanostructures with multiple applications are required for cost-effective, sustainable applications to save the environment from toxic activities. Nickel vanadate (Ni_xV₂O_y), possessing three phases, such as NiV₂O₆, Ni₂V₂O₇, and Ni₃V₂O₈, acts as an effective electrode material and potential electrochemical sensors. Nickel vanadate phases (NiV₂O₆, Ni₂V₂O₇, and Ni₃V₂O₈) were synthesized through the gel-matrix technique, and their phase purity, crystallinity, morphology, optical properties, etc., were evaluated and studied. Electrochemical studies infer that NiV₂O₆ exhibits the highest specific capacity of 251 C g⁻¹ (69.7 mA h g⁻¹) at 1 A g⁻¹ compared to the other nickel vanadate phases and provides better cyclic stability of 80.19% for 5000 cycles. The asymmetric supercapacitor device fabricated from NiV₂O₆ results in a specific capacity of 189 C g⁻¹ (52.5 mA h g⁻¹), energy density of 59.06 W h kg⁻¹, and a power density of 1125 W kg⁻¹ with a capacitive retention rate of 74.91% and coulombic efficiency of 99.61% for 10 000 cycles. The electrochemical detection potential of Ni_xV₂O_y in bifenox herbicide has been studied with all the synthesized nanostructures. Among them, NiV₂O₆-based sensor probes demonstrated excellent characteristics, including high sensing current and low detection limits of 0.6 nM with a linear range of 1–57 nM. The real-time herbicide detection of NiV₂O₆ in live samples was checked with freshly harvested potatoes. This advancement further enhances the utilization of Ni_xV₂O_y materials for electrochemical applications.