A simple hydrothermal synthesis approach was used to synthesize porous MgNiO₂ Chrysanthemum Flowers (CFs) nanostructures and applied as a sensing electrode for quick detection of hazardous mercury (Hg²⁺ ions). The morphological, structural, and electrochemical properties of MgNiO₂ CFs were investigated. The morphological characteristic of MgNiO₂ CFs, with a specific surface area of 45.618 m²/g, demonstrated strong electrochemical characteristics, including cations in different oxidation states of Ni³⁺/Ni²⁺. Using a three-electrode system for electrochemical detection, the MgNiO₂ CFs based electrode revealed a good correlation coefficient (R²) of ~0.9721, a limit of detection (LOD) of ~11.7 μM, a quick response time (10 s), and a sensitivity of 8.22 μA∙μM⁻¹∙cm⁻² for Hg²⁺ ions over a broad linear range of 10–100 μM. Moreover, the selectivity for Hg²⁺ ions in tap water and drinking water was determined, and a promising stability of 25 days by MgNiO² CFs electrode was exhibited. The obtained results indicate that the developed MgNiO₂ CFs are a promising electrode for detecting hazardous Hg²⁺ ions in water and have the potential to be commercialized in the future.

The study presents a novel route towards the synthesis of NiO nanostructures by using various green amino acids. The nanostructures were obtained by hydrothermal methodology assisted by threonine, arginine, aspartic acid, leucine, isoleucine and serine respectively. The characterization of the synthesized materials was studied by different techniques such as XRD, SEM and TEM. The synthesized structural features were explored for their electro-chemical properties and used for fabrication of glucose sensors based on non-enzymatic functions. The developed sensors demonstrated a promising result in terms of sensitivity, selectivity, and stability. The most important finding in the present study is the oxidation of glucose at low potentials such as 0.125, 0.23, 0.093, 0.26, 0.037, and -0.02 V respectively for the isoleucine, leucine, serine, threonine, arginine, and aspartic acid assisted NiO nanostructures. This unique finding is attributed to the morphology of different nanostructures of NiO grown with the addition of green additives. The glucose sensing ability of glucose was not affected in presence of species such as uric acid, ascorbic acid, and other carbohydrates due to their close oxidation potential compared with glucose. The sensitivities of proposed non-enzymatic glucose sensors were found to be for the isoleucine, leucine, serine, threonine, arginine, and aspartic acid assisted NiO nanostructures as 4930, 3173, 2648, 1724, 1070, and 525 µA/mM/cm² respectively. The maximum sensing capability was recorded for isoleucine structures which showed higher sensitivity of 4930 µA/mM/cm², greater stability and excellent anti-interference capability compared to other nanostructures. The limit LOD and LOQ were also found and remain 0.01 (S/N = 3) and 1.9 µM individually, for the newly developed method for the sensor based on NiO grown with isoleucine amino acid. The potential application of isoleucine assisted NiO nanostructures composite material for the blood sample quantities analysis which further it demonstrates the feasibility of developed based for the non-enzymatic glucose sensor.

In this study, well-defined tungsten oxide (WO₃) nanowall (NW) thin films were synthesized via a controlled hot filament chemical vapor deposition (HFCVD) technique and applied for electrochemical detection of methylamine toxic substances. Herein, for the thin-film growth by HFCVD, the temperature of tungsten (W) wire was held constant at ~1450 °C and gasification was performed by heating of W wire using varied substrate temperatures ranging from 350 °C to 450 °C. At an optimized growth temperature of 400 °C, well-defined and extremely dense WO₃ nanowall-like structures were developed on a Si substrate. Structural, crystallographic, and compositional characterizations confirmed that the deposited WO₃ thin films possessed monoclinic crystal structures of high crystal quality. For electrochemical sensing applications, WO₃ NW thin film was used as an electrode, and cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were measured with a wide concentration range of 20 μM~1 mM of methylamine. The fabricated electrochemical sensor achieved a sensitivity of ~183.65 μA mM⁻¹ cm⁻², a limit of detection (LOD) of ~20 μM and a quick response time of 10 s. Thus, the fabricated electrochemical sensor exhibited promising detection of methylamine with considerable stability and reproducibility.