Mesoporous NiO nanosphere: a sensitive strain sensor for determination of hydrogen peroxide

Eco-friendly spark-generated CoxOy nanoparticle-modified graphite screen-printed sensing surfaces for the determination of H2O2 in energy drinks

The modification of graphite screen-printed electrodes (SPEs) is reported using an eco-friendly and extremely fast method based on the direct cobalt pin electrode-to-SPE spark discharge at ambient conditions. This approach does not utilize any liquids or chemical templates, does not produce any waste, and allows the in-situ generation of CoxOy nanoparticles onto the electrode surface and the development of efficient electrocatalytic sensing surfaces for the determination of H2O2. Co-spark SPEs were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy and x-ray photoelectron spectroscopy (XPS), revealing the formation of surface confined CoxOy nanoparticles and the diverse oxidation states of cobalt species. Co-spark SPEs were also characterized with cyclic voltammetry and electrochemical impedance spectroscopy. Redox transitions of the surface confined electrocatalysts are demonstrated by electrochemical polarization studies, showing the formation of different oxides (CoxOy), varying the XPS results. Amperometric measurements at 0.3 V vs. Ag/AgCl revealed a linear relationship between the current response and the concentration of H2O2 over the range 1 - 102 μM, achieving a limit of detection (3σ/m) of 0.6 μM. The interference effect of various electroactive species was effectively addressed by employing dual measurements in the absence and presence of the enzyme catalase. The analytical utility of the method was evaluated in antioxidant rich real-world samples, such as energy drinks, demonstrating sufficient recovery.

Facile preparation of urchin-like NiCo2O4 microspheres for efficient hydrogen peroxide detection

The fabricated NiCo2O4 microspheres acted as excellent sensors for H2O2, with much better performance than the reported NiCo2O4-based H2O2 sensors.

The fabrication of an Ni6MnO8 nanoflake-modified acupuncture needle electrode for highly sensitive ascorbic acid detection

The current work describes the use of a steel acupuncture needle as an electrode substrate in order to construct an Ni₆MnO₈ nanoflake layer-modified microneedle sensor for highly sensitive ascorbic acid detection. For the purpose of constructing the functionalized acupuncture needle, first, a carbon film was layered on the needle surface as the seed layer. Subsequently, a straightforward hydrothermal reaction-calcination process was employed for the growth of Ni₆MnO₈ nanoflakes on the needle to function as a sensing interface. Electrochemical investigations illustrated the fact that the Ni₆MnO₈ nanoflake-altered acupuncture needle electrode manifested outstanding efficiency toward the amperometric identification of ascorbic acid. In addition, the electrode manifested elevated sensitivity of 3106 μA mM⁻¹ cm⁻², detection limit of 0.1 μM, and a broad linear range between 1.0 μM and 2.0 mM. As demonstrated by the results, the Ni₆MnO₈ nanoflake-modified acupuncture needle constitutes a potentially fresh platform to construct non-enzymatic ascorbic acid sensors.

An Ni₆MnO₈ nanoflake layer-modified microneedle sensor was constructed for highly sensitive ascorbic acid detection.