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This work reports the memristive properties of solution-processable cobalt oxide nanoparticles (CoO NPs) for resistive memory application. The memristive current–voltage hysteresis loop with good bipolar-resistive switching (BRS) property was shown by the developed device. Substantiate to this, the asymmetric device charge and double-valued charge–magnetic flux characteristics were calculated from the experimental electrical data and demonstrated the existence of the non-ideal memristor properties. The CoO memristive device can switch up to 103 BRS cycles and can retain the data up to 5 × 103 s. The switching uniformity of the CoO memory device was elucidated by a cumulative probability distribution and statistical calculations. The low-resistance state shows little variation whereas broad variation was observed for high-resistance state. The theoretical model fitting results suggested that the conduction in the device during high-resistance sate was due to the Schottky and space charge-limited current and Ohmic current dominated in the low-resistance state. The formation and rupture of conductive filament with the assistance of interfacial dynamic is a possible reason for BRS in the CoO NPs-based memristive device.

In order to raise possible ways of MoO3 synthesis and improve its existing applications, MoO3 nanomaterial was successfully synthesized through the solvo-hydrothermal route by utilizing a mixture of ionic liquid (1-butyl-3-methylimidazolium bromide) as a solvent, and water as co-solvent in 1:1 ratio. The morphology and structural parameters of IL-as­sisted MoO3 product were examined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). Additionally, the surface wettability and particle size distribution were inspected using the contact angle and dynamic light scattering (DLS) analysis. Glassy carbon electrode (GCE) surface was then modified by IL-assisted MoO3. The formed IL-MoO3/GCE was employed as an electro­chemical sensor for determination of 4-nitrophenol (4-NP), which is very toxic and important pollutant. The redox behavior of 4-NP at the surface of IL-MoO3/GCE was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Limits of detection (LOD) and limits of quantification (LOQ) determined from CV were found to be 6.76 and 22.5 mM, while from DPV recordings, 5.41 and 18.0 mM are found. The obtained results clearly reveal possible application of MoO3 for selective and sensitive sensing of 4-NP. The decorated electrode was successfully employed for determination of 4-NP in the river water real samples.

A simple, rapid, selective, sensitive and reliable extractive spectrophotometric method was developed for the determination of ruthenium(III) using 2-nitrobenzaldehyde thiocarbohydrazone (2-NBATCH) as a chromogenic chelating ligand. The ruthenium(III)‒2-NBATCH complex is formed in aqueous acetic acid media (0.7 M) containing an organic solvent after 5 min heating on a water bath. The red colored complex is extracted into 1,2-dichloroethane and absorbance is measured at 445 nm against reagent blank. The Beer’s law is obeyed within 1‒6 g/mL of ruthenium(III), the optimum concentration range was 2‒5 g/mL of ruthenium(III) evaluated by Ringbom’s plot. Molar absorptivity and Sandell’s sensitivity of complex were 1.41 × 104 L/mol/cm and 0.0075 μg/cm2, respectively. The stoichiometry of complex was 1: 3 established from Job’s method of continuous variation, molar ratio method and logarithmic slope method. The proposed method was applied for determination of ruthenium(III) in binary and ternary, synthetic mixtures corresponding to fission product elements alloy and ruthenium(III) catalysts.