NiCo 2 O 4 nanorods (assembled with small nanoparticles) with different aspect ratios were synthesized through a surfactant mediated reverse micellar route. Anisotropy of the nickel cobaltite nanorods was retained after calcination of nickel cobalt oxalate precursors. A high aspect ratio ($12) of the NiCo 2 O 4 nanorods was obtained by using a cationic surfactant (CTAB) while a non-ionic surfactant (Tergitol) led to the formation of a much lower aspect ratio ($5) of the nanorods. These nanorods could potentially be used as anodic electrocatalysts for the oxygen evolution reaction. Due to having a high surface roughness, nanorods assembled with the smallest particles, $5-10 nm in diameter (surface area $158 m 2 g À1 ), show a high current density of $140 mA cm À2 with a low onset potential of $0.31 V (at 0.9 V) towards the oxygen evolution reaction and the values of current density is significantly higher than earlier reports.

1-D nanostructured metal oxides exhibit high selectivity having efficient catalytic trends toward a number of analytes. Tungsten oxide (WO3) is known for its catalytic properties, conductivity, and stability, which can be further enhanced by doping. This study deals with the synthesis of hafnium-doped tungsten oxide (Hf.WO3) nanorods via a hydrothermal process and their characterizations using X-ray diffraction, transmission electron microscopy, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy. The materials developed were used to fabricate an electrochemical sensor by modifying the carbon paste electrode (CPE), which was utilized to estimate paracetamol (PAR) and salbutamol (SBM) drugs. The results showed enhanced peak current compared to the nascent CPE, indicating facile transfer of the electrons. The catalytic properties, conductive nature, and broad surface area of the prepared 1-D nanostructures have shown remarkable improvement to detect the chosen analytes. A square wave voltammetric technique was also used to estimate detection limits of 1.28 × 10–9 and 2.42 × 10–9 M for PAR and SBM, respectively. The estimation of PAR and SBM in biological samples and pharmaceutical doses of the drugs demonstrated the usefulness of the sensor device for real analytical applications.

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Solar-blind self-powered UV-C photodetectors suffer from low performance, while heterostructure-based devices require complex fabrication and lack p-type wide band gap semiconductors (WBGSs) operating in the UV-C region (<290 nm). In this work, we mitigate the aforementioned issues by demonstrating a facile fabrication process for a high-responsivity solar-blind self-powered UV-C photodetector based on a p–n WBGS heterojunction structure, operating under ambient conditions. Here, heterojunction structures based on p-type and n-type ultra-wide band gap WBGSs (i.e. both are characterized by energy gap ≥4.5 eV) are demonstrated for the first time; mainly p-type solution-processed manganese oxide quantum dots (MnO QDs) and n-type Sn-doped β-Ga2O3 microflakes. Highly crystalline p-type MnO QDs are synthesized using cost-effective and facile pulsed femtosecond laser ablation in ethanol (FLAL), while the n-type Ga2O3 microflakes are prepared by exfoliation. The solution-processed QDs are uniformly dropcasted on the exfoliated Sn-doped β-Ga2O3 microflakes to fabricate a p–n heterojunction photodetector, resulting in excellent solar-blind UV-C photoresponse characteristics (with a cutoff at ∼265 nm) being demonstrated. Further analyses using XPS demonstrate the good band alignment between p-type MnO QDs and n-type β-Ga2O3 microflakes with a type-II heterojunction. Superior photoresponsivity (922 A/W) is obtained under bias, while the self-powered responsivity is ∼86.9 mA/W. The fabrication strategy adopted in this study will provide a cost-effective means for the development of flexible and highly efficient UV-C devices suitable for energy-saving large-scale fixable applications.

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