We report the hydrogen-sensing response on low-cost-solution-derived ZnO nanorods (NRs) on a glass substrate, integrated with aluminum as interdigitated electrodes (IDEs). The hydrothermally grown ZnO NRs on ZnO seed-layer-glass substrates are vertically aligned and highly textured along the c-axis (002 plane) with texture coefficient ∼2.3. An optimal hydrogen-sensing response of about 21.46% is observed for 150 ppm at 150 °C, which is higher than the responses at 100 and 50 °C, which are ∼12.98 and ∼10.36%, respectively. This can be attributed to the large surface area of ∼14.51 m2/g and pore volume of ∼0.013 cm3/g, associated with NRs and related defects, especially oxygen vacancies in pristine ZnO nanorods. The selective nature is investigated with different oxidizing and reducing gases like NO2, CO, H2S, and NH3, showing relatively much lower ∼4.28, 3.42, 6.43, and 3.51% responses, respectively, at 50 °C for 50 ppm gas concentration. The impedance measurements also substantiate the same as the observed surface resistance is initially more than bulk, which reduces after introducing the hydrogen gas during sensing measurements. The humidity does not show any significant change in the hydrogen response, which is ∼20.5 ± 1.5% for a large humidity range (from 10 to 65%). More interestingly, the devices are robust against sensing response, showing no significant change after 10 months or even more. 

Low-Temperature Highly Robust Hydrogen Sensor Using Pristine ZnO Nanorods with Enhanced Response and Selectivity

Recent advances in polyoxometalates for spectroscopic sensors: a review

In this work, diode temperature sensors based on silicon nanowires (SiNWs) were fabricated. SiNWs were obtained by means of metal-assisted chemical etching of silicon (MACE). The surface morphology of silicon nanowires was studied by the scanning electron microscopy (SEM). The SEM results showed that a periodic array of silicon nanowires with a height of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4.9 \ldots 5.8\ \mu \mathrm{m}$</tex> and a width of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$k$</tex> was obtained. The influence of MACE synthesis parameters on electrical and thermosensitive characteristics of the devices was studied. Obtained thermodiodes were studied in two different modes: constant current mode and constant voltage mode. It was found that the maximum values of the rectification ratio (1207) and thermal sensitivity (3 mV/K) were obtained for the deposition time of Ag-NPs of 20 s and the etching time of silicon of 90–150 min. For comparison, obtained rectification coefficient was 3 times higher, and thermal sensitivity was about 50% better than that of a silicon diode without SiNWs. 

Silicon Diode Structures Based on Nanowires for Temperature Sensing Application

Novel covalent organic framework (COF) composites containing a bipyridine multimetal complex were designed and obtained via the coordination interaction between bipyridine groups and metal ions. The obtained Pt and polyoxometalate (POM)–loaded COF complex (POM–Pt@COF–TB) exhibited excellent oxidation of methane. In addition, the resultant Co/Fe–based COF composites achieved great performance in an electrocatalytic oxygen evolution reaction (OER). Compared with Co–modified COFs (Co@COF–TB), the optimized bimetallic modified COF composites (Co0.75Fe0.25@COF–TB) exhibited great performance for electrocatalytic OER activity, showing a lower overpotential of 331 mV at 10 mA cm−2. Meanwhile, Co0.75Fe0.25@COF–TB also possessed a great turnover frequency (TOF) value (0.119 s−1) at the overpotential of 330 mV, which exhibited high efficiency in the utilization of metal atoms and was better than that of many reported COF-based OER electrocatalysts. This work provides a new perspective for the future coordination of COFs with bimetallic or polymetallic ions, and broadens the application of COFs in methane conversion and electrocatalytic oxygen evolution.

https://www.mdpi.com/1420-3049/27/16/5193/pdf?version=1660628916

Covalent Organic Frameworks Composites Containing Bipyridine Metal Complex for Oxygen Evolution and Methane Conversion

In this work, diode temperature sensors based on silicon nanowires (SiNWs) were fabricated. SiNWs were obtained by means of metal-assisted chemical etching of silicon (MACE). The surface morphology of silicon nanowires was studied by the scanning electron microscopy (SEM). The SEM results showed that a periodic array of silicon nanowires with a height of $4.9 \ldots 5.8\ \mu \mathrm{m}$ and a width of $k$ was obtained. The influence of MACE synthesis parameters on electrical and thermosensitive characteristics of the devices was studied. Obtained thermodiodes were studied in two different modes: constant current mode and constant voltage mode. It was found that the maximum values of the rectification ratio (1207) and thermal sensitivity (3 mV/K) were obtained for the deposition time of Ag-NPs of 20 s and the etching time of silicon of 90–150 min. For comparison, obtained rectification coefficient was 3 times higher, and thermal sensitivity was about 50% better than that of a silicon diode without SiNWs.

Gopal Tamil selvi

Papers

Development and investigation of the flexible hydrogen sensor based on ZnO-decorated Sb2O3 nanobelts

Synthesis of rare earth hydroxycarbonate (LaOHCO3) nanocrystals with tuneable morphology and luminescence properties

Synthesis of chitosan-g-aniline-crotonic acid: Optimization of processing parameters for efficient grafting using taguchi method