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

Abstract

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 m 2 /g and pore volume of ∼0.013 cm 3 /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 NO 2 , CO, H 2 S, and NH 3 , 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.

Recent progress in solar cells based on one dimensional ZnO nanostructures

“…One-dimensional (1D) metal-oxide nanostructures, including nanowires (NWs), nanorods (NRs) and nanotubes (NTs), have attracted a considerable attention recently because of their exceptional chemical and physical properties that can be employed for the realization of next-generation high-performance electronic and opto-electronic devices, such as solar cells [1], light emitting diodes [2], non-volatile memory applications, lasers, photodetectors, transistors and gas sensors [3][4][5][6][7]. In particular, one-dimensional ZnO material, a member of the II-VI family, has been extensively studied among the other onedimensional metal-oxides due to its excellent properties, which includes its relatively large exciton binding energy (60 meV) at room temperature, wide direct bandgap (3.37 eV), high electron mobility, effective light confinement, biocompatibility, extraordinary chemical and thermal stability characteristics [8].…”

Capacitively coupled contactless conductivity detection (C4D) of ZnO nanostructures gas sensor by adding Au:Pd metal with response to ethanol and acetone vapor

“…Its sensitivity arises from the surface reactions between ZnO and target gases, leading to changes in its electrical or optical properties. They are sensitive to gases such as carbon monoxide (CO), hydrogen (H2), ethanol (C2H5OH), ammonia (NH3), nitrogen dioxide (NO 2 ), ozone (O 3 ), and various VOCs [1][2][3][4][5]. Moreover, ZnO gas sensors exhibit rapid response and recovery times, allowing for real-time gas monitoring and detection [6].…”