H₂ Gas Sensor Based on Pd/ZnO Nanostructures Deposited on Tapered Optical Fiber

Abstract

A novel H 2 sensor using tapered optical fiber coated with Pd/ZnO nanostructures have been developed. The ZnO nanostructures was synthesized and deposited onto tapered optical fiber via chemical bath deposition (CBD) method. The ZnO was characterized by FESEM, XRD and EDX to confirm the material properties. It was discovered that the sensor is sensitive towards different concentrations of H 2 in synthetic air at 180° C of operating temperature. By varying the deposition time of ZnO coating, different thickness of ZnO layer can be obtained. It was observed that with 280 nm thickness, the maximum absorbance response can be achieved. Further investigation with sensor sample of as-prepared and annealed was carried out to study its sensing performance towards H 2 . The absorbance response of 280 nm thickness of annealed Pd/ZnO has increased 64% as compared to as-prepared Pd/ZnO upon 1% H 2 exposure in the synthetic air when measured in the visible to near infra-red optical wavelength. It can be concluded that the Pd/ZnO optical fiber sensor with thickness around 280 nm provided better sensitivity in sensing H 2 at 180°C as compared to other thicknesses investigated.

Sensing Performance of Ethanol Microfiber Probe Augmented by ZnO Nanosheet and UV Glue Film

“…In recent years, microfiber sensors have been widely studied due to their high-sensitivity performance on strong evanescent field properties. Yahya coated the surface of microfiber tapers with Pd/ZnO nanostructures [38] and experimentally demonstrated its sensing performance for H 2 .…”

Noble Metal‐Decorated Nanostructured Zinc Oxide: Strategies to Advance Chemiresistive Hydrogen Gas Sensing

“…The mechanism behind the scene was linked to the “spill‐over effect” wherein strong oxygen dissociation is enhanced due to the presence of noble metal nanoparticles. Extensive progress has been reported on gold (Au), Silver (Ag), Platinum (Pt) and palladium (Pd)‐loaded ZnO [25,38–42] . However, one needs to understand the influence of surface‐dependent reactions and adsorption on H 2 sensing.…”

“…[17][18][19][20][21] Although, there are a variety of metal oxides studied so far in H 2 gas sensing applications, zinc oxide (ZnO) has been able to draw great interest mainly due to its long-term chemical/ thermal stability and abundant nanostructures. [22][23][24][25] ZnO is an n-type II-VI semiconductor having a wide bandgap (3.37 eV), large excitation binding energy (60 meV) and high electron mobility (~400 cm 2 /Vs) making it superior to other metal oxides. [26][27][28] The sensing characteristics of ZnO were reported long back in the 1960's and have been one of the most widely studied materials since then.…”

“…Extensive progress has been reported on gold (Au), Silver (Ag), Platinum (Pt) and palladium (Pd)-loaded ZnO. [25,[38][39][40][41][42] However, one needs to understand the influence of surface-dependent reactions and adsorption on H 2 sensing. In this context, ZnO nanostructures and hierarchically three-dimensional architectures facilitate much higher surface exposure to target gases.…”

“…Amongst many types of H 2 sensors, such as acoustic wave, optical, thermoelectric, and electrochemical sensors, metal oxide‐based sensors have been reported to be one of the most promising resistive‐type H 2 sensors [17–21] . Although, there are a variety of metal oxides studied so far in H 2 gas sensing applications, zinc oxide (ZnO) has been able to draw great interest mainly due to its long‐term chemical/thermal stability and abundant nanostructures [22–25] . ZnO is an n‐type II–VI semiconductor having a wide bandgap (3.37 eV), large excitation binding energy (60 meV) and high electron mobility (∼400 cm 2 /Vs) making it superior to other metal oxides [26–28] .…”