Development of Pd/TiO2 Porous Layers by Pulsed Laser Deposition for Surface Acoustic Wave H2 Gas Sensor

Abstract

The influence of sensitive porous films obtained by pulsed laser deposition (PLD) on the response of surface acoustic wave (SAW) sensors on hydrogen at room temperature (RT) was studied. Monolayer films of TiO 2 and bilayer films of Pd/TiO 2 were deposited on the quartz substrates of SAW sensors. By varying the oxygen and argon pressure in the PLD deposition chamber, different morphologies of the sensitive films were obtained, which were analyzed based on scanning electron microscopy (SEM) images. SAW sensors were realized with different porosity degrees, and these were tested at different hydrogen concentrations. It has been confirmed that the high porosity of the film and the bilayer structure leads to a higher frequency shift and allow the possibility to make tests at lower concentrations. Thus, the best sensor, Pd-1500/TiO 2 -600, with the deposition pressure of 600 mTorr for TiO 2 and 1500 mTorr for Pd, had a frequency shift of 1.8 kHz at 2% hydrogen concentration, a sensitivity of 0.10 Hz/ppm and a limit of detection (LOD) of 1210 ppm. SAW sensors based on such porous films allow the detection of hydrogen but also of other gases at RT, and by PLD method such sensitive porous and nanostructured films can be easily developed.

High-Performance Cataluminescence Sensor Based on Nanosized V2O5 for 2-Butanone Detection

“…Gas sensors represent a versatile technology for harmful gas monitoring because of their advantages of low-cost, small size and easy operation [ 7 , 8 , 9 , 10 ]. Nowadays, various gas sensors based on different principles, such as electrochemistry [ 11 , 12 , 13 , 14 ], surface acoustic wave [ 15 , 16 ], quartz crystal microbalance [ 17 , 18 ], and cataluminescence (CTL) [ 19 , 20 , 21 ], have been designed for the detection of different analytes. Among them, gas sensors based on CTL have attracted a great deal of scientific interest.…”

ZnO Metal Oxide Semiconductor in Surface Acoustic Wave Sensors: A Review

“…For all types of sensors, including SAW sensors, it is important to operate at RT, and at the same time, to ensure that a signal is obtained at the lowest analyte concentrations. The reference metal oxide semiconductors used in the domain of sensors include In 2 O 3 [ 34 , 107 , 108 , 109 , 110 ], ZnO [ 45 , 111 , 112 , 113 ], Co 3 O 4 [ 114 , 115 , 116 ], SnO 2 [ 99 , 117 ], CuO/Cu 2 O [ 100 , 118 ], TiO 2 [ 24 , 119 ], NiO [ 58 , 120 ], Fe 2 O 3 [ 121 , 122 ], and WO 3 [ 23 , 123 ]. They were most often used to detect volatile organic compounds, hydrogen, ammonia, etc.…”

“…To achieve the best sensitivity and RT detection, another method to improve ZnO sensor properties is through the formation of heterostructures and functionalization with metals, such as Au, Pd, or Pt [ 128 , 142 , 143 ]. In papers that reported improved ZnO sensitivity through such nanostructures, Pd was most often reported as improving the ZnO activity in gas detection [ 45 , 119 , 122 ].…”

The Adsorption and Sensing Performances of Ir-modified MoS2 Monolayer toward SF6 Decomposition Products: A DFT Study

“…Among various detection methods, the metal-oxides-based gas sensor was considered a convenient and effective approach [ 9 ]. However, these traditional gas sensors have defects, such as low sensitivity and instability, limiting their further development [ 10 , 11 ]. Two-dimensional (2D) materials are widely used in gas sensing, catalysis, energy storage, etc., due to their large specific surface areas and distinctive physical and chemical properties [ 12 , 13 , 14 ].…”