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Twofold Porosity and Surface Functionalization Effect on Pt–Porous GaN for High-Performance H2‑Gas Sensors at Room Temperature
journal contribution
posted on 2019-01-18, 18:39 authored by Muhammad Shafa, Davide Priante, Rami T. ElAfandy, Mohamed Nejib Hedhili, Saleh T. Mahmoud, Tien Khee Ng, Boon S. Ooi, Adel NajarThe
achievement of H2 detection, up to 25 ppm, at room
temperature using sulfur-treated, platinum (Pt)-decorated porous GaN
is reported in this study. This achievement is attributed to the large
lateral pore size, Pt catalyst, and surface treatment using organic
sulfide. The performance of H2-gas sensors is studied as
a function of the operating temperature by providing an adsorption
activation energy of 22 meV at 30 ppm H2, confirming the
higher sensitivity of the sulfide-treated Pt–porous GaN sensor.
Furthermore, the sensing response of the sulfide-treated Pt–porous
GaN gas sensor increases with the increase in porosity (surface-to-volume
ratio) and pore radii. Using the Knudsen diffusion–surface
reaction equation, the H2 gas concentration profile is
simulated and fitted within the porous GaN layer, revealing that H2 diffusion is limited by small pore radii because of its low
diffusion rate. The simulated gas sensor responses to H2 versus the pore diameter show the same trend as observed for the
experimental data. The sulfide-treated Pt–porous GaN sensor
achieves ultrasensitive H2 detection at room temperature
for 125 nm pore radii.