Twofold Porosity and Surface Functionalization Effect on Pt-Porous GaN for High-Performance H 2 -Gas Sensors at Room Temperature

• Published in: ACS omega 2019-01, Vol.4 (1), p.1678-1684
• Main Authors: Shafa, Muhammad, Priante, Davide, ElAfandy, Rami T, Hedhili, Mohamed Nejib, Mahmoud, Saleh T, Ng, Tien Khee, Ooi, Boon S, Najar, Adel
• Format: Article
• Language: English
• ISSN: 2470-1343; 2470-1343
• DOI: 10.1021/acsomega.8b02730

The achievement of H 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 H -gas sensors is studied as a function of the operating temperature by providing an adsorption activation energy of 22 meV at 30 ppm H , 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 H gas concentration profile is simulated and fitted within the porous GaN layer, revealing that H diffusion is limited by small pore radii because of its low diffusion rate. The simulated gas sensor responses to H versus the pore diameter show the same trend as observed for the experimental data. The sulfide-treated Pt-porous GaN sensor achieves ultrasensitive H detection at room temperature for 125 nm pore radii.