Hydrogen sensing properties of Pt/Pd bimetal decorated on highly hydrophobic Si nanowires

• Hydrophobic Si nanowires synthesized by a metal assisted chemical etching process.
• Quantum size (3/3 nm) Pt/Pd bimetal decorated on Si NWs by PLD method.
• Feasibility of H2 sensing properties is investigated.
• The mechanism for H2 response was described by diffusion pathway.

This paper describes the synthesis of Pt/Pd bimetal decorated highly hydrophobic rough silicon nanowires (Si NWs) by using a facile metal assisted chemical etching and pulse laser deposition (PLD) process. In addition, the potential of the Si NWs as a new hydrogen (H2) detection matrix was investigated. The Pt/Pd bimetal was coated as a discrete ultra-thin film manner in a semi-dense configuration over the basal podium and along the length of vertical-standing and semi-densely distributed rough Si NW clusters. The resulting structure showed significant advantages in H2 sensing performances such as a large detection range of 1–40,000 ppm, high response magnitude of nearly 5.02%, and fast response-recovery time of 7/7 s to 10,000 ppm (1 vol%) hydrogen concentration at an optimum operating temperature of 75 °C. The observed characteristics of fast response-recovery time could relate to the enhanced hydrogen-induced changes in the work function of the Pt/Pd bimetal decorated Si NWs (Pt/Pd–Si NWs), which were configured as an array matrix comprising of many nanowire clusters with variable distances between the two electrodes. Finally, the fabricated sensor showed excellent repeatability towards (1 vol%) hydrogen concentration.

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