Abstract

Abstract Single layer carbon film has been produced to fabricate a highly selective hydrogen sensor by depositing a partially crystalline carbon film from a single layer suspension onto an alumina substrate. The deposited carbon film, which has a hexagonal-turbostratic structure with an interlayer spacing of (d002) 3.58 A, show high orientation with intense (00 l ) Bragg diffraction lines in their X-ray diffraction patterns. When the deposited films were promoted with catalysts selected from Pt-group metals, a covalent Pt–C bond is formed between highly dispersed Pt particles and the unsaturated dangling carbon bonds at the edges and/or at dislocation sites. These catalyst particles are responsible for the dissociation of hydrogen molecules and subsequent electron donation to the conduction band, resulting in high sensitivity and selectivity hydrogen gas sensors. At a temperature of 110°C, the sensor's response to hydrogen is linear in concentration up to 103 ppm, with a 15–30 s response time and a 20–60 s recovery time. The lower operating temperature enhances safety when dealing with hydrogen gas.

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