Selective Detection of H2 by Pt-MCF/ZSA Bilayer Sensor Prepared in Situ Via EHD Jet Printing

A micron-scale bilayer sensor was fabricated in situ by electrohydrodynamic jet printing for detecting H2 gas with highly selectivity, sensitivity and stability. The sensor consisted of a Pt loaded mesocellular silica foam (Pt-MCF) catalytic filter layer, and a ZnO/SnO2/Au (ZSA) sensing layer. Benefiting from the selective catalytic oxidation for CO in the catalytic filter layer, the cross-interference of CO on this sensor was reduced from 58% to 15%. The sensor also demonstrated a satisfactory selectivity to H2 in interfering gases of CO2 and CH4 due to its high specific response to H2. In the ZSA sensing layer, the n-n heterojunction (ZnO-SnO2) and abundant active sites on the Undaria pinnitafida-like curved nanosheet structure effectively enhanced the response of H2 by 6.7 times. The sensors exhibited a wide H2 dynamic range of 0.5–500 ppm with low detection limit of 94 ppb. The response/recovery time to 50 ppm H2 was 24s/35s. The sensor also showed good long-term stability in 28-day response-repeatability measurement (RSD=5.3%) and good anti-humidity.