Abstract:
The increased usage of hydrogen as a next generation clean fuel strongly demands the parallel
development of room temperature and low power hydrogen sensors for their safety operation. In
this work, we report strong evidence for preferential hydrogen adsorption at edge-sites in an edge
oriented vertically aligned 3-D network of MoS2 flakes at room temperature. The vertically aligned
edge-oriented MoS2 flakes were synthesised by a modified CVD process on a SiO2/Si substrate and
confirmed by Scanning Electron Microscopy. Raman spectroscopy and PL spectroscopy reveal the
signature of few-layer MoS2 flakes in the sample. The sensor’s performance was tested from room
temperature to 150 C for 1% hydrogen concentration. The device shows a fast response of 14.3 s
even at room temperature. The sensitivity of the device strongly depends on temperature and
increases from 1% to 11% as temperature increases. A detail hydrogen sensing mechanism was
proposed based on the preferential hydrogen adsorption at MoS2 edge sites. The proposed gas sensing mechanism was verified by depositing 2–3 nm of ZnO on top of the MoS2 flakes that partially
passivated the edge sites. We found a decrease in the relative response of MoS2-ZnO hybrid structures. This study provides a strong experimental evidence for the role of MoS2 edge-sites in the fast
hydrogen sensing and a step closer towards room temperature, low power (0.3 mW), hydrogen sensor development. Published by AIP Publishing.
