Highly stable and reversible hydrogen sensors using Pd-coated SnO2 nanorods and an electrode–substrate interface as a parallel conduction channel

Abstract

We demonstrated highly stable and reversible H2 sensors using a dual electron-conduction channel comprising Pd-coated SnO2 nanorods (NRs) and a parallel conduction channel containing Cr/native oxide/p-type Si interface. The dual-channel sensor exhibited highly reversible resistance changes during H2 in-and-out cycles at operating temperatures of 25 °C− 100 °C, while typical single-channel sensors with SnO2 NRs fabricated on SiO2 (300 nm)/Si substrates showed irreversible response because of insufficient recovery from Pd-Hx to Pd-Ox. In particular, the sensor showed significantly high repeatability, long-term stability, and selectivity for H2 sensing at 80 °C. Additionally, the time taken to detect H2 above 1% was less than 2 s and the response to H2 above 500 ppm was unaffected by high humidity. These results indicate that the dual-channel Pd-coated SnO2 NR sensor is suitable for applications such as hydrogen leak detectors that require high speed and precision. Moreover, it was found that the sensor could detect H2 below 0.5 ppm even at low temperatures. This work provides a pathway for improving gas-sensing performance by interface engineering, enabling various practical hydrogen sensor applications.