Enhanced Pd/a-WO 3 /VO 2 Hydrogen Gas Sensor Based on VO 2 Phase Transition Layer.

The utilization of clean hydrogen energy is becoming more feasible for the sustainable development of this society. Considering the safety issues in the hydrogen production, storage, and utilization, a sensitive hydrogen sensor for reliable detection is essential and highly important. Though various gas sensor devices are developed based on tin oxide, tungsten trioxide, or other oxides, the relatively high working temperature, unsatisfactory response time, and detection limitation still affect the extensive applications. In the current study, an amorphous tungsten trioxide (a-WO ) layer is deposited on a phase-change vanadium dioxide film to fabricate a phase transition controlled Pd/a-WO /VO hydrogen sensor for hydrogen detection. Results show that both the response time and sensitivity of the hydrogen sensor are improved greatly if increasing the working temperature over the transition temperature of VO . Theoretical calculations also reveal that the charge transfer at VO /a-WO interface becomes more pronounced once the VO layer transforms to the metal state, which will affect the migration barrier of H atoms in a-WO layer and thus improve the sensor performance. The current study not only realizes a hydrogen sensor with ultrahigh performance based on VO layer, but also provides some clues for designing other gas sensors with phase-change material.