Conductivity-Type Sensor Based on CNT-WO3 Composite for NO 2 Detection

Abstract EN

The CNTs with 20–50 nm in diameter were directly grown on Au microgap electrode by means of thermal CVD at 700∘C for 60 minutes under EtOH-Ar-H2 atmosphere (6 kPa).

The CNTs with entangled shape formed the network structure with contacting each other.

In the CNTs-WO3 composite, WO3 grains with disk shape (50–200 nm) were independently trapped.

The CNTs-WO3 composite sensor showed the fairly good sensor response (Ra/Rg = 3.8 at 200∘C).

The sensor response was greatly improved with CNTs-WO3 composite, comparing with that of CNT sensor (Ra/Rg = 1.05).

This phenomenon can be explained by formation of p-n junction, between CNT(p) and WO3(n), and thus improvement of NO2 adsorption.

The sensor response was decreased with increasing the WO3 amount in CNTs-WO3 composite, suggesting the electronic conduction due to WO3 connection.