Enhanced room-temperature NH3 sensing properties of Cu2O concave octahedron/CNTs heterostructured hybrid via efficient charge transfer

Abstract

As a typical semiconductor metal oxide, Cu2O concave octahedrons exposed with high-energy facets have attracted much attention due to their good gas-sensing performance, but their gas sensors usually exhibit very large baseline resistance at room temperature which usually exceed the testing limitation and thus cannot be applied widely. Herein, Cu2O concave octahedrons exposed with high-energy facets (511) were hybridized with carbon nanotubes (CNTs) to form Cu2O/CNTs heterostructures and then employed as gas sensors. The sensor exhibited lower baseline resistance and higher response to NH3 gas at room temperature compared with that pure Cu2O. This was probably because that efficient charge transfer between exposed {511} facets of Cu2O concave octahedrons and CNTs can reduce the baseline resistance greatly, and also facilitate the adsorption of more oxygen and subsequent reaction with NH3 gas, leading to an increased response. In addition, sensor response was increased at first and reached the maximum at 5%, and then decreased with increasing the content of CNTs from 1% to 10%. This was probably because excess CNTs can reduce adsorption sites of Cu2O particles and thus result in a low response. Therefore, this work can provide a facile method to fabricate room-temperature NH3 sensor with high performance.