New research conducted by team of Prof. FANG Xiaodong and MENG Gang from the Anhui Institute of Optics and Fine Mechanics (AIOFM) developed sensors with better performance to test Volatile organic compounds (VOCs).

VOCs, which are widely used as chemical reagents in industrial processes, are critical environmental pollutants with high neurotoxicity. The common way of testing is to use a sensor with p-type metal oxide semiconductor (MOS). But the inherent "hole accumulation layer" configuration in the air atmosphere usually leads to low sensitivity. An effective strategy is oxygen defect engineering. However, it's still far for application as it’s hard to define which type of defects determines the electrical response of p-type oxide sensors to VOCs.

In this study, the researchers used p-type CuCrO₂ as the sensing channel and revealed that the surface unsaturated oxygen vacancy defects were gas-sensitive active sites. More oxygen vacancy defects could be introduced through either the synthesis process, or post-annealing or Ar&H₂ plasma processing technology.

At the same time, in order to stabilize the oxygen vacancy active sites of p-type oxides, the team used p-type NiO as the research object, through the element doping (Sc/Li) induced NiO lattice distortion, to achieve a high concentration of oxygen vacancy defects.

The result showed good stability of up to seven months, preliminarily satisfying the requirements of practical application for long-term stability of the sensor.

This research offered a more stable and convenient way to test VOCs at subparts-per-million (ppm) level.

These works were financially supported by the projects of International Cooperation and the National Natural Science Foundation of China, etc.