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

 
On one hand, they 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.

 
On the other hand, 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.

  
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.

 
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.

Figure The gas-sensitive response characteristics of the p-type Sc-Li co-doped NiO sensor to 100 ppm ethanol (a) sensitivity and repeatability, (b) sensitivity comparison with literature results, (c) long-term stability.

Link to the paper: Oxygen Vacancy Defects Boosted High Performance p-Type Delafossite CuCrO2 Gas Sensors

                            Surface oxygen vacancy defect engineering of p-CuAlO2via Ar&H2 plasma treatment for enhancing VOCs

                             sensing performances

                             Sc-doped NiO nanoflowers sensor with rich oxygen vacancy defects for enhancing VOCs sensing 

                             performances

                             Aliovalent Sc and Li co-doping boosts the performance of p-type NiO sensor

Contact:

ZHOU Shu
Hefei Institutes of Physical Science (http://english.hf.cas.cn/)
Email: zhous@hfcas.ac.cn