Oxygen Vacancy Defects Boosted High Performance p-Type Delafossite CuCrO 2 Gas Sensors.

p-type ternary oxides can be extensively explored as alternative sensing channels to binary oxides with diverse structural and compositional versatilities. Seeking a novel approach to magnify their sensitivities toward gas molecules, e.g. volatile organic compounds (VOCs), will definitely expand their applications in the frontier area of healthcare and air-quality monitoring. In this work, delafossite CuCrO2 (CCO) nanoparticles with different grain sizes have been utilized as p-type ternary oxide sensors. It was found that singly ionized oxygen vacancies (Vo∙) defects, compared with the grain size of CCO nanoparticles, play an important role in enhancing the charge exchange at VOCs molecules/CCO interface. In addition to suppressing the hole concentration of sensor channel, the unpaired electron trapped in Vo∙ provides an active site for chemisorptions of environmental oxygen and VOCs molecules. The synergetic effect is response for the observed increase of sensitivity. Furthermore, the sensitive (Vo∙ defect-rich) CCO sensor exhibits good reproducibility and stability under a moderate operation temperature (< 325 °C). Our work highlights that Vo∙ defects, created via either in-situ synthesis or post annealing treatment, could be explored to rationally boost the performance of p-type ternary oxide sensors.