Fine-tuning of ceramic-based chemical sensors via novel microstructural modification: Part II: Low level CO sensing by molybdenum oxide, MoO3

Employing a buffer gas mixture of CO and CO2, the equilibrium oxygen partial pressure was varied across the Mo/MoO3 proximity line by varying the ratio of concentration of the two gases, as described in an earlier communication. This led to the reduction of MoO3 in one case and oxidation of the reduced phase (Mo or MoO2) in the other with a concomitant variation in the microstructural features of the resulting species. The formation and growth of the new oxide surface under conditions of oxygen potential modulation has been found to impart enhanced sensing characteristics to the MoO3-based chemical sensors for low levels of carbon monoxide (14–100 ppm CO) in the ambient.