Doubly ionized oxygen vacancies dominated Co3O4 nanoparticles for highly selective NH3 sensing application at room temperature

Polycrystalline Co3O4 nanoparticles were synthesized using a hydrothermal method with calcination. The microstructure and surface defects of these materials were investigated systematically. Room temperature gas sensing properties of Co3O4 nanoparticles were tested towards ammonia (NH3). The response value of Co3O4-2 h gas sensor to 200 ppm NH3 is 102.8 with response and recovery time of 65 s and 208 s, respectively. The Co3O4-2 h sensor also exhibited high selectivity, good repeatability and long-term stability. After excluding the impact of specific surface area and grain-size effect on sensitivity, the boosted sensing performance of Co3O4-2 h nano particles is mainly attributed to the high Co3+ concentration and the abundant doubly ionized oxygen vacancies (V-O(center dot)). This work provides a promising strategy to enhance gas sensing properties of p-type oxides by adjusting charge states of oxygen vacancy.

Automated summary

Polycrystalline Co3O4 nanoparticles synthesized by hydrothermal method with calcination show promising gas sensing properties towards ammonia, with high selectivity, good repeatability, and long-term stability. The enhanced sensing performance is mainly attributed to the high Co3+ concentration and abundant doubly ionized oxygen vacancies in the nanoparticles.