The enhanced CO gas sensing performance of Pd/SnO2 hollow sphere sensors under hydrothermal conditions

Pd-doped SnO2 hollow spheres were synthesized via a facile one-step hydrothermal route. Utilized as the materials in sensors, the 3.0 wt% Pd-doped SnO2 demonstrated more excellent gas-sensing properties towards CO than 1.5 wt% and 4.5 wt% Pd-doped SnO2. Compared with the SnO2 hollow spheres gas sensor, the optimum operating temperature of the Pd-doped SnO2 hollow spheres gas sensor dropped to 200 °C from 250 °C; the response value to 100 ppm CO was raised to 14.7 from 2.5 accordingly. Furthermore, the response and recovery times of the 3.0 wt% Pd-doped SnO2 sensor are 5 s and 92 s, respectively, to 100 ppm CO at 200 °C. It is believed that its enhanced gas-sensing performances are derived from the synergistic interactions between the dispersed Pd and the characteristic configuration of the SnO2 hollow sphere. In addition, theoretical calculations have also been performed with periodic slab models by using density functional theory, which explain well our experimental phenomenon.