High acetone sensitive and reversible P- to N-type switching NO2 sensing properties of Pt@Ga-ZnO core-shell nanoparticles

The typical core-shell Pt@ZnO, 1 mol% Ga doped Pt@ZnO and 2 mol% Ga doped Pt@ZnO nanoparticles were synthesized and utilized in acetone and NO 2 sensing. Among those nanoparticles, 1 mol% Ga doped Pt@ZnO based sensor presents excellent acetone sensitive and interesting reversible switching from P- to N-type NO 2 sensing. The response of the 1 mol% Ga doped Pt@ZnO based sensor to 50 ppm acetone is as high as 296, and the detecting concentration limit to acetone and NO 2 is as low as 10 ppb and 20 ppb. The analogical binary p-n transition phase diagram was established to understand the NO 2 -sensing reversible switching as a function of operating temperature (T) and NO 2 gas concentration (C). The role of Ga doping in enhancing the sensing property and the mechanism of NO 2 p–n sensing transition is elaborated. In conclusion, the doping of Ga into core-shell Pt@ZnO was proved to be a feasible method for fabricating acetone and NO 2 sensor, with high sensitivity and selectivity.