Abstract
•Highly sensitive trimethylamine sensor using Au-loaded Cr2O3 yolk-shell spheres.•High response is explained by electronic and chemical sensitization of Au particles.•Gas sensing characteristics depend closely on size and distribution of Au particles.•P-type Cr2O3 can be used to detect sub-ppm-level trimethylamine.
An ultrasensitive and selective trimethylamine (TMA) sensor was fabricated by the urea-assisted uniform loading of Au nanoparticles (∼5nm) on Cr2O3 yolk-shell spheres prepared by ultrasonic spray pyrolysis. The response (resistance ratio) of the Cr2O3 yolk-shell spheres uniformly loaded with fine Au nanoparticles to 5ppm TMA was 200.9 at 225°C, which was significantly higher than those of pure Cr2O3 yolk-shell spheres (24.6) and Cr2O3 yolk-shell spheres loaded with heavily agglomerated Au particles (9.2). The detection limit of Cr2O3 yolk-shell spheres uniformly loaded with Au nanoparticles was as low as 4.3ppb. The unprecedentedly high TMA response is explained and discussed in relation to the gas-accessible morphology of the yolk-shell spheres, and the catalytic and electronic promotion of the gas sensing reaction by both Cr2O3 and well-dispersed Au nanoparticles.