Oxygen vacancy–enriched Y2O3 nanoparticles having reactive facets for selective sensing of methyl ethyl ketone peroxide explosive

Methyl ethyl ketone peroxide (MEKP) is a highly-reactive and exothermically unstable compound that has caused many explosion accidents. Therefore, a simple, rapid and sensitive method for online monitoring of MEKP is urgently required to address such problems. Herein, yttrium oxide (Y2O3) nanoparticles with different levels of oxygen vacancies (OV) and exposed reactive facets were synthesised at different calcination temperatures. Gas-sensing studies revealed that a cataluminescence (CTL) sensor based on Y2O3 nanoparticles annealed at 600 °C achieved the highest response to MEKP with a limit of detection of 1 ppb at a working temperature of 80 °C. Density functional theory calculations indicated the {222} and {440} facets in Y2O3 as the most reactive sites towards MEKP. Moreover, the introduction of OV into the exposed reactive facets can considerably enhance the adsorption of O2 and MEKP on Y2O3 nanoparticles. Further sensing mechanism studies unveiled the singlet and triplet excited states of acetaldehyde produced by the catalytic oxidation of MEKP as the possible luminophores for CTL emission. This study not only offers a promising method for online monitoring of MEKP but also offers deep insights into the improved sensing mechanism caused by OV and exposed reactive facets, thus providing guidance for designing high-performance CTL sensors.