Asymmetric interfacial oxygen sites of porous CeO2-SnO2 nanosheets enabling highly sensitive and selective detection of 3-hydroxy-2-butanone biomarkers

Abstract

The local environment of active sites and the number of oxygen vacancies can greatly affect the reactivity of semiconductor metal oxides (SMOs). However, rare work has been reported to investigate the relationship between the state of oxygen vacancies and sensing performance of SMOs. Herein, a series of porous CeO2-SnO2 hetero-structure nanosheets with fine modulation of the local environment active sites and oxygen defect activity have been successfully constructed. We have investigated their sensing performance towards 3-hydroxy-2-butanone, which is a biomarker of food pathogenic microbe Listeria monocytogenes. We found that the amount of asymmetric Ce-O-Sn sites rather than total oxygen vacancies amount of CeO2/SnO2 materials can greatly affect their sensing performance. Impressively, the porous CeO2/SnO2-400 nanosheets, which possessed abundant active O-(ad) species originated from the asymmetric Ce-O-Sn sites, exhibited high sensitivity (Ra/Rg=637.94 to 50 ppm), fast response (29 s) and recovery (172 s), excellent selectivity and high stability toward 3-hydroxy-2-butanone at a working temperature of 160 °C. Both the surface O-(ad) species associated with the asymmetric oxygen sites and porous nanosheet hetero-structure contribute to the enhanced gas adsorption and diffusion process, further boosting their sensing performance. Our work provides new sights for identification of active sites in sensing materials as well as paves the way for detection of pathogenic microbes in food.