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 (R_a/R_g=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.

活性位点的局部环境和氧空位的数量会极大地影响半导体金属氧化物（SMO）的反应性。然而，很少有报道研究氧空位状态与 SMO 传感性能之间的关系。在此，成功构建了一系列对局部环境活性位点和氧缺陷活性进行微调的多孔CeO ₂ -SnO _{2异质结构纳米片。}我们研究了它们对 3-羟基-2-丁酮的传感性能，3-羟基-2-丁酮是一种食品病原微生物李斯特菌的生物标志物。我们发现不对称 Ce-O-Sn 位点的数量而不是 CeO ₂ /SnO _{2的总氧空位数量}材料会极大地影响其传感性能。令人印象深刻的是，多孔 CeO ₂ /SnO ₂ -400 纳米片具有丰富的源自不对称 Ce-O-Sn 位点的活性 O ^{- (ad) 物种，表现出高灵敏度（R} _a /R _g =637.94 至 50 ppm），在 160 °C 的工作温度下，响应速度快 (29 s) 和回收率 (172 s)，对 3-羟基-2-丁酮具有出色的选择性和高稳定性。两个表面 O ^-(ad) 与不对称氧位点和多孔纳米片异质结构相关的物质有助于增强气体吸附和扩散过程，进一步提高其传感性能。我们的工作为识别传感材料中的活性位点提供了新的视野，也为检测食品中的病原微生物铺平了道路。