Construction of mesoporous silica-implanted tungsten oxides for selective acetone gas sensing

As a key biomarker for noninvasive diagnosis of diabetes,the selective detection of trace acetone in exhaled gas using a portable and low-cost device remains a great challenge.Semiconductor metal oxide(SMO)based gas sensors have drawn signification attention due to their potential in miniaturization,user-friendliness,high cost-effectiveness and selective real-time detection for noninvasive clinical diagnosis.Herein,we propose a one-pot solvent evaporation induced tricomponent co-assembly strategy to design a novel ordered mesoporous SMO of silica-implanted WO_(3)(Si O_(2)/WO_(3))as sensing materials for trace acetone detection.The controlled co-assembly of silicon and tungsten precursors and amphiphilic diblock copolymer poly(ethylene oxide)-block-polystyrene(PEO-b-PS),and the subsequent thermal treatment enable the local lattice disorder of WO_(3)induced by the amorphous silica and the formation of ordered mesoporous Si O_(2)/WO_(3)hybrid walls with a unique metastableε-phase WO_(3)framework.The obtained mesoporous SiO_(2)/WO_(3)composites possess highly crystalline framework with large uniform pore size(12.0-13.3 nm),high surface area(99-113 m^(2)/g)and pore volume(0.17-0.23 cm^(3)/g).Typically,the asfabricated gas sensor based on mesoporous 2.5%Si O_(2)/WO_(3)exhibits rapid response/recovery rate(5/17 s),superior sensitivity(R_(air)/R_(gas)=105 for 50 ppm acetone),as well as high selectivity towards acetone.The limit of detection is as low as 0.25 ppm,which is considerably lower than the thresh value of acetone concentration(>1.1 ppm)in the exhaled breath of diabetic patients,demonstrating its great prospect in real-time monitoring in diabetes diagnosis.Moreover,the mesoporous 2.5%Si O_(2)/WO_(3)sensor is integrated into a wireless sensing module connected to a smart phone,providing a convenient real-time detection of acetone.