共价有机框架COF(DhaTph)-WO3复合材料的制备及其气敏性能OA

Covalent organic framework COF(DhaTph)nanomaterials were synthesized by solvothermal method using 2,5-dihydroxyp-phenylaldehyde(Dha)and 5,10,15,20-tetris(4-aminophenyl)-porphyrin(Tph)as raw materials and WO3 nanomaterials were prepared via a hydrothermal method.A series of COF(DhaTph)-WO3 composites with different COF(DhaTph)mass fractions(2％,5％,8％,and 11％)were obtained through ultrasonic dispersion.The structure and morphology of the materials were characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),and X-ray photoelectron spectroscopy(XPS)to investigate the effect of the COF(DhaTph)content on the gas-sensing performance of the WO3-based sensors.The results indicate that the incorporation of COF(DhaTph)significantly enhances the sensing performance of WO3 toward toluene.Specifically,at a COF(DhaTph)mass fraction of 5％and an operating temperature of 110 ℃,the sensor exhibits the highest response value of 12.8 toward 100 mg/L toluene gas.This represents an approximate 7-fold increase compared to the pure WO3 sensor(1.85)and a 10-fold increase compared to the pure COF(DhaTph)sensor(1.25).Moreover,at a concentration of 100 mg/L,the sensor shows response values below 3 for seven other gases—trimethylamine,acetone,acetaldehyde,ethanol,acetic acid,ammonia,and formaldehyde—demonstrating excellent selectivity.The detection limit of the sensor for toluene can reach as low as 1 mg/L(with a response value of 1.5),indicating its potential for low-concentration toluene detection applications.The enhancement in performance can be attributed to the porous structure of COF(DhaTph),which increases the specific surface area of the composite and provides more active sites for gas adsorption.This study presents a viable strategy for designing composite materials for high-performance,low-temperature gas sensors and broadens the application prospects of COFs in the field of gas sensing.