In this study, hexylresorcinol calix[4]arene-ZnO-Au (HRCA-ZnO-Au) micro–nano materials are synthesized by a simple atmospheric reflux. AuCl4− ions are in situ reduced to Au by the phenolic hydroxyl groups of amphiphilic HRCA and deposited on the primarily formed ZnO sheets, which prevents Zn2+ ions in the solution from depositing at this position. Finally, the flake sample is obtained. HRCA and chloroauric acid effectively shape the morphology of ZnO from micron-sized flowers to nanometer sheets, and they significantly increase the specific surface area of the sample. Low temperature calcination of the HRCA-ZnO-Au composite micro–nano materials partially removes calixarene molecules and exposes the surface of ZnO–Au. Thus, the photocatalytic activity of ZnO–Au is significantly improved due to the synergistic effect between ZnO and Au.
Yue Hu,Lijiu Cao,Yunpeng Gong,Xu Ma,Yufang Chen,Tao Jin
Formaldehyde sensors represent an effective technology for real-time, online monitoring of formaldehyde concentrations. The selectivity of gas-sensitive materials for formaldehyde is a fundamental determinant of sensor performance and is crucial for the development of formaldehyde sensing technology. In this work, Sn-doped Zn-MOFs were employed to fabricate SnO 2 /ZnO micro-nano materials, and their selective response behaviors to formaldehyde were systematically explored. The results demonstrate that 5 % SnO 2 /ZnO, prepared with 5 % Sn doping, exhibits exceptional selectivity for formaldehyde. Under testing conditions of 170 °C and relative humidity below 60 %, the 5 % SnO 2 /ZnO sensor achieved a selectivity coefficient of 0.87 toward 50 ppm formaldehyde, with a response value of 72.8, response and recovery times of 81/30 s, a linear regression coefficient of 0.9997, and a minimum detection limit of 0.047 ppm. Moreover, the 5 % SnO 2 /ZnO sensor demonstrates excellent selectivity, anti-interference capability, and stability for formaldehyde detection. The enhanced formaldehyde selectivity is attributed to the high specific surface area, abundant pore structure, abundant oxygen vacancies, and n–n heterojunctions present in the 5 % SnO 2 /ZnO composite.
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