The ppb-level formaldehyde detection with UV excitation for yolk-shell MOF-derived ZnO at room temperature

Abstract

The ppb-level detection at room temperature, urgently demanded in application, is such a promising and challenging technology for formaldehyde sensing. This research has achieved the yolk-shell structural Zn-MOF and MOF-derivates via adjusting the ratio of metal ions to organic-ligand in solvothermal process and subsequent calcination. Under the synergistic effect of yolk-shell MOF-derived structure and assistance of UV irradiation of 8.31 mW/cm2, the sensors exhibit superb sensing performance to formaldehyde even at room temperature about 20 ℃, i.e., the response/ recovery time and sensitivity of MOF-derived ZnO are respectively 6 s/22 s and ~ 14.05–100 ppm formaldehyde. More notably, the detection limit is as low as 100 ppb. The relevant mechanism is summarily interpreted as follows: (i) Yolk-shell structure MOF-derived ZnO with mesoporous provides affluent oxygen vacancies and excellent adsorption capacity; (ii) UV radiation produces the electron-hole pairs to increase intra-grain conductivity and facilitate the capture of oxygen ions at room temperature.