Synergistic effect of ZnO/ZIF8 heterostructure material in photodegradation of methylene blue and volatile organic compounds with sensor operating at room temperature

Abstract To improve the performance of ZnO in photocatalytic processes and gas sensing, ZnO was modified by coating the surface with a zeolitic-imidazolate framework-8 (ZIF-8). Partially dissolved Zn2+ ions from ZnO interacted with 2-methylimidazole (MeIM) to achieve a ZIF-8 coating on the ZnO surface as a ZnO@ZIF8 heterostructure. The ZnO@ZIF8 was further used as a photocatalyst for methylene blue degradation and the performance was compared with that of pure ZnO and pure ZIF-8. The result showed that the photocatalytic efficiency of ZnO@ZIF8 is better than that of pure ZnO. Furthermore, ZnO@ZIF8 was also used as a gas-sensing material for volatile organic compound (VOC) detection. The results indicated that ZnO@ZIF8 could respond to VOCs at room temperature (26 ± 2 °C) and was selective to ammonia while pure ZnO was unable to respond to all of the VOCs. The higher efficiency of ZnO@ZIF8 results from the synergistic effect between ZIF-8 and ZnO. Moreover, the combination of ZIF-8 and ZnO could be decreased by the electron-hole recombination process and also reduce the energy band gap which led to low energy operation.