Fig. 20.

a Schematic illustration of ZnO@ZIF-CoZn core-sheath NWAs sensor; b Response-recovery curves to acetone at different concentrations in dry air and in 10 ppm acetone with different relative humidity and at 260 °C; and c temperature-dependent responses of ZnO@5 nm ZIF-CoZn. Reproduced with permission [76]. Copyright 2016, Wiley–VCH. d Plots of Au@ZnO and Au@ZnO@ZIF-8 size versus time; insets are the representative TEM images of the products at specific times. e Kinetics of HCHO adsorption (solid symbols). f Proposed mechanism of oxidation of HCHO into HCOOH. Reproduced with permission [77]. Copyright 2018, Springer