Improving sensing performance of the ZnO foam structure with exposed {001} facets by hydrogenation and sensing mechanism at molecule level

The ZnO foam structure assembled from nanoflakes with exposed {001} facets has been successfully prepared by heating aqueous Zn(NO₃)₂-polyvinyl pyrrolidone mixed solution. Response of the ZnO foam structure towards ethanol, acetone and n-Butylamine was observably increased by increasing the amounts of 3-coordinated Zn (Zn_3c) atoms on the ZnO (001) surface through hydrogenation. The unsaturated Zn_3c atoms are regarded as the reaction active sites and they contribute to generating free electrons, adsorbing oxygen molecules and catalyzing the reaction of the target gas with chemisorbed oxygen. The sensing mechanism will be instructive for the understanding of the gas sensing and heterogeneous catalytic reactions and the design of high performance sensing materials and catalysts. The hydrogenation optimizing surface-structural engineering may be a general strategy to enhancing sensing and catalytic properties.