Enhancing gas sensitivity of CdO octahedrons having {111} facets by hydrogenation and sensing mechanism of 3-coordinated Cd atoms as the reactive centers.

• Sensitivity of {1 1 1} faced CdO octahedrons is signally enhanced by hydrogenation. • Density of 3-coordinated Cd atoms at (1 1 1) surface is increased by hydrogenation. • The 3-coordinated Cd atoms are regarded to function as the sensing reactive centers. • They can absorb oxygen, generate free electrons and catalyze the sensing reaction. • Properties of other sensing materials and catalysts may be enhanced by hydrogenation. As a surface optimization strategy, hydrogenation has been successfully used to enhancing the responses of CdO octahedrons sensors to acetone, ethanol and triethylamine by increasing the numbers of 3-coordinate Cd (Cd 3c) atoms on the CdO (111) surface. The Cd 3c atom with three dangling bonds at Cd-CdO (111) surface is considered to be a reactive center for gas sensing, which has three functions: adsorbing oxygen from air, generating free electrons, and catalyzing the redox reaction of the target gas with adsorbed oxygen. The sensing mechanism of surface Cd 3c atom acting as a reactive center can not only deepen understanding the mechanisms of gas sensing and heterogeneous catalytic reactions, but also provide a new insight for developing highly performance sensing and catalytic materials. In addition, hydrogenation may be a general effective strategy for improving sensing and catalytic performances of semiconductor materials. [ABSTRACT FROM AUTHOR]