Novel Ag-doped ZnO/CdO ternary heterostructures (AZC composite) were fabricated and characterized by X-ray diffractometer (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission elec-tron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and etc. The results showed that Ag nano-particles were attached onto the ZnO/CdO surface and multiple heterojunctions including Ag/ZnO, Ag/CdO Schottky junctions and ZnO/CdO homo-type heterojunction were generated. The formaldehyde (HCHO)-sensing performance of the AZC composites was tested. Compared with the ZnO/CdO composite, the AZC composites demonstrated much higher response and faster response/recovery rate. In particular, the AZC sample with an Ag content of 3.04 wt (AZC-2) exhibited a high response of 164 to 50 ppm HCHO at 150 degrees C, a ppb-level detection limit, and acceptable humidity resistance. This work illustrated that Ag nanoparticles is a promising candidate for improving the sensing property of transition metal oxide due to its catalytic sensitization effect and relatively low cost.
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