Enhanced CO Sensing Performances of PdO/WO(3) Determined by Heterojunction Structure under Illumination

[Image: see text] The CO sensing performances and mechanism of PdO/WO(3)-based sensors were investigated by experiments and density functional theory calculations. The CO sensing performance can be significantly enhanced by decorating WO(3) with PdO, which is attributed to the catalyst (chemical sensitization) and P–N junction (electronic effect). On the one hand, PdO is an excellent catalyst used to promote the adsorption of oxygen species. On the other hand, the constructed P–N junction structure between PdO and WO(3) can facilitate the migration of carriers and suppress the recombination of electrons and holes, which promote the adsorption of more oxygen species. Furthermore, the calculation results verify that decorating WO(3) with PdO can significantly enhance the CO sensing response by providing more adsorption sites available for oxygen species and make more electrons to transfer from CO to PdO/WO(3) configuration. Moreover, the band gap energies of the WO(3) sensor can be reduced by PdO decoration, and the light absorption range in the visible light region can be expanded. More photogenerated electron–hole pairs can be produced based on the P–N junction structure, which can promote the progress of electrochemical reactions. Thus, the PdO/WO(3) material can be a promising candidate to detect CO, and it can effectively utilize the UV–visible light to destruct the CO contaminant.