Regulation of surface oxygen (OV, OC) and enhancement of triethylamine sensing performance of MOF-derived Co3O4 hollow nanocubes by g-C3N4 coupling

The regulation of oxygen defects and chemisorbed oxygen plays an essential role in the sensing behavior of oxide semiconductor sensors. MOF derivatization and the construction of heterojunction are potential approaches to obtain high-performance sensors. Here, MOF-derived Co3O4 hollow nanocubes coupled with 2-dimensional g-C3N4 were prepared and further applied to triethylamine sensing. XPS results reveal the significant increase of oxygen defects and chemisorbed oxygen in the composite. Calculations of oxygen escape energy show that the construction of oxygen defects mainly originates from the anoxic environment caused by g-C3N4 coating. And calculation of surface models indicates that oxygen vacancies could enhance the interaction and charge transport at the heterointerface, and simultaneously serves as an adsorption site to improve the adsorption and activity of oxygen molecule. Combined with the energy band adjustment, Co d‐band center regulation and diffusion channel resulted from g-C3N4 coupling, the sensor based on the composite shows higher response, faster response speed and better selectivity to triethylamine. This study could provide a reference for the regulation of oxygen defects, chemisorbed oxygen, and the preparation of high-performance sensors.