Zeolitic imidazolate framework-derived n-ZnO/p-Co3O4 heterojunction by ion-etching method for superior CO toxic gas sensor

A new method of etching-calcination is proposed to produce superior CO gas sensing materials of porous n-ZnO/p-Co3O4 nanoplates. The solid rhombic dodecahedral ZIF-67 is used as a template to assemble nanoplates in the solvothermal reaction accompanying with the Zn2+ etching strategy. After the calcination treatment, porous n-ZnO/p-Co3O4 nanoplates can be obtained. The characterization results proved its high specific surface area (132 m2/g), large ratio of surface oxygen vacancies (42%) and p-n heterojunction. This gas sensing material performed exceptionally to CO detection with the high response value (Rg/Ra=35.4 at 50 ppm CO) and excellent anti-interference ability (SCO/SH2=4.8) at 150 °C. In addition, Co2+ and different Zn2+ ion usages were utilized as a comparison to investigate the synthesis and gas sensing mechanism thoroughly.