Facile engineering of n-p-n In2O3-Co3O4-ZnO ternary: Influence of structure and optical band gap toward acetone detection

Acetone gas monitoring and detection must be done fast and precisely to preserve air quality and detect diabetes non-invasively. Thus, herein, we report on the fabrication of various n-p-n ternary structures of In 2 O 3 -Co 3 O 4 -CeO 2 (In-Co-Ce), In 2 O 3 -Co 3 O 4 -SnO 2 (In-Co-Sn), In 2 O 3 -Co 3 O 4 -ZnO (In-Co-Zn), and In 2 O 3 -Co 3 O 4 -ZrO 2 (In-Co-Zr) using a hydrothermal approach. Structural disclosed the formation of ternary structures. Comparing the performance of the tested In-Co-Ce, In-Co-Sn, In-Co-Zn, and In-Co-Zr sensors, the In-Co-Zn sensor displayed n-type characteristics with excellent sensitivity, selectivity, and reliable stability to acetone (C 3 H 6 O) at 150 °C. These exceptional gas sensing characteristics are recognized by the improved interfacial synergy between the In 2 O 3 , Co 3 O 4 , and ZnO, which enhanced the electrical conductivity and resulted in better sensing performance. Furthermore, the improved oxygen vacancies and establishment of the n-p-n heterojunction modulated the heterojunction barrier. The higher BET surface area of In-Co-Zn, consisting of a large pore diameter, enabled the gas molecules to penetrate and interact with the sensing surface, leading to improved sensing. The fabricated In-Co-Zn ternary structure exhibited a reduced band gap compared to other ternary nanostructures, making it minimal for capturing electrons by C 3 H 6 O in the conduction band. The molecular orbital diagram of ZnO was used to justify the improved sensing performance of In-Co-Zn ternary structures toward C 3 H 6 O. Therefore, the engineering of n-p-n In-Co-Zn ternary structures provided a facile approach for the detection of acetone at low ppm levels. • n-p In 2 O 3 -Co 3 O 4 incorporated with n-type SMOs was synthesized using a hydrothermal approach. • The integrated n-p-n In-Co-Zn-based sensor responded more to 2.3 ppm acetone at 150 °C. • In-Co-Zn sensor showed limit detection of 100 ppb and sensitivity of 0.14 ppm −1 to acetone. • The sensor demonstrated enhanced response towards acetone in relative humidity at 150°C.