Enhanced gas sensing performance of ethanol gas by the construction of dual Co3O4/ N-MX heterojunction structures

MXene has found widespread application in gas sensing applications through the formation of composite materials with metal oxides, with its excellent electrical conductivity and high specific surface area being its core advantages. However, during the synthesis of composite materials, MXene oxidizes to TiO 2 , leading to reduced electrical conductivity and a decrease in specific surface area. Additionally, MXene oxidation issues arise during gas sensing tests. To address these limitations, we developed a pre-oxidation doping strategy using nitrogen annealing, which preserves MXene's large specific surface area and conductivity during subsequent experiments. Experimental data confirmed that the pre-oxidation single-doping strategy retained the Ti 2p orbital characteristics, indicating that the treated MXene still maintains its two-dimensional material properties. The optimized Co 3 O 4 /N-MX7.5 composite exhibits peak ethanol sensing performance at 120°C, with improved selectivity attributed to enhanced conductivity due to nitrogen doping. This study establishes a methodological approach to mitigate MXene oxidation and functional group interference, advancing the rational design of MXene-based gas sensors.