Engineering pore-size in mesoporous Co3O4 stacked nanosheets for xylene-sensing response

Abstract

Surface pore-size effect plays a crucial role in determining the gas-sensing ability of metal oxides. However, it maintains a certain challenge to reveal the relationship between the pore-size distribution and sensing response due to the limited identical structure models with various pore sizes. In this work, the mesoporous Co3O4 stacked nanosheets with varied average pore diameters (3.6, 7.4, 19.1, and 33.6 nm) were developed through a wet-chemical and followed annealing approach at different temperatures (200∼500 °C). The results of pore size-dependent sensing measurements proved that the Co3O4-300 sample showed the best xylene-sensing response (Rg/Ra = 29.2–100 ppm) at 160 °C against the other three samples (Co3O4-200, Co3O4-400, and Co3O4-500) at their optimal working temperatures. In addition, an excellent selectivity and real detection limit (1 ppm) of this sensor were also demonstrated. Moreover, the enhanced sensing response towards xylene was also clarified. This work provides a reliable approach to optimize the gas-sensing performance via surface pore-size engineering.