MOF-derived Mo-doped stacked Co3O4 nanosheets for chemiresistive toluene vapor sensing

Toluene is one typical indoor pollutant, which is harmful to our health and safety. However, it remains a hinder for high-performance detecting it due to the low chemical reactivity. In this paper, the Mo-doped stacked Co3O4 nanosheets derived from metal-organic frameworks (MOF) are successfully prepared using a facile wet-chemical route and subsequent annealing treatment. The incorporation of Mo6+ into Co3O4 lattice promotes the contents of Co3+ and specific surface area. Consequently, the as-fabricated gas sensor using 0.5 at% Mo-doped Co3O4 announces a remarkable response (Rg/Ra = 42.90–100 ppm), actual detection limit (∼ 0.1 ppm), and apparent selectivity towards toluene gas at a low temperature (∼ 150 °C). Furthermore, an in-situ DRIFTS result proves the possible intermediates (such as benzene alcohol, benzaldehyde, and benzoic acid) in this toluene-sensing reaction. The enhancement in toluene-sensing response is also clarified in detail from the aspects of structural merits and Mo-doped effect in this stacked Co3O4 nanosheets. The research results further verify a viable solution for detecting low reactive gas using high valence cation-doped catalytic oxides.