Room-temperature catalytic removal of indoor trace hexanal by weakly crystallized MnO2 ultrafine nanowires

• Published in: Building and environment 2022-12, Vol.226, p.109701, Article 109701
• Main Authors: Hu, Tingxia, Sui, Shanhong, Li, Jiale, Zhang, Pengyi
• Format: Article
• Language: English
• Subjects: Aldehyde; Hexanal; MnO2; Room-temperature catalysis; Trace VOC; Ultrafine nanowires
• ISSN: 0360-1323; 1873-684X
• DOI: 10.1016/j.buildenv.2022.109701

Aldehydes besides formaldehyde are ubiquitous in indoor environment and pose great threats to human health, however few efforts have been made to catalytically decompose them at room temperature. Here, weakly crystallized ultrafine MnO2 nanowires (φ ∼ 5 nm) were hydrothermally synthesized for decomposing hexanal-a frequently detected indoor odorant. As-synthesized ultrafine nanowires were assembled into three-dimensional porous structure, which is conducive to expose active sites. Due to its high specific surface area, abundant oxygen vacancies and ability to generate superoxide radicals at room temperature, as-synthesized ultrafine nanowire MnO2 not only realized fast complete oxidation of 15 ppm hexanal at temperature significantly lower than that required by catalysts reported in literatures, but also exhibited excellent room-temperature catalytic activity for ppb-level hexanal removal. Though trace acetic acid was released as major intermediate during hexanal decomposition, this work first demonstrates it is feasible to catalytically remove aldehydes besides formaldehyde at room temperature. Ultrafine MnO2 nanowires interweaved into a porous structure and exhibited significant activity in decomposing ppb-ppm level hexanal into CO2 and H2O at room temperature. [Display omitted] •Catalytic decomposition of hexanal into CO2 at room temperature first reported.•Continuous room-temperature catalytic removal of ppb-level hexanal first realized.•The decomposition intermediates of hexanal at room temperature is first identified.•Ultrafine MnO2 produces a lot of superoxide radicals at room temperature.•Highly active ultrafine MnO2 nanowires interweaved into a porous structure.