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

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 (phi similar to 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.

Automated summary

Aldehydes, apart from formaldehyde, are commonly found in indoor environments and pose significant threats to human health. However, there have been limited efforts to catalytically decompose them at room temperature. In this study, hydrothermally synthesized weakly crystallized ultrafine MnO2 nanowires were used to decompose hexanal, a frequently detected indoor odorant. The nanowires formed a three-dimensional porous structure, exposing active sites. With its high specific surface area, abundant oxygen vacancies, and ability to generate superoxide radicals at room temperature, the MnO2 nanowires achieved fast and complete oxidation of hexanal at significantly lower temperatures compared to catalysts reported in previous literatures. Moreover, the nanowires exhibited excellent room-temperature catalytic activity for the removal of hexanal at ppb levels. This work demonstrates the feasibility of catalytically removing aldehydes other than formaldehyde at room temperature.