MnO2/Al foil decorated air cleaner with self-driven property for the abatement of indoor formaldehyde

•A self-driven device featuring bi-functions (air cleaning, and heating) was designed.•The device consists of painted board, carbon membrane, Al board, and Mn/Al foil.•α-MnO2 with exposed (3 1 0) facet was integrated with Al foil for formaldehyde oxidation.•The generated heat by electrothermal membrane not only activated MnO2 but also facilitated air disturbance. In this work, a self-driven indoor formaldehyde cleaner is designed by integrating α-MnO2 with exposed (3 1 0) crystal facet onto an electrothermal carbon membrane. The integrated device features bi-functions (air cleaning, and heating) and consists of four parts: painted board, the carbon membrane, the aluminum (Al) board, and the MnO2 decorated Al (Mn/Al) foil. The electrothermal carbon membrane can convert electrical energy into heat energy. At the maximum power of 846 W, the saturated temperature can be up to 97.1 °C and the heated MnO2 catalysts inhibit the accumulation of intermediates (formate and bicarbonate species) during formaldehyde abatement process. Furthermore, due to the temperature difference, the generated gradient force drives the movement of the gas and leads to the formation of four large recirculation zones in a simulated room, which facilitates the air disturbance. As a result, the concentration of formaldehyde in a chamber reduced from 1.24 to 0.13 mg/m3 in 90 min at operating temperature of 97.1 °C. More importantly, the contribution of temperature to mass transfer was comparable (only 11.9% less) to that of the fan disturbance reinforcement, which makes it possible to operate without additional fan assistance. This type of air cleaner by integrating MnO2 catalysts with heating equipment not only utilizes the residual heat to prolong the life span of active components but also provides a novel idea for the design of indoor formaldehyde cleaner.