Efficient HCHO oxidation at room temperature via maximizing catalytic sites in 2D coralloid δ-MnO2@GO

• Published in: Applied catalysis. B, Environmental Vol. 341; p. 123322
• Main Authors: Li, Yiheng, Dong, Tao, Huang, Pingli, Ji, Jian, Huang, Haibao
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2024
• Subjects: Catalytic site exposure; Formaldehyde catalytic elimination; Graphene oxide; Indoor air pollution; δ-MnO2; Graphene oxide; Formaldehyde catalytic elimination; Catalytic site exposure; Indoor air pollution; δ-MnO2
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2023.123322

Airborne formaldehyde (HCHO) in indoor environments causes serious health problems and needs to be efficiently eliminated. However, the efficient and stable catalytic oxidation of HCHO can be hardly achieved at room temperature over transition metal oxides due to the limited exposure of active sites. Herein, δ-MnO2@GO catalysts were originally synthesized via a facile in situ growth of δ-MnO2 on the trace graphene oxide (GO) substrate (1%) and stably exhibited nearly 100% HCHO elimination at room temperature. δ-MnO2@GO showed the unique 2D coralloid structure with uniformly dispersed δ-MnO2 nanorod on planar-structured GO, which greatly enhanced the exposure of catalytic sites and mass transfer of reactants. The abundant surface reactive oxygen species (ROS) and hydroxyl (-OH) groups were rapidly generated from the activation of O2 and surface-adsorbed water over highly exposed catalytic sites. The ROS and -OH groups cooperated well cooperated to maintain the exceptional catalytic activity and stability towards HCHO degradation. In-situ DRIFTS results showed that catalytic HCHO oxidation predominantly follows the Langmuir-Hinshelwood (L-H) mechanism over the δ-MnO2@GO. This study presents a simple yet effective strategy for maximizing exposure to catalytic active sites and rational design of efficient catalysts for indoor HCHO elimination. [Display omitted] •2D coralloid δ-MnO2@GO-RT was synthesized via facile in situ growth of δ-MnO2 on the graphene oxide (GO) substrate.•The unique 2D coralloid structure of δ-MnO2@GO-RT can dramatically promote catalytic site exposure and reactant mass transfer.•The highly exposed catalytic sites can rapidly activate O2 and H2O to form abundant surface ROS and -OH.•The ROS and -OH can greatly maintain the excellent catalytic activity and stability towards HCHO degradation.