Logical formulation and in-situ assembly of MnCo2O4@MnO2 nanoflower arrays on nickel foam as monolithic catalyst for formaldehyde degradation at indoor temperature

The development and design of efficient and cost-effective catalysts for oxidizing low concentrations of formaldehyde at low temperatures, has been a significant challenge in HCHO oxidation. In this study, MnCo2O4@MnO2-NF (Ni foam) was synthesized as a monolithic catalyst for the degradation of HCHO in indoor environments. Using carrier immobilization, morphology modulation, and doping modification. The results revealed that the Co3O4 nanoarrays could be grown in a directional and orderly manner on the surface of the substrate through morphological modulation, showing a pompom-like, flower-like shape of the nanoneedles, thus providing sufficient growth sites for MnO2. Doping the Co3O4 nanoarrays with Mn via in-situ growth resulted in MnCo2O4 nanoarrays, following which the MnO2 expanded the pore sizes of the sample and provide more surface adsorption sites upon using MnCo2O4 as the carrier. In addition, numerous oxygen vacancies formed on the catalyst surface because of the synergistic interaction between Co and Mn, which formed more Mn3+ species and Oads, resulting in superior low-temperature redox ability and catalytic cycle stability. The catalyst achieved a HCHO removal efficiency of over 85 % within 60 min for five test cycles when the KMnO4 concentration was 0.05 M and Mn/Co ratio was 1:2.