Effect of Fe doping on the surface properties of δ-MnO2 nanomaterials and its decomposition of formaldehyde at room temperature

In this paper, δ-MnO 2 and Fe/δ-MnO 2 -X (X = 0, 1, 2 and 5) nanomaterials were prepared by a one-step water bath co-precipitation method, and then their performance in catalytic oxidation of HCHO at room temperature was investigated. The catalytic oxidation performance of Fe/δ-MnO 2 -5 nanomaterials for formaldehyde was significantly improved by the modification with iron doping and sulfuric acid, and the conversion of 3.35 ppm HCHO reached 99.4% within 8 h at room temperature. Next, the nanomaterials were characterized by X-ray diffraction (XRD), spectroscopy scanning electron microscope (SEM), High-resolution transmission electron microscopy (HR-TEM)，Brunauer-Emmett-Teller (BET), temperature-programmed reduction by H 2 (H 2 -TPR), X-ray photoelectron spectroscopy (XPS) methods to investigate the structural properties of the nanomaterials. It was found that the specific surface area of the composite nanomaterials increased, the particle distribution was more uniform, and the distribution of Mn on the catalyst surface changed significantly. Among them, the content of Mn 3+ increased significantly, which was beneficial to the catalytic oxidation of formaldehyde. • One-step method prepared Fe/δ-MnO 2 -X (X = 0, 1, 2 and 5) nanomaterials. • The doping of ferrous ion is beneficial to the conversion of Mn 2+ and Mn 4+ to Mn 3+ . • After modification, lattice defects on the surface of δ-MnO 2 . • Mn 3+ plays a decisive role in the catalytic oxidation of formaldehyde.