Metal and nonmetal co-doping in α-MnO2 for boosting the catalytic performance of low-temperature formaldehyde oxidation
Tong Shen, Jie Xie, Weidong Shi, Fagen Wang
Abstract
Designing efficient catalysts capable of oxidizing formaldehyde (HCHO) at ambient temperature continues to pose significant challenges for indoor air remediation. In this study, MnO 2 /NC-M (M = Mg, Fe, Ce) catalysts were fabricated by co-doping metal (Mg 2 + , Fe 3+ , or Ce 4+ ) and nonmetal (C and N) into α-MnO 2 for HCHO oxidative removal. Among the catalysts, α-MnO 2 /NC-Ce exhibited superior formaldehyde removal efficiency. 90 % HCHO removal efficiency was reached over the α-MnO 2 /NC-Ce catalyst in comparison to the efficiencies of 85.5 % and 75.7 % for the Mg- and Fe-doped counterparts at 35 °C, respectively. Characterizations of O 2 -TPD and XPS, etc., demonstrated that the α-MnO 2 /NC-Ce possessed optimal oxygen vacancy and oxygen mobility, synergistically enhancing molecular O 2 activation and oxidative capacity of active oxygen species. In-situ DRIFT spectroscopy identified the intermediates of dioxymethylene (DOM), formate, and Mn(IV)-CO ad , which were subsequently oxidized to CO 2 by adsorbed O 2 and surface lattice oxygen. This work developed an efficient α-MnO 2 /NC-Ce catalyst for HCHO abatement, and the metallic and nonmetallic elements co-doping strategy provides a universal design principle for multi-element-doped catalysts in volatile organic compound abatement.