Experimental and Theoretical Investigation of Mesoporous MnO₂ Nanosheets with Oxygen Vacancies for High-Efficiency Catalytic DeNO_<i>x</i>

Abstract

A solvent-free synthetic method was employed for the construction of mesoporous α-MnO₂ nanosheets. Benefiting from a solid interface reaction, the obtained MnO₂ nanosheets with large oxygen vacancies exhibit a high surface area of up to 339 m²/g and a mesopore size of 4 nm. The MnO₂ nanosheets as a catalyst were applied in NH₃-assisted selective catalytic reduction (NH₃-SCR) of DeNO_<i>x</i> at a relatively low temperature range. The conversion efficiency could reach 100% under a gas hourly space velocity (GHSV) of 700000 h^–1 at 100 °C. To gain insight into the mechanism about NH₃-SCR of nitric oxide on the MnO₂ nanosheets, temperature-programmed desorption of NH₃, a density functional theory study, and in situ diffuse reflectance infrared Fourier transform spectra were carried out, revealing the cooperative effect of catalytic sites on the reduction of nitric oxide. This work provides a strategy for the facile preparation of porous catalysts in low-temperature DeNO_<i>x</i>