Mn-Ce oxide nanoparticles supported on nitrogen-doped reduced graphene oxide as low-temperature catalysts for selective catalytic reduction of nitrogen oxides

In this study, we use nitrogen-doped reduced graphene oxide as a catalyst support for selective catalytic reduction (SCR) and extend its application to various catalysts by synthesizing graphene supports with high thermal stability and abundant surface functional groups. In order to clarify the role of graphene support, we used three supports, viz., graphene oxide (GO) and two N-doped reduced graphene oxide (N-rGO) samples obtained using two different doping agents, NH₄NO₃ and NH₄OH. The dispersion of the catalytically active materials on the graphene support improved with nitrogen doping, as confirmed by the results of X-ray photoelectron spectroscopy and transmission electron microscopy, the texture properties evaluated by N₂ adsorption/desorption measurements, and the thermal stability of the catalyst at the operating temperature evaluated by thermogravimetric analysis. The N-rGO supports inhibited the catalyst aggregation; they enhanced the dispersibility of Mn-Ce oxide nanoparticles owing to the rich anchoring sites on their surface, leading to a high NO_x conversion efficiency of >90% at 200 °C.