Combined Experimental and Density Functional Theory Study on the Mechanism of the Selective Catalytic Reduction of NO with NH 3 over Metal-Free Carbon-Based Catalysts.

Metal-free carbon-based catalysts are attracting much attention in the low-temperature selective catalytic reduction of NO x with NH 3 (NH 3 -SCR). However, the mechanism of the NH 3 -SCR reaction on carbon-based catalysts is still controversial, which severely limits the development of carbon-based SCR catalysts. Herein, we successfully reconstructed carbon-based catalysts through oxidation treatment with nitric acid, thereby enhancing their low-temperature activity in NH 3 -SCR. Combining experimental results and density functional theory (DFT) calculations, we proposed a previously unreported NH 3 -SCR reaction mechanism over carbon-based catalysts. We demonstrated that C-OH and C-O-C groups not only effectively activate NH 3 but also remarkedly promote the decomposition of intermediate NH 2 NO. This study enhances the understanding of the NH 3 -SCR mechanism on carbon-based catalysts and paves the way to develop low-temperature metal-free SCR catalysts.