Theoretical Study of NO Adsorption by Hydroxyl-Containing Char with the Participation of Na/K

Abstract

The study of the effects of Na and K on the heterogeneous adsorption of hydroxyl-containing char with NO is important for the clean utilization of high alkali coal. In this paper, the effects of Na/K atoms on the adsorption of NO on the char surface were investigated at the GGA-PBE level by choosing zigzag type, armchair type, and saturated hydroxyl-containing char structures based on DFT. It was found that the adsorption stability of NO on structures with active sites was greater for sites close to the hydroxyl group than that for sites far from the hydroxyl group. The stability of char doped by Na/K is related to the char structure and the position of functional groups. The most stable Na/K doped structures are Z-OH-2 (E ads = −350.50 kJ/mol) and A-OH-1-2 (E ads = −339.17 kJ/mol), respectively. The participation of Na/K can increase the adsorption energy of the three structures with NO, and especially the adsorption energy of saturated char with NO is increased by as much as 5 times. The reason for that is the promotion of the hybridization of the C and NO p orbitals.The comprehensive analysis of electrostatic potential, charge transfer, and front orbitals indicates that the effects of decorated sodium and potassium atoms on the char surface are very similar. This study lays a theoretical foundation for the study of the heterogeneous reduction process.

Cooperative defect engineering and ligand modification in UiO-66 to achieve high proton conductivity

“…In order to address carbon emissions and climate change, efforts towards the global energy structure transformation from fossil fuels to renewable and clean energy are being implemented. 1–3 The proton exchange membrane fuel cell (PEMFC) has emerged as an alternative to traditional engines because of its high energy density and pollution-free characteristics. 4,5 However, achieving widespread commercialization of PEMFCs still faces many challenges, such as reducing costs, increasing power density, and improving stability and durability.…”

“…Metal–organic frameworks (MOFs) are considered potential materials for exploring proton conductors due to their clear structures and functional frameworks. 2 The clear structural information of MOFs plays a promoting role in understanding the proton conduction mechanism. 11 On the other hand, the functionalized framework of MOFs provides the possibility for the directed synthesis of a stable proton conductor with high proton conductivity.…”