Descriptor-Led Nonmetal Doping of MnO₂ Enables Selective NH₃-SCR With Suppressed N₂O Formation.

Authors

Kai Xie, Ying Wang, Fenghui Li, Haiqiao Wei, Pengfei Ou, Lei Zhou

Published in

Small (Weinheim an der Bergstrasse, Germany). Pages e74760. Jul 27, 2026. Epub Jul 27, 2026.

Abstract

Low-temperature ammonia-selective catalytic reduction (NH₃-SCR) over MnO₂ is attractive for nitrogen oxides (NO_x) abatement yet is intrinsically penalized by nitrous oxide (N₂O) formation, a potent greenhouse byproduct. Here, we show that oxygen-site nonmetal substitution in β-MnO₂ can simultaneously suppress N₂O and accelerate NH₃-selective SCR, enabled by a feasibility-to-mechanism computational workflow. Screening by structural compatibility, orbital hybridization, thermochemical and kinetic stability identifies viable dopants, among which F and S most effectively rewire reaction branching. Kinetics estimated by the density functional theory calculations reveal that F and S raise the N₂O-forming rate-determining barrier from 0.80 eV to 0.93/0.92 eV, while lowering the N₂-forming barrier from 0.48 eV to 0.40/0.42 eV. At 200°C, F- and S-doped β-MnO₂ increase TOF by a factor of 8.40 and 4.24, respectively, and enhance kinetic N₂ selectivity by a factor of 1.66 and 1.38, respectively. We identify Mn(d)-nonmetal(p) band center alignment as a mechanistic descriptor that points to a volcano-like trend for the energy barriers of N₂O and N₂, supported by Bader charge, COHP/ICOHP, and ELF analyses. These results serve as a theoretical design reference for tuning the activity-selectivity trade-off in oxygen-site-modified oxide SCR catalysts.

PMID:
42504605
Bibliographic data and abstract were imported from PubMed on 27 Jul 2026.

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