NO Oxidation Using H2O2 at a Single-Atom Iron Catalyst

Nitrogen oxide (NO) is a major worldwide environmental pollutant, which can be eliminated effectively by catalytic oxidation. However, conventional catalysts generally suffer from poor activity and low oxidation rates, limiting the development of gas pollutant removal. To overcome this issue, the high activity of a single-atom catalyst and the strong oxidizability of H2O2 are proposed for the catalytic oxidation of NO in this work. Herein, the 14 reaction pathways of NO oxidation using H2O2 were obtained through spin-polarized density functional theory calculation with van der Waals corrections and microkinetic modeling. Considering the possible H2O2 activation products of *OH, *OOH, and *O, we obtained the dominant reaction pathways for different oxidizing species: (i) Langmuir–Hinshelwood mechanism of *OH (mainly forming *HNO2), (ii) Eley–Rideal mechanism of *O (forming *NO2), and (iii) *OOH (forming *HNO3), with the energy barriers of 0.94, 1.42, and 0.14 eV, respectively. Among the three reaction patterns, NO oxidation using *OOH is the most favorable, with the highest reaction rate. *HNO3 is the most likely oxidation product of NO oxidation using H2O2. Meanwhile, it is notable that the *OH catalytic oxidation of NO has multiple reaction pathways and products, including HNO2, NO2, and HNO3. Compared to the use of conventional oxidants and catalysts, using H2O2 to oxidize NO at Fe–N4–C catalyst has lower reaction energy barriers and allows for the deep oxidation of NO. This study illustrates the reaction pathway of NO oxidation using H2O2 and demonstrates that it is theoretically feasible, which provides guidance for the subsequent preparation of the material.