Catalytic Reduction Mechanisms for Nitric Oxide

The catalytic reduction of nitric oxide (NO) underpins modern strategies for abating NOx emissions from automotive exhausts and industrial flue gases. Central to this process are heterogeneous catalysts, typically comprising noble or base metal nanoparticles dispersed on oxide supports, as well as emerging two-dimensional materials. Mechanistically, NO reduction involves sequential steps of adsorption, bond activation and dissociation into surface-bound N and O atoms, followed by recombination pathways that yield benign gases such as N₂ and H₂O or CO₂. Competing routes include direct NO dissociation, dimer-mediated pathways and selective catalytic reduction (SCR) with reductants like CO, H₂ or NH₃. Electronic properties of the active metal sites, often characterised by d-band centre positions, govern adsorption energies and activation barriers. Advances in operando spectroscopy and computational modelling have elucidated transient intermediates (e.g. NO*, NOH*, N₂O*) and highlighted the role of support defects, such as oxygen vacancies, in facilitating vacancy refilling and turnover. Practical applications demand catalysts that maximise N₂ selectivity, minimise N₂O by-product formation and maintain long-term stability under high-temperature, oxidative conditions. Current research focusses on reducing noble-metal loadings, engineering single-atom active centres and exploiting synergistic metal-support interactions to enhance activity and durability.

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Catalytic Reduction Mechanisms for Nitric Oxide publication trend

The graph below shows the total number of articles in catalytic reduction mechanisms for nitric oxide across all publications each year (not limited to Nature Index journals).

Technical terms

Adsorption: Attachment of NO molecules to active sites on a catalyst surface.

Dissociation: Cleavage of the N–O bond to form surface-bound N and O atoms.

Dimer: A species formed by the association of two NO molecules, often denoted (NO)₂.

Operando spectroscopy: In situ measurement of catalyst surface species under reaction conditions.

Oxygen vacancy: A defect site in oxide supports where an oxygen atom is missing, enhancing catalytic activity.

Density functional theory (DFT): Computational method for evaluating electronic structure and reaction barriers on catalyst surfaces.

References

1. Operando Shell‐Isolated Nanoparticle‐Enhanced Raman Spectroscopy of the NO Reduction Reaction over Rhodium‐Based Catalysts. ChemPhysChem (2021).
2. Al-Decorated C2N Monolayer as a Potential Catalyst for NO Reduction with CO Molecules: A DFT Investigation. Molecules (2022).
3. Theoretical insights into the support effect on the NO activation over platinum-group metal catalysts. The Journal of Chemical Physics (2023).