Unexpectedly rapid SO<sub>2</sub> heterogeneous reaction on the surface of vehicular brake wear particles.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 42716925.
- Also identified by DOI 10.1038/s41467-026-76820-w.
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Abstract
Sulfate is a major aerosol component whose rapid growth in polluted air remains insufficiently explained. Here, we demonstrate that brake wear particles (BWPs), an emerging urban aerosol source, possess exceptional catalytic efficiency for SO<sub>2</sub> oxidation and sulfate production under dark ambient conditions. Their SO<sub>2</sub> uptake coefficient (up to 2.87 × 10<sup>-5</sup>) is orders of magnitude higher than those of mineral dust or soot. This remarkable reactivity originates from a self-sustained synergy between α-Fe<sub>2</sub>O<sub>3</sub> and carbonaceous components: oxygen vacancies in α-Fe<sub>2</sub>O<sub>3</sub> continuously activate atmospheric O<sub>2</sub> and H<sub>2</sub>O to generate reactive oxygen species and Fe-OH for SO<sub>2</sub> oxidation, while organics and elemental carbon promote H<sub>2</sub>O dissociation through proton abstraction and enhance SO<sub>2</sub> adsorption at carbon defects, respectively. Together, these processes sustain cyclic catalysis and mitigate site deactivation. Our findings establish BWPs as a previously overlooked class of reactive aerosols, with broad implications for multiphase chemistry, atmospheric modeling, and air quality management.