A breakthrough method reveals active species responsible for carbon monoxide oxidation over platinum surfaces on the microsecond timescale.
A new study has identified chemisorbed oxygen as the primary species involved in the oxidation of carbon monoxide (CO) over platinum (Pt) surfaces, enhancing our comprehension of catalytic mechanisms.
The oxidation of CO, which is of significant environmental and industrial relevance, has long been debated, particularly concerning the active species involved. A recent study, published on February 1, 2025, conducted by researchers at the MAX IV Laboratory, sheds new light on this area. By employing time-resolved ambient pressure X-ray photoelectron spectroscopy (tr-APXPS), the team tracked surface transformations as they occurred on microsecond timescales.
Prior research highlighted contrasting theories about the CO oxidation mechanism, including the traditional Langmuir-Hinshelwood (LH) and alternative Mars-van-Krevelen (MvK) mechanisms. The LH mechanism suggests the participation of reactive surface species adsorbed onto the catalyst, whereas the MvK mechanism focuses on oxides forming active catalytic surfaces. The new findings lean heavily on supporting the LH mechanism, identifying chemisorbed oxygen as the main reactive species.
The researchers utilized tr-APXPS to address the limitations of steady-state measurements, which do not capture transient dynamics. This technique allowed them to simultaneously monitor both reaction products and surface intermediates, effectively distinguishing active from spectator species during the catalytic reaction. Notably, the integration of advanced detection techniques, such as delay-line detection, significantly improved the collection efficiency of data.
According to the authors of the article, "Our findings reveal chemisorbed oxygen plays the main role during CO oxidation, shedding new light on the fundamental mechanisms of this heavily debated reaction." This pivotal discovery opens the door to re-evaluations within the fields of heterogeneous catalysis, particularly concerning catalyst efficiency and industrial applications.
The outcomes of this study could lead to constraints on how automotive catalytic converters optimize emissions control through efficient CO oxidation. Enhanced control over the catalytic process is anticipated as this research informs the next steps for refining resource use and diminishing pollutants derived from vehicular emissions.
Overall, this advancement enriches our knowledge of catalytic processes, advocating for periodic and dynamic operational methodologies as opposed to traditional steady-state approaches. The successful isolation and identification of reactive species present new pathways for both theoretical and applied chemistry.
Moving forward, the incorporation of even faster temporal resolution techniques could yield novel insights and applications, as researchers continue to explore the dynamic behavior of catalytic systems.