Resolving active species during the carbon monoxide oxidation over Pt(111) on the microsecond timescale.

Catalytic studies traditionally rely on steady-state conditions resulting in time-averaged datasets that do not differentiate between active and spectator species. This limitation can cause misinterpretations of catalytic function, as the signal of short-lived intermediates responsible for producing desired reaction products is often masked by more intense spectator species. Time-resolved ambient pressure X-ray photoelectron spectroscopy (tr-APXPS) mitigates this issue by combining microsecond time resolution under reaction conditions.