Transient Absorption Microscopy Explores the Effect of Pt Deposition on Charge Carrier Dynamics in Individual Carbon...

This study aims to spatially understand the effect of Pt deposition on slow (μs-s) carrier dynamics in carbon nitride (CN_x) photocatalysts, using a homebuilt microsecond diffuse reflectance transient absorption microscopy setup. It is found that Pt deposition lengthens the overall charge half-lives about threefold, while having a spatial preference for binding with respect to defects that induce charge trapping in the μs-s timescale. The initial trapped charge population shows a slight decrease after Pt deposition, suggesting that the more reactive and mobile charges are extracted by Pt sites, leaving behind deeply trapped and long-lived charges. The results emphasize that spatial heterogeneity of surface cocatalysts likely plays a major role in controlling the charge carrier dynamics and activity of photocatalysts.