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

## TL;DR

The study uses microscopy to show how platinum affects charge behavior in carbon nitride particles, revealing spatial variations that impact photocatalyst performance.

## Contribution

The novel use of microsecond transient absorption microscopy reveals spatial heterogeneity in Pt's effect on charge carrier dynamics in CNx photocatalysts.

## Key findings

- Pt deposition triples the half-lives of charge carriers in CNx particles.
- Pt preferentially binds to defect sites that trap charges, reducing initial trapped charge populations.
- Spatial heterogeneity of Pt binding influences photocatalyst activity and charge dynamics.

## Abstract

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.

Transient absorption microscopy in the microsecond and micrometer regime is used to investigate the effect of Pt on individual carbon nitride (CN
x
) photocatalytic particles. A pixel‐by‐pixel comparison of particles before and after Pt deposition highlights that Pt has a spatially heterogeneous impact on the charge carrier dynamics, with implications for the optimization of photocatalyst/cocatalyst interfaces.© 2025 WILEY‐VCH GmbH