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Loading cocatalysts on semiconductor-based photocatalysts to create active reaction sites is a preferable method to enhance photocatalytic activity and a widely adopted strategy to achieve effective photocatalytic applications. Although theoretical calculations suggest that the broad density of states of noble metal cocatalysts, such as Pt, act as a recombination center, this has never been experimentally demonstrated. Herein, we employed pico-nano and nano-micro second transient absorption spectroscopy to investigate the often overlooked photogenerated holes, instead of the widely studied electrons on Pt- and Ni-loaded SrTiO3 to evaluate the effects of cocatalysts as a recombination center. It is demonstrated that Pt serves as the recombination center with no sacrificial agent; recombination can be suppressed by a hole scavenger, while recombination is not significant on Ni with localized density of states. It is also found that photo-generated holes in SrTiO3 tend to migrate to Pt within 400 ps, and photo-generated holes generated in the bulk gradually migrate to Pt cocatalysts in a micro-second regime.

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• cc-by-nc-3.0
  

Keyword: Photocatalytic H2 evolution, Recombination center

Date published: 2025-01-20

Publisher: Royal Society of Chemistry (RSC)

Journal:

• Nanoscale (ISSN: 20403364) vol. 17 issue. 5 p. 2567-2576

Funding:

• Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) (World Premier International Research Center Initiative (WPI Initiative) on Materials Nanoarchitectonics (MANA), MEXT, Japan)

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1039/d4nr04725g

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Updated at: 2025-12-10 08:30:03 +0900

Published on MDR: 2025-12-10 08:23:45 +0900