Imaging nanoscale photocarrier traps in solar water-splitting catalysts

Levi D. Palmer; Wonseok Lee; Pushp Raj Prasad; Bradley W. Layne; Han-Hsuan Wu; Zejie Chen; Jianguo Wen; Yuzi Liu; Xiaoqing Pan; A. Alec Talin; Akihiko Kudo; Shane Ardo; Joseph P. Patterson; Thomas E. Gage; Scott K. Cushing

arXiv · 2512.24543

Imaging nanoscale photocarrier traps in solar water-splitting catalysts

Levi D. Palmer·Wonseok Lee·Pushp Raj Prasad·Bradley W. Layne·Han-Hsuan Wu·Zejie Chen·Jianguo Wen·Yuzi Liu·Xiaoqing Pan·A. Alec Talin·Akihiko Kudo·Shane Ardo·Joseph P. Patterson·Thomas E. Gage·Scott K. Cushing

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Abstract

Defects trap photocarriers and hinder solar water splitting. The nanoscale photocarrier transport, trapping, and recombination mechanisms are usually inferred from ensemble-averaged measurements and remain elusive. Because an individual high-performing nanoparticle photocatalyst may outperform the ensemble average, design rules that would otherwise enhance catalytic efficiency remain unclear. Here, we introduce photomodulated electron energy-loss spectroscopy (EELS) in an optically coupled scanning transmission electron microscope (STEM) to map photocarrier localization. Using rhodium-doped strontium titanate (SrTiO3:Rh) solar water-splitting nanoparticles, we directly image the carrier densities concentrated at oxygen-vacancy surface trap states. This is achieved by separating photothermal heating from photocarrier populations through experimental and computational analyses of low-loss spectra. Photomodulated STEM-EELS enables angstrom-scale imaging of defect-induced photocarrier traps and their impact on photocatalytic efficiency.

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Levi D. Palmer, Wonseok Lee, Pushp Raj Prasad, Bradley W. Layne, Han-Hsuan Wu, Zejie Chen, Jianguo Wen, Yuzi Liu, Xiaoqing Pan, A. Alec Talin, Akihiko Kudo, Shane Ardo, Joseph P. Patterson, Thomas E. Gage, Scott K. Cushing. 2025-12-31. Imaging nanoscale photocarrier traps in solar water-splitting catalysts. https://arxiv.org/abs/2512.24543

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