Guo, Qian;
Zhao, Qi;
Crespo-Otero, Rachel;
Di Tommaso, Devis;
Tang, Junwang;
Dimitrov, Stoichko D;
Titirici, Maria-Magdalena;
... Jorge Sobrido, Ana Belén; + view all
(2023)
Single-Atom Iridium on Hematite Photoanodes for Solar Water Splitting: Catalyst or Spectator?
Journal of the American Chemical Society
10.1021/jacs.2c09974.
(In press).
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Abstract
Single-atom catalysts (SACs) on hematite photoanodes are efficient cocatalysts to boost photoelectrochemical performance. They feature high atom utilization, remarkable activity, and distinct active sites. However, the specific role of SACs on hematite photoanodes is not fully understood yet: Do SACs behave as a catalytic site or as a spectator? By combining spectroscopic experiments and computer simulations, we demonstrate that single-atom iridium (sIr) catalysts on hematite (α-Fe2O3/sIr) photoanodes act as a true catalyst by trapping holes from hematite and providing active sites for the water oxidation reaction. In situ transient absorption spectroscopy showed a reduced number of holes and shortened hole lifetime in the presence of sIr. This was particularly evident on the second timescale, indicative of fast hole transfer and depletion toward water oxidation. Intensity-modulated photocurrent spectroscopy evidenced a faster hole transfer at the α-Fe2O3/sIr/electrolyte interface compared to that at bare α-Fe2O3. Density functional theory calculations revealed the mechanism for water oxidation using sIr as a catalytic center to be the preferred pathway as it displayed a lower onset potential than the Fe sites. X-ray photoelectron spectroscopy demonstrated that sIr introduced a mid-gap of 4d state, key to the fast hole transfer and hole depletion. These combined results provide new insights into the processes controlling solar water oxidation and the role of SACs in enhancing the catalytic performance of semiconductors in photo-assisted reactions.
| Type: | Article |
|---|---|
| Title: | Single-Atom Iridium on Hematite Photoanodes for Solar Water Splitting: Catalyst or Spectator? |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1021/jacs.2c09974 |
| Publisher version: | https://doi.org/10.1021/jacs.2c09974 |
| Language: | English |
| Additional information: | © 2023 The Authors. Published by American Chemical Society. This is an open access article under the CC BY 4.0 license Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/) |
| Keywords: | Hematite, Hole transfer, Photonics, Transition metals, Water oxidation |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10163311 |
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