As a single atom Pd outperforms Pt as the most active co-catalyst for photocatalytic H2 evolution

Gihoon Cha; Imgon Hwang; Seyedsina Hejazi; Ana S Dobrota; Igor A Pašti; Benedict Osuagwu; Hyesung Kim; Johannes Will; Tadahiro Yokosawa; Zdeněk Badura; Štěpán Kment; Shiva Mohajernia; Anca Mazare; Natalia V Skorodumova; Erdmann Spiecker; Patrik Schmuki

doi:10.1016/j.isci.2021.102938

As a single atom Pd outperforms Pt as the most active co-catalyst for photocatalytic H₂ evolution

iScience. 2021 Jul 31;24(8):102938. doi: 10.1016/j.isci.2021.102938. eCollection 2021 Aug 20.

Authors

Gihoon Cha¹, Imgon Hwang¹, Seyedsina Hejazi¹, Ana S Dobrota², Igor A Pašti^{2

3}, Benedict Osuagwu¹, Hyesung Kim¹, Johannes Will⁴, Tadahiro Yokosawa⁴, Zdeněk Badura⁵, Štěpán Kment⁵, Shiva Mohajernia¹, Anca Mazare¹, Natalia V Skorodumova^{3

6}, Erdmann Spiecker⁴, Patrik Schmuki^{1

5

7}

Affiliations

¹ Institute for Surface Science and Corrosion WW4-LKO, Department of Materials Science, University of Erlangen-Nuremberg, Martensstraße 7, 91058 Erlangen, Germany.
² Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, Belgrade, 11000 Serbia.
³ Department of Materials Science and Engineering, School of Industrial Engineering and Management, KTH-Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden.
⁴ Institute of Micro- and Nanostructure Research & Center for Nanoanalysis and Electron Microscopy (CENEM), University of Erlangen-Nuremberg, IZNF, Cauerstraße 3, 91058 Erlangen, Germany.
⁵ Regional Centre of Advanced Technologies and Materials, Šlechtitelů 27, Olomouc, 78371 Czech Republic.
⁶ Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden.
⁷ Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, 21569 Saudi Arabia.

Abstract

Here, we evaluate three different noble metal co-catalysts (Pd, Pt, and Au) that are present as single atoms (SAs) on the classic benchmark photocatalyst, TiO₂. To trap the single atoms on the surface, we introduced controlled surface vacancies (Ti³⁺-O_v) on anatase TiO₂ nanosheets by a thermal reduction treatment. After anchoring identical loadings of single atoms of Pd, Pt, and Au, we measure the photocatalytic H₂ generation rate and compare it to the classic nanoparticle co-catalysts on the nanosheets. While nanoparticles yield the well-established the hydrogen evolution reaction activity sequence (Pt > Pd > Au), for the single atom form, Pd radically outperforms Pt and Au. Based on density functional theory (DFT), we ascribe this unusual photocatalytic co-catalyst sequence to the nature of the charge localization on the noble metal SAs embedded in the TiO₂ surface.

Keywords: Catalysis; Materials characterization; Nanomaterials.