Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 12, Issue 34, Pages 38211-38221Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.0c10968
Keywords
TiO2 nanotube; solid-state dewetting; platinum; copper; PtCu alloy nanoparticle; photocatalysis; H-2 evolution
Funding
- ERC
- DFG
- DFG cluster of excellence EAM
- Emerging Talents Initiative ETI by the FAU Friedrich Alexander University Erlangen-Nuremberg, Germany [ETI2018/2_Tech_11]
- DESY.PETRA III [I-20190283]
- project CALIPSOplus from the EU Framework Programme for Research and Innovation HORIZON 2020 [730872]
- Alexander von Humboldt Foundation
- MIUR through the grant PRIN 2017 MOSCATo [2017KKP5ZR]
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We investigate the co-catalytic activity of PtCu alloy nanoparticles for photocatalytic H-2 evolution from methanol- water solutions. To produce the photocatalysts, a few-nanometer-thick Pt-Cu bilayers are deposited on anodic TiO2 nanocavity arrays and converted by solid-state dewetting via a suitable thermal treatment into bimetallic PtCu nanoparticles. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results prove the formation of PtCu nanoalloys that carry a shell of surface oxides. X-ray absorption near-edge structure (XANES) data support Pt and Cu alloying and indicate the presence of lattice disorder in the PtCu nanoparticles. The PtCu co-catalyst on TiO2 shows a synergistic activity enhancement and a significantly higher activity toward photocatalytic H-2 evolution than Pt- or Cu-TiO2. We propose the enhanced activity to be due to Pt-Cu electronic interactions, where Cu increases the electron density on Pt, favoring a more efficient electron transfer for H-2 evolution. In addition, Cu can further promote the photoactivity by providing additional surface catalytic sites for hydrogen recombination. Remarkably, when increasing the methanol concentration up to 50 vol % in the reaction phase, we observe for PtCu-TiO2 a steeper activity increase compared to Pt-TiO2. A further increase in methanol concentration (up to 80 vol %) causes for Pt-TiO2 a clear activity decay, while PtCu-TiO2 still maintains a high level of activity. This suggests improved robustness of PtCu nanoalloys against poisoning from methanol oxidation products such as CO.
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