Marić, Ivan; Dražić, Goran; Radin, Edi; Peter, Robert; Škrabić, Marko; Jurkin, Tanja; Pustak, Anđela; Baran, Nikola; Mikac, Lara; Ivanda, Mile; Petravić, Mladen; Štefanić, Goran; Gotić, Marijan (2022) Impact of platinum loading and dispersion on the catalytic activity of Pt/SnO2 and Pt/α-Fe2O3. Applied Surface Science, 607 . ISSN 0169-4332
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Abstract
The Pt/SnO2 (SP-samples) and Pt/-Fe2O3 (FP-samples) with platinum loadings between 1 and 10 mol% were synthesized mechanochemically starting from platinum(II) acetylacetonate dissolved in toluene and from SnO2 and -Fe2O3 powders obtained from tin(II) and iron(II) acetates. In addition to cassiterite (SnO2), a small amount of Sn and Sn2O3 was found in SP-samples using XRD. The FP-samples consisted exclusively of -Fe2O3. The platinum maxima were not found in the XRD patterns of any sample, even at the highest platinum loading of 10 mol%. The STEM results show that the ultrasmall platinum nanoparticles (PtNPs) are well dispersed on the SnO2 and -Fe2O3 supports. The PtNPs size distributions calculated with lognormal functions ranged from 1.0 to 1.3 nm. The main difference between the Pt dispersion on SnO2 supports and -Fe2O3 supports is the presence of very small spots of about 0.1 nm in size, indicating a region of atomically dispersed platinum in the Pt/SnO2 sample with 5 mol% Pt, while such regions were not found in the Pt/-Fe2O3 samples. The results of temperature programmed reduction in hydrogen showed maxima at 120-160 oC due to the reduction of PtOx to Pt0. The Pt-4f-XPS results showed that the dispersed platinum on the SnO2 and -Fe2O3 supports consisted of all three oxidation states of platinum: Pt4+, Pt2+ and Pt0. The platinum on SnOx and -Fe2O3 supports showed high catalytic activity for the reduction of 4-nitropenol (4-NP) to 4-aminophenol (4-AP), which can be explained by the high dispersion of non-aggregated ultrasmall PtNPs with a size of about 1 nm on the SnOx and -Fe2O3 supports. The optimal platinum loading for the reduction of 4-NP to 4-AP on a SnO2 support is 1 mol% with an apparent rate constant k = 1.53 × 10-2 s-1 , while on a -Fe2O3 support the optimal platinum loading is 5 mol% with k = 1.11 × 10-2 s-1 if we assume pseudo-first order kinetics.
| Item Type: | Article | ||||||||
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| Uncontrolled Keywords: | platinum; dispersion; XPS; ball-milling; reducible supports; catalytic; 4-nitrophenol | ||||||||
| Subjects: | NATURAL SCIENCES > Chemistry > Physical Chemistry NATURAL SCIENCES > Interdisciplinary Natural Sciences |
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| Divisions: | Division of Materials Physics Division of Materials Chemistry |
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| Depositing User: | Marijan Gotić | ||||||||
| Date Deposited: | 14 Jan 2025 09:03 | ||||||||
| URI: | http://fulir.irb.hr/id/eprint/9438 | ||||||||
| DOI: | 10.1016/j.apsusc.2022.155073 |
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