Catalytically Active Oxidized PtOx Species on SnO2 Supports Synthesized via Anion Exchange Reaction for 4-Nitrophenol Reduction

Ðurasović, Izabela; Peter, Robert; Dražić, Goran; Faraguna, Fabio; Anelić, Rafael; Marciuš, Marijan; Jurkin, Tanja; Mohaček Grošev, Vlasta; Gracheva, Maria; Klencsár, Zoltán; Ivanda, Mile; Štefanić, Goran; Gotić, Marijan (2025) Catalytically Active Oxidized PtOx Species on SnO2 Supports Synthesized via Anion Exchange Reaction for 4-Nitrophenol Reduction. Nanomaterials, 15 (5). ISSN 2079-4991

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Official URL: https://www.mdpi.com/2079-4991/15/15/1159

Abstract

An anion exchange-assisted technique was used for the synthesis of platinum-decorated SnO2 supports, providing nanocatalysts with enhanced activity for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). In this study, a series of SnO2 supports, namely SnA (synthesized almost at room temperature), SnB (hydrothermally treated at 180 °C), and SnC (annealed at 600 °C), are systematically investigated, all loaded with 1 mol% Pt from H2PtCl6 under identical mild conditions. The chloride ions from the SnCl4 precursors were efficiently removed via a strong-base anion exchange reaction, resulting in highly dispersed, crystalline ~5 nm cassiterite SnO2 particles. All Pt/SnO2 composites displayed mesoporous structures with type IVa isotherms and H2-type hysteresis, with SP1a (Pt on SnA) exhibiting the largest surface area (122.6 m2/g) and the smallest pores (~3.5 nm). STEM-HAADF imaging revealed well-dispersed PtOx domains (~0.85 nm), while XPS confirmed the dominant Pt4+ and Pt2+ species, with ~25% Pt0 likely resulting from photoreduction and/or interactions with Sn–OH surface groups. Raman spectroscopy revealed three new bands (260–360 cm−1) that were clearly visible in the sample with 10 mol% Pt and were due to the vibrational modes of the PtOx species and Pt-Cl bonds introduced due the addition and hydrolysis of H2PtCl6 precursor. TGA/DSC analysis revealed the highest mass loss for SP1a (~7.3%), confirming the strong hydration of the PtOx domains. Despite the predominance of oxidized PtOx species, SP1a exhibited the highest catalytic activity (kapp = 1.27 × 10−2 s−1) and retained 84.5% activity for the reduction of 4-NP to 4-AP after 10 cycles. This chloride-free low-temperature synthesis route offers a promising and generalizable strategy for the preparation of noble metal-based nanocatalysts on oxide supports with high catalytic activity and reusability.

Item Type:

Article

Uncontrolled Keywords:

platinum; SnO2; anion exchange; Dowex 550; catalyst; 4-nitrophenol; XPS; 119Sn Mössbauer

Subjects:

NATURAL SCIENCES > Chemistry > Inorganic Chemistry

Divisions:

Division of Materials Physics
Division of Materials Chemistry

Projects:

Project title	Project leader	Project code	Project type
Platinom dekorirane čvrste otopine željezovog i kositrovog oksida za vodikove senzore-HydGasSens	Marijan Gotić; Goran Dražić	IP-2019-04-1195	HRZZ
Potpora vrhunskim istraživanjima Centra izvrsnosti za napredne materijale i senzore-	Mile Ivanda; Milko Jakšić; Mario Stipčević; Marko Kralj	KK.01.1.1.01.0001	EK
Grant from Hungarian National Research, Development, and Innovation Office (NKFIH)	Marijan Gotić	2019-2.1.11-TÉT-2020-00221	bilaterala HR-HU