SYNTHESIS AND FUNCTIONAL PROPERTIES OF TіO2-Pt/Pd ELECTROCATALYSTS
DOI: https://doi.org/10.17721/1728-2209.2025.1(60).13
Keywords:
titanium suboxide, encapsulation, noble metals, oxygen evolution reaction, semiconductor propertiesAbstract
Background. This study is focused on the development and comprehensive characterization of novel composite electrocatalytic materials based on porous titanium dioxide modified with Pt and Pd. The primary objective was to create highly efficient and stable systems for electrocatalytic applications, particularly for reactions involving high anodic potentials, such as the oxygen evolution reaction.
Methods. The porous TiO2 matrix was synthesized using a two-step anodization process of titanium foil in ethylene glycol-based electrolytes containing ammonium fluoride / phosphoric acid, followed by electrochemical reduction in a perchloric acid solution. This method allowed for precise control over the morphology and specific surface area of the resulting oxide layer. Modification with noble metals was achieved through galvanic deposition of Pt and/or Pd from appropriate plating baths, with subsequent thermal treatment at 500 °C in an air atmosphere. This crucial annealing step facilitated the formation of the final composite structure by promoting surface layer oxidation and the encapsulation of metal particles within the titanium oxide matrix. The morphology, elemental composition, and phase structure of the synthesized composites were investigated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and powder X-ray diffraction.
Results. The analyses confirmed the formation of a developed porous microstructure with a uniform distribution of Pt and Pd nanoclusters. The phase composition was predominantly anatase, with the presence of metallic Pt and Pd, as well as palladium oxide. The electrochemical properties were evaluated through quasi-stationary voltammetry and electrochemical impedance spectroscopy in a 1 M HClO4 solution. The materials exhibited semiconductor behavior of the n-type with a high charge carrier concentration, as determined by Mott-Schottky analysis. The TiO2-Pt composite demonstrated the highest activity in the OER, characterized by a Tafel slope of 122 mV/dec. The bimetallic system, while showing a higher Tafel slope (172 mV/dec) indicative of a more complex reaction mechanism influenced by the semiconductor properties of the substrate, displayed exceptional operational stability. It retained its catalytic activity and structural integrity for over 215 hours under severe testing conditions (0.5 A, 1 M HClO4), significantly outperforming the unstable Pd-only modified electrode.
Conclusions. The research establishes a correlation between the synthesis conditions, the structural characteristics of the composites, and their functional electrocatalytic properties. The developed composites show significant promise for use as durable anode materials in various electrochemical processes, including oxygen evolution, and serve as a foundational template for further development of advanced (photo)electrocatalysts. The proposed synthesis strategy offers a viable route for creating efficient electrocatalysts with reduced noble metal content.
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Copyright (c) 2025 Дмитро КОВТУНОВ, Сергій ЧЕРНИХ, Валентина КНИШ, Олеся ШМИЧКОВА, Тетяна ЛУК'ЯНЕНКО, Олександр ВЕЛІЧЕНКО
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