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Povzetek: The development of efficient and durable oxygen evolution reaction (OER) electrocatalysts is critical for advancing proton exchange membrane water electrolyzers (PEMWEs). This study presents a nanostructured iridium oxide anchored on high-surface-area carbon (IrOx/C) OER electrocatalyst, synthesized through ultrasonication-assisted deposition of hydrolysis-derived colloidal IrOx nanoparticles onto the carbon support. The as-prepared IrOx/C exhibits a mass activity exceeding five times that of unsupported benchmark commercial IrO2, attributed to its uniform nanoparticle distribution and enhanced surface chemistry. Post-synthesis heat-treatments at two different temperatures (200 or 300 °C) were employed to stabilize the catalyst structure. Notably, the sample treated at 200 °C retained 84% of its initial activity after accelerated stress testing, outperforming the commercial counterpart, which retained 67 % under identical conditions. Comprehensive structural and morphological analyses revealed that the heat-treatment increased the IrOx particle size and decreased the Ir³⁺/Ir⁴⁺ ratio while leaving the amorphous nature of IrOx unaffected, which combinedly led to the improved durability. These findings offer valuable insights into designing stable low-iridium OER electrocatalysts for acidic PEMWE applications.
Ključne besede: iridium oxide, oxygen evolution reaction, carbon support, stability
Objavljeno v DiRROS: 15.01.2026; Ogledov: 478; Prenosov: 285
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Povzetek: Nanoparticulate Ir-oxides are frequently used as highly active and robust anode electrocatalysts for acidic water electrolyzers. While their dissolution during the electrolyzer operation is unsought, it could be a green route for recovery of Ir from the spent electrodes. In this study, we explore such a possibility and show that the electrochemical dissolution of Ir-oxides during a potential cycling treatment can be enhanced by introducing transition metal ions (such as Cu2+) in the acidic electrolyte. Dissolution of Ir from a nanoparticulate Ir-oxide containing electrode through potential cycling between 0.0 and 1.65 V in 1 M HCl increases by a factor of ∼3 in the presence of low concentrations (e.g. 10 mM) of Cu2+. Impact of the presence of the metal ions on the Ir-oxide dissolution mechanism is characterized. Cyclic deposition and stripping of the Cu2+ ion on the Ir-oxide may be attributed to the enhanced Ir dissolution, as evidenced by cyclic voltammograms studied in detail for Cu2+. Apart from exploration of the possibility of the electrochemical dissolution-based recovery of Ir from the spent Ir-oxide electrocatalysts, the study highlights the generally negative impacts of the presence of certain metal ions in the feedstock water on the electrocatalyst durability in acidic water electrolysis. Outcomes of this study are highly relevant for the fast-growing acidic water electrolysis industry.
Ključne besede: electrocatalysts, oxygen evolution reaction, acidic environment
Objavljeno v DiRROS: 05.01.2026; Ogledov: 557; Prenosov: 284
Celotno besedilo (6,86 MB)
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Povzetek: Single metal atom catalysts (SACs) are receiving widespread attention in electrochemical energy conversion reactions due to the rational use of metal resources and maximum atom utilization efficiency. The role of the support in stabilizing the single atoms is crucial for their catalytic stability. Carbon nitride (CN) is an excellent support for SACs but its low electrical conductivity is not appropriate for electrochemical applications. Here, we report an engineered composite material based on multiwall carbon nanotubes (MWCNTs) and single nickel atoms stabilized on CN (Ni–CN) as efficient and robust electrocatalyst for the oxygen evolution reaction (OER). Composites with different mass Ni–CN:MWCNT ratios have been prepared to optimize the contribution of both materials, and characterized by X-ray diffraction, transmission electron microscopy, X-ray absorption, and X-ray photoemission spectroscopy. Results confirmed the self-assembly of both materials and the condensation of the triazine-based structure of CN into heptazine-based onto the MWCNTs’ surface during the synthesis, as well as the presence of single Ni atoms in the composites. The co-presence of NiO nanoparticles was detected for the samples with the highest Ni content. The ratio of NiO nanoparticles to single-atom Ni centers was governed by the Ni–CN:MWCNT ratio employed during synthesis. Electrochemical characterization showed a synergistic effect between Ni–CN and MWCNTs that boosted the OER activity of the composites respect to the individual components. The 1:2 ratio turned out to be the optimal one for the composite preparation, maximizing the combined effects of the catalytic activity of the Ni centers and the electrical conductivity of MWCNTs. The mass activity obtained by this composite was 30 times higher than that of the Ni–CN starting material, attributable to its superior electrical conductivity and improved accessibility of Ni active sites. This study underscores the potential of composite materials to advance SACs toward large-scale application.
Ključne besede: carbon nanotubes, carbon nitride, single atom catalysts, nickel oxygen evolution reaction
Objavljeno v DiRROS: 18.09.2025; Ogledov: 682; Prenosov: 347
Celotno besedilo (5,18 MB)
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Ključne besede: electrocatalysis, bifunctional electrocatalysts, oxygen evolution reaction, oxygen reduction reaction, IL-TEM, IL-SEM, EFC-ICP-MS
Objavljeno v DiRROS: 24.11.2020; Ogledov: 3632; Prenosov: 2063
Celotno besedilo (3,51 MB)
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