IrO₂-Decorated Titania Nanotubes as Oxygen Evolution Anodes.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Titania nanotubes (TNTs) and their reduced black analogues (bTNTs) are explored as catalyst supports.
• Metallic conductivity in bTNTs is achieved via solid-state reaction with CaH2.
• Oxygen evolution reaction (OER) is a critical process in various electrochemical applications.

Purpose of the Study:

• To investigate the electrocatalytic activity of iridium oxide (IrO2) supported on TNTs and bTNTs for OER.
• To evaluate the effect of nanotube structure (close-packed vs. open) on catalyst performance.
• To compare the performance of novel catalysts with existing literature benchmarks.

Main Methods:

• Preparation of TNTs and bTNTs with varying structural properties (close-packed vs. open).
• Deposition of iridium (Ir) via galvanic replacement of nickel, followed by anodization to IrO2.
• Electrocatalytic testing for OER, including overpotential, current density, and mass-specific current density measurements.

Main Results:

• Open-structure bTNTs supported IrO2 catalysts exhibit superior OER activity compared to close-packed structures and plain TNTs.
• IrO2 nanoparticles on open-structure bTNTs showed improved distribution and smaller particle sizes.
• The optimized catalyst achieved an overpotential of 240 mV at 10 mA cm-2 and demonstrated 72-hour stability in acidic media.

Conclusions:

• Open-structure bTNTs are highly effective supports for IrO2 catalysts in OER.
• The developed IrO2/open-bTNTs electrode offers competitive or superior performance to existing OER catalysts.
• The catalyst exhibits promising medium-term stability for applications in acidic environments.