Nanostructured IrO supported on N-doped TiO₂ as an efficient electrocatalyst towards acidic oxygen evolution reaction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The development of efficient and cost-effective electrocatalysts is crucial for advancing solid polymer electrolyte water electrolysis (SPEWE).
• Iridium (Ir) based catalysts are highly effective for the oxygen evolution reaction (OER) but their high cost and scarcity limit widespread application.
• Reducing Iridium loading without sacrificing performance is a key challenge in developing sustainable SPEWE systems.

Purpose of the Study:

• To develop a novel electrocatalyst for the oxygen evolution reaction (OER) that minimizes Iridium (Ir) consumption.
• To enhance the catalytic activity, electrical conductivity, and stability of Ir-based catalysts using a modified support material.
• To investigate the potential of nitrogen-doped titanium dioxide (N-TiO2) as a support for IrO2 nanoparticles in acidic OER applications.

Main Methods:

• Nitrogen (N) doping of titanium dioxide (TiO2) was achieved through facile ammonia (NH3) gas treatment.
• Iridium oxide (IrO2) nanoparticles were synthesized and supported on the N-doped TiO2 (N-TiO2) material.
• Electrocatalytic performance for OER was evaluated in acidic media, focusing on overpotential, mass activity, and long-term stability.
• Single cell electrolysis tests were conducted to assess the practical performance of the developed catalyst.

Main Results:

• The N-doping of TiO2 significantly improved its electrical conductivity and the dispersion/anchoring of IrO2 nanoparticles.
• The resulting IrO2/N-TiO2 electrocatalyst demonstrated excellent catalyst utilization, activity, and stability for the OER.
• An overpotential of only 270 mV was required to achieve 10 mA cm-2, with a mass activity of 278.7 A gIr-1 at 1.55 VRHE.
• In a single cell, the IrO2/N-TiO2 anode catalyst resulted in a lower cell voltage (1.761 V at 2.0 A cm-2) compared to commercial IrO2.

Conclusions:

• Nitrogen doping of TiO2 is an effective strategy to enhance the performance of IrO2 catalysts for acidic OER.
• The IrO2/N-TiO2 electrocatalyst offers a promising pathway to reduce Iridium loading while maintaining high catalytic efficiency and durability.
• This advancement contributes to the cost-effective development of solid polymer electrolyte water electrolysis systems for sustainable energy.