Polymer electrolyte membrane electrolytic cells (PEMECs) is one of appropriate energy storage systems connected with renewable energy due to high drive current and endurance under road fluctuation. In water electrolysis, oxygen evolution reaction (OER) occurs under acidic and high potential. So, the large amount of precious metal catalyst is needed for performance and stability. Introduction of supporting materials could reduce the amount of precious metal catalyst without performance degradation. Titanium oxide (TiO₂) is one of few materials which shows good stability under acidic and high potential conditions. Also low electronic conductivity of TiO₂ (~10^-6 S/cm) can overcome with introduction of appropriate doping element into TiO₂.

In this work, various metal elements were doped into TiO₂ supporting materials. M-doped TiO₂ were prepared by electrospinning method. Figure 1 (a) is a SEM image of prepared nanofiber TiO₂. M-doped TiO₂ were characterized to study physical and chemical properties. Then, iridium catalysts on M-doped TiO₂ support (Ir/M-doped TiO₂) were synthesized by polyol method and were electrochemically evaluated. OER activity of prepared catalysts was measured by linear sweep voltammetry in oxygen-saturated 0.5 M H₂SO₄, respectively. As shown in fig. 1 (b), polarization curves for each catalysts were changed as variation of doping elements. Ir/M-doped TiO₂ shows higher OER activity than iridium black. From these results, it was obtained that introduction of dopant into TiO₂ change the characteristics of TiO₂ and this change contribute to improvement OER activity. Ir/M-doped TiO₂could be suggested OER catalyst to reduce the amount of precious metal catalyst without performance degradation.

Fig 1. (a) SEM images of electrospun TiO₂ nanofiber, (b) Polarization curves of prepared catalysts and commercial Ir black measured in O₂-saturated 0.5 M H₂SO₄ solution at room temperature with rotation speed of 1600 rpm and scan rate of 2 mV/sec