Iridium Nanosheet Catalysts Supported on Titanium Oxide for Oxygen Evolution Reaction in Polymer Electrolyte Membrane Water Electrolysis

In order to overcome the disadvantage of intermittent production of renewable energy, Polymer electrolyte membrane water electrolysis(PEMWE), which is one of the technologies of producing hydrogen by electrolyzing water, is attracting attention. For the commercialization of PEMWE, it is important to reduce usage of iridium(Ir) for oxygen evolution reaction(OER) in the anode electrode. Many studies have been reported to reduce the amount of iridium used by developing a catalyst with higher performance than the iridium nanoparticle catalyst used as a commercial catalyst. As one of the strategies, the introduction of support materials that can increase the active area of the catalyst is drawing attention. While carbon-based supports are mainly used in other applications, in OER environments, carbon is easily corroded due to high voltage and strong acid conditions. Therefore, it is necessary to use a metal oxide support with high corrosion resistance. In particular, titanium oxide(TiO 2 ) is one of the suitable support candidates because it is a stable material in an acidic OER environment. However, catalysts loaded on TiO 2 with nanoparticles cause an electrical contact problem due to the low electrical conductivity of TiO 2 , which causes a degradation in activity. Many studies have reported doping methods to increase the conductivity of TiO 2 , but there are also reports that these methods reduce the durability of support. Thus, a new approach to synthesizing a better structure of catalysts is needed to utilize metal oxide support. Herein, we present an approach to iridium nanosheet (NS) catalysts supported on TiO 2 (Ir NS/TiO 2 ). Ir NSs were synthesized by an facile method by directly annealing a mixture of Ir precursor and alkali salt. Ir NSs were supported on TiO 2 to be utilized as a reaction site and also acts as an electron path to compensate for the low electrical conductivity of TiO 2 . Ir NS/TiO 2 showed superior OER activity and stability under acidic conditions. These results showed that Ir NS/TiO 2 could be utilized to reduce the amount of precious metal catalyst in PEMWE and increase the stability of OER supported catalysts.