Lattice Strain Enhances the Activity of Ir−IrO<sub>2</sub>/C for Acidic Oxygen Evolution Reaction
Meng Wang, Wenxiang Zhu, Mengjie Ma, Zhenglong Fan, Junjun Yang, Fan Liao, Mingwang Shao
Abstract
Abstract Lattice strain plays a critical role in regulating the electronic structure and improving the performance of catalysts. Here, Ir−IrO 2 /C catalysts with different iridium content are obtained by annealing Ir/C in air. The growth of IrO 2 on Ir nanoparticles can form a core–shell structure and introduces strain at their interface. The local compressive strain on Ir nanoparticles is 7.2 % in the optimal Ir−IrO 2 /C sample with Ir content of 14.3 % (Ir−IrO 2 /C‐3), which regulates the adsorption energy of intermediates and improves the catalytical performance of oxygen evolution reaction (OER). The overpotential of Ir−IrO 2 /C‐3 at 10 mA ⋅ cm −2 is 264 mV in acidic electrolyte, 35 mV lower than that of Ir−IrO 2 /C with no lattice strain. Ir−IrO 2 /C‐3 also exhibits the highest mass activity of 1304 A ⋅ g Ir −1 at 1.55 V vs. RHE, which is higher than those of commercial catalysts. Furthermore, the activity of Ir−IrO 2 /C‐3 can maintain 42 h with the potential increase of only 18 mV at 10 mA ⋅ cm −2 , proving that the lattice strain can also effectively improve the electrochemical stability.