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Synthesis of Ni–Ir Nanocages with Improved Electrocatalytic Performance for the Oxygen Evolution Reaction

Wang, Chao, Sui, Yongming, Xu, Man, Liu, Chuang, Xiao, Guanjun, Zou, Bo
ACS sustainable chemistry 2017 v.5 no.11 pp. 9787-9792
catalysts, catalytic activity, electrolytes, nanoparticles, nickel, oxygen production, polymers, reaction mechanisms
Design and fabrication of inexpensive and efficient oxygen evolution reaction (OER) catalysts are of great importance for polymer electrolyte membrane water electrolyzers (PEMWEs). Although the best electrocatalyst is IrO₂ for OER in the PEMWEs, the practical application of Ir has been impeded because of its high cost and limited activity. Herein, a galvanic replacement reaction mechanism was developed for the preparation of polycrystalline Ni–Ir nanocages (NCs) by using Ni nanoparticles as templates. The formation of Ni–Ir NCs achieves the enhancement of OER catalytic performance, accompanied by the reduction of Ir loading but significantly increasing the efficiency of Ir atoms. The as-prepared Ni₂.₅₃Ir NCs exhibit improved catalytic activity toward OER in acid solution, which requires only an overpotential of 302 mV to deliver a current density of 10 mA/cm². At an overpotential of 300 mV, the Ir-based mass activity of Ni₂.₅₃Ir catalysts reaches 114.7 mA/mgIᵣ, which is 2.1 times higher than that of commercial Ir black. The obtained Ni₂.₅₃Ir NCs could be potentially applied for industrial scale PEMWE systems.