Lee, Woong Hee Yi, Jaekyung Hong Nhan Nong Strasser, Peter Chae, Keun Hwa Min, Byoung Koun Hwang, Yun Jeong Oh, Hyung-Suk 2024-01-19T17:02:58Z 2024-01-19T17:02:58Z 2021-09-05 2020-07-21 2040-3364 https://pubs.kist.re.kr/handle/201004/118370 Electrochemical oxidation processes can affect the electronic structure and activate the catalytic performance of precious-metal and transition-metal based catalysts for the oxygen evolution reaction (OER). Also there are emerging requirements to develop OER electrocatalysts under various pH conditions in order to couple with different reduction reactions. Herein, we studied the effect of pH on the electroactivation of IrNi alloy nanoparticles supported on carbon (IrNi/C) and evaluated the electrocatalytic activities of the activated IrNiOx/C for water oxidation under neutral conditions. In addition, their electronic structures and atomic arrangement were analyzed byin situ/operandoX-ray absorption spectroscopy (XAS) and identical location transmission electron microscopy techniques, showing the reconstruction of the metal elements during electroactivation due to their different stabilities depending on the electrolyte pH. IrNiOx/C activated under neutral pH conditions showed a mildly oxidized thin IrO(x)shell. Meanwhile, IrNiOx/C activated in acidic and alkaline electrolytes showed Ni-leached IrO(x)and Ni-rich IrNiO(x)surfaces, respectively. Particularly, the surface of IrNiOx/C activated under alkaline conditions shows IrO(x)with a high d-band hole and NiO(x)with a high oxidation state leading to excellent OER catalytic activity in neutral media (eta= 384 mV at 10 mA cm(-2)) whereas much lower OER activity was reported under alkaline or acid conditions. Our results, which showed that electrochemically activated catalysts under different pH conditions exhibit a unique electronic structure by modifying the initial alloy catalyst, can be applied for the design of catalysts suitable for various electrochemical reactions. English ROYAL SOC CHEMISTRY OXYGEN EVOLUTION REACTION ELECTRONIC-STRUCTURE IRIDIUM EFFICIENT STABILITY CATALYSTS ELECTROCATALYSTS NANODENDRITES Electroactivation-induced IrNi nanoparticles under different pH conditions for neutral water oxidation Article 10.1039/d0nr02951c 1 NANOSCALE, v.12, no.27, pp.14903 - 14910 NANOSCALE 12 27 14903 14910 scie scopus 000549588900052 2-s2.0-85088252350 Chemistry, Multidisciplinary Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Chemistry Science & Technology - Other Topics Materials Science Physics Article OXYGEN EVOLUTION REACTION ELECTRONIC-STRUCTURE IRIDIUM EFFICIENT STABILITY CATALYSTS ELECTROCATALYSTS NANODENDRITES Oxygen evolution reaction (OER) Iridium pH effect Neutral condition