Unveiling the Spatially Dependent Cooperative Effect in Iridium Sites for Enhanced Acidic Water Oxidation
Xiaoxia Chen, Hanwen Hu, Meihuan Liu, Xiaoyan Zhong, Donghai Wu, Hui Su
Abstract
The spatial distance between active sites is a critical factor governing hydroxyl (*OH)-group-mediated synergies in multiphase electrocatalysis. But direct experimental evidence correlating atomic-scale spatial arrangement with synergistic behavior, reaction kinetics, and catalytic mechanisms remains scarce. Using the acidic oxygen evolution reaction (OER) as a model, this study employs in situ synchrotron radiation infrared spectroscopy to demonstrate that adjacent active sites enable direct *OH coupling, forming the *O–O* intermediate. Complementary in situ X-ray absorption spectroscopy and theoretical calculations reveal that adjacent Ir sites induce electronic restructuring. This optimized electronic configuration facilitates unlocking a dual-site synergistic mechanism. Conversely, isolated sites (at a farther distance) exhibit spatial inaccessibility of *OH intermediates, forcing a higher-energy pathway via *OOH formation. These findings establish a universal paradigm for manipulating interfacial *OH dynamics through atomic-scale spatial engineering, applicable to diverse reactions including hydrogen evolution, oxygen reduction, and CO 2 reduction.