Cho, Min Gee Ophus, Colin Lee, Jung-Hoon Park, Inchul Chung, Dong Young Kim, Jeong Hyun Kim, Dokyoon Sung, Yung-Eun Kang, Kisuk Scott, Mary C. Alivisatos, A. Paul Hyeon, Taeghwan Oh, Myoung Hwan 2025-11-17T07:32:17Z 2025-11-17T07:32:17Z 2025-11-11 2025-10 0897-4756 https://pubs.kist.re.kr/handle/201004/153511 Engineering grain boundary (GB) strain provides a promising pathway to tune the catalytic properties of nanocrystals. However, structural heterogeneity from random grain orientation and geometry has limited clear structure-property correlations. Here, we utilize a multigrain Co3O4/Mn3O4 core/shell nanocrystal platform as a model system to systematically investigate how geometric misfit strain at GBs serves as catalytically active sites for the oxygen reduction reaction. Through precise subnanometer-level control over grain morphology and by integrating multiscale electronic structure characterization, we identify the electronic structural signature of GB defects and establish a direct correlation between localized strain fields and modified electronic states. Strain modulation at GBs alters the eg orbital energy levels, with elongation along the z-axis combined with shear strain stabilizing the eg states, in contrast to the destabilization observed under pure shear strain. This stabilization mechanism enhances the electrocatalytic activity and selectivity of strained GBs compared with strain-relaxed grain surfaces. Furthermore, we reveal that GBs exhibit a radial strain gradient, producing a spatial energy shift that further modulates local electronic structures, as resolved through the classification of electron energy loss spectroscopy data. Together, these findings demonstrate that geometric misfit strain enables precise tuning of grain geometry and the resulting electronic structures, offering a robust strategy for engineering next-generation nanocatalysts. English American Chemical Society Design Principles in Engineering of Multigrain Nanocatalysts via Multiscale Electronic Structure Characterization Article 10.1021/acs.chemmater.5c01154 1 Chemistry of Materials, v.37, no.19, pp.7741 - 7752 Chemistry of Materials 37 19 7741 7752 N scie scopus 001579203600001 2-s2.0-105018583097 Chemistry, Physical Materials Science, Multidisciplinary Chemistry Materials Science Article GRAIN-BOUNDARIES MANGANESE OXIDES WATER-OXIDATION STRAIN CONTROL NANOCRYSTALS CATALYSIS METALS OXYGEN REDUCTION