Oscillatory redox behavior in oxides: Cyclic surface reconstruction and reactivity modulation via the Mars-van Krevelen mechanism

• 成果类型: Article
• 署名作者: Sun, Xianhu; Wu, Dongxiang; Wang, Jianyu; Patel, Shyam B.; Zhu, Wenhui; Yang, Ji; Yang, Timothy T.; Ye, Shuonan; Chen, Xiaobo; Zhu, Yaguang; Qiao, Linna; Li, Meng; House, Stephen D.; Su, Ji; Saidi, Wissam A.; Boscoboinik, Jorge Anibal; Yang, Judith C.; Sharma, Renu; Zhou, Guangwen
• 署名单位: State University of New York (SUNY) System; Binghamton University, SUNY; Chinese Academy of Sciences; University of Chinese Academy of Sciences, CAS; United States Department of Energy (DOE); Lawrence Berkeley National Laboratory; Pennsylvania Commonwealth System of Higher Education (PCSHE); University of Pittsburgh; Pennsylvania Commonwealth System of Higher Education (PCSHE); University of Pittsburgh; United States Department of Energy (DOE); Brookhaven National Laboratory; National Institute of Standards & Technology (NIST) - USA
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12903
• DOI: 10.1073/pnas.2422711122
• 发表日期: 2025-06-17
• 关键词: carbon-monoxide; oxidation; kinetics; nanoparticles; methane

摘要

The breaking of translational symmetry at oxide surfaces gives rise to coordinatively unsaturated cations/anions and surface restructuring-key factors that govern surface reactivity. Using direct in situ environmental transmission electron microscopy (TEM) observations along with atomistic modeling, we report oscillatory redox behavior in CuO under H2, where cyclic surface reconstruction and reactivity modulation occur via the Mars-van Krevelen (MvK) mechanism. We observe self-switching between oxygen-rich and oxygen-deficient surface reconstructions, alternately activating and deactivating the surface for H2O formation. During periods of chemical inactivity, the oxygen-deficient surface undergoes slow reoxidation via lattice oxygen diffusing from subsurface and bulk reservoirs, restoring the active oxygen-rich surface termination. The inherent disparity in chemical activity among undercoordinated surface ions, along with sluggish subsurface-to-surface oxygen replenishment, drives this oscillatory redox cycle, modulating H2-induced loss of lattice oxygen at the surface and its delayed replenishment from the subsurface. This creates spatiotemporally separated redox steps at the oxide surface. The phenomena and atomistic insights presented here have significant implications for manipulating the surface reactivity of oxides by tuning the separation of these redox steps.