Interplay of Electronic and Steric Effects to Yield Low‐Temperature CO Oxidation at Metal Single Sites in Defect‐Engineered HKUST‐1
Weijia Wang, Dmitry Sharapa, Abhinav Chandresh, Alexei Nefedov, Stefan Heißler, Lars Heinke, Felix Studt, Yuemin Wang, Christof Wöll
Abstract
Abstract In contrast to catalytically active metal single atoms deposited on oxide nanoparticles, the crystalline nature of metal‐organic frameworks (MOFs) allows for a thorough characterization of reaction mechanisms. Using defect‐free HKUST‐1 MOF thin films, we demonstrate that Cu + /Cu 2+ dimer defects, created in a controlled fashion by reducing the pristine Cu 2+ /Cu 2+ pairs of the intact framework, account for the high catalytic activity in low‐temperature CO oxidation. Combining advanced IR spectroscopy and density functional theory we propose a new reaction mechanism where the key intermediate is an uncharged O 2 species, weakly bound to Cu + /Cu 2+ . Our results reveal a complex interplay between electronic and steric effects at defect sites in MOFs and provide important guidelines for tailoring and exploiting the catalytic activity of single metal atom sites.