Dynamic Evolution from Single-Atom Catalysts to Active Nanograins for CO 2 Reduction

Understanding dynamic catalyst evolution, particularly Cu-based single-atom catalysts, faces tremendous challenges of tracking rapid and nanoscale evolution and uncontrolled catalyst reoxidation during post-reaction air exposure. Although ex situ / in situ studies have indirectly indicated the structural reconstruction of single-atom catalysts, direct probing of single-atom catalyst evolution requires time-resolved nanoscale operando methods. Here, we present direct experimental evidence of dynamic evolution from single-atom catalysts to Cu nanostructures rich in active nanograins, based on a conductive metal–organic framework-based Cu single-atom catalyst (Cu-SAC). Operando synchrotron-based high-energy-resolution X-ray spectroscopy and IR absorption spectroscopy quantitatively tracked the structural and molecular fingerprints during single-atom-to-nanograin evolution. Cu-SAC supported …