Synthetic mimics of chlorophyll, which is
designed by replacing the Mg center of porphyrin unit with other metal atoms
(Au, Cu, Co) on metal-organic frameworks, may maximize atom
utilization and optimize catalytic activity. Simultaneously, porphyrin ligand
can be easily interfered by visible
light, which offers an opportunity to develop photo-coupled
electrocatalyst for CO2 reduction. The single-Au-atom catalyst
exhibits an ultrahigh turnover frequency of 37069 h-1 at -1.1 V and CO faradaic efficiency of
94.2% at -0.9 V. Interestingly, with visible light interfered (67% solar
intensity), the electrocatalyst reaches an approximate turnover frequency value and faradaic efficiency with reduced potential of ~130
mV. The similar trend is also observed on single-Cu-atom electrocatalyst under visible light, displaying a positive
shift of 100 mV with a highest HCOOH faradaic efficiency of 77.3% at -0.7 V versus RHE. Interestingly,
the light-induced positive shifts of 20, 100 and 130 mV for single-Co-atom,
single-Cu-atom and single-Au-atom electrocatalysts are in consistent with their
energy gaps of 0, 1.5 and 1.7 eV, respectively, suggesting the
porphyrin not only serves as ligand, but also photoswitch to regulate electron transfer
pathway to metal atom.