Reordering d Orbital Energies of Single‐Site Catalysts for CO2 Electroreduction.

The single‐site catalyst (SSC) characteristic of atomically dispersed active centers will not only maximize the catalytic activity, but also provide a promising platform for establishing the structure–activity relationship. However, arbitrary arrangements of active sites in the existed SSCs make it difficult for mechanism understanding and performance optimization. Now, a well‐defined ultrathin SSC is fabricated by assembly of metal‐porphyrin molecules, which enables the precise identification of the active sites for d‐orbital energy engineering. The activity of as‐assembled products for electrocatalytic CO2 reduction is significantly promoted via lifting up the energy level of metal dz2 orbitals, exhibiting a remarkable Faradaic efficiency of 96 % at the overpotential of 500 mV. Furthermore, a turnover frequency of 4.21 s−1 is achieved with negligible decay over 48 h. [ABSTRACT FROM AUTHOR]