Synergistic Effect in a Metal-Organic Framework Boosting the Electrochemical CO Overall Splitting.

It is a very important but still challenging task to develop bifunctional electrocatalysts for highly efficient CO overall splitting. Herein, we report a stable metal-organic framework (denoted as -), composed of (2,3,9,10,16,17,23,24-octahydroxyphthalocyaninato)nickel(II) (PcNi-(O)) ligands and the planar CoO nodes, for CO overall splitting. When working as both cathode and anode catalysts (i.e., -||-), - achieved a commercial-scale current density of 123 mA cm (much higher than the reported values (0.2-12 mA cm)) with a Faradic efficiency (CO) of 98% at a low cell voltage of 4.4 V. Mechanism studies suggested the synergistic effects between two active sites, namely, (i) electron transfer from CoO to PcNi sites under electric fields, resulting in the raised oxidizability/reducibility of CoO/PcNi sites, respectively; (ii) the energy-level matching of cathode and anode catalysts can reduce the energy barrier of electron transfer between them and improve the performance of CO overall splitting.