Induced CO Electroreduction to Formic Acid on Metal-Organic Frameworks via Node Doping.

Metal-organic frameworks (MOFs), combining the advantages of heterogeneous and homogeneous components, have been explored as catalytic materials for the CO electroreduction reaction (CO ERR). However, the unmatched metal nodes result in MOFs having lower faradaic efficiencies (FEs) and limited current densities in CO ERR. Herein, we report a general strategy to promote activities of MOFs via node doping in CO ERR. With ion exchange, an active tin node was doped into zeolitic imidazolate framework-8 (ZIF-8) to facilitate the reduction kinetics of CO . The divalent Sn node accelerates the formation of formic acid (HCOOH), resulting in the highest HCOOH FE of 74 % and total current density (J ) of 27 mA/cm at -1.1 V (vs. reversible hydrogen electrode, RHE) over 0.6 wt% Sn-doped ZIF-8 with stable catalytic performance after seven reuse cycles, which is clearly better compared to the catalytic properties of pristine ZIF-8 (FE =0 %, J =13 mA/cm ). This work opens an avenue for promoting the CO ERR performance of MOFs by node doping.