A Stable and Conductive Covalent Organic Framework with Isolated Active Sites for Highly Selective Electroreduction of Carbon Dioxide to Acetate.

Electroreduction of CO 2 to acetate provides a promising strategy to reduce CO 2 emissions and store renewable energy, but acetate is usually a by-product. Here, we show a stable and conductive two-dimensional phthalocyanine-based covalent-organic framework (COF) as an electrocatalyst for reduction of CO 2 to acetate with a single-product Faradaic efficiency (FE) of 90.3(2)% at -0.8 V (vs. RHE) and a current density of 12.5 mA cm -2 in 0.1 M KHCO 3 solution. No obvious degradation was observed over 80 hours of continuous operation. Combined with the comparison of the properties of other catalysts with isolated metal active sites, theoretical calculations and in situ infrared spectroscopy revealed that the isolated copper-phthalocyanine active site with high electron density is conducive to the key step of C-C coupling of *CH 3 with CO 2 to produce acetate, and can avoid the coupling of *CO with *CO or *CHO to produce ethylene and ethanol.