Conductive Two-Dimensional Phthalocyanine-based Metal-Organic Framework Nanosheets for Efficient Electroreduction of CO2.

The electrocatalytic conversion of CO 2 into value-added chemicals using renewable electricity is a promising approach to reduce atmospheric CO 2 concentration and realize carbon-energy balance. However, the low current density still limits CO 2 electroreduction reaction (CO 2 RR) for commercial application. Crystalline porous metal-organic frameworks (MOFs) are one class of promising alternatives for CO 2 RR due to their high CO 2 adsorption uptakes and periodically arranged isolated metal active sites. However, the poor conductivity and slow electron-transfer capability of the traditional MOFs usually result in low current density in CO 2 RR. Herein, conductive two-dimensional (2D) phthalocyanine-based MOF (NiPc-NiO 4 ) nanosheets were prepared by the construction of nickel phthalocyanin-2,3,9,10,16,17,23,24-octaol (NiPc-OH) and nickel(II) ions, which can be employed as highly efficient electrocatalysts for CO 2 RR towards production of CO. The obtained NiPc-NiO 4 has a good conductivity with a high value of 4.8 ´ 10 - 5 S m -1 due to the in-plane full π-d conjugation. Thus, the as-prepared NiPc-NiO 4 nanosheets exhibited a very high selectivity of 98.4% towards production of CO and a large CO partial current density of 34.5 mA cm -2 , outperform ing the reported MOF catalysts. This work offers an opportunity to design conductive crystalline frameworks for improving energy efficiency in electrocatalysis.