A Facile Strategy of Constructing Carbon Particles Modified Metal-Organic-Framework for Enhancing the Efficiency of CO2 Electroreduction into Formate

Electrocatalytic reduction of carbon dioxide by metal-organic framework (MOF) catalysts has been widely investigated in recent years, but the poor conductivity strongly limits the application of most MOFs catalysts. In order to overcome the above obstacles, we tried to use a gentle strategy to uniformly introduce highly dispersed carbon nanoparticles into the framework to improve the catalytic activity. Herein, a porous 3D In-MOF {(Me2NH2)[In(BCP)]·2DMF}n (V11) with good stability was constructed, and there are two types of large 1D channels with a diameter of 1.6 and 1.2 nm in the framework. Experimental results show that V11 exhibits a moderate catalytic activity in CO2 electroreduction with 76.0% of Faradaic efficiency for formate. To improve the catalytic activity of V11, methylene blue molecules were introduced into the framework as a carbon source due to its suitable size and carbonization temperature. After calcination at an appropriate temperature, carbon nanoparticles (CPs) with an average diameter of 3.85 nm were anchored in V11 and the framework can keep stable during the synthesis process. The obtained catalyst CPs@V11 was also applied in the CO2 electroreduction, and the maximum Faradaic efficiency of formate increases from 76.0% to 90.1% and the current density increased by 2.2 times. Control experiments and catalytic characterizations demonstrate that the introduced carbon nanoparticles can serve as accelerant to promote the charges and mass transfer in framework, and benefit to sufficiently expose active sites. Furthermore, this strategy can also work on other In-MOFs to improve the catalytic performance in selectivity and current density, demonstrating the good universality of this facile method and giving inspiration to construct more effective catalysts for electroreduction of CO2.