Large-scale synthesis of low-cost 2D metal–organic frameworks for highly selective photocatalytic CO_(2)reduction

Two-dimensional metal–organic frameworks(2D MOFs),as a new type of 2D materials,have been widely applied in various applications because of their unique structures and exposed active sites.Herein,we reported two low-cost 2D MOFs constructed by a raw chemical succinic acid(SA),M-SA(M=Ni or Co),which served as efficient photocatalysts for the reduction of CO_(2)to CO.Taking advantage of the thinness and open metal sites,the ultrathin Ni-SA nanosheets(ca.3.6 nm)exhibited excellent CO production of 6.96(7)mmol·g^(−1)·h^(−1)and CO selectivity of 96.6%.Photoelectrochemical tests and theoretical calculations further confirmed the higher charge transfer efficiency and unsaturated metal sites for promoting photocatalytic performances.More importantly,Ni-SA can also be synthesized in large-scale by an energy-saving method under room temperature,strongly suggesting its promising future and potential for practical applications.

Local Weak Hydrogen Bonds Significantly Enhance CO_(2)Electroreduction Performances of a Metal-Organic Framework

Technological application of the electrochemical reduction of CO_(2)relies on efficient electrocatalysts.We demonstrate that the introduction of amino groups alongside the porphyrin cobalt centers in a metal-organic framework(MOF)can dramatically accelerate the electrochemical CO_(2)reduction performance.A classic cobalt porphyrin-based MOF showing moderate CO_(2)-to-CO electroreduction performance(turnover frequency[TOF]=0.20 s^(−1),Faradic efficiency[FE]=47.4%)is modified.By molecular design of the porphyrin-based ligand,amino groups are introduced alongside the cobalt center,giving remarkably enhanced CO_(2)-to-CO electroreduction performance as high as FE 99.4%,current density 7.2 mA cm^(−2),and TOF 21.17 s^(−1),in a nearneutral aqueous solution at a low overpotential of 525 mV.Density functional theory calculations showed that the prepositioned amino groups,although located not sufficiently close to the active center,serve as hydrogen-bonding donors to stabilize the intermediate Co-CO_(2)adduct and impede the formation of Co-H_(2)O adduct,which not only promotes the CO_(2)reduction reaction but also restrains the hydrogen evolution reaction.