Abstract
Efficient electro-reduction of CO2 over metal–organic framework (MOF) materials is hindered by the poor contact between thermally synthesized MOF particles and the electrode surface, which leads to low Faradaic efficiency for a given product and poor electrochemical stability of the catalyst. We report a MOF-based electrode prepared via electro-synthesis of MFM-300(In) on an indium foil, and its activity for the electrochemical reduction of CO2 is assessed. The resultant MFM-300(In)-e/In electrode shows a 1 order of magnitude improvement in conductivity compared with that for MFM-300(In)/carbon-paper electrodes. MFM-300(In)-e/In exhibits a current density of 46.1 mA cm–2 at an applied potential of −2.15 V vs Ag/Ag+ for the electro-reduction of CO2 in organic electrolyte, achieving an exceptional Faradaic efficiency of 99.1% for the formation of formic acid. The facile preparation of the MFM-300(In)-e/In electrode, coupled with its excellent electrochemical stability, provides a new pathway to develop efficient electro-catalysts for CO2 reduction.
Highlights
Efficient conversion of is a highly desirableCO2 but into chemical feedstocks and fuels extremely challenging target.[1−3]Reduction of CO2 and photocatalysis into useful chemicals has been studied very via thermo-catalysis widely.[4−7] the former often requires both high temperature and pressure to activate CO2, while the latter relies heavily upon the use of sacrificial agents, typically organic amines, limiting longterm applications
We found that the electro-synthesized metal−organic framework (MOF) incorporates structural defects in the form of additional framework In3+ sites, which, coupled with improved charge transfer capacity, greatly promote the activation of CO2 to the radicals, consistent with the observed excellent electrocatalytic activity and stability of the catalyst
The formation of MOF occurred rapidly at an applied potential of 10 V and 60 °C, and the indium foil (In-foil) anode was covered by particles of MFM300(In)-e within 200 s (Figure 1b)
Summary
Reduction of CO2 and photocatalysis into useful chemicals has been studied very via thermo-catalysis widely.[4−7] the former often requires both high temperature and pressure to activate CO2, while the latter relies heavily upon the use of sacrificial agents, typically organic amines, limiting longterm applications. All three electrodes were reused over five cycles for electro-reduction of CO2 (Figure 3g,h) Both the current density and Faradaic efficiency for formation of formic acid show excellent stability for all three electrodes. The absence of In0 at the electrode surface suggests that In3+ sites in MFM-300(In) are not reduced during electrolysis,[48] consistent with the excellent electrochemical stability of MFM-300(In)-e/In. calculations afford the Gibbs free energy for the electroreduction of CO2 to formic acid over the pristine and defective MFM-300(In), representing MFM-300(In)-t and MFM-. This is consistent with the DFT calculation and Qst analysis
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