Theoretical Screening of CO₂ Electroreduction over MOF-808-Supported Self-Adaptive Dual-Metal-Site Pairs

Abstract

Electrochemical CO2 reduction to transportation fuels and valuable platform chemicals provides a sustainable avenue for renewable energy storage and realizes an artificially closed carbon loop. However, the rational design of highly active and selective CO2 reduction electrocatalysts remains a challenging task. Herein, a series of metal–organic framework (MOF)-supported flexible, self-adaptive dual-metal-site pairs (DMSPs) including 21 pairwise combinations of six transition metal single sites (MOF-808-EDTA-M1M2, M1/M2 = Fe, Cu, Ni, Pd, Pt, Au) for the CO2 reduction reaction (CO2RR) were theoretically screened using density functional theory calculations. Against the competitive hydrogen evolution reaction, MOF-808-EDTA-FeFe and MOF-808-EDTA-FePt were identified as the promising CO2RR electrocatalysts toward C1 and C2 products. The calculated limiting potential for CO2 electroreduction to C2H6 and C2H5OH over MOF-808-EDTA-FeFe is −0.87 V. Compared with an applied potential of −0.56 eV toward CH4 production over MOF-808-EDTA-FeFe, MOF-808-EDTA-FePt exhibits an even better activity for CO2 reduction to C1 products at a limiting potential of −0.35 V. The present work not only identifies promising candidates for highly selective CO2RR electrocatalysts leading to C1 and C2 products but also provides mechanistic insights into the dynamic nature of DMSPs for stabilizing various reaction intermediates in the CO2RR process.

Rational Design of Advanced Metal Organic Framework‐Based Nanostructured Catalysts toward Electrocatalytic CO2 Conversion: A Mini Review

“…Therefore, several theoretical studies have been done on CO 2 conversion and its intermediates' energy requirements for transformation. Mei et al [61] have taken a long survey on a series of MOF-supported transition metals with single sites (MOF-808- Theoretical calculations have shown that generation of formic acid over MOF-FeFe structures are highly endergonic through protonation of COOH* intermediates. Thereby, it is expectable that instead of HCOOH* intermediate generation, the formation of COOH* would require less energy and in turn it would lead to the generation of CO* over MOF-FeFe.…”

“…However, it should be considered that desorption of CO* and HCOOH* intermediates from the Fe-Fe electroactive spots would be hard, requiring high-desorption energies of þ1.74 and þ1.28 eV, respectively. [61,62] Otherwise, the methane generation from CO 2 conversion can be formed through CH 3 O* intermediate (Figure 4). This can be done by protonation on the C atom of the CH 3 O* intermediate.…”

“…Therefore, several theoretical studies have been done on CO 2 conversion and its intermediates’ energy requirements for transformation. Mei et al [ 61 ] have taken a long survey on a series of MOF‐supported transition metals with single sites (MOF‐808‐EDTA‐M 1 M 2 , M 1 /M 2 = Fe, Cu, Ni, Pd, Pt, Au) for the CO 2 electroreduction. They have used density‐functional theory (DFT) calculations to measure Gibbs free energy of the compounds and their required energy for conversion of CO 2 to each product.…”

“…However, it should be considered that desorption of CO* and HCOOH* intermediates from the Fe–Fe electroactive spots would be hard, requiring high‐desorption energies of +1.74 and +1.28 eV, respectively. [ 61,62 ]…”

“…The free energy of each intermediate state is relative to the free energy (zero) of the reference system, that is, MOF-FeFe and gaseous CO 2 . Reproduced with permission [61]. Copyright 2023, American Chemical Society.…”