Restructuring of Cu₂O to Cu₂O@Cu-Metal–Organic Frameworks for Selective Electrochemical Reduction of CO₂

Abstract

Electrochemical reduction of carbon dioxide to hydrocarbons, driven by renewable power sources, is a fascinating and clean way to remedy greenhouse gas emission as a result of overdependence on fossil fuels and produce value-added fine chemicals. The Cu-based catalysts feature unique superiorities; nevertheless, achieving high hydrocarbon selectivity is still inhibited and remains a great challenge. In this study, we report on a tailor-made multifunction-coupled Cu-metal–organic framework (Cu-MOF) electrocatalyst by time-resolved controllable restructuration from Cu2O to Cu2O@Cu-MOF. The restructured electrocatalyst features a time-responsive behavior and is equipped with high specific surface area for strong adsorption capacity of CO2 and abundant active sites for high electrocatalysis activity based on the as-produced MOF on the surface of Cu2O, as well as the accelerated charge transfer derived from the Cu2O core in comparison with the Cu-MOF. These intriguing characteristics finally lead to a prominent performance towards hydrocarbons, with a high hydrocarbon Faradaic efficiency (FE) of 79.4%, particularly, the CH4 FE as high as 63.2% (at −1.71 V). This work presents a novel and efficient strategy to configure MOF-based materials in energy and catalysis fields, with a focus on big surface area, high adsorption ability, and much more exposed active sites.

Engineering Metal–Organic Frameworks for the Electrochemical Reduction of CO2: A Minireview

“…Stability is one of the most concerning issues facing the CO 2 ER. Whilst most authors have claimed that pristine MOFs that are based on readily reducible metals are stable under CO 2 ER reaction conditions, catalyst stability has only been confirmed in a few cases by using post‐analysis characterization . Herein, we would like to clarify that the stability of the crystalline MOF does not necessarily need to be an issue.…”

“…In a recent study, Tan et al. synthesized a tailor‐made Cu 2 O@Cu‐MOF electrocatalyst through the in situ etching of Cu 2 O spheres with H3BTC to form a Cu‐MOF shell . The as‐prepared electrocatalyst exhibited intriguing performance for the formation of hydrocarbons from CO 2 , with a high FE for CH 4 and C 2 H 4 of 79.4 %, and especially a FE for CH 4 of up to 63.2 % at −1.71 V.…”

Potential Link between Cu Surface and Selective CO2 Electroreduction: Perspective on Future Electrocatalyst Designs

“…[ 121 ] Tan et al reported a Cu 2 O@Cu‐MOF restructured catalyst with a unique CO 2 ‐adsorption ability and demonstrated outstanding performance with a total FE of 79.4% toward hydrocarbon products. [ 122 ] Figure 8d shows a schematic illustration of the process of Cu 2 O@Cu‐MOF catalyst synthesis. Based on the TEM and HRTEM images of the catalyst, shown in Figure 8e,f, the residual oxidized Cu derived from the Cu + species on the surface of initially formed Cu 2 O nanospheres that fully coated the Cu‐MOF, wherein trimesic acid (H 3 BTC) functioned as both an etching agent and an organic ligand for the formation of the Cu‐MOF hybrid.…”

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“…CH4, C2H6, and other products were also reported in the study. Similarly in 2019, Tan et al [12] developed a novel metal organic framework in Cu2O-based electrodes and reported improved faradaic efficiency towards CH4 while also producing other higher order carbon products.…”

“…The surface porosity in electrode structures has been reported to change both reagent and product transport pathways [17] and these changes in transport phenomena have shown to increase current density and change product selectivity [18,19]. Since most studies have used smaller sizes of Cu2O particles in combination with either copper metal [20][21][22][23] or glassy carbon [12,24], it was our hypothesis that the use of larger size of Cu2O particles supported on a structurally porous CP substrate would offer new product distributions.…”