Photo‐Assisted Electrochemical CO₂ Reduction to CH₄ Using a Co‐Porphyrin‐Based Metal–Organic Framework

Abstract

Metal–organic frameworks (MOFs) are a promising platform for assembling large concentrations of molecular catalysts on surfaces to drive the electroreduction of CO2. Yet until now, these MOF‐based systems were shown to produce only 2‐electron/proton products, i.e., CO or formic acid. Herein, it is demonstrated that a cobalt 5,10,15,20‐tetra(4‐carboxyphenyl) porphyrin (CoTCPP)‐based MOF can produce significant quantities of an 8‐electron/proton CH4, via a photo‐assisted electrocatalytic approach. Specifically, detailed electrochemical and spectro‐electrochemical analyses show that the addition of light illumination during electrocatalysis promotes the stabilization of a catalyst‐bound CO intermediate, allowing its further reduction to the final product, CH4. Using the photo‐assisted electrocatalysis method, maximum CH4 Faradaic efficiency of 14% was obtained at a low potential of −0.49 V NHE. Hence, the presented concept provides an additional step toward the design of more efficient MOF‐based electrocatalytic systems.

Solution Shearing of Zirconium (Zr)-Based Metal–Organic Frameworks NU-901 and MOF-525 Thin Films for Electrocatalytic Reduction Applications

“…To show the generalizability of this solution shearing method toward the synthesis of other Zr-based MOFs, we decided to fabricate MOF-525 thin films on indium tin oxide (ITO) coated glass substrates due to their applicability for electrocatalysis. , The solution shearing of MOF-525 precursor solution at 140 °C yielded no MOF formation, as the GIXD pattern showed no characteristic peaks of MOF-525 (Figure S20) and SEM image showed no particle-like morphology (Figure S21). To promote the MOF formation, we increased the temperature from 140 to 160 °C.…”

MOFs as Versatile Catalysts: Synthesis Strategies and Applications in Value-Added Compound Production

“…The results exhibited that CH 4 is the major CO 2 reduction product obtained of this compound during light-assisted electrocatalysis conditions (Figure 14). 183 Less attention has been carried out for the photocatalytic activity and their performance of graphene/2D MOF heterojunctions to produce H 2 and CH 4 from CO 2 . 184,185 A 2D Cu MOF with tetrahydroxyquinone linker (CuTHQ) was prepared that promoted photocatalytic overall water splitting under simulated sunlight (164 μmol of H 2 /g and 80 μmol of O 2 /g), showing near linear H 2 evolution at a long-term (96 h) experiment.…”

“…The results exhibited that CH 4 is the major CO 2 reduction product obtained of this compound during light-assisted electrocatalysis conditions ( Figure 14 ). 183 …”

Nickel–Iron-Modified 2D Metal–Organic Framework as a Tunable Precatalyst for Electrochemical Water Oxidation

“…For this matter, metal–organic framework (MOF) is a promising porous platform that could be utilized for effective control over Ni–Fe metal loading. MOFs are crystalline porous materials composed of metal ions or clusters and organic linkers. − Their unique properties of high surface area, chemical stability, and synthetic tunability led to their usage in many applications such as gas storage and separation, − sensing, drug delivery, chemical catalysis, − and electrocatalysis. − ,− Indeed, Ni–Fe-based 3D MOFs have been shown to act as highly potent OER electrocatalysts, driving water oxidation at low overpotentials and high rates while exhibiting high durability. − Nevertheless, recent studies presented the advantages of using 2D MOFs for electrochemical applications (rather than the highly researched 3D MOFs), since their porous 2D-nanosheet structure improves the active sites’ electrolyte accessibility and reduces mass-transport limitations during operation. , Electrocatalytic MOFs can be used in their pristine form. However, this form generally suffers from an intrinsically low electrical conductivity.…”