Electrochemically Triggered Dynamics Within a Hybrid Metal-Organic Electrocatalyst

Abstract

<p> A wide array of systems, ranging from enzymes to synthetic catalysts, exert adaptive motifs to maximize their functionality. In a related manner, select metal-organic frameworks (MOFs) and related systems exhibit structural modulations under stimuli such as the infiltration of guest species. Probing their responsive behavior <i>in-situ</i> is a challenging but important step towards understanding their function and subsequently building from there. In this report, we investigate the dynamic behavior of an electrocatalytic Mn-porphyrin containing MOF system (Mn-MOF). We discover, using a combination of electrochemistry and <i>in-situ</i> probes of UV-Vis absorption, resonance Raman and infrared spectroscopy, a restructuration of this system via a reversible cleavage of the porphyrin carboxylate ligands under an applied voltage. We further show, by combining experimental data and DFT calculations, as a proof of concept, the capacity to utilize the Mn-MOF for electrochemical CO<sub>2</sub> fixation and to spectroscopically capture the reaction intermediates in its catalytic cycle. The findings of this work and methodology developed opens opportunities in the application of MOFs as dynamic, enzyme-inspired electrocatalytic systems.</p>

Electrochemical Conversion of Biomass Derived Products into High-Value Chemicals

“…In another study, surface enhanced Raman spectroscopy (SERS), as shown in Figure 3D, was utilized in understanding reactivity of Au nanoparticle surfaces toward HMF electrooxidation, yielding DFF as a primary product. 86 Appearance of new spectral bands (338 and 355 cm À1 ) takes place only at potentials >0.8 V (versus Ag/AgCl), within potential range over which surface O x (oxides/hydroxides) form, indicating dependence between HMF oxidation of alcohol moiety and available adsorbed O x * species. These band intensities correspond to alkoxy intermediate, prior to aldehyde formation.…”

“…63,84 (C and D) SFG (C) and SERS (D) spectra respectively, obtained for HMF electrooxidation to study molecular structure and transformations of active species at the electrode/electrolyte interface as influenced by time and potential. 85,86 rise to multiple possible orientations of glycerol adsorption with characteristic spectral fingerprints lying in the region between 1,100 and 1,700 cm À1 , originating from the relevant organic derivatives. 88,89 The diverse spectrum of chemicals of similar molecular structure and functional groups introduces poor discernibility of spectral features and identification of a single corresponding candidate.…”

“…Understanding Mechanisms through Operando Characterizations (A and B) In situ FTIR spectra for GEOR obtained over a catalyst (A) and contour plot (B), to gain information on potential-dependant generation of intermediates/products 63,84. (C and D) SFG (C) and SERS (D) spectra respectively, obtained for HMF electrooxidation to study molecular structure and transformations of active species at the electrode/electrolyte interface as influenced by time and potential 85,86.…”