ATR-SEIRAS Investigation of the Electro-oxidation Mechanism of Biomass-Derived C₅ Furanics on Platinum Electrodes

Abstract

The electrochemical oxidation of furfural and down-pathway intermediate and product species (furoic acid, 2­(5H)-furanone, 5-hydroxy-2­(5H)-furanone, and maleic acid) is investigated on platinum electrodes via attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) with modulation excitation spectroscopy (MES). Density functional theory (DFT) calculations are performed to further illuminate the elementary reaction mechanism and the surface orientations of key reaction intermediates. Evidence from these techniques suggests that oxidation selectivity of the furanic compounds is governed by a balance between several properties of the catalyst. Propensity toward C–C cleavage steps yields self-limiting accumulation of adsorbed CO at low potentials and promotes the formation of C4 products and CO2 at higher potentials. Affinity for surface carboxylates such as furoate and maleate species also leads to their accumulation on the surface at higher potentials. It is thus suggested that correlations between the various surface oxygenate binding energies represent a challenge in balancing accumulation of strongly bound intermediates against a need for the surface to bind hydroxyl to initiate O-addition steps.

Electrochemical Flow Reactor Design Allows Tunable Mass Transport Conditions for Operando Surface Enhanced Infrared Absorption Spectroscopy

“…A research challenge ahead will be developing sophisticated transport models to accurately determine how these gradients develop over the electrode and understand how they impact overall activity and selectivity [83] . The design principles of this reactor can enable vibrational spectroscopy studies of electrochemical reactions in a wide range of electrolytes, mass transport conditions, and electrocatalysts, accelerating fundamental understanding of the CO 2 RR, and the electrocatalytic conversions of other small (O 2, CH 4 , CO, N 2 , H 2 O, NO x ) [2–7] and complex bio‐derived molecules [8,9] relevant for sustainable technologies and chemical‐dependent industries.…”

“…Additionally, we observed a 6-fold improvement in CO partial current densities at À 1 V vs RHE with a similarly rough Au catalyst over the benchmarked reactor, which we attributed to the enhanced mass transport (Note S3); however, electrolyte impingement on the electrode is expected to induce complex concentration gradients across the electrode during CO 2 R. [82] A research challenge ahead will be developing sophisticated transport models to accurately determine how these gradients develop over the electrode and understand how they impact overall activity and selectivity. [83] The design principles of this reactor can enable vibrational spectroscopy studies of electrochemical reactions in a wide range of electrolytes, mass transport conditions, and electrocatalysts, accelerating fundamental understanding of the CO 2 RR, and the electrocatalytic conversions of other small (O 2, CH 4 , CO, N 2 , H 2 O, NO x ) [2][3][4][5][6][7] and complex bio-derived molecules [8,9] relevant for sustainable technologies and chemical-dependent industries.…”

“…As anthropogenic CO 2 emissions continue to increase, they will continue to exacerbate changes to local and global climate leading to detrimental impacts on our society. [1] The impetus for developing zero or net-negative greenhouse gas emissions processes and technologies is growing; this includes the electrocatalytic conversion of simple, environmentally abundant chemicals or pollutants (e. g., CO 2 , O 2, CH 4 , CO, N 2 , H 2 O, NO x ) [2][3][4][5][6][7] and complex bio-derived molecules [8,9] with sustainable energy. For example, electrochemical CO 2 reduction (CO 2 R) can upgrade CO 2 into value-added chemicals, with the potential to supplant petroleum as a source of liquid fuel and feedstocks for making products such as plastic.…”

Elucidating the Influence of Metal Surface Composition on Organic Adsorbate Binding Using Active Particle Dynamics

“…Such information in principle can be provided by vibrational spectroscopy studies at the metal−water interface. For example, Hasse et al 43 have employed surface-enhanced infrared spectroscopy to investigate furfural adsorption and electro-oxidation on Pt surfaces. They found that furfural adsorption was accompanied by some CO surface formation at low potentials, and that high (oxidizing) potentials led to surface oxidation of furfural to furoic acid and other surface-bound products.…”

Diamonds in the Rough: Direct Surface Enhanced Infrared Spectroscopic Evidence of Nitrogen Reduction on Boron-Doped Diamond Supported Metal Catalysts

“…The former issue can be resolved using IREs made from micromachined Si wafers. , The lower path length through silicon gives improved S/N from about 1400 cm –1 to the low-frequency limit of standard MCT detectors, and micromachined Si IREs have been used to great effect in electrochemical ATR-SEIRAS studies. − Furthermore, rather than depositing gold directly on Si, SEIRAS-active films can be formed starting with an IRE coated with a thin film of conductive metal oxide (CMO) such as indium zinc oxide (IZO) or indium tin oxide (ITO) . Such layers are conductive and largely transparent at mid-IR wavelengths and adhere extremely well with Si surfaces.…”