Elucidating the role of electrochemical polarization on the selectivity of the CO2 hydrogenation reaction over Ru

Electrochemical Promotion of CO2 Hydrogenation Using a Pt/YSZ Fuel Cell Type Reactor

The hydrogenation of CO₂ is a reaction of key technological and environmental importance, as it contributes to the sustainable production of fuels while assisting in the reduction of a major greenhouse gas. The reaction has received substantial attention over the years within the catalysis and electrocatalysis communities. In this respect, the electrochemical promotion of catalysis (EPOC) has been applied successfully to the CO₂ hydrogenation reaction to improve the catalytic activity and selectivity of conductive films supported on solid electrolytes. However, designing an effective electrocatalytic reactor remains a challenge due to the connections required between the electrodes and the external potentiostat/galvanostat. This drawback could be alleviated if the catalytic reaction occurs in a reactor that simultaneously operates as a power generator. In this work, the Electrochemical Promotion of the CO₂ hydrogenation reaction in a low-temperature solid oxide electrolyte fuel cell (SOFC) reactor is studied using yttria-stabilized zirconia (YSZ) and a platinum (Pt) electrode catalyst. The system has been studied in two distinct operation modes: (i) when the necessary energy for the electrochemical promotion is produced through the parallel reaction of H₂ oxidation (galvanic operation) and (ii) when a galvanostat/potentiostat is used to impose the necessary potential (electrolytic operation). The performance of the fuel cell declines less than 15% in the presence of the reactant mixture (CO₂ and H₂) while producing enough current to conduct EPOC experiments. During the electrolytic operation of the electrochemical cell, the CO production rate is significantly increased by up to 50%.

Electrochemical control of the RWGS reaction over Ni nanoparticles deposited on yttria stabilized zirconia

Transition metal oxides are promising candidates for the activation of the reverse water gas shift (RWGS) reaction. The in-situ formation and stabilization of these oxides appears to be a key...

Electrochemical Promotion of Copper Nanoparticles for the Reverse Water Gas Shift Reaction

Electrochemical promotion of catalysis (EPOC) is one of the promising ways to in-situ control and enhance catalytic processes of the reverse water gas shift reaction (RWGS), which recycles carbon dioxide...

Demystifying the Atomistic Origin of the Electric Field Effect on Methane Oxidation

Understanding the role of an electric field on the surface of a catalyst is crucial in tuning and promoting the catalytic activity of metals. Herein, we evaluate the oxidation of methane over a Pt surface with varying oxygen coverage using density functional theory. The latter is controlled by the electrode polarization, giving rise to the non-Faradaic modification of catalytic activity phenomenon. At -1 V, the Pt(111) surface is present, while at 1 V, α-PtO₂ on Pt(111) takes over. Our results demonstrate that the alteration of the platinum oxide surface under the influence of an electrochemical potential promotes the catalytic activity of the metal oxides by lowering the activation energy barrier of the reaction.

Revisiting the Active Sites at the MoS2/H2O Interface via Grand-Canonical DFT: The Role of Water Dissociation

MoS₂ is a promising low-cost catalyst for the hydrogen evolution reaction (HER). However, the nature of the active sites remains a subject of debate. By taking the electrochemcal potential explicitly into account using grand-canonical density functional theory (DFT) in combination with the linearized Poisson-Boltzmann equation, we herein revisit the active sites of 2H-MoS₂. In addition to the well-known catalytically active edge sites, also specific point defects on the otherwise inert basal plane provide highly active sites for HER. Given that HER takes place in water, we also assess the reactivity of these active sites with respect to H₂O. The thermodynamics of proton reduction as a function of the electrochemical potential reveals that four edge sites and three basal plane defects feature thermodynamic overpotentials below 0.2 V. In contrast to current proposals, many of these active sites involve adsorbed OH. The results demonstrate that even though H₂O and OH block "active" sites, HER can also occur on these "blocked" sites, reducing protons on surface OH/H₂O entities. As a consequence, our results revise the active sites, highlighting the so far overlooked need to take the liquid component (H₂O) of the functional interface into account when considering the stability and activity of the various active sites.