The role of Ru clusters in Fe carbide suppression for the reverse water gas shift reaction over electropromoted Ru/FeOx catalysts

Abstract The formation of an iron carbide phase has been shown to inhibit the efficiency of Fe-based catalysts in the initial step of adsorbing carbon dioxide (CO2). In this study, we evaluate the effect of adding Ru clusters (20% at.) to FeOx nanowires deposited on yttria-stabilized zirconia (YSZ) for the reverse water gas shift (RWGS) reaction carried out at 300–400 °C under atmospheric conditions. STEM shows that Ru-FeOx formed a bi-phase structure with Ru clusters (1.5–2 nm) supported on FeOx nanowires (5 nm) that remain as mixed oxides after the reaction. Open-circuit catalytic measurements demonstrated that addition of Ru increased the catalytic activity and stabilized high selectivity (>99%) towards CO. The synergetic effect of Ru and FeOx was further emphasized through electrochemical polarization, which led to a reversible catalytic activity increase of up to 2.4 times. The addition of Ru inhibits the formation of inactive Fe carbide by acting as the reducing component and stabilizing the FeOx active state. This results in an improved and lasting catalytic performance and makes Ru/FeOx catalysts attractive for industrial applications

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

International audienceThe hydrogenation of CO2 into high-value fuels is a potentially effective approach to reduce anthropogenic dependence on fossil fuels and effects of climate change. In this study, we evaluated the hydrogenation of CO2 into CO and CH4 under the electrochemical promotion of catalysis (EPOC) effect through experimental and computational studies using Ru nanoparticles. Ru nanoparticles (1-2 nm) supported on yttria-stabilized zirconia (YSZ) solid electrolyte were evaluated at 250 °C at atmospheric pressure. Under positive polarization, the methanation reaction was promoted and the competitive reverse water gas shift (RWGS) reaction was impeded. On the other hand, negative polarization resulted in suppressing permanently the methanation reaction and minimally affecting the RWGS reaction. To qualitatively rationalize the tuning of selectivity via EPOC, Density Functional Theory (DFT) computations were used to model the EPOC effect induced on the Ru(0001) surface. DFT computations uncovered that electric field effects together with a change in surface electrochemical potential between intermediates are responsible for the contrasting influence of EPOC on the CH4 and CO formation over Ru catalysts

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

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