Publications by authors named "R Sayos"

The critical levels of CO emissions reached in the past decade have encouraged researchers into finding techniques to reduce the amount of anthropogenic CO expelled to the atmosphere. One possibility is to capture the produced CO from the source of emission or even from air (i.e.

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The search for cheap and active materials for the capture and activation of CO has led to many efforts aimed at developing new catalysts. In this context, earth-abundant transition metal carbides (TMCs) have emerged as promising candidates, garnering increased attention in recent decades due to their exceptional refractory properties and resistance to sintering, coking, and sulfur poisoning. In this work, we assess the use of Group 5 TMCs (VC, NbC, and TaC) as potential materials for carbon capture and sequestration/utilization technologies by combining experimental characterization techniques, first-principles-based multiscale modeling, vibrational analysis, and catalytic experiments.

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A detailed multiscale study of the mechanism of CO hydrogenation on a well-defined Ni/CeO model catalyst is reported that couples periodic density functional theory (DFT) calculations with kinetic Monte Carlo (kMC) simulations. The study includes an analysis of the role of Eley-Rideal elementary steps for the water formation step, which are usually neglected on the overall picture of the mechanism, catalytic activity, and selectivity. The DFT calculations for the chosen model consisting of a Ni cluster supported on CeO (111) show large enough adsorption energies along with low energy barriers that suggest this catalyst to be a good option for high selective CO methanation.

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Metals supported on transition metal carbides are known to exhibit good catalytic activity and selectivity, which is interpreted in terms of electron polarization induced by the support. In the present work we go one step further and investigate the effect that a titanium carbide (TiC) support has on the structural, electronic, and magnetic properties of a series of Ni nanoparticles of increasing size exhibiting a two- or three-dimensional morphology. The obtained results show that three-dimensional nanoparticles are more stable and easier to form than their homologous two-dimensional counterparts.

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Transition Metal Carbides (TMCs) are proposed as replacements for and expensive late Transition Metals (TMs) as heterogeneous catalysts, often implying hydrogenation reactions or steps. Present density functional theory based calculations support using group IV TMCs and δ-MoC as viable TM alternatives, given the moderate exoergicity and affordable reaction step energy barriers.

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