Ruthenium

About: Ruthenium is a research topic. Over the lifetime, 40184 publications have been published within this topic receiving 996514 citations. The topic is also known as: Ru & element 44.

Ru-Pt core-shell nanoparticles for preferential oxidation of carbon monoxide in hydrogen.

Abstract: Most of the world’s hydrogen supply is currently obtained by reforming hydrocarbons. ‘Reformate’ hydrogen contains significant quantities of CO that poison current hydrogen fuel-cell devices. Catalysts are needed to remove CO from hydrogen through selective oxidation. Here, we report first-principles-guided synthesis of a nanoparticle catalyst comprising a Ru core covered with an approximately 1–2-monolayer-thick shell of Pt atoms. The distinct catalytic properties of these well-characterized core–shell nanoparticles were demonstrated for preferential CO oxidation in hydrogen feeds and subsequent hydrogen light-off. For H2 streams containing 1,000 p.p.m. CO, H2 light-off is complete by 30 ∘C, which is significantly better than for traditional PtRu nano-alloys (85 ∘C), monometallic mixtures of nanoparticles (93 ∘C) and pure Pt particles (170 ∘C). Density functional theory studies suggest that the enhanced catalytic activity for the core–shell nanoparticle originates from a combination of an increased availability of CO-free Pt surface sites on the Ru@Pt nanoparticles and a hydrogen-mediated low-temperature CO oxidation process that is clearly distinct from the traditional bifunctional CO oxidation mechanism. To produce hydrogen by reforming hydrocarbons, efficient catalysts capable of removing carbon monoxide are needed. This can now be achieved via a preferential oxidation mechanism using nanoparticle catalysts consisting of a ruthenium core covered with platinum.

An efficient and pH-universal ruthenium-based catalyst for the hydrogen evolution reaction

Abstract: Ruthenium nanoparticles homogeneously dispersed in a nitrogenated, two-dimensional carbon matrix show high turnover frequency and small overpotential for hydrogen evolution reaction both in acidic and alkaline media. The hydrogen evolution reaction (HER) is a crucial step in electrochemical water splitting and demands an efficient, durable and cheap catalyst if it is to succeed in real applications1,2,3. For an energy-efficient HER, a catalyst must be able to trigger proton reduction with minimal overpotential4 and have fast kinetics5,6,7,8,9. The most efficient catalysts in acidic media are platinum-based, as the strength of the Pt–H bond10 is associated with the fastest reaction rate for the HER11,12. The use of platinum, however, raises issues linked to cost and stability in non-acidic media. Recently, non-precious-metal-based catalysts have been reported, but these are susceptible to acid corrosion and are typically much inferior to Pt-based catalysts, exhibiting higher overpotentials and lower stability13,14,15. As a cheaper alternative to platinum, ruthenium possesses a similar bond strength with hydrogen (∼65 kcal mol–1)16, but has never been studied as a viable alternative for a HER catalyst. Here, we report a Ru-based catalyst for the HER that can operate both in acidic and alkaline media. Our catalyst is made of Ru nanoparticles dispersed within a nitrogenated holey two-dimensional carbon structure (Ru@C2N). The Ru@C2N electrocatalyst exhibits high turnover frequencies at 25 mV (0.67 H2 s−1 in 0.5 M H2SO4 solution; 0.75 H2 s−1 in 1.0 M KOH solution) and small overpotentials at 10 mA cm–2 (13.5 mV in 0.5 M H2SO4 solution; 17.0 mV in 1.0 M KOH solution) as well as superior stability in both acidic and alkaline media. These performances are comparable to, or even better than, the Pt/C catalyst for the HER.

Acid-Base Equilibria of (2,2'-Bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) Complexes and the Effect of Protonation on Charge-Transfer Sensitization of Nanocrystalline Titania.

Abstract: The ruthenium complexes [Ru(dcbpyH2)2(Cl)2] (1), [Ru(dcbpyH2)2(NCS)2] (2), (Bu4N)4[Ru(dcbpy)2(NCS)2] (3), and (Bu4N)2[Ru(dcbpyH)2(NCS)2] (4) were synthesized and characterized by cyclic voltammetry, UV−vis absorption, and emission, IR, Raman, and NMR spectroscopy. The absorption and emission maxima of these complexes red shifted with decreasing pH, and showed pH-dependent excited-state lifetimes. The ground-state pKa values were determined by spectrophotometeric methods, and the dissociation of protons was found to occur in two steps (pKa = 3 and 1.5). The Ru(II)/(III) couple in the complex (Bu4N)4[Ru(dcbpy)2(NCS)2] is shifted ca. 290 mV negatively with regard to that of the complex [Ru(dcbpyH2)2(NCS)2] due to the replacement of H+ by tetrabutylammonium cation. The negative shift for the dcbpy-based reduction potential is even larger, i.e., about 600 mV compared to that of the complex [Ru(dcbpyH2)2(NCS)2]. The effect of deprotonation on the performance of these complexes as photosensitizers for nanocrysta...