Ru Doping Research Articles

Electrochemical performance of Li2MnSiO4/C lithium-ion cathode materials with low-level doping of Ru in the Mn site

Lithium manganese orthosilicate (Li2MnSiO4, LMS), a prospective high-voltage lithium-ion battery cathode material, exhibits poor cycling performance due to structural instabilities during charge and discharge. To alleviate cathode degradation and understand the effects of transition metal dopants on the material properties, Mn was partially substituted by Ru between 0.5 and 3 mol% in carbon-coated LMS (LMS/C) cathode. Undoped LMS/C had orthorhombic LMS structure in the Pmn21 space group. While Ru doping of 0.5 and 1 mol% yielded phase-pure orthorhombic Pmn21 phase, Ru doping of 3 mol% yielded an additional orthorhombic Pmnb phase. The galvanostatic charge-discharge profiles showed a slight improvement in first discharge capacity for 0.5 mol% Ru-doped LMS/C compared to undoped LMS/C, but the discharge capacity decreased with higher doping levels. The capacity retention, however, improved with increasing doping level. In situ XRD results showed that Ru-doped LMS/C was able to retain a higher level of crystallinity than undoped LMS/C during the first charge. By the end of the first charge, in situ XANES of LMS/C revealed that Mn2+ in [MnO4] was partially oxidized to Mn3+ in [MnO6] ligand upon first charging, which coincided with a reduction in crystallinity of LMS/C. As shown by in situ XANES, Ru doping decreased the extent of oxidation of Mn2+ to Mn3+ upon charging. The results revealed that Ru doping of LMS/C between 0.5 and 3 mol% in the Mn site could help maintain Li2MnSiO4 crystallinity during the initial charging step.

Ruthenium (Ru) doped zinc oxide nanostructure-based radio frequency identification (RFID) gas sensors for NH3 detection

Zinc oxide (ZnO) and ZnO:Ru nanopowdersare successfully synthesized using a 0.25м solution of zinc nitrate ((Zn(NO3)2), Diethanolamine (DEA)and different weight ratios of Ruthenium chloride hydrate (RuCl3)using the hydrothermal technique by autoclaving the solutions at 70 °C for 24 h. Different weight ratios (1, 5 and 10%) of Ru-doped ZnO gas sensors are fabricated which are sensitive to ammonia gas at room temperature for low gas concentrations. Field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) examined the produced nanopowders to investigate their morphological, chemical compositions and crystalline structures respectively. Some parts of an antenna tag for commercial UHF radio frequency identification (RFID) are lumped by the nanomaterials of undoped Zinc oxide and doped with Ruthenium to produce RFID gas sensors. With the same concentration of ammonia gas (100 ppm), different reflections and shift of peak frequency is measured for all the prepared tag sensors at room temperature. The tag with 5% Ru doping has the maximum change for resonance frequency which reaches to 940 MHz and maximum sensitivity of 35% with aresponse time of about 6.5 Sec. and recovery time of 15 Sec.

Improving alkaline hydrogen evolution reaction kinetics on molybdenum carbide: Introducing Ru dopant

Hydrogen evolution reaction (HER) under alkaline media plays a pivotal role in industrial electrocatalytic hydrogen production but even the platinum-based electrocatalysts suffer from high overpotential and low kinetics due to the high energy barrier of water dissociation. Here, by employing in-situ produced graphitic carbon nitride (g-C3N4) as template to induce the formation of a lamellar structure, we reported evenly dispersed Ru-doped Mo2C nanoparticles on ultrathin nitrogen-doped carbon nanosheets (Ru-Mo2C/CN) as a highly efficient alkaline HER electrocatalyst. The optimal Ru-Mo2C/CN displays a remarkable activity with a low overpotential of only 34 mV to afford 10 mA cm−2 and good stability of more than 30 h, which is much better than that of commercial Pt/C and recently reported electrocatalysts in the landmark literatures. Density functional theory (DFT) calculations show that the introduced Ru dopant on Mo2C significantly reduce the water dissociation energy barrier of HER and inhibit the competitive adsorption between H* and OH* on the surrounding Mo sites. This work highlights a simple yet effective strategy for designing electrocatalysts with excellent performance of hydrogen evolution reaction in alkaline media.

Insights on improved room temperature ferromagnetism in chemically co-precipitated Ru-doped ZnS nanopowders

In this paper, we have reported the room temperature weak ferromagnetism in Ruthenium (Ru)-doped ZnS nanopowders (Zn1-xRuxS; x = 0.00, 0.02, 0.04 and 0.06) prepared using chemical co-precipitation route. Powder x-ray diffraction (XRD) divulges that pure as well as Ru-doped ZnS (Zn1-xRuxS) nanopowders exhibit cubic structure. Photoluminescence (PL) measurements depict the presence of defects in chemically co-precipitated Zn1-xRuxS nanopowders. Replacement of host Zn atoms with Ru is confirmed by X-ray absorption spectroscopy (XAS). Ru L3-edge XANES spectral changes clearly depict the charge transfer from S 2p state to Ru 4d state. Weak ferromagnetism is shown by pure ZnS nanopowders at room temperature. Ru doping in ZnS enhances the weak ferromagnetic ordering with magnetic moment nearly three times in comparison to pure ZnS at room temperature. Ru doping leads to metallic nature which further favors RKKY (Ruderman–Kittel–Kasuya–Yosida) exchange interaction for ferromagnetism.

Evolution of structural, magnetic, and electrical transport properties in Ru-doped pyrochlore iridate Eu2Ir2O7

We report the evolution of crystal structural, magnetic, and electrical transport properties in the iridates Eu2Ir2−xRuxO7 (x = 0.0, 0.1, 0.3, and 0.5). Powder X-ray diffraction measurement indicates the prepared polycrystalline samples retain the cubic pyrochlore-type structure. The evolution of magnetism has been studied using dc magnetic susceptibilities. Although the magnetic irreversibility temperature changes marginally, the magnetic moment increases with progressive Ru doping. A distinct metal-insulator transition is observed for Eu2Ir2−xRuxO7 series. The nature of electronic conduction in the low temperature insulating state has been found to follow a power law behavior. Interestingly, we found the resistivity increases with Ru doping in Eu2Ir2−xRuxO7. The results may be ascribed to increased electronic correlation and Ir/Ru substitutional disorder, which interrupt direct Ir–Ir hopping in the samples.

Boosting Electrocatalytic Hydrogen Evolution of Nickel foam Supported Nickel Hydroxide by Ruthenium Doping

AbstractHydrogen evolution reaction (HER) in acid electrolytes has advantages for electrolysis of water due to large supply of hydrogen ions. Herein, we report the synthesis of ruthenium doped nickel hydroxide on commercial nickel foam (Ru−Ni(OH)2/NF) by using simple hydrothermal method. Due to integrated assembly and porous structure, as prepared Ru−Ni(OH)2/NF is explored as an electrocatalyst for HER in 0.5 M H2SO4 solution at room temperature. The Ru−Ni(OH)2/NF showed excellent electrocatalytic HER activity with Tafel slope of 94 mV/dec. The overpotential of Ru−Ni(OH)2/NF required to deliver 10 mAcm−2 current density was calculated to be 27 mV, which is smaller than that of commercial Pt/C/NF catalyst (33 mV). Furthermore, the Ru−Ni(OH)2/NF has shown decent stability and notable durability. The enhanced HER activity of Ru−Ni(OH)2/NF is attributed to Ru doping Ni(OH)2/NF and effective contacts between the Ru−Ni(OH)2 and NF substrate. Finally, these results may provide guidance to the design of Pt‐free catalysts for effective energy related electrocatalytic applications.

Effects of Ru substitution on the structural, magnetic and magnetocaloric properties of Pr0.68Ca0.22Sr0.1Mn1−xRuxO3 (x = 0, 0.05, 0.1 and 0.2) compounds

The structural, magnetic and magnetocaloric properties of polycrystalline Pr0.68Ca0.22Sr0.1Mn1−xRuxO3 (x = 0, 0.05, 0.1 and 0.2) compounds were studied. All the samples crystallized in an orthorhombic symmetry. A significant increase in the lattice parameters in the doped samples was attributed to the existence of Ru with a the mixed-valence state (Ru3+/Ru4+). The increase in the Curie temperature (Tc) with increasing Ru content was interpreted as Ru doping promoting the ferromagnetic interactions between Ru4+–Mn3+ and Ru4+–Mn4+pairs. The decrease in saturation magnetisation was attributed to an AFM interaction between the Ru3+–Mn3+ and Ru3+–Mn4+ pairs and smaller magnetic moments of Ru than those of Mn. The decrease in |ΔSM| (from 4.66 J kg−1 K−1 for x = 0.05 to 2.32 J kg−1 K−1 for x = 0.2 at 5 T) was attributed to the nature of phase transition (from a first-order to second-order transition) and a decrease in the saturation magnetisation.

Interface Effect of Ru‐MoS2 Nanoflowers on Lignin Substrate for Enhanced Hydrogen Evolution Activity

The catalytic performance of Molybdenum disulfide (MoS2) has been still far from that of Pt‐based catalysts for inadequate active sites and sluggish electron transfer kinetics. Through engineering the interface between MoS2‐based materials and supported substrates, hybrid Ru‐doped MoS2 on carbonized lignin (CL) is designed and prepared as efficient catalyst for hydrogen evolution reaction (HER). The CL substrate not only facilitates the growth of MoS2 nanoflowers, but also promotes the electron transfer. Ru doping increases active sites greatly for HER. The hybrid catalyst achieves a low onset overpotential of 25 mV and a low Tafel slope of 46 mV dec−1. The favorable HER activity ascribes to the interfacial interaction between MoS2 and CL. Density functional theory calculations further confirm the improved HER performance with doped Ru atoms. This study presents a prototype application to design electrocatalysts with enhanced carrier mobility and high‐density active sites based on interface effect.

Construction of Ni–Al–Ru EAM potential and application in misfit dislocation system

In Ni-based single crystal superalloys, ruthenium is sometimes introduced as one of the creep resistances through retarding the thermally-activated deformation processes, such as dislocation glide and climb. In the present study, an embedded-atom-method potential of Ni–Al–Ru system was constructed. Using the present potential, the effect of Ru on the lattice misfit between γ(Ni) and γ'(Ni3Al) phases was investigated. The results show that Ru doping decreases the lattice misfit, which is consistent with the calculations from first-principles. The interaction between Ru and misfit dislocation was also studied. The results of interaction energy between Ru and misfit dislocation, and the simulations of misfit dislocation motion in the Ru-doping system by molecular dynamics method both show that Ru possesses the pinning effect on the misfit dislocation. These results can provide useful help for further insights of the role of Ru in the alloys.

Rational design of PdRu/TiO2 composite material for advancing electrochemical catalysis of methanol oxidation

Rational design of the durable catalysts is an important issue for improving the application performance of synthesized electrocatalysts for methanol oxidation reaction (MOR). In this work, mesoporous Pd6Ru4/TiO2-1 composite catalyst is prepared by using two-step reaction. Compared with 20%Pd/C, PdRu, Ru/TiO2-1, and Pd/TiO2-1 catalysts, Pd6Ru4/TiO2-1 catalyst has several merits of abundant electrochemical surface areas, excellent electrocatalytic activity and long-term-use stability. Ru doping into Pd/TiO2-1 greatly optimizes the electronic structure of Pd by decreasing its electron density. Pd6Ru4/TiO2-1 also exhibits high turnover number (TON), low activation energy (ΔEa) values for MOR, and higher tolerance to CO-poisoning. A satisfactory level of methanol conversion to the final products is validated by chromatographic results. Density functional theory (DFT) calculation could deepen the understanding of excellent tolerance to CO-poisoning.

On the search of small Cu-Ru atomically precise Superatoms. Cu10Ru cluster as a stable 18-ve endohedral structure

Here we discussed the plausible formation of the Cu10Ru cluster as a superatomic specie accounted for its 1S21P61D10 shell order. By stochastic structure search on Cu10Ru clusters, we found six low-lying cluster isomers with ΔE values from 0.0 to 4.7 kcal∙mol above the ground state denoting an endohedral motif with the Ru dopant inside the Cu10 cage. By using molecular dynamics simulations we found a clear trend of encapsulation of the Ru atom at low temperatures. These results are useful for further rationalization and design of novel spherical superatoms expanding the libraries of stable endohedral clusters.

Structural, electromagnetic properties and broad microwave absorption bandwidth of SrFe12-2xCoxRuxO19

SrFe12-2xCoxRuxO19 become magnetically soft with Co and Ru doping. The magnetization is high, but the anistropic field becomes low. The FT-IR spectra suggest that Co and Ru substitute for Fe at the 4f1 site. At this site, the substitution of Co and Ru with low magnetic moments weakens the anisotropy. The sharp magnetic resonances observed in x = 0.3, 0.5 and 0.7 are due to the domain wall movement. The natural magnetic resonance frequency falls in the frequency of 2–18 GHz. The Co and Ru doping increases both the magnetic loss tangent and the dielectric loss tangent. The high magnetic and dielectric loss tangents are in favor of high attenuation factors. With good impedance matching and high attenuation factor, the microwave absorption properties are excellent in x ≥ 0.3. In x = 0.5, the bandwidth is 11.8 GHz centered at 10.5 GHz. In each x > 0.5 sample, the optimum bandwidth is broader than 9 GHz. In x = 1.1, at 1.9 mm, the absorption bandwidth is broader than 9 GHz from 9 GHz to higher than 18 GHz centered at 11.6 GHz. Compared with the advanced materials published in recent decades, the bandwidth of the present work are very competitive.

DFT study of electronic structure and optical properties of Ru-doped low-temperature γ-Bi2MoO6 phase

Bismuth molybdate low-temperature γ-phase (γ-Bi2MoO6) has been widely studied as catalytic compound, and a recent experimental study demonstrated that Ruthenium (Ru) doping on γ-Bi2MoO6 enhanced their CO to CO2 conversion capacity at low temperature. To elucidate the effect of Ru-doping on γ-Bi2MoO6 electronic properties, in the present work are calculated the electronic structure and optical properties of γ-Bi2MoO6 and Ru-doped γ-Bi2MoO6 (γ-Bi2MoO6:Ru) compounds, in terms of the Density Functional Theory (DFT), using the modified Becke-Johnson (mBJ) approximation to the exchange-correlation potential. The electronic band structure, the total and projected density of states (DOS and PDOS, respectively), the real and imaginary part of dielectric function, ε, and the absorption spectra of both γ-Bi2MoO6 and γ-Bi2MoO6:Ru compounds, were obtained after the structural optimization of its crystalline lattices. The results show that Ru doping contributes to the generation of electronic states into the forbidden region of γ-Bi2MoO6, leading to a band-gap reduction, increasing their absorption along the visible-light regime. Our results provide insights for the development of novel ruthenium doped bismuth semiconductors for catalytic-related applications.

High-performance acetone gas sensor based on Ru-doped SnO2 nanofibers

We report the Ru doping effect on the gas-sensing properties of SnO2 nanofibers for acetone detection in this paper. For this purpose, pure and 1, 2, 3 mol% Ru-doped SnO2 nanofibers were prepared through electrospinning technique combined with calcination treatment. The fibrous microstructure of these nanofibers were maintained and the grain size of the SnO2 nanoparticals were decreased from 9.2 nm (pure) to 5.1 nm (3% Ru-doped) after Ru doping. In order to confirm that Ru doping is an effective way to improve the gas sensing properties of the SnO2-based gas sensor, the gas sensing properties of the sensors based on pure and Ru doped SnO2 nanofibers were investigated systematically. The results showed that the response to 100 ppm acetone of 2 mol% Ru-doped SnO2 nanofibers was 118.8, which was 12 times higher than that of pure SnO2 nanofibers. In the end, the role of Ru in the gas sensing mechanism of SnO2 nanofibers was analyzed according to the results of the X-ray photoelectron spectroscopy (XPS) and Ultraviolet photoelectron spectroscopy (UPS).

New Materials to Battle the Transistor Interconnect Bottleneck

With ever decreasing transistor size, materials that combine both diffusion barrier and liner material properties are needed to successfully electroplate Cu and thus beat the current interconnect bottleneck. In order to facilitate coating of high aspect ratio vias, the material should be as thin as possible. One possibility to achieve this is presented in this study, where we investigate through density functional theory, the behavior Cu on Ru-doped and Ru passivated ε-TaN (1 1 0). Initially, the adsorption, diffusion and association of one and two Cu atoms on the different surfaces was studied in order to probe the early stages of film growth. This showed that, while surface diffusion of atoms was more favourable on the Ru-passivated surface, the Ru dopant acts as a nucleation site for Cu, with atoms preferentially diffusing towards it.In order to understand the mechanism of film growth on this surface in more detail and to fine-tune the barrier and liner properties of the material, the effect of different percentages of surface doping were studied. Further, the behavior of Cu13 and Cu29 clusters on different doped surfaces and on the passivated surfaces was investigated. In particular, the study focused on the pathways toward agglomeration as well as the associated activation energies. We find that on a Ru doped surface the atoms agglomerate spontaneously to form a two-layer film, whereas they remain in a monolayer on Ru-passivated TaN (1 1 0).

WO3 thin films doped with Ru by facile chemical method with enhanced electrochromic properties for electrochromic window application

We report on WO3 thin films observed as platelets doped with Ruthenium (Ru) in various doping concentrations and synthesized using a facile surfactant free acid precipitation method. The synthesized thin films annealed at 500 °C for an hourrevealedchanges in morphology from plate-like structure to agglomerated nanoparticles after doping of Ru (0.05 and 0.1 wt%) in WO3. The resulting Ru doped WO3 thin films reveals two times improved performance in cycle stability and diffusion coefficient is increased by ten times as compared to synthesized pristine WO3thin films and these are discussed in terms of Ru doping effect in host matrix which induced compositional inhomogeneity, morphological change and disorder to show a fast switching response (coloration time; Tc = 2.28 s and beaching time; Tb = 1.98 s) and high reversibility 87% with coloration efficiency of 67 cm2/C and retention after 1000 cycles.

The role of Ru passivation and doping on the barrier and seed layer properties of Ru-modified TaN for copper interconnects.

Size reduction of the barrier and liner stack for copper interconnects is a major bottleneck in further down-scaling of transistor devices. The role of the barrier is to prevent diffusion of Cu atoms into the surrounding dielectric, while the liner (also referred to as a seed layer) ensures that a smooth Cu film can be electroplated. Therefore, a combined barrier + liner material that restricts the diffusion of Cu into the dielectric and allows for copper electro-deposition is needed. In this paper, we have explored barrier + liner materials composed of 1 and 2 monolayers (MLs) of Ru-passivated ϵ-TaN and Ru doped ϵ-TaN and focused on their interactions with Cu through the adsorption of small Cu clusters with 1-4 atoms. Moreover, different doping patterns for Ru doping in TaN are investigated to understand how selective doping of the ϵ-TaN surface influences surface stability. We found that an increased concentration of Ru atoms in the outermost Ta layer improves the adhesion of Cu. The strongest binding of the Cu atoms was found on the 100% Ru doped surface followed by the 1 ML Ru passivated surface. These two surfaces are recommended for the combined barrier + liner for Cu interconnects. The closely packed arrangements of Cu were found to exhibit weak Cu-slab and strong Cu-Cu interactions, whereas the sparse arrangements of Cu exhibit strong Cu-slab and weak Cu-Cu interactions. The Cu atoms seem to bind more favorably when they are buried in the doped or passivated surface layer due to the increase in their coordination number. This is facilitated by the surface distortion arising from the ionic radius mismatch between Ta and Ru. We also show that the strong Cu-Cu interaction alone cannot predict the association of Cu atoms as a few 2D Cu clusters showed stronger Cu-Cu interaction than the 3D clusters, highlighting the importance of Cu-surface interactions.

Ruthenium (Ru) Doped Titanium Dioxide (P25) Electrode for Dye Sensitized Solar Cells

In this study, P25-titanium dioxide (TiO2) was doped with ruthenium (Ru) by systematically varying the Ru content at 0.15, 0.30, 0.45 and 0.6 mol%. The synthesized Ru-doped TiO2 nanomaterials have been characterized by X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray (EDX) analysis, UV-visible (UV–Vis) spectroscopy, and electrochemical impedance (EIS) spectroscopy. The XRD patterns of undoped and Ru-doped TiO2 nanomaterials confirm the presence of mixed anatase and rutile phases of TiO2 while EDX spectrum confirms the presence of Ti, O and Ru. Further, UV-visible absorption spectra of doped TiO2 nanomaterial reveal a slight red shift on Ru-doping. The short circuit current density (JSC) of the cells fabricated using the Ru-doped TiO2 photoanode was found to be dependent on the amount of Ru present in TiO2. Optimized cells with 0.3 mol% Ru-doped TiO2 electrodes showed efficiency which is 20% more than the efficiency of the control cell (η = 5.8%) under stimulated illumination (100 mWcm−2, 1 sun) with AM 1.5 filter. The increase in JSC resulted from the reduced rate of recombination upon doping of Ru and this was confirmed by EIS analysis.

Acetone sensors with high stability to humidity changes based on Ru-doped NiO flower-like microspheres

Humidity dependence of gas sensors is one of the main obstacles for practical application. Through Ru doping into NiO flower-like microspheres, which are synthesized by a one-step hydrothermal route, the gas sensors exhibit high stability to humidity changes. The sensors based on 0.5 at% Ru-doped NiO have almost the same responses to 100 ppm acetone at 200 °C when the relative humidity ranges from 15 % to 90 %. At the same time, they possess the highest response (∼12 to 100 ppm acetone), which is about 9 times higher than that based on pure NiO. In addition, the sensors based on 0.5 at% Ru doped NiO sample show good selectivity and good long-term stability. Gas sensing mechanism for the enhanced gas sensing performance is also discussed. The results demonstrate that doping Ru into NiO flower-like microspheres is a promising way for designing high performance acetone gas sensors.

Cations’ ordering, magnetic properties and strongly enhanced microwave absorption properties of La2NiMn1-xRuxO6

The properties of the A2BB’O6 perovskites strongly depend on the cations' orderings at the B site. The cations' orderings of La2NiMn1-xRuxO6 are improved with the Ru doping especially in x ≥ 0.5, as illustrated in the XRD patterns. It is also supported by the FT-IR spectra. The magnetic properties show that the x = 1.0 sample is antiferromagnetic with the Neel temperature at 23 K. The antiferromagnetic transition is also observed in the other samples with the transition temperature slightly varying from 23 K to 38 K. In x = 0.1, one ferromagnetic transition is observed at 242 K, and it linearly decreases to 38 K in x = 0.8. The magnetic moments are calculated based on the superexchange model. From the comparison of the calculated and the measured one, it suggests that both ordered and disordered patches coexist in x = 0.1 and 0.3, while in x ≥ 0.5 the cations are fully ordered. The Ru doping increases the dielectric permittivity due to the enhanced dipolar polarization. The dielectric loss tangents are higher in x ≥ 0.5 than those in x = 0.1 and 0.3. In x ≥ 0.8, the effective absorption with RL < −10 dB is able to cover the full frequency range of 2.2 GHz–18 GHz. In x = 1.0, the thickness with RL < −10 dB is as thin as 1.9 mm. Triple sets of microwave absorption peaks are observed. The quarter-wavelength criteria explains the relationship between the optimum thickness and the frequency.