Ru Clusters Research Articles

Hydrogen Evolution Reactivity of Pentagonal Carbon Rings and p‐d Orbital Hybridization Effect with Ru

AbstractTopological defects are inevitable existence in carbon‐based frameworks, but their intrinsic electrocatalytic activity and mechanism remain under‐explored. Herein, the hydrogen evolution reaction (HER) of pentagonal carbon‐rings is probed by constructing pentagonal ring‐rich carbon (PRC), with optimized electronic structures and higher HER activity relative to common hexagonal carbon (HC). Furthermore, to improve the reactivity, we couple Ru clusters with PRC (Ru@PRC) through p‐d orbital hybridization between C and Ru atoms, which drives a shortcut transfer of electrons from Ru clusters to pentagonal rings. The electron‐deficient Ru species leads to a notable negative shift in d‐band centers of Ru and weakens their binding strength with hydrogen intermediates, thus enhancing the HER activity in different pH media. Especially, at a current density of 10 mA cm−2, PRC greatly reduces alkaline HER overpotentials from 540 to 380 mV. And Ru@PRC even exhibits low overpotentials of 28 and 275 mV to reach current densities of 10 and 1000 mA cm−2, respectively. Impressively, the mass activity and price activity of Ru@PRC are 7.83 and 15.7 times higher than that of Pt/C at the overpotential of 50 mV. Our data unveil the positive HER reactivity of pentagonal defects and good application prospects.

C60 Fullerene‐Induced Reduction of Metal Ions: Synthesis of C60‐Metal Cluster Heterostructures with High Electrocatalytic Hydrogen‐Evolution Performance

AbstractMetal clusters, due to their small dimensions, contain a high proportion of surface atoms, thus possessing a significantly improved catalytic activity compared with their bulk counterparts and nanoparticles. Defective and modified carbon supports are effective in stabilizing metal clusters, however, the synthesis of isolated metal clusters still requires multiple steps and harsh conditions. Herein, we develop a C60 fullerene‐driven spontaneous metal deposition process, where C60 serves as both a reductant and an anchor, to achieve uniform metal (Rh, Ir, Pt, Pd, Au and Ru) clusters without the need for any defects or functional groups on C60. Density functional theory calculations reveal that C60 possesses multiple strong metal adsorption sites, which favors stable and uniform deposition of metal atoms. In addition, owing to the electron‐withdrawing properties of C60, the electronic structures of metal clusters are effectively regulated, not only optimizing the adsorption behavior of reaction intermediates but also accelerating the kinetics of hydrogen evolution reaction. The synthesized Ru/C60‐300 exhibits remarkable performance for hydrogen evolution in an alkaline condition. This study demonstrates a facile and efficient method for synthesizing effective fullerene‐supported metal cluster catalysts without any pretreatment and additional reducing agent.

Manufacturing Single‐Atom Alloy Catalysts for Selective CO2 Hydrogenation via Refinement of Isolated‐Alloy‐Islands

AbstractSingle‐atom alloy (SAA) catalysts exhibit huge potential in heterogeneous catalysis. Manufacturing SAAs requires complex and expensive synthesis methods to precisely control the atomic scale dispersion to form diluted alloys with less active sites and easy sintering of host metal, which is still in the early stages of development. Here, we address these limitations with a straightforward strategy from a brand‐new perspective involving the ‘islanding effect’ for manufacturing SAAs without dilution: homogeneous RuNi alloys were continuously refined to highly dispersed alloy‐islands (~1 nm) with completely single‐atom sites where the relative metal loading was as high as 40 %. Characterized by advanced atomic‐resolution techniques, single Ru atoms were bonded with Ni as SAAs with extraordinary long‐term stability and no sintering of the host metal. The SAAs exhibited 100 % CO selectivity, over 55 times reverse water‐gas shift (RWGS) rate than the alloys with Ru cluster sites, and over 3–4 times higher than SAAs by the dilution strategy. This study reports a one‐step manufacturing strategy for SAA's using the wetness impregnation method with durable high atomic efficiency and holds promise for large‐scale industrial applications.

Constructing Electron-Rich Ru Clusters on Non-Stoichiometric Copper Hydroxide for Superior Biocatalytic ROS Scavenging to Treat Inflammatory Spinal Cord Injury.

Traumatic spinal cord injury (SCI) represents a complex neuropathological challenge that significantly impacts the well-being of affected individuals. The quest for efficacious antioxidant and anti-inflammatory therapies is both a compelling necessity and a formidable challenge. Here, in this work, the innovative synthesis of electron-rich Ru clusters on non-stoichiometric copper hydroxide that contain oxygen vacancy defects (Ru/def-Cu(OH)2), which can function as a biocatalytic reactive oxygen species (ROS) scavenger for efficiently suppressing the inflammatory cascade reactions and modulating the endogenous microenvironments in SCI, is introduced. The studies reveal that the unique oxygen vacancies promote electron redistribution and amplify electron accumulation at Ru clusters, thus enhancing the catalytic activity of Ru/def-Cu(OH)2 in multielectron reactions involving oxygen-containing intermediates. These advancements endow the Ru/def-Cu(OH)2 with the capacity to mitigate ROS-mediated neuronal death and to foster a reparative microenvironment by dampening inflammatory macrophage responses, meanwhile concurrently stimulating the activity of neural stem cells, anti-inflammatory macrophages, and oligodendrocytes. Consequently, this results in a robust reparative effect on traumatic SCI. It is posited that the synthesized Ru/def-Cu(OH)2 exhibits unprecedented biocatalytic properties, offering a promising strategy to develop ROS-scavenging and anti-inflammatory materials for the management of traumatic SCI and a spectrum of other diseases associated with oxidative stress.

Optimizing the size and electronic effects of core-shell heterostructures via well-constructed Ru clusters encapsulated in N-doped carbon layers

Optimizing the size and electronic effects of core-shell heterostructures via well-constructed Ru clusters encapsulated in N-doped carbon layers

Fully Exposed Ru Clusters for the Efficient Multi-Step Toluene Hydrogenation Reaction.

Liquid organic hydrogen carriers (LOHCs) are attractive platform molecules that play an important role in hydrogen energy storage and utilization. The multi-step hydrogenation of toluene (TOL) to methylcyclohexane (MCH) has been widely studied in the LOCHs systems, due to their relatively low toxicity and reasonable hydrogen storage capacity. Noble metal catalysts such as Ru has exhibited good performance in multi-step hydrogenation reactions, while the application is still hindered by their high cost and low specific activity. Therefore, the primary challenge lies in the development of noble metal catalysts with both robust activity and efficient atomic utilization. In this study, a series of Ru species ranging from single atoms, fully exposed clusters to nanoparticles were fabricated to investigate their structural evolution in the TOL multi-step hydrogenation reaction. The fully exposed and atomically dispersed Ru clusters, composed of an average of 3 Ru atoms, exhibit superior catalytic performance and recycle ability in TOL multi-step hydrogenation. Moreover, it delivers a high turnover frequency of 9850.3 h-1 under the relatively mild reaction (100 °C, 1.5 MPa), compared with those of single atoms and nanoparticles, and shows a notable advantage over catalysts reported in previous studies. From density functional theory (DFT) calculations, the overall barrier of the TOL multi-step hydrogenation reaction over the fully exposed Ru clusters is significantly lower than that of single atoms and nanoparticles, resulting in its higher activity. The present work provides an efficient strategy to regulate the reaction pathway of multi-step complicated catalytic reactions by designing fully exposed metal cluster catalysts.

Metal clusters modified hexagonal boron nitride for adsorption and sensing of lithium batteries thermal runaway gases

Developing efficient gas sensing materials for monitoring lithium batteries thermal runaway gases is essential for human safety. In this study, a detailed examination of the CH4, CO2, CO, and H2 adsorption property for the h-BN with metal clusters modification was conducted utilizing density functional theory. The incorporation of metal clusters (Pd4, Rh4, and Ru4) significantly improved the adsorption energy and charge transfer of h-BN towards gases compared to the unmodified h-BN. The Ru4/h-BN system demonstrated the highest adsorption capacity across all four gases, while the Pd4/h-BN system displayed remarkable recovery ability at room temperature (298 K). Furthermore, studying the adsorption mechanism via DOS revealed enhanced gas adsorption due to orbital hybridization. The work offers reliable theoretical foundation for the detection and prevention of thermal runaway gases in lithium batteries through the use of h-BN modified with metal clusters.

Encapsulation of Ru nanoparticles within NaY zeolite for ammonia decomposition

Uniform and minuscule Ru particles confined in NaY zeolite (Ru@NaY) are prepared via a simple in situ synthesis technique. Transmission electron microscopy studies indicate that the Ru particles are encapsulated within the micropores of NaY zeolite and form a uniform size of 1.5–3.5 nm. Thanks to the effective confinement of Ru particles within the NaY zeolite, as well as the high concentration of B-5 sites and basic sites, the prepared Ru@NaY catalysts show excellent NH3 decomposition activity and highly efficient H2 formation. Notably, the 0.1Ru@NaY catalyst achieves a 92.7% NH3 conversion and a H2 formation rate of 690 mmol min−1·gRu−1 at 500 °C and GHSV = 9000 mLNH3·gcat−1·h−1 and shows outstanding stability throughout a 95-h lifetime test. The encapsulation synthesis of Ru clusters in zeolites endows the catalysts with exceptional catalytic activities and excellent stability, thus providing new prospects for the production of H2 from NH3 decomposition.

Hydrogen Evolution Reactivity of Pentagonal Carbon Rings and p-d Orbital Hybridization Effect with Ru.

Topological defects are inevitable existence in carbon-based frameworks, but their intrinsic electrocatalytic activity and mechanism remain under-explored. Herein, the hydrogen evolution reaction (HER) of pentagonal carbon-rings is probed by constructing pentagonal ring-rich carbon (PRC), with optimized electronic structures and higher HER activity relative to common hexagonal carbon (HC). Furthermore, to improve the reactivity, we couple Ru clusters with PRC (Ru@PRC) through p-d orbital hybridization between C and Ru atoms, which drives a shortcut transfer of electrons from Ru clusters to pentagonal rings. The electron-deficient Ru species leads to a notable negative shift in d-band centers of Ru and weakens their binding strength with hydrogen intermediates, thus enhancing the HER activity in different pH media. Especially, at a current density of 10 mA cm-2, PRC greatly reduces alkaline HER overpotentials from 540 to 380 mV. And Ru@PRC even exhibits low overpotentials of 28 and 275 mV to reach current densities of 10 and 1000 mA cm-2, respectively. Impressively, the mass activity and price activity of Ru@PRC are 7.83 and 15.7 times higher than that of Pt/C at the overpotential of 50 mV. Our data unveil the positive HER reactivity of pentagonal defects and good application prospects.

Controllable selective anchoring of subnanometric Ru clusters or single-atoms/clusters on tungsten nitride for the hydrogen oxidation

Controllable selective anchoring of subnanometric Ru clusters or single-atoms/clusters on tungsten nitride for the hydrogen oxidation

C60 Fullerene-Induced Reduction of Metal Ions: Synthesis of C60-Metal Cluster Heterostructures with High Electrocatalytic Hydrogen-Evolution Performance.

Metal clusters, due to their small dimensions, contain a high proportion of surface atoms, thus possessing a significantly improved catalytic activity compared with their bulk counterparts and nanoparticles. Defective and modified carbon supports are effective in stabilizing metal clusters, however, the synthesis of isolated metal clusters still requires multiple steps and harsh conditions. Herein, we develop a C60 fullerene-driven spontaneous metal deposition process, where C60 serves as both a reductant and an anchor, to achieve uniform metal (Rh, Ir, Pt, Pd, Au and Ru) clusters without the need for any defects or functional groups on C60. Density functional theory calculations reveal that C60 possesses multiple strong metal adsorption sites, which favors stable and uniform deposition of metal atoms. In addition, owing to the electron-withdrawing properties of C60, the electronic structures of metal clusters are effectively regulated, not only optimizing the adsorption behavior of reaction intermediates but also accelerating the kinetics of hydrogen evolution reaction. The synthesized Ru/C60-300 exhibits remarkable performance for hydrogen evolution in an alkaline condition. This study demonstrates a facile and efficient method for synthesizing effective fullerene-supported metal cluster catalysts without any pretreatment and additional reducing agent.

Anchored Ru nanoclusters strategy enhances hydrogen spillover effect for high-efficiency hydrogen storage

Enhancing the hydrogen spillover effect of catalysts is an effective method for optimizing hydrogen storage reactions. In this study, we report a catalyst consisting of Ru nanoclusters (1.2–2.7 nm) anchored on nitrogen-doped carbon (NC) that are highly dispersed on an Al2O3 substrate. Both experimental and density functional theory-based calculations indicate that these constrained, highly dispersed ultrafine nanoclusters significantly improve the intrinsic catalytic activity of Ru and reduce the reaction barriers. Moreover, the electron transfer between NC and Ru clusters increases the adsorption inertness of Ru with hydrogen, enhances hydrogen desorption, and promotes hydrogen spillover, synergistically improving the activity of catalytic hydrogen storage. Notably, the aromatic compounds in the ethylene tar narrow fraction were effectively converted at a low temperature of 80 °C, and the total cycloalkanes yield reached 99.04 %. The hydrogen storage capacity can be about 5.70 wt%. Liquid Organic Hydrogen Carriers model compounds were fully hydrogenated at temperatures no higher than 70 °C with low Ru loading (2 wt%). This work provides a potential utilization strategy of ethylene tar narrow fraction as hydrogen carriers based on its hydrogenation over the highly active and stable Ru nanocluster catalysts.

Unilamellar MnO2 nanosheets confined Ru-clusters combined with pulse electrocatalysis for biomass electrooxidation in neutral electrolytes

The electrochemical oxidation of 5-hydroxymethylfurfural (HMFOR) in alkaline electrolyte is a promising strategy for producing high-value chemicals from biomass derivatives. However, the disproportionation of aldehyde groups under strong alkaline conditions and the polymerization of HMF to form humic substances can impact the purity of 2,5-furandicarboxylic acid (FDCA) products. The use of neutral electrolytes offers an alternative environment for electrolysis, but the lack of OH− ions in the electrolyte often leads to low current density and low yields of FDCA. In this study, a sandwich-structured catalyst, consisting of Ru clusters confined between unilamellar MnO2 nanosheets (S-Ru/MnO2), was used in conjunction with an electrochemical pulse method to realize the electrochemical conversion of 5-hydroxymethylfurfural into FDCA in neutral electrolytes. Pulse electrolysis and the strong electron transfer between Ru clusters and MnO2 nanosheets help maintain Ru in a low oxidation state, ensuring high activity. The increased *OH generation led to a groundbreaking current density of 47 mA/cm2 at 1.55 V vs. reversible hydrogen electrode (RHE) and an outstanding yield rate of 98.7 % for FDCA in a neutral electrolyte. This work provides a strategy that combines electrocatalyst design with an electrolysis technique to achieve remarkable performance in neutral HMFOR.

Manufacturing Single-Atom Alloy Catalysts for Selective CO2 Hydrogenation via Refinement of Isolated-Alloy-Islands.

Single-atom alloy (SAA) catalysts exhibit huge potential in heterogeneous catalysis. Manufacturing SAAs requires complex and expensive synthesis methods to precisely control the atomic scale dispersion to form diluted alloys with less active sites and easy sintering of host metal, which is still in the early stages of development. Here, we address these limitations with a straightforward strategy from a brand-new perspective involving the 'islanding effect' for manufacturing SAAs without dilution: homogeneous RuNi alloys were continuously refined to highly dispersed alloy-islands (~ 1 nm) with completely single-atom sites where the relative metal loading was as high as 40%. Characterized by advanced atomic-resolution techniques, single Ru atoms were bonded with Ni as SAAs with extraordinary long-term stability and no sintering of the host metal. The SAAs exhibited 100% CO selectivity, over 55 times reverse water-gas shift (RWGS) rate than the alloys with Ru cluster sites, and over 3-4 times higher than SAAs by the dilution strategy. This study reports a one-step manufacturing strategy for SAA's using the wetness impregnation method with durable high atomic efficiency and holds promise for large-scale industrial applications.

Electronic interaction between sub-nanometric Ru entity and TiO2 support regulates the hydrogenation chemistry for selective C-O bond cleavage

Selective C-O bond cleavage without ring saturation is the pillar pursuit in the hydrotreating process for lignin valorization/depolymerization since it avoids the consumption of excessive hydrogen. In this work, the sub-nanometric cluster and nanometric particle of Ru were supported on TiO2 for the hydrogenolysis of C-O bond in aromatic ether. The experimental and theoretical results reveal that, in the catalyst of larger Ru nanoparticles, less electron transfer occurs from individual Ru atom to TiO2, making the Ru-related domains retain the nature of bulky Ru for deep hydrogenation. Sub-nanometric Ru cluster shows more intense electron transfer for individual Ru atom, leading to a stronger modification to Ru domain by TiO2. Such electronic hybridization makes Ru gain the catalytic property of TiO2 to attenuate the activation of aromatic ring, inhibiting ring saturation with maintained C-O cleavage activity. This work implies that further decrease of Ru entity size to single-atom level may achieve the complete inhibition of ring saturation.

Oxophilic gallium single atoms bridged ruthenium clusters for practical anion-exchange membrane electrolyzer

The development of highly efficient and durable alkaline hydrogen evolution reaction (HER) catalysts is crucial for achieving high-performance practical anion exchange membrane water electrolyzer (AEMWE) at ampere-level current density. Herein, we report a design concept by employing Ga single atoms as an electronic bridge to stabilize the Ru clusters for boosting alkaline HER performance in practical AEMWE. Experimental and theoretical results collectively reveal that the bridged Ga sites trigger strong metal-support interaction for the homogeneous distribution of Ru clusters with high density, as well as optimize the Ru–H bond strength due to the electron transfer between Ru and Ga for enhanced intrinsic HER activity. Moreover, the oxophilic Ga sites near the Ru clusters tend to adsorb the hydroxyl species and accelerate the water dissociation for sufficient proton supplement in an alkaline medium. The Ru–GaSA/N–C catalyst exhibits a low overpotential of 4 ± 1 mV (10 mA cm−2) and high mass activity of 9.3 ± 0.5 A mg−1Ru at −0.05 V vs RHE. In particular, the Ru–GaSA/N–C-based AEMWE in 1 M KOH delivers a voltage of only 1.74 V to reach an industrial current density of 1 A cm−2, and can steadily operate at 1 A cm−2 for more than 170 h.

Rapid Joule heating fabrication of Ru cluster-loaded WO3 on carbon nanotubes to enhance alkaline electrocatalytic hydrogen production activity

The design of efficient electrocatalysts for hydrogen evolution reaction (HER) suitable for industrial applications remains a challenging task. In this work, Ru clusters were loaded onto WO3 which were grown on carbon nanotubes (WRu/C-JH) using a rapid Joule heating method. The crystal phases of WO3 was transformed, and abundant active sites were exposed during the rapid heating and cooling process. All these modifications contributed to the greatly improved electrocatalytic activity in HER. As tested, in 1 M KOH, it only required an overpotential of 22 mV to reach 10 mA cm−2 and 401 mV to reach a high current density of 1 A cm−2 on WRu/C-JH. Moreover, WRu/C-JH demonstrated excellent stability at 500 mA cm−2 for 100 h. Furthermore, a two-electrode system was constructed to assess overall water splitting performance of WRu/C-JH. This system was capable of reaching 100 mA cm−2 at a low voltage of 1.94 V. The mechanism of the enhancement in HER for as-prepared sample was also deeply discussed.

The effect of calcination gas atmosphere on the structural organization of Ru/Ce0.75Zr0.25O2 catalysts for CO2 methanation

In this study, supported 5 wt% Ru/Ce0.75Zr0.25O2 catalysts were prepared by sorption-hydrolytic deposition technique, followed by calcination under different conditions, namely in reductive H2/N2 (Ru/CeZr_red) and oxidative air (Ru/CeZr_ox) atmospheres. A thorough characterization of the catalysts was carried out by XRD, CO chemisorption, HRTEM, Raman spectroscopy, XPS, and in situ DRIFTS. The findings showed that the choice of the calcination atmosphere has a great impact on the structural organization of the catalyst. Calcination in air results in the formation of the larger crystalline RuO2 particles, which tend to enlarge upon reduction under CO2 methanation conditions. The reductive treatment results in a much higher dispersion of supported Ru species and a more pronounced metal-support interaction (MSI). In the Ru/CeZr_red catalyst, a large amount of atomic scale Ru species was detected along with metallic Ru nanoparticles and clusters. However, it was found that the superiority of the Ru/CeZr_red catalyst in the Ru dispersion did not result in the significant advantage in the CO2 methanation activity. In situ DRIFTS results suggested that the MSI affects the ability of Ru species to adsorb and activate reagent molecules, in particular, enhances the adsorption strength of the intermediate CO species.

Ru3@Mo2CO2 MXene single-cluster catalyst for highly efficient N2-to-NH3 conversion.

Single-cluster catalysts (SCCs) representing structurally well-defined metal clusters anchored on support tend to exhibit tunable catalytic performance for complex redox reactions in heterogeneous catalysis. Here we report a theoretical study on an SCC of Ru3@Mo2CO2 MXene for N2-to-NH3 thermal conversion. Our results show that Ru3@Mo2CO2 can effectively activate N2 and promotes its conversion to NH3 through an association mechanism, in which the rate-determining step of NH2* + H* → NH3* has a low energy barrier of 1.29eV. Notably, with the assistance of Mo2CO2 support, the positively charged Ru3 cluster active site can effectively adsorb and activate N2, leading to 0.74 |e| charge transfer from Ru3@Mo2CO2 to the adsorbed N2. The supported Ru3 also acts as an electron reservoir to regulate the charge transfer for various intermediate steps of ammonia synthesis. Microkinetic analysis shows that the turnover frequency of the N2-to-NH3 conversion on Ru3@Mo2CO2 is as high as 1.45×10-2 s-1 site-1 at a selected thermodynamic condition of 48bar and 700K, the performance of which even surpasses that of the Ru B5 site and Fe3/θ-Al2O3(010) reported before. Our work provides a theoretical understanding of the high stability and catalytic mechanism of Ru3@Mo2CO2 and guidance for further designing and fabricating MXene-based metal SCCs for ammonia synthesis under mild conditions.

Low-Crystalline Cobalt Iron Oxide-Supported Single Ru Atoms and Ru Clusters for 2,5-Hydroxymethylfurfural Electro-Oxidation Coupled with Hydrogen Evolution

Low-Crystalline Cobalt Iron Oxide-Supported Single Ru Atoms and Ru Clusters for 2,5-Hydroxymethylfurfural Electro-Oxidation Coupled with Hydrogen Evolution