Semi-Ionic F Modified N-Doped Porous Carbon Implanted with Ruthenium Nanoclusters toward Highly Efficient pH-Universal Hydrogen Generation.

Developing high electroactivity ruthenium (Ru)-based electrocatalysts for pH-universal hydrogen evolution reaction (HER) is challenging due to the strong bonding strengths of key Ru─H/Ru─OH intermediates and sluggish water dissociation rates on active Ru sites. Herein, a semi-ionic F-modified N-doped porous carbon implanted with ruthenium nanoclusters (Ru/FNPC) is introduced by a hydrogel sealing-pyrolying-etching strategy toward highly efficient pH-universal hydrogen generation. Benefiting from the synergistic effects between Ru nanoclusters (Ru NCs) and hierarchically F, N-codoped porous carbon support, such synthesized catalyst displays exceptional HER reactivity and durability at all pH levels. The optimal 8Ru/FNPC affords ultralow overpotentials of 17.8, 71.2, and 53.8 mV at the current density of 10 mA cm-2 in alkaline, neutral, and acidic media, respectively. Density functional theory (DFT) calculations elucidate that the F-doped substrate to support Ru NCs weakens the adsorption energies of H and OH on Ru sites and reduces the energy barriers of elementary steps for HER, thus enhancing the intrinsic activity of Ru sites and accelerating the HER kinetics. This work provides new perspectives for the design of advanced electrocatalysts by porous carbon substrate implanted with ultrafine metal NCs for energy conversion applications.

Ruthenium Nanoclusters and Single Atoms on α-MoC/N-Doped Carbon Achieves Low-Input/Input-Free Hydrogen Evolution via Decoupled/Coupled Hydrazine Oxidation.

The hydrazine oxidation-assisted H2 evolution method promises low-input and input-free hydrogen production. However, developing high-performance catalysts for hydrazine oxidation (HzOR) and hydrogen evolution (HER) is challenging. Here, we introduce a bifunctional electrocatalyst α-MoC/N-C/RuNSA, merging ruthenium (Ru) nanoclusters (NCs) and single atoms (SA) into cubic α-MoC nanoparticles-decorated N-doped carbon (α-MoC/N-C) nanowires, through electrodeposition. The composite showcases exceptional activity for both HzOR and HER, requiring -80 mV and -9 mV respectively to reach 10 mA cm-2. Theoretical and experimental insights confirm the importance of two Ru species for bifunctionality: NCs enhance the conductivity, and its coexistence with SA balances the H ad/desorption for HER and facilitates the initial dehydrogenation during the HzOR. In the overall hydrazine splitting (OHzS) system, α-MoC/N-C/RuNSA excels as both anode and cathode materials, achieving 10 mA cm-2 at just 64 mV. The zinc hydrazine (Zn-Hz) battery assembled with α-MoC/N-C/RuNSA cathode and Zn foil anode can exhibit 97.3 % energy efficiency, as well as temporary separation of hydrogen gas during the discharge process. Therefore, integrating Zn-Hz with OHzS system enables self-powered H2 evolution, even in hydrazine sewage. Overall, the amalgamation of NCs with SA achieves diverse catalytic activities for yielding multifold hydrogen gas through advanced cell-integrated-electrolyzer system.

Manipulating the Rectifying Contact between Ultrafine Ru Nanoclusters and N-Doped Carbon Nanofibers for High-Efficiency pH-Universal Electrocatalytic Hydrogen Evolution.

The rational design of ingenious strategies to boost the intrinsic activity and stability of ruthenium (Ru) is of great importance for the substantial progression of water electrolysis technology. Based on Mott-Schottky effect, electronic regulation within a metal/semiconductor hybrid electrocatalyst represents a versatile strategy to boost the electrochemical performance. Herein, a typical Mott-Schottky hydrogen evolution reaction (HER) electrocatalyst composed of uniform ultrafine Ru nanoclusters in situ anchored on N-doped carbon nanofibers (abbreviated as Ru@N-CNFs hereafter) through a feasible and scalable "phenolic resin-bridged" strategy is reported. Both spectroscopy analyses and density functional theory calculations manifest that such rectifying contact can induce the spontaneous electron transfer from Ru to N-doped carbon nanofibers to generate a built-in electric field, thus enormously promoting the charge transfer efficiency and HER intrinsic activity. Moreover, the seamless immobilization of Ru nanoclusters on the substrate can prevent the active sites from unfavorable migration, coarsening, and detachment, rendering the excellent structural stability. Consequently, the well-designed Ru@N-CNFs afford prominent pH-universal HER performances with small overpotentials of 16 and 17 mV at 10 mA cm-2 and low Tafel slopes of 31.8 and 28.5 mV dec-1 in acidic and alkaline electrolytes, respectively, which are superior to the state-of-the-art commercial Pt/C and Ru/C benchmarks.

Highly Stable and Efficient Oxygen Evolution Electrocatalyst Based on Co Oxides Decorated with Ultrafine Ru Nanoclusters.

Exploring highly active and durable electrocatalysts for oxygen evolution reaction (OER) is significant to achieve efficient anion exchange membrane (AEM) water electrolysis. Herein, hollow Co-based N-doped porous carbon spheres decorated with ultrafine Ru nanoclusters (HS-RuCo/NC) are reported as efficient OER electrocatalysts via the pyrolysis of carboxylate-terminated polystyrene-templated bimetallic zeolite imidazolate frameworks accommodating Ru (III) ions. The unique hollow structure with hierarchically porous characteristics contributes to the electrolyte penetration for fast mass transport and the exposure of more metal sites. Theoretical and experimental studies reveal the synergistic effect between the in situ formed RuO2 and Co3 O4 as another critical factor for the high OER performance, where the coupling of RuO2 with Co3 O4 can optimize the electronic configuration of RuO2 /Co3 O4 heterostructure and decrease the energy barrier during OER. Meanwhile, the presence of Co3 O4 can efficiently suppress the over-oxidation of RuO2 , endowing the catalysts with high stability. As expected, when the resultant HS-RuCo/NC was integrated into an AEM water electrolyzer, the obtained electrolyzer exhibits a cell voltage of 2.07 V to launch the current density of 1 A cm-2 and excellent long-term stability at 500 mA cm-2 under room temperature in alkaline solution, outperforming the commercial RuO2 -based AEM water electrolyzer (2.19 V).

Ultrafine Nanoparticle-Supported Ru Nanoclusters with Ultrahigh Catalytic Activity.

The design of an ideal heterogeneous catalyst for hydrogenation reaction is to impart the catalyst with synergetic surface sites active cooperatively toward different reaction species. Herein a new strategy is presented for the creation of such a catalyst with dual active sites by decorating metal and metal oxide nanoparticles with ultrafine nanoclusters at atomic level. This strategy is exemplified by the design and synthesis of Ru nanoclusters supported on Ni/NiO nanoparticles. This Ru-nanocluster/Ni/NiO-nanoparticle catalyst is shown to exhibit ultrahigh catalytic activity for benzene hydrogenation reaction, which is 55 times higher than Ru-Ni alloy or Ru on Ni catalysts. The nanoclusters-on-nanoparticles are characterized by high-resolution transmission electron microscope, Cs-corrected high angle annular dark field-scanning transmission electron microscopy, elemental mapping, high-sensitivity low-energy ion scattering, and X-ray absorption spectra. The atomic-scale nanocluster-nanoparticle structural characteristics constitute the basis for creating the catalytic synergy of the surface sites, where Ru provides hydrogen adsorption and dissociation site, Ni acts as a "bridge" for transferring H species to benzene adsorbed and activated at NiO site, which has significant implications to multifunctional nanocatalysts design for wide ranges of catalytic reactions.

Electronic structure optimizing of Ru nanoclusters via Co single atom and N, S co-doped reduced graphene oxide for accelerating water electrolysis.

The development of efficient and stable electrocatalysts for hydrogen evolution reaction (HER) is impending for the advancement of water-splitting. In this study, we developed a novel electrocatalyst consisting of highly dispersed Ru nanoclusters ameliorated by cobalt single atoms and N, S co-doped reduced graphene oxide (CoSARuNC@NSG). Benefitted from the optimized electronic structure of the Ru nanoclusters induced by the adjacent single atomic Co and N, S co-doped RGO support, the electrocatalyst exhibits exceptional HER performance with overpotentials of 15 mV and 74 mV for achieving a current density of 10 mA cm-2 in alkaline and acidic water. The catalyst outperforms most noble metal-based HER electrocatalysts. Furthermore, the electrolyzer assembled with CoSARuNC@NSG and RuO2 demonstrated an overall voltage of 1.56 V at 10 mA cm-2 and an excellent operational stability for over 25 h with almost no attenuation. Theoretical calculations also deduce its high HER activity demonstrated by the smaller reaction energy barrier due to the optimized electronic structure of Ru nanoclusters. This strategy involving the regulation of metal nanoparticles activity through flexible single atom and GO support could provide valuable insights into the design of high-performance and low-cost HER catalysts.

Electronic properties and adsorption mechanism of Ru-doped copper clusters towards CH3OH molecule: A DFT investigation.

In this study, we have investigated the stability and electronic properties of the CunRu (n = 2-10) nanoclusters and their interaction with the CH3OH molecule without and with the presence of O2 molecule by using DFT calculations with TPSS/SDD/6-311g(d,p) level of theory. Based on the second energy difference (Δ2E), the results reveal that the CunRu (n = 4, 6 and 8) clusters are relatively more stable than their neighboring clusters. The values obtained for the Fukui function (f-) proves that the Ru atom in the CunRu clusters is an excellent adsorption site for the molecules. The interaction of the CunRu clusters with CH3OH molecule exhibits that the Ru atom is the preferred adsorption site for the CH3OH molecule, where the O atom of the CH3OH molecule is strongly chemisorbed onto the Ru site of the clusters, forming a strong bond between the Ru and O atoms. The copper sites of the clusters were found less preferred for the adsorption of CH3OH, and the complexes formed between both species are less stable than those obtained from the CH3OH chemisorption over the Ru site of the clusters. The interaction of CH3OH with the clusters was also evaluated in an oxidizing environment, and the results obtained reveal that the molecule is greatly chemisorbed over the ruthenium site with adsorption energies which vary from - 1.18 to - 2.05 eV. In the presence of the oxygen, the gap energy of the clusters was sharply changed after their interactions with the CH3OH molecule, suggesting that these clusters can easily detect the above molecule with great sensitivity. Therefore, the presence of the oxygen not only does not prevent the adsorption process, but it considerably promotes the CH3OH chemisorption onto the ruthenium site of the clusters and therefore significantly rises their sensitivity performance. In conclusion, the CunRu clusters could be employed as effective nanosensors for the CH3OH molecule detection.

Ruthenium nanoclusters modified by zinc species towards enhanced electrochemical hydrogen evolution reaction.

Ruthenium (Ru) has been considered a promising electrocatalyst for electrochemical hydrogen evolution reaction (HER) while its performance is limited due to the problems of particle aggregation and competitive adsorption of the reaction intermediates. Herein, we reported the synthesis of a zinc (Zn) modified Ru nanocluster electrocatalyst anchored on multiwalled carbon nanotubes (Ru-Zn/MWCNTs). The Ru-Zn catalysts were found to be highly dispersed on the MWCNTs substrate. Moreover, the Ru-Zn/MWCNTs exhibited low overpotentials of 26 and 119 mV for achieving current intensities of 10 and 100 mA cm-2 under alkaline conditions, respectively, surpassing Ru/MWCNTs with the same Ru loading and the commercial 5 wt% Pt/C (47 and 270 mV). Moreover, the Ru-Zn/MWCNTs showed greatly enhanced stability compared to Ru/MWCNTs with no significant decay after 10,000 cycles of CV sweeps and long-term operation for 90 h. The incorporation of Zn species was found to modify the electronic structure of the Ru active species and thus modulate the adsorption energy of the Had and OHad intermediates, which could be the main reason for the enhanced HER performance. This study provides a strategy to develop efficient and stable electrocatalysts towards the clean energy conversion field.

Inner Co Synergizing Outer Ru Supported on Carbon Nanotubes for Efficient pH-Universal Hydrogen Evolution Catalysis.

Exploring highly active but inexpensive electrocatalysts for the hydrogen evolution reaction (HER) is of critical importance for hydrogen production from electrochemical water splitting. Herein, we report a multicomponent catalyst with exceptional activity and durability for HER, in which cobalt nanoparticles were in-situ confined inside bamboo-like carbon nanotubes (CNTs) while ultralow ruthenium loading (~ 2.6 µg per electrode area ~ cm-2) is uniformly deposited on their exterior walls (Co@CNTsǀRu). The atomic-scale structural investigations and theoretical calculations indicate that the confined inner Co and loaded outer Ru would induce charge redistribution and a synergistic electron coupling, not only optimizing the adsorption energy of H intermediates (ΔGH*) but also facilitating the electron/mass transfer. The as-developed Co@CNTsǀRu composite catalyst requires overpotentials of only 10, 32, and 63 mV to afford a current density of 10 mA cm-2 in alkaline, acidic and neutral media, respectively, representing top-level catalytic activity among all reported HER catalysts. The current work may open a new insight into the rational design of carbon-supported metal catalysts for practical applications.

Coupling of Ru nanoclusters decorated mixed-phase (1T and 2H) MoSe2 on biomass-derived carbon substrate for advanced hydrogen evolution reaction.

The development of efficient catalysts for hydrogen evolution reaction (HER) from water splitting is one of the most promising strategies to achieve the goal of peak carbon dioxide emissions and carbon neutrality. Herein, Ru nanoclusters decorated MoSe2 nanosheets supported on a Crepis tectorum fluff biomass-derived hollow carbon tube (Ru-MoSe2/CMT) are prepared as the HER catalysts in both alkaline and acidic conditions. The Ru modification induces the transformation of MoSe2 from 2H phase to 1T phase. Benefiting from the strong water dissociation ability of Ru, Ru-MoSe2/CMT exhibits a low overpotential of 70 mV with a Tafel slope of 39 mV dec-1 in 1 M KOH. Furthermore, the assembled Ru-MoSe2/CMT || RuO2 system with a low cell voltage of 1.54 V at 10 mA cm-2 exhibits outstanding overall water splitting performance superior to Pt/C || RuO2 system. The Ru-MoSe2/CMT || RuO2 system also achieves the excellent stability of up to 30 h in 1 M KOH. The synergy effect between Ru and MoSe2, as well as the improved electron transfer kinetics provided by the biomass-derived carbon substrate together contribute to the excellent HER activity of Ru-MoSe2/CMT.

Catalytic Kinetics Regulation for Enhanced Electrochemical Nitrogen Oxidation by Ru-Nanoclusters-Coupled Mn3 O4 Catalysts Decorated with Atomically Dispersed Ru Atoms.

Electrochemical N2 oxidation reaction (NOR), using water and N2 in the atmosphere, represents a sustainable approach for nitric production to replace the conventional industrial synthesis with high energy consumption and greenhouse gas emission. Meanwhile, owing to chemical inertness of N2 and sluggish kinetics for 10-electron transfer, emerging electrocatalysts remain largely underexplored. Herein, Ru-nanoclusters-coupled Mn3 O4 catalysts decorated with atomically dispersed Ru atoms (Ru-Mn3 O4 ) are designed and explored as an advanced electrocatalyst for ambient N2 oxidation, with an excellent Faraday efficiency (28.87%) and a remarkable NO3 - yield (35.34 µg h-1 mg-1 cat. ), respectively. Experiments and density functional theory calculations reveal that the outstanding activity is ascribed to the coexistence of Ru clusters and single-atom Ru. The synergistic effect between the Ru clusters and Mn3 O4 can effectively activate the chemically inert N2 , lowering the kinetic barrier for the vital breakage of N≡N. The intensive *OH supply and enhanced conductivity are used to regulate the catalytic kinetics for optimized performance. This work provides brand-new ideas for the rational design of electrocatalysts in complicated electrocatalytic reactions with multiple dynamics-different steps.

Elucidating the role of confinement and shielding effect over zeolite enveloped Ru catalysts for propane low temperature degradation.

Volatile organic compounds (VOCs) are the main precursor for ozone formation and hazardous to human health. Light alkane as one of the typical VOCs is difficult to degrade to CO2 and H2O by catalytic degradation method due to its strong C-H bond. Herein, a series of ultrafine Ru nanoclusters (<0.95 nm) enveloped in silicalite-1 (S-1) zeolite catalysts were designed and prepared by a simple one-pot method and applied for catalytic degradation of propane. The results demonstrate that the enveloped Ru1@S-1 catalyst has excellent propane degradation performance. Its T95 is as low as 294 °C with moisture, and the turnover frequency (TOF) value is up to 5.07 × 10-3 s-1, evidently higher than that of the comparison supported catalyst (Ru1/S-1). Importantly, Ru1@S-1 exhibits superior thermal stability, water resistance and recyclability, which should be attributed to the confinement and shielding effect of the S-1 shell. The in-situ DRIFTS result reveals that the propane degradation over Ru1@S-1 follows the Mars-van-Krevelen (MvK) mechanism, where the hydroxy from the framework of zeolite can provide the active oxygen species. Our work provides a new candidate and guideline for an efficient and stable catalyst for the low-temperature degradation of the light alkane VOCs.

Crystalline Modulation Engineering of Ru Nanoclusters for Boosting Ammonia Electrosynthesis from Dinitrogen or Nitrate.

Developing highly efficient nitrogen reduction reaction (NRR) and nitrate reduction reaction (NITRR) electrocatalysts is an ongoing challenge. Herein, we report the in situ growth of ultrafine amorphous Ru nanoclusters with a uniform diameter of ∼1.2 nm on carbon nanotubes as a highly efficient electrocatalyst for both the NRR and the NITRR. The amorphous Ru nanoclusters were prepared via a convenient ambient chelated co-reduction method, in which trisodium citrate as a chelating agent played a key role to form amorphous Ru instead of crystalline Ru. The strong d-π interaction between Ru metal and carbon nanotubes led to the homogeneous distribution and good long-term stability of ultrafine Ru nanoclusters. Compared with crystalline Ru, amorphous Ru nanoclusters with abundant low-coordinate atoms can provide more catalytic sites. The amorphous Ru nanoclusters exhibited an NH3 yield of 10.49 µg·h-1·mgcat.-1 and a FENH3 of 17.48% at -0.2 V vs reversible hydrogen electrode (RHE) for NRR. For the NITRR, an NH3 yield of 145.1 µg·h-1·mgcat.-1 and a FENH3 of 80.62% were also achieved at -0.2 V vs RHE. This work provides new insights into crystalline modulation engineering of metal nanoclusters for electrocatalytic ammonia synthesis.

Ordered Macroporous Superstructure of Nitrogen-Doped Nanoporous Carbon Implanted with Ultrafine Ru Nanoclusters for Efficient pH-Universal Hydrogen Evolution Reaction.

The electrochemical hydrogen evolution reaction (HER) is an attractive technology for the mass production of hydrogen. Ru-based materials are promising electrocatalysts owing to the similar bonding strength with hydrogen but much lower cost than Pt catalysts. Herein, an ordered macroporous superstructure of N-doped nanoporous carbon anchored with the ultrafine Ru nanoclusters as electrocatalytic micro/nanoreactors is developed via the thermal pyrolysis of ordered macroporous single crystals of ZIF-8 accommodating Ru(III) ions. Benefiting from the highly interconnected reticular macro-nanospaces, this superstrucure affords unparalleled performance for pH-universal HER, with order of magnitude higher mass activity compared to the benchmark Pt/C. Notably, an exceptionally low overpotential of only 13 mV@10 mA cm-2 is required for HER in alkaline solution, with a low Tafel slope of 40.41 mV dec-1 and an ultrahigh turnover frequency value of 1.6 H2 s-1 at 25 mV, greatly outperforming Pt/C. Furthermore, the hydrogen generation rates are almost twice those of Pt/C during practical overall alkaline water splitting. A solar-to-hydrogen system is also demonstrated to further promote the application. This research may open a new avenue for the development of advanced electrocatalytic micro/nanoreactors with controlled morphology and excellent performance for future energy applications.