Ultrafine and Ligand‐Free Precious Metal (Ru, Ag, Au, Rh and Pd) Nanoclusters Supported on Phosphorus‐Doped Carbon

Metal Cluster Triggered-Assembling Heterogeneous Au-Ag Nanoclusters with Highly Loading Performance and Biocompatible Capability

In this work, we firstly report the preparation of heterogeneously assembled structures Au-Ag nanoclusters (NCs) as good drug carriers with high loading performance and biocompatible capability. As glutathione-protected Au and Ag clusters self-assembled into porous Au-Ag NCs, the size value is about 1.358 (±0.05) nm. The morphology characterization revealed that the diameter of Au-Ag NCs is approximately 120 nm, as well as the corresponding potential ability in loading performance of the metal cluster triggered-assembling process. Compared with individual components, the stability and loading performance of heterogeneous Au-Ag NCs were improved and exhibit that the relative biocompatibility was enhanced. The exact information about this is that cell viability was approximately to 98% when cells were incubated with 100 µg mL−1 particle solution for 3 days. The drug release of Adriamycin from Au-Ag NCs was carried out in PBS at pH = 7.4 and 5.8, respectively. By simulating in vivo and tumor microenvironment, the release efficiency could reach over 65% at pH = 5.8 but less than 30% at pH = 7.2. Using an ultrasound field as external environment can accelerate the assembling process while metal clusters triggered assembling Au-Ag NCs. The size and morphology of the assembled Au-Ag NCs can be controlled by using different power parameters (8 W, 13 W, 18 W) under ambient atmosphere. Overall, a novel approach is exhibited, which conveys assembling work for metal clusters triggers into heterogeneous structures with porous characteristic. Its existing properties such as water-solubility, stability, low toxicity and capsulation can be considered as dependable agents in various biomedical applications and drug carriers in immunotherapies.

Advanced Carbon-Based Nanocatalysts and their Application in Catalytic Conversion of Renewable Platform Molecules

The transformation of renewable platform molecules to produce value-added fuels and fine-chemicals is a promising strategy to sustainably meet future demands. Owing to their finely modified electronic and geometric properties, carbon-based nanocatalysts have shown great capability to regulate their catalytic activity and stability. Their well-defined and uniform structures also provide both the opportunity to explore intrinsic reaction mechanisms and the site-requirement for valorization of renewable platform molecules to advanced fuels and chemicals. This Review highlights the progress achieved in carbon-based nanocatalysts, mainly by using effective regulation approaches such as heteroatom anchoring, bimetallic synergistic effects, and carbon encapsulation to enhance catalyst performance and stability, and their applications in renewable platform molecule transformations. The foundation for understanding the structure-performance relationship of carbon-based catalysts has been established by investigating the effect of these regulation methods on catalyst performance. Finally, the opportunities, challenges and potential applications of carbon-based nanocatalysts are discussed.

Environmentally benign general synthesis of nonconsecutive carbon-coated RuP2 porous microsheets as efficient bifunctional electrocatalysts under neutral conditions for energy-saving H2 production in hybrid water electrolysis

A nonconsecutive carbon-coated RuP2 porous microsheet (RuP2@InC-MS) with bifunctionality for HzOR and HER is realized. DFT calculations evidence that C is more thermoneutral for HER while Ru boosts the dehydrogenation kinetics during HzOR process.

Surface Roughed and Pt-Rich Bimetallic Electrocatalysts for Hydrogen Evolution Reaction

Platinum-based alloys with low cost transition metals have been considered as promising electrocatalysts in the field of sustainable energy conversion and storage. Herein, chloroplatinic acid, cobalt chloride, and carbon nanotubes are used as platinum, cobalt precursors, and carriers, respectively, to prepare rich Pt dealloying PtCo nanoparticles (SD-PtCo/CNT) via co-liquid phase reduction and chemical dealloying methods. The characterization and test results confirm that PtCo alloy nanoparticles are evenly dispersed on carbon nanotubes, further dealloying and resulting in the partial dissolving of cobalt, simultaneously generating a rich Pt layer and roughly active surface. Benefiting from the unique structure, the SD-PtCo/CNT catalyst displays obviously enhanced HER activity in both acidic and alkaline conditions. In 1.0 M KOH, SD-PtCo/CNT exhibits a low overpotential of 78 mV at 10 mA/cm² and a small tafel slope (38.28 mV/dec). In 0.5 M H₂SO₄, SD-PtCo/CNT still shows the superior performance compared with un-dealloying PtCo/CNT, with an overpotential of 17 mV at 10 mA/cm² and corresponding tafel slope of 21.35 mV/dec. The high HER activity of SD-PtCo/CNT can be attributed to the formation of a platinum rich layer and the uniformly dispersed PtCo nanoparticles supported on superior conductive carbon nanotubes, suggesting its great potential for hydrogen generation via water splitting.

N-Doped carbon nanotubes decorated with Fe/Ni sites to stabilize lithium metal anodes

Use of N-doped carbon nanotubes decorated with Fe/Ni sites can significantly enhance the cycle life of a symmetric cell to up to 1200 h as well as yield a lowered hysteresis.

Single-Atom Iron as Lithiophilic Site To Minimize Lithium Nucleation Overpotential for Stable Lithium Metal Full Battery

High lithium nucleation overpotential on a lithiophobic matrix results in uncontrollable growth of lithium dendrites and thus restricts the wide application of lithium-metal batteries. Herein, the single-atom iron in a N-doped carbon matrix (Fe_SA-N-C) is first reported as a lithiophilic site to minimize Li nucleation overpotential from 18.6 mV to a very low value of 0.8 mV. Molecular dynamics simulations quantitatively confirmed the excellent affinity between Li ions and Fe_SA-N-C in the atomic level. Induced by the homogeneously distributed Fe_SA-N in the carbon substrate, uniform and stable metallic Li plating/stripping behaviors are realized and lithium dendrite growth is greatly suppressed. The proposed strategy of using single-atom iron as a lithiophilic site to minimize lithium nucleation overpotential opens a promising avenue for solving intrinsic problems of Li-metal-based batteries.

Encapsulation of Metal Nanoparticle Catalysts Within Mesoporous Zeolites and Their Enhanced Catalytic Performances: A Review

Metal nanoparticles (NPs) exhibit desired activities in various catalytic reactions. However, the aggregation and sintering of metal NPs usually cause the loss of catalytic performance in practical reaction processes. Encapsulation of catalytically active metal NPs on/within a high-surface-area inorganic support partially resolve such concerns. Microporous zeolites, owing to their rigid frameworks and porous structural features, have been considered as one of ideal inorganic supports. Metal NPs can be easily encapsulated and stabilized within zeolitic frameworks to prevent unwished aggregation during the catalysis. Unfortunately, sole microporous nanochannels (generally <1 nm) in conventional zeolites are not easy to be accessed. The introduction of another set of nanochannel (e.g., mesopore), known as mesoporous zeolites, can greatly improve the mass-transfer efficiency, which is structurally beneficial for most catalytic reactions. The coexistence of micropores and mesopores in inorganic supports provides the synergetic advantages of both fine confinement effect for metal NPs and easy diffusion for organic reactants/intermediates/products. This review focuses on the recent advances in the design and synthesis of mesoporous zeolites-encapsulated metal NP catalysts as well as their desired catalytic performances (activity and stability) in organic reactions. We first discuss the advantages of mesoporous zeolites as the supports and present general strategies for the construction of mesoporous zeolites. Then, the preparation methods on how to encapsulate NP catalysts within both microporous and mesoporous zeolites are clearly demonstrated. Third, some recent important cases on catalytic applications are presented to verify structural advantages of mesoporous zeolite supports. Within the conclusion, the perspectives on future developments in metal NP catalysts encapsulated within mesoporous zeolites are lastly discussed.

Multimetallic Hollow Mesoporous Nanospheres with Synergistically Structural and Compositional Effects for Highly Efficient Ethanol Electrooxidation

Controlling the nanostructures and chemical compositions of the electrochemical nanocatalysts has been recognized as two prominent means to kinetically promote the electrocatalytic performance. Herein, we report a general "dual"-template synthesis methodology for the formation of multimetallic hollow mesoporous nanospheres (HMSs) with an adjustable interior hollow cavity and cylindrically opened mesoporous shell as a highly efficient electrocatalyst for ethanol oxidation reaction. Three-dimensional trimetallic PdAgCu HMSs were synthesized via in situ coreduction of Pd, Ag, and Cu precursors on "dual"-template structural directing surfactant of dioctadecyldimethylammonium chloride in optimal synthesis conditions. Due to synergistic advantages on hollow mesoporous nanostructures and multimetallic compositions, the resultant PdAgCu HMSs exhibited significantly enhanced electrocatalytic performance toward ethanol oxidation reaction with a mass activity of 5.13 A mg_Pd ^-1 at a scan rate of 50 mV s^-1 and operation stability (retained 1.09 A mg_pd ^-1 after the electrocatalysis). The "dual"-template route will open a new avenue to rationally design multimetallic HMSs with controlled functions for broad applications.

Gold nanocatalysts supported on carbon for electrocatalytic oxidation of organic molecules including guanines in DNA

Gold (Au) is chemically stable and resistant to oxidation. Although bulk Au is catalytically inert, nanostructured Au exhibits unique size-dependent catalytic activity. When Au nanocatalysts are supported on conductive carbon (denoted as Au@C), Au@C becomes promising for a wide range of electrochemical reactions such as electrooxidation of alcohols and electroreduction of carbon dioxide. In this mini-review, we summarize Au@C nanocatalysts with specific attention on the most recent achievements including the findings in our own laboratories, and show that Au nanoclusters (AuNCs, <2 nm) on nitrided carbon are excellent electrocatalysts for the oxidation of organic molecules including guanines in DNA. The state-of-the-art synthesis and characterization of these nanomaterials are also documented. Synergistic interactions among Au-containing multicomponents on carbon supports and their applications in electrocatalysis are discussed as well. Finally, challenges and future outlook for these emerging and promising nanomaterials are envisaged.

Electrochemical Hydrogen Evolution Reaction Efficiently Catalyzed by Ru2 P Nanoparticles

Developing alternatives to Pt catalysts is a prerequisite to cost-effectively produce hydrogen. Herein, we demonstrate Ru₂ P nanoparticles (without any doping and modifications) as a highly efficient Pt-like catalyst for the hydrogen evolution reaction (HER) in different pH electrolytes. On transferring the hexagonal close-packed crystal structure of Ru to the orthorhombic structure of Ru₂ P, a greatly improved catalytic activity and stability toward HER is found owing to Ru-P coordination. The electronic state change originates from the P-Ru bonding structures, which accounts for the HER activity improvement compared with Ru nanoparticles. Specifically, Ru₂ P nanoparticles can drive 10 mA cm^-2 at a very low overpotential of 55 mV, only 8 mV more than Pt/C in an acidic solution; and an extremely low overpotential of approximately 50 mV is needed in alkaline solution, about 20 mV less than the Pt/C catalyst. The Volmer-Tafel mechanism is indicated on Ru₂ P nanoparticles with the typical Tafel slope of 30 mV dec^-1 of Pt metal indicating a Pt-like catalytic ability. Ru₂ P is more active in the Ru-P family as H atoms prefer to adsorb on Ru atoms rather than on the P element according to theoretical calculations. Considering the low price of Ru (20 % of Pt), anti-corrosion ability in the electrolyte, and the safe and reliable fabrication approach, the powder Ru₂ P nanoparticles make an excellent HER catalyst with great promise for large-scale water electrolysis applications.