Enhanced Versatility in Thorium Removal: Mesoporous Silica-Coated Magnetic Nanoparticles Functionalized by Phenanthroline Diamide as a Selective Adsorbent.

In order to promote the sustainable development of nuclear energy through thorium (Th(IV)) recycling, we synthesized SiO2-coated magnetic functional nanocomposites (SiO2@Fe3O4) that were modified with 2,9-diamide-1,10-phenanthroline (DAPhen) to serve as an adsorbent for Th(IV) removal. SiO2@Fe3O4-DAPhen showed effective Th(IV) adsorption in both weakly and strongly acidic solutions. Owing to its porous structure that facilitated rapid adsorption kinetics, equilibrium was achieved within 5 and 0.5 min at pH 3 and 1 mol L-1 HNO3, respectively. In weakly acidic solutions, Th(IV) primarily formed chemical coordination bonds with DAPhen groups, while in strongly acidic solutions, the dominant interaction was electrostatic attraction. Density functional theory (DFT) calculations indicated that electrostatic attraction was weaker compared to chemical coordination, resulting in reduced diffusion resistance and consequently faster adsorption rates in strongly acidic solutions. Furthermore, SiO2@Fe3O4-DAPhen exhibited a high adsorption capacity for Th(IV); it removed Th(IV) through chelation and electrostatic attraction at pH 3 and 1 mol L-1 HNO3, with maximum adsorption capacities of 833.3 and 1465.7 mg g-1, respectively. SiO2@Fe3O4-DAPhen also demonstrated excellent tolerance to salinity, adsorption selectivity, and radiation resistance, thereby highlighting its practical potential for Th(IV) removal in diverse contaminated water sources. Hence, SiO2@Fe3O4-DAPhen represents a promising choice for the rapid and efficient removal of Th(IV).

Functionalized hierarchically porous carbon doped boron nitride for multipurpose and efficient treatment of radioactive sewage.

In order to recycle Uranium (U) for the sustainable development of nuclear energy, diamide bipyridine (DABP) modified hierarchically porous carbon doped boron nitride (BCN-DABP) was synthesized as an adsorbent for the multipurpose removal of U. BCN-DABP displayed good adsorption performance for U in both weakly and highly acidic solutions. The hierarchically porous structure endowed BCN-DABP with ultrafast adsorption kinetics, and adsorption reached equilibrium within 180.0 and 0.5 min under pH = 4.0 and 2.00 mol L-1 HNO3, respectively. Moreover, combination of adsorption isotherm studies and DFT calculations showed that BCN-DABP possessed high adsorption capacities for U and displayed different adsorption performance under different conditions. BCN-DABP adsorbed UO22+ by chelation and electrostatic attraction under pH 4.0 and 2.00 mol L-1 HNO3, the maximum adsorption capacity under two conditions reached 818.7 and 1296.7 mg g-1, respectively. As a result, BCN-DABP is expected to be used for the rapid and efficient removal of U in various kinds of contaminated water. Furthermore, excellent salinity tolerance, good adsorption selectivity, and outstanding radiation resistance also endowed BCN-DABP with great practical potential for removing U in radioactive contaminated water as well as high level liquid waste.

Integrating a metal framework with Co-confined carbon nanotubes as trifunctional electrocatalysts to boost electron and mass transfer approaching practical applications.

A facile and large-scale construction of robust and inexpensive trifunctional self-supporting electrodes for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in metal-air batteries and water splitting is crucial but remains challenging. Herein, we report a direct and up-scalable all-solid-phase strategy for the synthesis of a porous three-dimensional electrode consisting of cobalt nanoparticles wrapped in nitrogen-doped carbon tubes (Co/N-CNTs), which are in situ planted onto the surface of a cobalt foam. The resultant Co/N-CNTs can directly serve as a self-supporting and adhesive-free electrode with excellent and durable catalytic performances for the ORR, OER and HER. The metal framework substrate with an open-pore architecture is favorable for electron and mass transfer and allows fast catalytic kinetics. More importantly, when used in Zn-air batteries and overall water splitting, the as-prepared Co/N-CNT electrode displays a remarkable performance, implying bright perspects for practical application.

Exposing the Delocalized Cu-S π Bonds on the Au24 Cu6 (SPhtBu)22 Nanocluster and Its Application in Ring-Opening Reactions.

Bimetallic nanomaterials are of major importance in catalysis. A Au-Cu bimetallic nanocluster was synthesized that is effective in catalyzing the epoxide ring-opening reaction. The catalyst was analyzed by SCXRD and ESI-MS and found to be Au24 Cu6 (SPhtBu)22 (Au24 Cu6 for short). Six copper atoms exclusively occupy the surface positions in two groups with three atoms for each, and each group was bonded with three thiolate ligands to give a planar motif reminiscent of a benzene ring. In the epoxide-ring opening reaction, Au24 Cu6 exhibited superior catalytic activity compared to other homometallic and Au-Cu alloy NCs, such as Au25 and Au38-x Cux . Control experiments and DFT calculations revealed that the π conjugation among the Cu-S bonds played a pivotal role. This study demonstrates a unique π conjugation established among the Cu-S bonds as a critical structural motif in the nanocluster, which facilitates the catalysis of a ring-opening reaction.

Highly Selective and Sharp Volcano-type Synergistic Ni2Pt@ZIF-8-Catalyzed Hydrogen Evolution from Ammonia Borane Hydrolysis.

Ammonia borane hydrolysis is considered as a potential means of safe and fast method of H2 production if it is efficiently catalyzed. Here a series of nearly monodispersed alloyed bimetallic nanoparticle catalysts are introduced, optimized among transition metals, and found to be extremely efficient and highly selective with sharp positive synergy between 2/3 Ni and 1/3 Pt embedded inside a zeolitic imidazolate framework (ZIF-8) support. These catalysts are much more efficient for H2 release than either Ni or Pt analogues alone on this support, and for instance the best catalyst Ni2Pt@ZiF-8 achieves a TOF of 600 molH2·molcatal-1·min-1 and 2222 molH2·molPt-1·min-1 under ambient conditions, which overtakes performances of previous Pt-base catalysts. The presence of NaOH boosts H2 evolution that becomes 87 times faster than in its absence with Ni2Pt@ZiF-8, whereas NaOH decreases H2 evolution on the related Pt@ZiF-8 catalyst. The ZIF-8 support appears outstanding and much more efficient than other supports including graphene oxide, active carbon and SBA-15 with these nanoparticles. Mechanistic studies especially involving kinetic isotope effects using D2O show that cleavage by oxidative addition of an O-H bond of water onto the catalyst surface is the rate-determining step of this reaction. The remarkable catalyst activity of Ni2Pt@ZiF-8 has been exploited for successful tandem catalytic hydrogenation reactions using ammonia borane as H2 source. In conclusion the selective and remarkable synergy disclosed here together with the mechanistic results should allow significant progress in catalyst design toward convenient H2 generation from hydrogen-rich substrates in the close future.

Au25(SR)18: the captain of the great nanocluster ship.

Noble metal nanoclusters are in the intermediate state between discrete atoms and plasmonic nanoparticles and are of significance due to their atomically accurate structures, intriguing properties, and great potential for applications in various fields. In addition, the size-dependent properties of nanoclusters construct a platform for thoroughly researching the structure (composition)-property correlations, which is favorable for obtaining novel nanomaterials with enhanced physicochemical properties. Thus far, more than 100 species of nanoclusters (mono-metallic Au or Ag nanoclusters, and bi- or tri-metallic alloy nanoclusters) with crystal structures have been reported. Among these nanoclusters, Au25(SR)18-the brightest molecular star in the nanocluster field-is capable of revealing the past developments and prospecting the future of the nanoclusters. Since being successfully synthesized (in 1998, with a 20-year history) and structurally determined (in 2008, with a 10-year history), Au25(SR)18 has stimulated the interest of chemists as well as material scientists, due to the early discovery, easy preparation, high stability, and easy functionalization and application of this molecular star. In this review, the preparation methods, crystal structures, physicochemical properties, and practical applications of Au25(SR)18 are summarized. The properties of Au25(SR)18 range from optics and chirality to magnetism and electrochemistry, and the property-oriented applications include catalysis, chemical imaging, sensing, biological labeling, biomedicine and beyond. Furthermore, the research progress on the Ag-based M25(SR)18 counterpart (i.e., Ag25(SR)18) is included in this review due to its homologous composition, construction and optical absorption to its gold-counterpart Au25(SR)18. Moreover, the alloying methods, metal-exchange sites and property alternations based on the templated Au25(SR)18 are highlighted. Finally, some perspectives and challenges for the future research of the Au25(SR)18 nanocluster are proposed (also holding true for all members in the nanocluster field). This review is directed toward the broader scientific community interested in the metal nanocluster field, and hopefully opens up new horizons for scientists studying nanomaterials. This review is based on the publications available up to March 2018.

Sulfonate, sulfide and thiolate ligands into an ultrasmall nanocluster: [Ag40.13Cu13.87S19(tBuS)20(tBuSO3)12].

A novel Ag-Cu bimetallic nanocluster, Ag40.13Cu13.87S19(tBuS)20(tBuSO3)12, has been synthesized by precise control. The crystal structure reveals that the alloy cluster consists of a Cu10Ag2S7 core, a M42(tBuS)20(tBuSO3)12 shell and another 12 bare S atoms. The sulfonate ligand is observed in NCs for the first time via in situ oxidation of thiolate.

Size-confined growth of atom-precise nanoclusters in metal-organic frameworks and their catalytic applications.

Using MOFs as size-selection templates, we have for the first time synthesized atom-precise Au11:PPh3 nanoclusters (NCs) and Au13Ag12:PPh3 NCs with high purity by a one-step, in situ reduction method. Specifically, we found that the product released from the frameworks of ZIF-8 is exclusively the Au11:PPh3 NCs rather than polydispersed NCs, and inside MIL-101(Cr) the Au13Ag12:PPh3 NCs constitute the exclusive product. The metal NC@MOF composites are also demonstrated for catalytic application. The high catalytic efficiency for the oxidation of benzyl alcohol indicates that atom-precise noble metal NCs@MOFs may act as a promising class of heterogeneous catalysts. The atom-precise NCs obtained in the MOF templated synthesis imply the future possibility of using MOFs of various pore sizes for the size-selective synthesis of atomically precise NCs. Meanwhile, metal NCs@MOFs will contribute to the understanding of the mechanism of nanocatalyst surface reactions and hence opens up enormous opportunities in heterogeneous catalysis.

X-Ray crystal structure, and optical and electrochemical properties of the Au15Ag3(SC6H11)14 nanocluster with a core-shell structure.

We report the X-ray crystallographic structure of an 18-metal atom Au-Ag bimetallic nanocluster (NC) formulated as [Au15Ag3(SC6H11)14]. This NC consists of a Au6Ag3 bi-octahedral kernel, which is built up by two octahedral Au3Ag3 units through sharing one Ag3 triangular face. The [Au15Ag3(SC6H11)14] can be viewed as a core-shell structure with the doped Ag atoms as the core and Au atoms as the shell. Detailed analyses by UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical measurements clearly show distinct differences in the electronic structure between [Au15Ag3(SC6H11)14] and the homometal [Au18(SC6H11)14] NC. This study contributes to the deep understanding on bimetallic nanoclusters.

A New Crystal Structure of Au36 with a Au14 Kernel Cocapped by Thiolate and Chloride.

This study presents a new crystal structure of a gold nanocluster coprotected by thiolate and chloride, with the formula of Au36(SCH2Ph-(t)Bu)8Cl20. This nanocluster is composed of a Au14 core with two Cl atoms, a pair of pentameric Au5(SCl5) staple motifs, and a pair of hexameric Au6(S3Cl4) motifs. It is noteworthy that the "Au-Cl-Au" staple motifs are observed for the first time in thiolate protected gold nanoclusters. More importantly, the formation of the Cl-Au3 motifs is found to be mainly responsible for the configuration of the gold nanocluster. This work will offer a new perspective to understand how the ligands affect the crystal structure of gold nanocluster.

Au25 clusters as electron-transfer catalysts induced the intramolecular cascade reaction of 2-nitrobenzonitrile.

Design of atomically precise metal nanocluster catalysts is of great importance in understanding the essence of the catalytic reactions at the atomic level. Here, for the first time, Au25(z) nanoslusters were employed as electron transfer catalysts to induce an intramolecular cascade reaction at ambient conditions and gave rise to high conversion (87%) and selectivity (96%). Electron spin-resonance spectra indeed confirmed the consecutive electron transfer process and the formation of N radical. UV-vis absorption spectra also verified Au25(z) was intact after the catalytic circle. Our research may open up wide opportunities for extensive organic reactions catalyzed by Au25(z).

Design of an ultrasmall Au nanocluster-CeO2 mesoporous nanocomposite catalyst for nitrobenzene reduction.

In this work we are inspired to explore gold nanoclusters supported on mesoporous CeO2 nanospheres as nanocatalysts for the reduction of nitrobenzene. Ultrasmall Au nanoclusters (NCs) and mesoporous CeO2 nanospheres were readily synthesized and well characterized. Due to their ultrasmall size, the as-prepared Au clusters can be easily absorbed into the mesopores of the mesoporous CeO2 nanospheres. Owing to the unique mesoporous structure of the CeO2 support, Au nanoclusters in the Au@CeO2 may effectively prevent the aggregation which usually results in a rapid decay of the catalytic activity. It is notable that the ultrasmall gold nanoclusters possess uniform size distribution and good dispersibility on the mesoporous CeO2 supports. Compared to other catalyst systems with different oxide supports, the as-prepared Au nanocluster-CeO2 nanocomposite nanocatalysts showed efficient catalytic performance in transforming nitrobenzene into azoxybenzene. In addition, a plausible mechanism was deeply investigated to explain the transforming process. Au@CeO2 exhibited efficient catalytic activity for reduction of nitrobenzene. This strategy may be easily extended to fabricate many other heterogeneous catalysts including ultrasmall metal nanoclusters and mesoporous oxides.

A novel quinoline-based two-photon fluorescent probe for detecting Cd2+ in vitro and in vivo.

A new two-photon fluorescent Cd(2+) probe APQ is developed by introducing a N(1),N(1)-dimethyl-N(2)-(pyridin-2-ylmethyl)ethane-1,2-diamine binding group and a 4-methoxyphenylvinyl conjugation-enhancing group to the 2- and 6-positions of quinoline. This probe shows a large red shift and good emission enhancement under Cd(2+) binding. It also exhibits a high ion selectivity for Cd(2+) (especially over Zn(2+)) and a large two-photon absorption cross section at 710 nm. Two-photon microscopy imaging studies reveal that the new probe is non-toxic and cell-permeable and can be used to detect intracellular Cd(2+) under two-photon excitation.