Qi-Long Zhu

Immobilizing metal nanoparticles to metal-organic frameworks with size and location control for optimizing catalytic performance.

AuNi alloy nanoparticles were successfully immobilized to MIL-101 with size and location control for the first time by double solvents method (DSM) combined with a liquid-phase concentration-controlled reduction strategy. When an overwhelming reduction approach was employed, the uniform 3D distribution of the ultrafine AuNi nanoparticles (NPs) encapsulated in the pores of MIL-101 was achieved, as demonstrated by TEM and electron tomographic measurements, which brings light to new opportunities in the fabrication of ultrafine non-noble metal-based NPs throughout the interior pores of MOFs. The ultrafine AuNi alloy NPs inside the mesoporous MIL-101 exerted exceedingly high activity for hydrogen generation from the catalytic hydrolysis of ammonia borane.

Liquid organic and inorganic chemical hydrides for high-capacity hydrogen storage

The search for hydrogen storage materials capable of efficiently storing hydrogen in a compact and lightweight package is one of the most difficult challenges for the upcoming hydrogen economy. Liquid chemical hydrides with high gravimetric and volumetric hydrogen densities have the potential to overcome the challenges associated with hydrogen storage. Moreover, the liquid-phase nature of these hydrogen storage systems provides significant advantages of easy recharging, and the availability of the current liquid fuel infrastructure for recharging. In this review, we briefly survey the research progress in the development of diverse liquid-phase chemical hydrogen storage materials, including organic and inorganic chemical hydrides, with emphases on the syntheses of active catalysts for catalytic hydrogen generation and storage. Moreover, the advantages and drawbacks of each storage system are discussed.

Metal‐Organic Framework‐Derived Honeycomb‐Like Open Porous Nanostructures as Precious‐Metal‐Free Catalysts for Highly Efficient Oxygen Electroreduction

Honeycomb-like porous carbon nanostructures are rationally constructed from a metal-organic framework composite. The unique architecture with uniformly distributed high-density active sites significantly enhances the electrocatalytic performance by increasing the accessible active sites and enhancing mass transport of the gas and electrolyte, rendering the resulting catalyst adequate in reaching the desired catalytic performance afforded by Pt for the oxygen reduction reaction.

Sodium hydroxide-assisted growth of uniform Pd nanoparticles on nanoporous carbon MSC-30 for efficient and complete dehydrogenation of formic acid under ambient conditions

Highly dispersed Pd nanoparticles (NPs) deposited on nanoporous carbon MSC-30 have been successfully prepared with a sodium hydroxide-assisted reduction approach. The modification by NaOH during the formation and growth of particles results in the well-dispersed ultrafine Pd NPs on carbon. The combination of distinct interaction between metal and support and high dispersion of NPs drastically enhances the catalytic performance of the resulted catalyst, over which the turnover frequency (TOF) for heterogeneously catalyzed decomposition of formic acid (FA) reaches 2623 h−1 at 50 °C with 100% H2 selectivity, the highest value ever reported under ambient conditions, comparable to those acquired from the most active homogeneous catalysts. Even at 25 °C, the complete dehydrogenation of FA with a TOF as high as 750 h−1 can be achieved.

Immobilizing Highly Catalytically Active Noble Metal Nanoparticles on Reduced Graphene Oxide: A Non-Noble Metal Sacrificial Approach

In this work, we have developed a non-noble metal sacrificial approach for the first time to successfully immobilize highly dispersed AgPd nanoparticles on reduced graphene oxide (RGO). The Co3(BO3)2 co-precipitated with AgPd nanoparticles and subsequently sacrificed by acid etching effectively prevents the primary AgPd particles from aggregation. The resulted ultrafine AgPd nanoparticles exhibit the highest activity (turnover frequency, 2739 h(-1) at 323 K) among all the heterogeneous catalysts for the dehydrogenation of formic acid to generate hydrogen without CO impurity. The sacrificial approach opens up a new avenue for the development of high-performance metal nanocatalysts.

Immobilizing Extremely Catalytically Active Palladium Nanoparticles to Carbon Nanospheres: A Weakly-Capping Growth Approach

Ultrafine palladium nanoparticles (Pd NPs) supported on carbon nanospheres have been successfully synthesized using a facile methanol-mediated weakly-capping growth approach (WCGA) with anhydrous methanol as a mild reductant and a weakly capping agent. The Pd NPs show exceedingly high catalytic activity for 100% selective dehydrogenation of aqueous formic acid (FA) at ambient temperatures. The small size and clean surface of the Pd NPs greatly improve the catalytic properties of the as-prepared catalyst, providing an average rate of CO-free H2 generation up to 43 L H2 gPd(-1) min(-1) and a turnover frequency of 7256 h(-1) at 60 °C. These values are much higher than those obtained even with the most active catalyst reported thus far for heterogeneously catalyzed dehydrogenation of FA. This remarkably facile and effective methanol-mediated WCGA provides a powerful entry into ultrafine metal NPs with clean surface to achieve enhanced performance. Moreover, the catalytic results open up new avenues in the effective applications of FA for hydrogen storage.

Non-noble bimetallic CuCo nanoparticles encapsulated in the pores of metal–organic frameworks: synergetic catalysis in the hydrolysis of ammonia borane for hydrogen generation

Non-noble bimetallic CuCo alloy nanoparticles (NPs) were successfully encapsulated in the pores of MIL-101 by using the double-solvent method combined with the overwhelming reduction approach. Compared with their monometallic counterparts, the bimetallic CuCo alloy NPs present much higher catalytic activity for hydrolytic dehydrogenation of ammonia borane (AB) to generate a stoichiometric amount of hydrogen at room temperature for chemical hydrogen storage. The synergistic effect between copper and cobalt species plays an important role for the improved performance in the catalytic hydrolysis of AB.

Highly active AuCo alloy nanoparticles encapsulated in the pores of metal–organic frameworks for hydrolytic dehydrogenation of ammonia borane

Ultrafine AuCo alloy nanoparticles were successfully encapsulated in the pores of MIL-101 by using the double solvents method combined with the overwhelming reduction approach, which exert excellent catalytic activity for hydrolytic dehydrogenation of ammonia borane.

Redox‐Responsive Photochromism and Fluorescence Modulation of Two 3D Metal–Organic Hybrids Derived from a Triamine‐Based Polycarboxylate Ligand

Photochromism is defined as the reversible transformation of a chemical species, induced by the absorption of electromagnetic radiation, to a form with a different vibronic absorption spectra. Photochromic materials have attracted considerable interest owing to prospective real or potential applications in many fields, including protection (in spectacles, photobarriers, anti-fake, and camouflage), decoration, information storage, displays, optical switches, photomechanics, and so forth. Although numerous photochromic families have been reported to date, those based on an electron-transfer (redox) chemical process, especially for metal–organic complexes (MOCs), are rare. One of the biggest challenges in photochromic MOCs without photochromic organic ligands is to design photoinduced bistable systems based on different electron-transfer mechanisms, such as metal-centered electron transition (MC), ligand-tometal charge transfer (LMCT), metal-to-metal charge transfer (MMCT), intra ACHTUNGTRENNUNGli ACHTUNGTRENNUNGgand charge transfer (ILCT), and ligand-to-ligand charge transfer (LLCT). Structurally well-defined hybrids will give us better insight into the structure–photochromism relationships; nevertheless, few hybrids based on transition metals have been explored with simultaneous characterization of their structure and photochromism. Chopoorian and Loeffler have discovered the electron-attractive ability of a porous glass matrix indicated by the blue radical-ion species after the irradiation with UV light, in which an aqueous solution of p-phenylenediaminetetraacetic acid (p-PTDA) is absorbed. Thus, in the presence of electron-accepting components, organic ligands containing N ACHTUNGTRENNUNG(CH2CO2H)2 groups in MOCs may undergo a similar electron-transfer process. However, no coordination polymer constructed from ligands containing N ACHTUNGTRENNUNG(CH2CO2H)2 groups shows photochromism so far. Guo and coworkers have reported the only metal-assisted LLCT photochromic MOC, [Cd2(ic)(mc)(4,4’-bipy)3]·4H2O (ic = itaconate, mc=mesaconate, bipy= bipyridine), which undergoes an interesting photochromic transformation from yellow to blue upon UV irradiation. Herein, we report two photochromic MOCs with adjustable fluorescent intensities, [Zn3ACHTUNGTRENNUNG(TTHA)(4,4’bipy)1.5 ACHTUNGTRENNUNG(H2O)2]·6H2O (1 a) and [Zn3ACHTUNGTRENNUNG(TTHA)(4,4’-bipy)1.5ACHTUNGTRENNUNG(H2O)2]·3H2O (2 a), derived from a novel triamine-based polycarboxylate ligand containing the N ACHTUNGTRENNUNG(CH2CO2H)2 group, 1,3,5-triazine-2,4,6-triamine hexaacetic acid (H6TTHA), as electron donor, although the ligand H6TTHA itself does not exhibit photochromism, and 4,4’-bipy as electron capturer. The photochromic mechanisms based on electron-transfer chemical processes have been verified with direct and powerful ESR and X-ray photoelectron spectroscopy (XPS) measurements. Yellow needlelike crystals of 1 a and prismatic crystals of 2 a were obtained by the hydrothermal reactions of ZnACHTUNGTRENNUNG(NO3)2, H6TTHA, and 4,4’-bipy in a molar ratio of 3:1:2 at 140 8C and 120 8C for 72 h, respectively. The single-crystal X-ray diffraction data reveal that complexes 1 a and 2 a are 3D networks. As shown in Figure 1 and S3 in the Supporting Information, the 3D frameworks can be described as 2D layers constructed of Zn ions and TTHA pillared by the coordinated 4,4’-bipy groups. The biggest difference between the structures of complexes 1 a and 2 a is the coordination modes of the ligands (Scheme 1). Due to the flexibility, six of the arms show sig[a] Q.-L. Zhu, Prof. T.-L. Sheng, Dr. R.-B. Fu, S.-M. Hu, Prof. L. Chen, C.-J. Shen, X. Ma, Prof. X.-T. Wu State Key Lab of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Science, Fuzhou Fujian 350002 (P.R. China) Fax: (+86) 591-8371-9238 E-mail : wxt@fjirsm.ac.cn [b] Q.-L. Zhu, C.-J. Shen, X. Ma Graduate School of the Chinese Academy of Sciences Beijing, 100049 (P.R. China) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201003274. Figure 1. 2D layer (left) and 3D framework along the c axis (right) in complex 1 a.

Formation of Zn(II) and Cd(II) coordination polymers assembled by triazine-based polycarboxylate and in-situ-generated pyridine-4-thiolate or dipyridylsulfide ligands: observation of an unusual luminescence thermochromism.

Three novel coordination polymers, [Cd(5)(HTTHA)(2)(Hpt)(4)(H(2)O)]·4H(2)O (1; H(6)TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, Hpt = pyridinium-4-thiolate), {[Cd(3)(TTHA)(dps)(H(2)O)(3)](2)}·H(2)O (2), and [Zn(3)(TTHA)(dps)(H(2)O)]·5H(2)O (3; dps =4,4-dipyridylsulfide), have been synthesized by the flexible hexapodal acid H(6)TTHA and in-situ-generated Hpt and dps ligands from a 4,4-dipyridyldisulfide (dpds) precursor through cleavage of both S-S and S-C(sp(2)) bonds and temperature-dependent chemical rearrangement under hydrothermal conditions. Polymers 2 and 3 exhibit 3D frameworks, while in 1, the extended 3D network can be described as 2D layers further bridged via H-bond interaction. Intriguingly, the three compounds have shown an unusual luminescence thermochromism. Upon decreasing the temperature from 298 to 10 K, the emission bands grow in intensity and change in color dramatically.