Chengli Jiao

High and selective CO2 uptake, H2storage and methanol sensing on the amine-decorated 12-connected MOF CAU-1

The amine-decorated microporous metal–organic framework CAU-1 was readily synthesized and activated using a home-made efficient protocol. It exhibited a high heat of adsorption for CO2, high CO2 uptake capacity, and an impressive selectivity for CO2 over N2. At 273 K and up to 1 atm, CO2 uptake capacity can reach as much as 7.2 mmol g−1. Comparatively, the CH4 and N2 uptakes at 273 K and 1 atm were only 1.34 mmol g−1 and 0.37 mmol g−1, respectively. The CO2/N2 selectivity was 101 : 1 at 273 K. The isosteric heat of adsorption (Qst) for CO2 was ∼48 kJ mol−1 at the onset of adsorption, and it decreases to ∼28 kJ mol−1 at higher CO2 pressures. Furthermore, CAU-1 can adsorb 2.0 wt% and 4.0 wt% hydrogen at 77 K under 1 atm and 30 atm, respectively. The adsorption characteristics of CAU-1 for methanol investigated in situ with a quartz crystal microbalance (QCM), indicated that this particular MOF structure can be used as a highly sensitive sensor for methanol detection such as direct methanol fuel cells.

Mesoporous metal–organic frameworks: design and applications

Metal–organic frameworks (MOFs), which are constructed from the assembly of organic ligands with metal ions or metal clusters, have high potential applications in the fields of gas storage, separations and catalysis. MOFs involving mesopores are considered to have specific performance in such fields. In this mini review, we are mainly focussing on the recent developments in mesoporous MOFs including the design strategies and their most important applications.

Nanosized Cu-MOFs induced by graphene oxide and enhanced gas storage capacity

Various MOFs with tailored nanoporosities have recently been developed as potential storage media for CO2 and H2. The composites based on Cu-BTC and graphene layers were prepared with different percentages of graphene oxide (GO). Through the characterization analyses and gas adsorption experiments, we found that the nanosized and well-dispersed Cu-BTC induced by the incorporation of GO greatly improved the carbon dioxide capture and hydrogen storage performance of the composites. The materials obtained exhibited about a 30% increase in CO2 and H2 storage capacity (from 6.39 mmol g−1 of Cu-BTC to 8.26 mmol g−1 of CG-9 at 273 K and 1 atm for CO2; from 2.81 wt% of Cu-BTC to 3.58 wt% of CG-9 at 77 K and 42 atm for H2). Finally, the CO2/CH4 and CO2/N2 selectivities were calculated according to single-component gas sorption experiment data.

Polarized micropores in a novel 3D metal-organic framework for selective adsorption properties.

A novel 3D porous metal-organic framework with 1D polarized channels was synthesized, and its adsorption properties for gas separation and chemical sensing were studied. The framework shows a preferential adsorption of CO(2) over N(2) with a selectivity of 22:1. It also exhibits a very good sensitivity to water with respect to most of the organic solvents in view of chemical sensing applications.

A novel sensor based on electrochemical polymerization of diglycolic acid for determination of acetaminophen

Diglycolic acid (DA) polymer was coated on glassy carbon (GC) electrode by cyclic voltammetry (CV) technique for the first time. The electrochemical performances of the modified electrode were investigated by CV and electrochemical impedance (EIS). The obtained electrode showed an excellent electrocatalytic activity for the oxidation of acetaminophen (ACOP). A couple of well-defined reversible electrochemical redox peaks were observed on the ploy(DA)/GC electrode in ACOP solution. Compared with bare GC electrode, the oxidation peak potential of ACOP on ploy(DA)/GC electrode moved from 0.289 V to 0.220 V. Meanwhile, the oxidation peak current was much higher on the modified electrode than that on the bare GC electrode, indicating DA polymer modified electrode possessed excellent performance for the oxidation of ACOP. This kind of capability of the modified electrode can be enlisted for the highly sensitive and selective determination of ACOP. Under the optimized conditions, a wide linear range from 2 × 10(-8) to 5.0 × 10(-4)M with a correlation coefficient 0.9995 was obtained. The detection limit was 6.7 × 10(-9)M (at the ratio of signal to noise, S/N=3:1). The modified electrode also exhibited very good stability and reproducibility for the detection of ACOP. The established method was applied to the determination of ACOP in samples. An average recovery of 100.1% was achieved. These results indicated that this method was reliable for determining ACOP.

NiCo nanoalloy encapsulated in graphene layers for improving hydrogen storage properties of LiAlH4

NiCo nanoalloy (4–6 nm) encapsulated in grapheme layers (NiCo@G) has been prepared by thermolysis of a 3D bimetallic complex CoCo[Ni(EDTA)]2·4H2O and successfully employed as a catalyst to improve the dehydrogenation performances of LiAlH4 by solid ball-milling. NiCo@G presents a superior catalytic effect on the dehydrogenation of LiAlH4. For LiAlH4 doped with 1 wt% NiCo@G (LiAlH4-1 wt% NiCo@G), the onset dehydrogenation temperature of LiAlH4 is as low as 43 °C, which is 109 °C lower than that of pristine LiAlH4. 7.3 wt% of hydrogen can be released from LiAlH4-1 wt% NiCo@G at 150 °C within 60 min. The activation energies of LiAlH4 dehydrogenation are extremely reduced by 1 wt% NiCo@G doping.

A mixed-valent CuI/CuII metal–organic framework with selective chemical sensing properties

A novel 3D mixed-valent CuI/CuII metal–organic framework has been solvothermally synthesized and characterized by single-crystal X-ray diffraction, photoluminescence spectroscopy, thermal gravimetric analysis, and powder X-ray diffraction. The structure possesses a 3D open framework constructed from the linkages of 1D [CuI(4,4′-bipy)]n chains with [CuII(oda)2]2− cationic subunits. The chemical sensing properties of this MOF have been studied by the quartz crystal microbalance technique. The framework exhibits good selectivity and sensitivity to water with respect to other organic solvents in view of chemical sensing applications.

Novel MgO/hollow carbon sphere composites for CO2 adsorption

Novel MgO/hollow carbon sphere composites for CO2 adsorption have been synthesized through a one-pot self-assembly approach followed by carbonization. The interaction between the carboxyl groups of precursors and Mg2+ benefits a high dispersion of MgO based species over the carbon support, inducing an enhanced CO2 uptake capacity up to 122.96 mg g−1 at 25 °C and 1 bar. The uniform distribution of MgO and the interaction between MgO and the carbon support suppresses the aggregation of MgO, and leads to a good recyclability.

Magnesium and Nitrogen Co-Doped Mesoporous Carbon with Enhanced Microporosity for CO2 Adsorption

Mesoporous carbons (MC) have attracted a tremendous amount of interest due to their efficient molecular transport properties. However, the limited number of active sites and low microporosity generally impede their use for practical applications. Herein, we have fabricated Mg and N co-doped mesoporous carbon (Mg-NMC) with high microporosity via one-pot synthetic route followed by further steam activation. In comparison with the parent N-doped mesoporous carbon, Mg-NMC shows partially ordered mesostructure and improved CO2 adsorption capacity attributed to the introduction of basic site after Mg doping. Upon further steam activation, the microporosity is enhanced to 37.3%, while the CO2 adsorption capacity is also increased by 70.4% at 273 K and 1.0 bar.

A nanosized metal–organic framework confined inside a functionalized mesoporous polymer: an efficient CO2 adsorbent with metal defects

Hybrids with a nanosized metal–organic framework (MOF) confined within a mesoporous structure have attracted increasing attention owing to their enhanced mass transfer and novel applications. However, effective control of MOF crystal growth within pores and further understanding of the structure–property relationship are challenging. Herein, we report the confinement of a nanosized metal–organic framework CAU-1 into a functionalized mesoporous polymer via a combined impregnation and solvent vapor growth process. Carbonyl and hydroxyl groups over the wall of the mesoporous polymer well boost the nucleation and growth of CAU-1, leading to the formation of a nanosized MOF inside the mesoporous polymer. In contrast to bulk CAU-1, the nanosized CAU-1 within the hybrid exhibits significantly enhanced CO2 adsorption capacity at low pressure. As confirmed using the 27Al MAS NMR characterization technique, the confined nanosized CAU-1 is rich in aluminium defects. The improved CO2 adsorption properties probably result from the favorable diffusion kinetics and the presence of metal defects as active binding sites.