Xiaodong Sun

Two heterovalent copper–organic frameworks with multiple secondary building units: high performance for gas adsorption and separation and I2 sorption and release

With the help of the multiple secondary building unit (SBU) strategy, two novel heterovalent Cu–MOFs, [(Cu4I4)Cu4L4(DABCO)2]·16DMF (JLU-Liu31) and [(Cu4I4)Cu3L3(DABCO)(DMF)2]·18DMF (JLU-Liu32) [H2L = pyridine-3,5-bis(phenyl-4-carboxylic acid), DABCO = 1,4-diazabicyclo[2.2.2]-octane], have been successfully solvothermally synthesized and structurally characterized. Both of the two compounds feature multiple SBUs and exhibit novel topologies. JLU-Liu31 possesses the largest sustainable pore volume among the MOFs based on Cu4I4 clusters. Moreover, the adsorption behaviours of the desolvated JLU-Liu31 material for some small gases (H2, O2, CO2, CH4, C2H6 and C3H8) have been analysed in low pressure regions; meanwhile, it exhibits commendable selectivity for O2 over N2, and C3H8 over CH4. The remarkable results illustrate that JLU-Liu31 is a good candidate for application in the separation of light hydrocarbons. Additionally, JLU-Liu32 exhibits impressive performance for I2 sorption and release in solvents.

An ultrastable Zr-MOF for fast capture and highly luminescence detection of Cr2O72− simultaneously in an aqueous phase

Herein, using the modulator synthesis approach, a zirconium-based metal–organic framework (Zr-MOF), [Zr6O4(OH)4L4(H2O)2(HCOO)4]·9DMF·12H2O (JLU-MOF50, L = H2MDCPB = 5′-methyl-[1,1′,3′,1′′-terphenyl]-4,4′′-dicarboxylic acid, DMF = N,N-dimethylformamide), with pcu topology was successfully synthesized and structurally characterized. JLU-MOF50 exhibits excellent chemical stability in both acidic and alkaline aqueous solutions. Due to the missing linker sites, high porosity (BET surface area of 1101 m2 g−1), and excellent luminescence property, JLU-MOF50 possesses dual functionalities, which exhibits not only a commendable trapping capacity (92 mg g−1) and an adsorption rate (32.5 mg g−1 min−1), but also high detection sensitivity and selectivity for Cr2O72− in an aqueous phase. It is worth mentioning that the KSV value of JLU-MOF50 towards Cr2O72− can reach up to 4.99 × 104 M−1, which is one of the highest values reported to date for MOF materials. Based on the aforementioned properties, JLU-MOF50 is a good candidate for fast capture and highly luminescence detection of Cr2O72− simultaneously in an aqueous phase.

A Flexible Doubly Interpenetrated Metal–Organic Framework with Breathing Behavior and Tunable Gate Opening Effect by Introducing Co2+ into Zn4O Clusters

A Zn4O clusters based flexible doubly interpenetrated metal-organic framework [(Zn4O)2(DCPB)6DMF]·2DMF·8H2O (JLU-Liu33, H2DCPB = 1,3-di(4-carboxyphenyl)benzene, DMF = N,N-dimethylformamide) with pcu topology has been solvothermally synthesized. Because of its flexible structure, JLU-Liu33 exhibits a breathing behavior upon N2 and CO2 adsorption at low temperature, and C2H6 and C3H8 adsorption at 273 and 298 K. Furthermore, by adopting the direct synthesis method, two isomorphic compounds-JLU-Liu33L and JLU-Liu33H-have been obtained by partial substituting Zn with different amounts of Co into the JLU-Liu33 framework. The gas adsorption study of Co-doped materials reveals that the gate opening effect of JLU-Liu33 can be modulated by introducing different contents of Co2+ into Zn4O clusters. Meanwhile, with the increasing amount of Co2+, the adsorption amount and isosteric enthalpy values for CO2 have been improved. It is worth mentioning that JLU-Liu33H exhibits commendable selectivity for CO2 over CH4 which may be a good candidate for industrial gas purification and air separation applications.

Lewis basic site (LBS)-functionalized zeolite-like supramolecular assemblies (ZSAs) with high CO2 uptake performance and highly selective CO2/CH4 separation

Herein, three functional isoreticular zeolite-like supramolecular assemblies (ZSAs), [Co4(NH2-ImDC)4(1,2-PDA)4]·8H2O (ZSA-7), [Co4(CH2OH-ImDC)4(1,2-PDA)4]·8H2O (ZSA-8), and [Co4(Pr-ImDC)4(1,2-PDA)4]·9H2O (ZSA-9), NH2-ImDC = 2-amino-4,5-imidazoledicarboxylic acid, CH2OH-ImDC = 2-hydroxymethyl-4,5-imidazoledicarboxylic acid, Pr-ImDC = 2-propyl-4,5-imidazoledicarboxylic acid, 1,2-PDA = 1,2-propanediamine, were hydrothermally synthesized and structurally characterized. All three compounds are isoreticular to ZSA-1, with the modification of different functional groups of –NH2, –CH2OH, and –Pr in imidazole dicarboxylate ligands. ZSA-7 and ZSA-8 display high CO2 adsorption abilities (109.8 and 114.0 cm3 g−1 at 273 K, respectively, under 1 bar) and outstanding natural gas selectivity separation, especially for CO2 over CH4 (39.8 and 35.7 for CO2/CH4 = 0.5/0.5 and 76.0 and 51.6 for CO2/CH4 = 0.05/0.95, respectively, under 1 bar at 298 K). In contrast, ZSA-9 is used for comparison to illustrate the effect of the introduction of Lewis basic sites (LBSs). Thus, all three ZSAs are promising materials for gas adsorption and purification applications.

Core–shell structured hierarchically porous NiO microspheres with enhanced electrocatalytic activity for oxygen evolution reaction

The design and synthesis of efficient catalysts to substitute the currently effective and sturdy electrocatalysts composed of precious metal-based materials (e.g., IrO2 and RuO2) for the oxygen evolution reaction (OER) is still a huge challenge. In this regard, nickel-based OER catalysts with specific properties have drawn widespread attention. Herein, we prepared core–shell structured hierarchically mesoporous NiO microspheres through the thermal decomposition of Ni(OH)2 microspheres, which were synthesized through a one-pot hydrothermal method. The obtained NiO microspheres possess numerous mesopores, a high BET surface area, and 2D nanosheet-like shells, which largely promote mass/charge transportation and reduce ion transport pathways. By increasing the molar ratio of HMTA/Ni2+, the thickness of the outer nanosheet-like shell can be varied in the range of 0–35 nm. In particular, the NiO-300/r = 2 microspheres possess excellent properties for OER (overpotential of 360 mV to reach 10 mV cm−2), compared with previously-reported Ni-based materials. Furthermore, improved activity with an overpotential of 340 mV was reached by introducing Co.