Huanzhi Zhang

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.

Fabrication and characterization of a novel nanoporous Co–Ni–W–B catalyst for rapid hydrogen generation

A highly active nanoporous Co–Ni–W–B alloy has been prepared using chemical reduction in an ethanol solution and tested as a novel catalyst for hydrolysis of ammonia borane. Compared with the alloy prepared in an aqueous solution, the as-prepared alloy shows a much higher surface area and hydrogen generation rate.

Synthesis of three-dimensional graphene aerogel encapsulated n-octadecane for enhancing phase-change behavior and thermal conductivity

We prepared a series of three-dimensional graphene aerogel (3D-GA) encapsulated n-octadecane (OD) composite phase change materials (PCMs) through both solution and vacuum impregnation to ensure that a homogeneous dispersion of OD in the porous structure of 3D-GA was present. At the same time, we also investigated the micro-structure, thermal storage properties, and thermal conductivity of the composite PCMs. We used scanning electron microscopy and Fourier transform infrared spectroscopy to demonstrate that OD was encapsulated effectively in the porous structure of 3D-GA and that the composite PCMs were prepared successfully. Differential scanning calorimetry (DSC) results confirmed that the composite PCMs possess good phase change behavior, fast thermal-response rates and excellent thermal cycling stability. The melting enthalpy and crystallization enthalpy can reach 195.70 J g−1 and 196.67 J g−1, respectively, and have almost no change for 60 DSC thermal cycles. Temperature–time curves suggested that the composite PCMs have excellent thermal regulation properties, and their temperature can be maintained in the range of 21–27 °C for about 640 s in a heating procedure. Thermal conductivity analysis indicated that the thermal conductivities of the composite PCMs are improved significantly by the highly thermally conductive 3D-GA. All these results demonstrated that the composite PCMs possess good comprehensive properties that can be used widely in energy storage systems.

Microencapsulation of phase change materials with carbon nanotubes reinforced shell for enhancement of thermal conductivity

Novel microencapsulated phase change materials (micro-PCMs) were synthesized via in-situ polymerization with modified carbon nanotubes(CNTs) reinforced melamine-formaldehyde resin as shell material and CNTs reinforced n-octadecane as PCMs core. DSC results confirm that the micro-PCMs possess good phase change behavior and excellent thermal cycling stability. Melting enthalpy of the micro-PCMs can achieve 133.1 J/g and has slight changes after 20 times of thermal cyclings. And the incorporation of CNTs supplies the micro-PCMs with fast thermal response rate which increases the crystallization temperature of the micro-PCMs. Moreover, the thermal conductivity of the micro-PCMs has been significantly enhanced by introducing CNTs into their shell and core materials. And the thermal conductivity of micro-PCMs with 1.67 wt.% CNTs can increase by 25%. These results exhibit that the obtained micro-PCMs have a good prospect in thermal energy storage applications.