Electrically Conductive, Monolithic Metal-Organic Framework-Graphene (MOF@G) Composite Coatings.

We present a novel approach to produce a composite of the HKUST-1 metal-organic framework (MOF) and graphene, which is suited for the fabrication of monolithic coatings of solid substrates. In order to avoid the degradation of graphene electrical properties resulting from chemical functionalization (e.g., oxidation yielding graphene oxide, GO), commercial, nonmodified graphene was utilized. The one-pot synthesis of the moldable composite material allows for a controllable loading of graphene and the tuning of porosity. Potentially, this facile synthesis can be transferred to other MOF systems. The monolithic coatings reported here exhibit high surface areas (1156-1078 m2/g). The electrical conductivity was high (a range of 7.6 × 10-6 S m-1to 6.4 × 10-1 S m-1) and was found to be proportional to the graphene content. The ability to readily attain different forms and shapes of the conductive, microporous composites indicates that the MOF@G system can provide a compelling approach to access various applications of MOFs, specifically in electrochemical catalysis, supercapacitors, and sensors.

Microscopic structure and properties of discrete water layer in Na-exchanged montmorillonite.

In this work, we focus on the atomic structure of the water interlayer of Na-exchanged montmorillonite. For two different surface charge densities, namely -0.086 and -0.172 C/m(2), the adsorption process in the presence of water is described by first principles calculations. We describe the interactions and forces for every water molecule entering the interlayer during the swelling process. In particular, the dielectric permittivity of the water interlayer is calculated. Finally, we confirm our results performing ab initio thermodynamics calculations leading to a wide range of realistic experimental scenarios.

New dielectric sensors and sensing techniques for soil and snow moisture measurements.

Measurements of material moisture are essential in fields such as agriculture or civil engineering. Electromagnetic techniques, more precisely dielectric methods, have gained wide acceptance in the last decades. Frequency or Time Domain methods take advantage of the high dielectric permittivity of water compared to dry materials. This paper presents four new dielectric sensors for the determination of soil or snow water content. After a short introduction into the principles, both the hardware and operating mode of each sensor are described. Field test results show the advantages and potentials such as automatic measurement and profiling, state-of-ground detection or large-scale determination. From the results it follows that the presented sensors offer promising new tools for modern environmental research.