In†Situ Generation of Electrolyte inside Pyridine-Based Covalent Triazine Frameworks for Direct Supercapacitor Integration.

The synthesis of porous electrode materials is often linked with the generation of waste that results from extensive purification steps and low mass yield. In contrast to porous carbons, covalent triazine frameworks (CTFs) display modular properties on a molecular basis through appropriate choice of the monomer. Herein, the synthesis of a new pyridine-based CTF material is showcased. The porosity and nitrogen-doping are tuned by a careful choice of the reaction temperature. An in-depth structural characterization by using Ar physisorption, X-ray photoelectron spectroscopy, and Raman spectroscopy was conducted to give a rational explanation of the material properties. Without any purification, the samples were applied as symmetrical supercapacitors and showed a specific capacitance of 141 F g-1 . Residual ZnCl2 , which acted formerly as the porogen, was used directly as the electrolyte salt. Upon the addition of water, ZnCl2 was dissolved to form the aqueous electrolyte in situ. Thereby, extensive and time-consuming washing steps could be circumvented.

General Colloidal Synthesis of Transition-Metal Disulfide Nanomaterials as Electrocatalysts for Hydrogen Evolution Reaction.

The material-efficient monolayers of transition-metal dichalcogenides (TMDs) are a promising class of ultrathin nanomaterials with properties ranging from insulating through semiconducting to metallic, opening a wide variety of their potential applications from catalysis and energy storage to optoelectronics, spintronics, and valleytronics. In particular, TMDs have a great potential as emerging inexpensive alternatives to noble metal-based catalysts in electrochemical hydrogen evolution. Herein, we report a straightforward, low-cost, and general colloidal synthesis of various 2D transition-metal disulfide nanomaterials, such as MoS2, WS2, NiSx, FeSx, and VS2, in the absence of organic ligands. This new preparation route provides many benefits including relatively mild reaction conditions, high reproducibility, high yields, easy upscaling, no post-thermal annealing/treatment steps to enhance the catalytic activity, and, finally, especially for molybdenum disulfide nanosheets, high activity in the hydrogen evolution reaction. To underline the universal application of the synthesis, we prepared mixed CoxMo1-xS2 nanosheets in one step to optimize the catalytic activity of pure undoped MoS2, which resulted in an enhanced hydrogen evolution reaction performance characterized by onset potentials as low as 134 mV and small Tafel slopes of 55 mV/dec.

Continuous droplet reactor for the production of millimeter sized spherical aerogels.

In order to enable future use of aerogels in heterogeneous solid or fluidized bed catalysis a method of production of millimeter sized monolithic Au/Al2O3 aerogel spheres by a continuous flow reactor is developed. Flow velocities and synthesis parameters are optimized to produce aerogel spheres in three different sizes. The resulting aerogel spheres exhibit a porous aluminium oxide aerogel matrix with a large specific surface area of 400 m2 g-1 on which gold nanoparticles are evenly distributed. The aerogel spheres are compared to xerogels of the same material in contrast to their surface area, pore size distribution, morphology, crystal structure and thermal properties. The presented method allows a broad access to various mixed aerogel systems of oxidic carrier material and noble metal nanoparticles and is therefore relevant for the shaping of different aerogel catalyst systems.

Hybrid Plasmonic-Aerogel Materials as Optical Superheaters with Engineered Resonances.

Solar radiation is a versatile source of energy, convertible to different forms of power. A direct path to exploit it is the generation of heat, for applications including passive building heating, but it can also drive secondary energy-conversion steps. We present a novel concept for a hybrid material which is both strongly photo-absorbing and with superior characteristics for the insulation of heat. The combination of that two properties is rather unique, and make this material an optical superheater. To realize such a material, we are combining plasmonic nanoheaters with alumina aerogel. The aerogel has the double function of providing structural support for plasmonic nanocrystals, which serve as nanoheaters, and reducing the diffusion rate of the heat generated by them, resulting in large local temperature increases under a relatively low radiation intensity. This work includes theoretical discussion on the physical mechanisms impacting the system's balanced thermal equilibrium.