3D printing of functional metal and dielectric composite meta‐atoms

In this report, a novel fabrication method, based on casting Field's metal inside dielectric molds made via fused deposition modeling, is presented. Fused deposition modeling (FDM) has become one of the most common rapid prototyping methods. Whilst it generally produces good quality mechanical structures in thermoplastics, few reliable methods have been demonstrated that produce good quality 3D electrically conductive structures. By using Field's metal to transform dielectric molds into conductive structures, nearly any continuous metal geometry buried within the polymer can be created, allowing for the realization of complex 3D architectures. A wide range of thermoplastic materials used in fused deposition modeling have been investigated, to identify the best candidates in terms of processing temperature, relative permittivity, and loss tangent. Experimental measurements and X-ray computer tomography scans are used to determine the quality of structures fabricated using this method. Based on these findings, functional metamaterials devices operating at 600–700 MHz with high Q-factors have been produced. This method shows potential to be incorporated into standard FDM setups and could be utilized for the fabrication of curved and 3D geometries

Highly Selective Electro-Oxidation of Glycerol to Dihydroxyacetone on Platinum in the Presence of Bismuth

A carbon supported platinum electrode in a bismuth saturated solution at a carefully chosen potential is capable of oxidizing glycerol to dihydroxyacetone with 100% selectivity. In the absence of bismuth, the primary alcohol oxidation is dominant. Using a combination of online HPLC and in situ FTIR, it is shown that Bi blocks the pathway for primary oxidation but also provides a specific Pt–Bi surface site poised for secondary alcohol oxidation

Standardized Benchmarking of Water Splitting Catalysts in a Combined Electrochemical Flow Cell/Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES) Setup

The oxygen evolution reaction (OER) is the limiting step in splitting water into its constituents, hydrogen and oxygen. Hence, research on potential OER catalysts has become the focus of many studies. In this work, we investigate capable OER catalysts but focus on catalyst stability, which is, especially in this case, at least equally as important as catalyst activity. We propose a specialized setup for monitoring the corrosion profiles of metal oxide catalysts during a stability testing protocol, which is specifically designed to standardize the investigation of OER catalysts by means of differentiating between catalyst corrosion and deactivation, oxygen evolution efficiency, and catalyst activity. For this purpose, we combined an electrochemical flow cell (EFC) with an oxygen sensor and an inductively coupled plasma–optical emission spectrometry (ICP-OES) system for the simultaneous investigation of catalyst deactivation, activity, and faradaic efficiency of catalysts. We tested various catalysts, with IrO₂ and NiCoO₂ used as benchmark materials in acidic and alkaline environment, respectively. The scalability of our setup will allow the user to investigate catalytic materials with supports of higher surface area than those which are typical for microelectrochemical flow cells (thus, under conditions more similar to those of commercial electrolyzers)