Challenges and rewards of the electrosynthesis of macroscopic aligned carbon nanotube array/conducting polymer hybrid assemblies

One-step electrodeposition of binder-containing Cu nanocube catalyst layers for carbon dioxide reduction

To reach industrially relevant current densities in the electrochemical reduction of carbon dioxide, this process must be performed in continuous-flow electrolyzer cells, applying gas diffusion electrodes. Beyond the chemical composition of the catalyst, both its morphology and the overall structure of the catalyst layer are decisive in terms of reaction rate and product selectivity. We present an electrodeposition method for preparing coherent copper nanocube catalyst layers on hydrophobic carbon paper, hence forming gas diffusion electrodes with high coverage in a single step. This was enabled by the appropriate wetting of the carbon paper (controlled by the composition of the electrodeposition solution) and the use of a custom-designed 3D-printed electrolyzer cell, which allowed the deposition of copper nanocubes selectively on the microporous side of the carbon paper substrate. Furthermore, a polymeric binder (Capstone ST-110) was successfully incorporated into the catalyst layer during electrodeposition. The high electrode coverage and the binder content together result in an increased ethylene production rate during CO2 reduction, compared to catalyst layers prepared from simple aqueous solutions.

Gas sensing materials roadmap

Gas sensor technology is widely utilized in various areas ranging from home security, environment and air pollution, to industrial production. It also hold great promise in non-invasive exhaled breath detection and an essential device in future internet of things. The past decade has witnessed giant advance in both fundamental research and industrial development of gas sensors, yet current efforts are being explored to achieve better selectivity, higher sensitivity and lower power consumption. The sensing layer in gas sensors have attracted dominant attention in the past research. In addition to the conventional metal oxide semiconductors, emerging nanocomposites and graphene-like two-dimensional materials also have drawn considerable research interest. This inspires us to organize this comprehensive 2020 gas sensing materials roadmap to discuss the current status, state-of-the-art progress, and present and future challenges in various materials that is potentially useful for gas sensors.

A novel electrochemical sensor based on carbon nanotubes array for selective detection of dopamine or uric acid

A novel single-walled carbon nanotubes array-modified glassy carbon electrode (SWCNTs array-GCE) has been fabricated through a simple electrochemical technique. Benefitting from their vertically aligned configuration on the electrode surface, the modified single-walled carbon nanotubes can be used more efficiently in comparison with other modified method. The as-fabricated SWCNTs array-GCE can separate the anodic oxidation potential of dopamine (DA), uric acid (UA) and ascorbic acid (AA) with well-defined peak separation in the presence of each other, and thus employs as a new electrochemical sensor for selective determination of DA and UA. It can make a further improvement of the electrocatalytic ability of the electrode to perform an acetone pretreatment to SWCNTs array-GCE before electrochemical detection, which has been confirmed by atomic force microscope and electrochemical impedance spectroscopic measurements. Especially, unlike other carbon nanotubes-based electrode at which only two redox pairs are observed for dopamine oxidations, a third two-electron oxidation of 5,6-dihydroxyindole to indole-5,6-quinone can be clearly observed at acetone-pretreated SWCNTs array-GCE, showing the excellent electrocatalytic performance of as-fabricated electrode toward dopamine. The practicability of SWCNTs array-GCE was evaluated for the selective detection of DA and UA in real sample solutions of human serum and urine. It revealed acceptable recovery results in the range of 94-104%, indicating that it might be a promising platform for further biosensor development.

Electrical anisotropy and multidimensional pressure sensor of aligned Fe3O4@silver nanowire/polyaniline composite films under an extremely low magnetic field

The PDMS sealed aligned Ag nanowire/PANI composite film as a multi-dimensional pressure sensor.

Decreasing the Effective Thermal Conductivity in Glass Supported Thermoelectric Layers

As thermoelectric devices begin to make their way into commercial applications, the emphasis is put on decreasing the thermal conductivity. In this purely theoretical study, finite element analysis is used to determine the effect of a supporting material on the thermal conductivity of a thermoelectric module. The simulations illustrate the heat transfer along a sample, consisting from Cu, Cu₂O and PbTe thermoelectric layers on a 1 mm thick Pyrex glass substrate. The influence of two different types of heating, at a constant temperature and at a constant heat flux, is also investigated. It is revealed that the presence of a supporting material plays an important role on lowering the effective thermal conductivity of the layer-substrate ensemble. By using thinner thermoelectric layers the effective thermal conductivity is further reduced, almost down to the value of the glass substrate. As a result, the temperature gradient becomes steeper for a fixed heating temperature, which allows the production of devices with improved performance under certain conditions. Based on the simulation results, we also propose a model for a robust thin film thermoelectric device. With this suggestion, we invite the thermoelectric community to prove the applicability of the presented concept for practical purposes.