Electrically heated microelectrodes have gained much attention in electroanalytical chemistry in recent years. It has been shown that the promotion of mass transport and reaction kinetics at high-temperatures often results in increased current signals. However, there is no study about the heat transfer inner the microelectrodes which is necessary for the design and operation for microsensors. This report introduces a finite element software (COMSOL) to analyze the factors that influence the surface temperature (T_s), which is crucial for the heating ability of micro-disk electrodes with coils. Distances between the electrode surface and the bottom of the heated copper wire also have a good linear relationship with T_s (R² = 1). Considering the cost, 25-mm length of the gold wire is enough to obtain a relatively high T_s. In addition, the highest T_s can be obtained when the electrode material is gold and the diameter of the gold disk is 0.2 mm. The relationship of diameters of heated copper wires with currents to obtain different temperatures has also been studied. It is expectable that the simulation results can be used to significantly help the design and operation of electrically heated microsensors in practical applications.

Hydrophobicity of the cathode catalyst layers (CCLs) crucially determines the performance of proton exchange membrane fuel cells (PEMFCs) by affecting the transports of oxygen and liquid water. In this regard, polytetrafluoroethylene (PTFE) is usually used as a hydrophobic additive to facilitate the oxygen and water transports in CCLs. So far, there remains lacking systematic effort to optimize the addition methods of PTFE in CCLs and the mechanisms behind. In this work, the effects of the approaches for PTFE addition and the distribution of PTFE on the mass transport of oxygen and the proton conduction in CCLs were studied by using a number of electrochemical characterization methods and contact angle tests. It was found that direct adding PTFE molecules is a better way than adding the PTFE-modified carbons to improve the electrochemical properties of CCLs, since the latter causes an increase in the proton transport resistance, whereas the direct molecule addition results in the obviously improved oxygen transport without affecting the proton conduction. In addition, the gradient distribution of PTFE in CCLs, more specifically, adding PTFE near the interface between CCL and gas diffusion layer (GDL), yielded higher catalyst utilization than the homogeneous distribution of PTFE due to the lower oxygen transport resistance.

The structural and operation parameters of the electrolyzer play important roles in the efficiency of alkaline water electrolysis. In this article, a three-dimensional numerical model coupled with the electric field and the Euler-Eulerian k-ε turbulence flow field was first established to simulate accurately the performance of alkaline electrolyzers, based on a compact assembly structure of the industrial alkaline water electrolyzers, especially at current densities higher than 5000 A·m^-2. The simulation results are compared with the experimental data to verify the accuracy of the model. Suitable operating conditions for concentration, flow rate and the optimal design method of the flow channel structure are obtained from the feedback of the electric and flow fields characteristics inside the electrolyzers. Properly increasing the electrolyte concentration and flow rate facilitates the reduction of cell voltage. The optimum concentration and flow rate of potassium hydroxide aqueous solution are evaluated to be 6.0-8.0 mol·L^-1 and 30.0-45.0 mL·min^-1, respectively. With the increase of the gap between electrode and membrane, the ohmic overpotential increases significantly. The triangular arrangement of conductive columns on the bipolar plate and the increase of the channel height are beneficial to improve the distribution uniformity of the fluid, while the channel height and the arrangement of the conductive columns have little effect on the voltage. Appropriately increasing the spacing between the conductive columns facilitates to reduce the voltage. Multiple outlets and inlets structure is conducive to produce a more uniform fluid distribution. The channel height has little effect on the multiple outlets and inlets electrolyzer. The multiple outlets and inlets electrolyzer G-2.5-T-0-5-3 with wide spacing of conductive columns combined with high flow rate not only can reduce the cell voltage, but also enhance the normal flow rate of the electrolyte on the electrode surface, allowing the best performance of the electrolyzer. This work provides useful guidance on the scale-up design and optimization of highly efficient electrolyzer for alkaline water electrolysis.

With a high cell-level specific energy and a low cost, lithium-sulfur (Li-S) battery has been intensively studied as one of the most promising candidates for competing the next-generation energy storage campaign. Currently, the practical use of Li-S battery is hindered by the rapidly declined storage performance during battery operation, as caused by irreversible loss of electroactive sulfide species at the cathode, dendrite formation at the anode and parasitic reactions at the electrode-electrolyte interface due to unfavorable cathode-anode crosstalk. In this perspective, we propose to stabilize the Li-S electrochemistry, and improve the storage performance of battery by designing asymmetric electrode-electrolyte interfaces that helps to simultaneously address the differentiated issues at both electrodes and facilitate charge transfer in the electrode/electrolyte and across the interfaces. The strategies discussed would shed lights on reasonable design of battery interfaces towards realization of high-performance Li-S batteries.