No abstract

The Cover Feature illustrates a glucose fuel cell that generates electricity through an electrochemical reaction with oxygen and glucose, which is an eco‐friendly and abundant energy resource in nature. In this study, we compared and analyzed glucose permeability and resulting electrochemical performance of nonenzymatic glucose fuel cells with various architectures of the anode diffusion layer and flow channel. More information can be found in the Research Article by H. Cha et al.

A nonenzymatic glucose fuel cell directly oxidizes glucose to gluconic acid as a Pt‐based abiotic catalyst in a proton exchange membrane environment and has various advantages (e. g., biocompatibility, chemical stability, high ionic conductivity). We report the permeability of a less hydrophobic diffusion layer for three flow‐field designs (serpentine, interdigitated, and parallel). In all cases, as the channel width of the flow path increases, the power density increases and the Ohmic resistance decreases. The serpentine shape (channel and rib widths: 1.5 and 0.5 mm, respectively) exhibits remarkable maximum power and current densities (cell voltage: 60 mV) of 103.4 μW cm−2 and 1,273 μA cm−2 compared to those of the parallel (46.5 μW cm−2 at 683 μA cm−2) and interdigitated (74.0 μW cm−2 at 878 μA cm−2) shapes, respectively. Furthermore, permeability and performance analyses according to the single‐cell temperature, glucose concentration, and flow rate changes provide various perspectives on glucose fuel cells.

Summary An ultrathin layer composed of carbon nanotubes (CNTs) was deposited on the cathodic catalyst layer to boost performance of polymer electrolyte membrane fuel cell (PEMFC) under low to mid relative humidity (RH) conditions. The CNT‐deposited layer (CDL) was formed without modifying the PEMFC components. To investigate the behavior of water and reactants at the inner interface of the membrane electrode assembly (MEA), we characterized the morphology of the CDL (contact angle, pore size distribution, specific surface area, field emission scanning electron microscopy, and energy dispersive spectroscopy images). The CDL in PEMFCs was used as a contributor to enhance the membrane hydration. Thereby performances have been significantly enhanced. Additionally, the three‐dimensional nanostructure of the CDL expanded the active area by uniform dispersion of the reactants. The polarization curves of the conventional MEA and MEA with CDL were evaluated under diverse RH (100%, 70%, 50%, and 30% RH). In the low to mid RH conditions, the maximum power densities were increased by 29.7% (70% RH), 26.6% (50% RH), and 25.5% (30% RH) compared with the conventional MEA. Especially, the maximum power density of the MEA with CDL (0.547 W/cm2 at 70% RH) was higher than that of the conventional MEA (0.482 W/cm2 at 100% RH). Thus, MEA with CDL demonstrated excellent performance enhancement under low to mid RH conditions.