Polymer electrolyte fuel cell (PEFC) technology is essential for using hydrogen as an energy source while enabling the reduction of CO₂ emissions. This paper reports the development of PEFC materials, including the use of bamboo for the gas diffusion layer (GDL) and surface modification of the electrocatalysts. To use bamboo as a material for the GDL, non-woven fabrics were made from bamboo fibers followed by carbonization. PEFC electrocatalysts, particularly cathode catalysts, were evaluated as a support of the electrocatalysts after chemical modification of the carbonaceous materials with tin oxide. The potential use of carbonaceous materials modified by titanium oxynitride was also investigated as the cathode catalyst. Modifying the surface of the carbonaceous support with organic compounds, such as O-methylation and amidine-group molecules, is also discussed.

Biofuel cells (BFCs) use biological catalysts for power generation and are promising for wearable devices due to their low cost and high power density. Enzyme-based BFCs convert organic fuels into electricity under physiological conditions but have problems such as enzyme instability and low power output. Improving their performance requires increasing the enzyme loading, stabilizing the enzymes, and using nanostructured electrodes to improve electrochemical activity. Porous carbons with controlled pore sizes are ideal for enzyme immobilization, offering large surface areas and improved mass transport. Balancing meso- and macroporous structures for optimal enzyme performance is crucial. MgO-templated carbons (MgOC) have controlled pore sizes and can be produced on a large scale, making them a viable alternative to traditional nanocarbons for BFCs and wearable applications. MgOC-modified electrodes increase enzyme adsorption and stability, improving glucose and lactate BFC performance with promising power densities, including self-powered glucose and lactate sensors. The electrode’s hydrophilicity/hydrophobicity plays a crucial role in improving the delivery of fuels. Problems of durability and cost-effectiveness remain, necessitating interdisciplinary collaboration for further development.

We recently reported the large-scale synthesis of zeolite-templated carbon (ZTC) using biomass resources (ACS Sustainable Chem. Eng. 10 (2022) 10827–10838, Carbon Trends 9 (2022) 100228). In the synthesis, undried NaY zeolite was mixed with a biomass resource such as sugar or starch as a carbon source. The mixture was subjected to chemical vapor deposition using propylene as an additional carbon source, followed by heat treatment for graphitization and zeolite removal with hydrofluoric acid. The resulting ZTCs exhibited high structural regularity and large specific surface areas of 3750–3820 m² g⁻¹. This simple method eliminated the use of organic solvents and minimized the amount of the carbon sources. In this study, we analyzed these ZTCs using temperature-programmed desorption (TPD) to quantitatively and qualitatively characterize oxygen-containing functional groups and evaluated additional structural features. Finally, the electric double-layer capacitor performances of these ZTCs were evaluated using an organic electrolyte, 1 M Et₄NBF₄/propylene carbonate. The TPD analysis revealed that the sucrose- and xylose-derived ZTCs contained more phenol groups than the glucose- and starch-derived ZTCs. Due to the initial deprotonation of the phenol groups and the reversible redox reaction of the resulting redox-active quinone groups, the sucrose- and xylose-derived ZTCs exhibited higher capacitance than the other ZTCs through significant pseudocapacitance while maintaining high capacitance retention of 89–92% at 2 A g⁻¹ by comparing the capacitance at 0.05 A g⁻¹. Although the area-normalized capacitances of these ZTCs (0.036–0.039 F m⁻²) are lower than that of activated carbon because of their low electrical conductivity, their capacitance can be further enhanced by electrochemical oxidation.

Carbon alloy (CA) catalysts have emerged as a promising class of nonplatinum electrocatalysts for polymer electrolyte fuel cells. A comprehensive understanding of their catalytic degradation mechanisms is crucial for improving the performance of these cells. This study uses a novel film-based CA model catalyst that facilitates in situ observations in acidic solutions using atomic force microscopy (AFM) to elucidate these degradation mechanisms. The findings reveal significant structural alterations in the nanoshell structure from a closed shell to the floppy configuration of CA catalysts under aqueous conditions (water and H₂SO₄ solution). These changes are undetectable by scanning electron microscopy. AFM analysis confirmed that oxidation-induced degradation leads to structural alterations and the subsequent loss of the structure of the carbon, which may be an important finding for improving the stability and performance of CA catalysts.