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Direct Methanol Fuel Cell (DMFC) is a powerful system for generating electrical energy for various applications. However, there are several limitations that hinder the commercialization of DMFCs, such as the expense of platinum (Pt) at market price, sluggish methanol oxidation reaction (MOR) due to carbon monoxide (CO) formation, and slow electrooxidation kinetics. This work introduces carbon nanocages (CNCs) that were obtained through the pyrolysis of polypyrrole (Ppy) as the carbon source. The CNCs were characterized using BET, XRD, HRTEM, TEM, SEM, and FTIR techniques. The CNCs derived from the Ppy source, pyrolyzed at 750 °C, exhibited the best morphologies with a high specific surface area of 416 m2g−1, allowing for good metal dispersion. Subsequently, PtRu catalyst was doped onto the CNC-Ppy750 support using chemical reduction and microwave-assisted methods. In electrochemical tests, the PtRu/CNC-Ppy750 electrocatalyst demonstrated improved CO tolerance and higher performance in MOR compared to PtRu-supported commercial carbon black (CB), with values of 427 mA mg−1 and 248 mA mg−1, respectively. The superior MOR performance of PtRu/CNC-Ppy750 was attributed to its high surface area of CNC support, uniform dispersion of PtRu catalyst, and small PtRu nanoparticles on the CNC. In DMFC single-cell tests, the PtRu/CNC-Ppy750 exhibited higher performance, approximately 1.7 times higher than PtRu/CB. In conclusion, the PtRu/CNC-PPy750 represents a promising electrocatalyst candidate for MOR and anodic DMFC applications. [ABSTRACT FROM AUTHOR]

The enhancement of carbon-supported components is a crucial factor in augmenting the interplay between carbon-supported and metal-active components in the utilization of catalysts for direct ethanol fuel cells (DEFCs). Here, we propose a strategy for designing a catalyst by modifying candle soot (CS) and loading nickel onto ordered carbon soot. The present study aimed to investigate the effect of the Ni nanoparticles content on the electrocatalytic performance of Ni–CS, ultimately leading to the identification of a maximum composition. The presence of an excessive quantity of nickel particles leads to a decrease in the number of active sites within the material, resulting in sluggishness of the electron transfer pathway. The electrocatalyst composed of nickel and carbon support, with a nickel content of 20 wt%, has demonstrated a noteworthy current activity of 18.43 mA/cm2, which is three times that of the electrocatalyst with a higher nickel content of 25 wt%. For example, the 20 wt% Ni–CS electrocatalytic activity was found to be good, and it was approximately four times higher than that of 20 wt% Ni–CB (nickel–carbon black). Moreover, the chronoamperometry (CA) test demonstrated a reduction in current activity of merely 65.80% for a 20 wt% Ni–CS electrocatalyst, indicating electrochemical stability. In addition, this demonstrates the great potential of candle soot with Ni nanoparticles to be used as a catalyst in practical applications. [ABSTRACT FROM AUTHOR]

Carbon nanoparticles (CNPs) have been identified as critical components in a variety of applications such as sensors, quantum dots, electrocatalysts, energy storage, and functional coatings. Candle soot can be used to produce uniform and efficient CNP materials. However, the known shortcomings, such as surface functionality and chemical stability have hindered the candle soot from being using as electrocatalysts. In this work, the synthesized of nitric acid functionalized candle soot (f-CS) will be compared with bare candle soot (CS) and wash candle soot (w-CS) in terms of physicochemical properties which to be used in electrochemical reaction. The nitric acid treatment was introduced into the candle soot surface to introduced oxygenated functionalities group and impeding the agglomeration and/or loss of active surface. The samples were evaluated using X-ray diffraction (XRD), Brunauer--Emmet--Teller (BET), field emission scanning electron microscopy (FESEM), and Raman analysis. After nitric acid treatment, the BET surface area has slightly reduced from 111.01 m²/g to 95.66 m²/g. These results demonstrated that oxygenated groups are incorporated into the carbon pore structure, blocking up the carbon pores. Experiments utilizing Raman demonstrated that functionalized candle soot has higher ID/IG ratio with value of 0.90 than bare soot with value of 0.82. Increased surface defects will give additional sites to anchor of metal particles, thereby increasing the number of metal-active sites. This f-CS will serve as a feasible basis material for an electrocatalysts, anode materials for energy storage, etc. [ABSTRACT FROM AUTHOR]

Membrane-less fuel cells are a promising power source for portable applications that enable the solving of membrane-related issues, such as water management and high cost, in conventional fuel cells. Apparently, research on this system uses a single electrolyte. This study focused on enhancing the performance of membrane-less fuel cells by introducing multiple reactants that are dual electrolytes with hydrogen peroxide (H2O2) and oxygen as oxidants in membrane-less direct methanol fuel cells (DMFC). The conditions tested for the system are (a) acidic, (b) alkaline, (c) dual medium with oxygen as an oxidant, and (d) dual medium and dual oxygen and hydrogen peroxide as an oxidant. Additionally, the effect of fuel utilization on different electrolyte and fuel concentrations was also studied. It was found that the fuel utilization decreases dramatically with the increasing of the fuel concentration, but it improved with the increasing of the electrolyte concentration until 2M. The performance of the dual oxidants in dual-electrolyte membrane-less DMFCs was 15.5 mW cm−2 of the power density achieved before optimization. Later, the system was optimized, and the power density increased to 30 mW cm−2. Finally, this work presented the stability of the cell using the suggested parameters from the optimization process. This study indicated that the performance of the membrane-less DMFC increased for dual electrolytes with mixed oxygen and hydrogen peroxide as oxidants compared to a single electrolyte. [ABSTRACT FROM AUTHOR]

A passive, air-breathing, 6-cell direct methanol fuel cell (DMFC) stack is designed, fabricated and tested based on the performance of a passive single-cell DMFC. A large methanol reservoir in a hexagonal shape is considered in designing the stack in order to increase the DMFC operation time without any interruption, i.e., to refill the methanol solution. Hence, the ratio of methanol solution volume in the reservoir for the single cell, i.e., 8 ml, and hexagonal stack, i.e., 240 ml, is 1:30. The power output of 500 mW is achieved at 1.5 V using a 5 M methanol solution at room temperature. With a large volume of methanol, i.e., 240 ml of 5 M methanol in the hexagonal stack, it can be operated continuously at 1.5 V for more than 40 h, whereas for a small volume, i.e., 8 ml in a single cell, the operation can reach only 3 h–4 h with a similar reduction of 25% from the initial power output. Moreover, the DMFC stack is used for long-term operation more than 3000 h, and the morphology of MEA is analyzed. [ABSTRACT FROM AUTHOR]