Zatil Amali Che Ramli

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.

In a combination of generation and storage of hydrogen gas, both formic acid (FA) and acetic acid (AA) have been notified as efficient hydrogen carriers. This study was conducted to synthesize the monometallic catalysts namely palladium (Pd), copper (Cu), and zinc (Zn) on graphitic-carbon nitride (g-C₃N₄) and to study the potential of these catalysts in FA and mixed formic acid (FA)-acetic acid (AA) decomposition reaction. Several parameters have been studied in this work such as the type of active metals, temperature, and metal loadings. The mass percentage of Pd, Cu, and Zn metal used in this experiment are 1, 3, and 5 wt%, respectively. At low temperature of 30 °C, 5 wt% Pd/g-C₃N₄ catalyst yielded higher volume of gas with 3.3 mL, instead of other Pd percentage loadings. However, at higher temperature of 70 °C and 98% FA concentration, Pd with 1 wt%, 3 wt%, and 5 wt% of loading over g-C₃N₄ has successfully produced optimum gas (H₂ and CO₂) of 4.3 mL, 7.4 mL, and 4.5 mL in each reaction, respectively. At higher temperature, Pd metal showed high catalytic performance and the most active element of monometallic system in ambient condition. Meanwhile, at higher percentage of Pd metal, the catalytic decomposition reaction also increased thus producing more gas. However, it can be seen the agglomeration of the particles formed at higher loadings of Pd (5 wt%), and remarkably lowering the catalytic activity at higher temperature, while higher activity at low temperature of 30 °C. The result also showed low catalytic decomposition reaction for Cu and Zn catalyst, due to the small formation of Cu and Zn metal, but presence of high metal oxide (CuO) and (ZnO) promotes the passive layer formation on the catalyst surface.

Summary: Fuel cells are the most promising alternative green and clean energy source in the future because of their low carbon emissions. Fuel cells have been employed in various applications, including large‐scale stationary power generation, distributed combination heat and power, transport, and mobile and stationary applications. Generally, a fuel cell system consists of a proton exchange membrane or polymer electrolyte membrane (PEM), a catalyst layer, a microporous layer, a gas diffusion layer, and a bipolar plate at the anode and cathode. PEMs are an important component in fuel cell applications that act as proton carriers and separators for the anode and cathode, while catalyst support materials are a major component of proton exchange membrane fuel cell. The membrane and catalyst affect the cost, durability, and electrochemical activity of fuel cells. Researchers have made serious attempts to develop materials that can reduce the cost of membrane and catalyst manufacturing, lowering the overall cost of fuel cells. Because of its unique features like 2D structure, ease of fabrication, and low production cost, graphitic carbon nitride (g‐CN or g‐C₃N₄) is now frequently mentioned. Due to their exceptional qualities, carbon‐based materials are also commonly used in a variety of applications, including fuel cells. The effectiveness of experiments using g‐C₃N₄, carbon nanotube (CNT), and graphene as essential materials in enhancing fuel cell performance is discussed in this study. This review, primarily for fuel cell applications, discusses ways of adjusting the structure in terms of porosity, dimension tailoring, and atomic and edge functionalization. The study also involved the properties of composite materials as well as their respective applications on membranes as well as fuel cell catalysts. This review is useful for investigations into g‐C₃N₄, CNT, and graphene because it offers ideas and direction for improving the potential of associated systems, including fuel cells, hydrogen production, solar cells, batteries, and supercapacitors.Highlights: The materials that can reduce the cost of membrane and catalysts manufacture, lowering the overall cost of fuel cells are discussed. The effectiveness of using g‐C₃N₄, carbon nanotube, and graphene as essential materials in enhancing fuel cell performance is presented. The properties of composite materials and their functioning in membranes and catalysts application are described thoroughly.

Platinum (Pt)-based nanoparticle metals have received a substantial amount of attention and are the most popular catalysts for direct methanol fuel cell (DMFC). However, the high cost of Pt catalysts, slow kinetic oxidation, and the formation of CO intermediate molecules during the methanol oxidation reaction (MOR) are major challenges associate with single-metal Pt catalysts. Recent studies are focusing on using either Pt alloys, such as Fe, Ni, Co, Rh, Ru, Co, and Sn metals, or carbon support materials to enhance the catalytic performance of Pt. In recent years, Pt and Pt alloy catalysts supported on great potential of carbon materials such as MWCNT, CNF, CNT, CNC, CMS, CNT, CB, and graphene have received remarkable interests due to their significant properties that can contribute to the excellent MOR and DMFC performance. This review paper summaries the development of the above alloys and support materials related to reduce the usage of Pt, improve stability, and better electrocatalytic performance of Pt in DMFC. Finally, discussion of each catalyst and support in terms of morphology, electrocatalytic activity, structural characteristics, and its fuel cell performance are presented.

At room temperature, dehydrating agent, concentrated sulfuric acid (H₂SO₄) was used to form porous carbon (BAC) from bamboo waste shows good properties as CO₂ adsorbent. Selection of nano-CuO supported BAC produce composite materials with high total surface area and smaller pores size composite of 660.8 cm²/g and 2.7 nm. XRD data showed the support data to confirm the hydroxide phase formation as intermediate for carbonate and accelerate the CO₂ chemisorption reaction. Besides, the presence of BAC together with metal oxide can improve the CO₂ interaction physically on the surface and pores resulting the higher adsorption capability of 32.2 cm³ of CO₂ per gram adsorbent. The combination of nano-CuO on BAC become a good adsorbent which can stimulate the CO₂ reduction programme as well as reduce the CO₂ emissions during BAC production.