Suppression of Methanol and Formate Crossover through Sulfanilic-Functionalized Holey Graphene as Proton Exchange Membranes

Proton exchange membranes with high proton conductivity and low crossover of fuel molecules are required to realize advanced fuel-cell technology. The selective transportation of protons, which occurs by blocking the transportation of fuel molecules across a proton exchange membrane, is crucial to suppress crossover while maintaining a high proton conductivity. In this study, a simple yet powerful method is proposed for optimizing the crossover-conductivity relationship by pasting sulfanilic-functionalized holey graphenes onto a Nafion membrane. The results show that the sulfanilic-functionalized holey graphenes supported by the membrane suppresses the crossover by 89% in methanol and 80% in formate compared with that in the self-assembled Nafion membrane; an ≈60% reduction is observed in the proton conductivity. This method exhibits the potential for application in advanced fuel cells that use methanol and formic acid as chemical fuels to achieve high energy efficiency.

A State-of-Art on the Development of Nafion-Based Membrane for Performance Improvement in Direct Methanol Fuel Cells

Nafion, a perfluorosulfonic acid proton exchange membrane (PEM), has been widely used in direct methanol fuel cells (DMFCs) to serve as a proton carrier, methanol barrier, and separator for the anode and cathode. A significant drawback of Nafion in DMFC applications is the high anode-to-cathode methanol fuel permeability that results in over 40% fuel waste. Therefore, the development of a new membrane with lower permeability while retaining the high proton conductivity and other inherent properties of Nafion is greatly desired. In light of these considerations, this paper discusses the research findings on developing Nafion-based membranes for DMFC. Several aspects of the DMFC membrane are also presented, including functional requirements, transport mechanisms, and preparation strategies. More importantly, the effect of the various modification approaches on the performance of the Nafion membrane is highlighted. These include the incorporation of inorganic fillers, carbon nanomaterials, ionic liquids, polymers, or other techniques. The feasibility of these membranes for DMFC applications is discussed critically in terms of transport phenomena-related characteristics such as proton conductivity and methanol permeability. Moreover, the current challenges and future prospects of Nafion-based membranes for DMFC are presented. This paper will serve as a resource for the DMFC research community, with the goal of improving the cost-effectiveness and performance of DMFC membranes.

Towards Integration of Two-Dimensional Hexagonal Boron Nitride (2D h-BN) in Energy Conversion and Storage Devices

The prominence of two-dimensional hexagonal boron nitride (2D h-BN) nanomaterials in the energy industry has recently grown rapidly due to their broad applications in newly developed energy systems. This was necessitated as a response to the demand for mechanically and chemically stable platforms with superior thermal conductivity for incorporation in next-generation energy devices. Conventionally, the electrical insulation and surface inertness of 2D h-BN limited their large integration in the energy industry. However, progress on surface modification, doping, tailoring the edge chemistry, and hybridization with other nanomaterials paved the way to go beyond those conventional characteristics. The current application range, from various energy conversion methods (e.g., thermoelectrics) to energy storage (e.g., batteries), demonstrates the versatility of 2D h-BN nanomaterials for the future energy industry. In this review, the most recent research breakthroughs on 2D h-BN nanomaterials used in energy-based applications are discussed, and future opportunities and challenges are assessed.

A three-dimensional flower-like Mn–Ni–Co–O microstructure as a high-performance electrocatalyst for the methanol oxidation reaction

A Mn–Ni–Co–O ternary metal oxide with a unique 3D microstructure shows high electrocatalytic activity and stability towards methanol electrooxidation.

Modification of Carbon Black with Hydrogen Peroxide for High Performance Anode Catalyst of Direct Methanol Fuel Cells

In this study, high-surface-area carbon black is used to support PtRu. In order to increase the functional groups on the surface of carbon black and to have a more homogenous dispersed PtRu metal, the surface of carbon black is functionalized by H₂O₂. PtRu/carbon black is synthesized by the deposition–precipitation method. NaH₂PO₂ is used as the reducing agent in preparation. These catalysts are characterized by N₂ sorption, temperature-programmed desorption, X-ray diffraction, transmission electron microscope, and X-ray photoelectron spectroscopy. The methanol oxidation ability of the catalyst is tested by cyclic voltammetry measurement. Using H₂O₂ to modify carbon black can increase the amount of functional groups on the surface, thereby increasing the metal dispersion and decreasing metal particle size. NaH₂PO₂ as a reducing agent can suppress the growth of metal particles. The best modified carbon black catalyst is the one modified with 30% H₂O₂. The methanol oxidation activity of the catalyst is mainly related to the particle size of PtRu metal, instead of the surface area and conductivity of carbon black. The PtRu catalyst supported by this modified carbon black has very high activity, with an activity reaching 309.5 A/g.

Potential carbon nanomaterials as additives for state-of-the-art Nafion electrolyte in proton-exchange membrane fuel cells: a concise review

Proton-exchange membrane fuel cells (PEMFCs) have received great attention as a potential alternative energy device for internal combustion engines due to their high conversion efficiency compared to other fuel cells. The main hindrance for the wide commercial adoption of PEMFCs is the high cost, low proton conductivity, and high fuel permeability of the state-of-the-art Nafion membrane. Typically, to improve the Nafion membrane, a wide range of strategies have been developed, in which efforts on the incorporation of carbon nanomaterial (CN)-based fillers are highly imperative. Even though many research endeavors have been achieved in relation to CN-based fillers applicable for Nafion, still their collective summary has rarely been reported. This review aims to outline the mechanisms involved in proton conduction in proton-exchange membranes (PEMs) and the significant requirements of PEMs for PEMFCs. This review also emphasizes the improvements achieved in the proton conductivity, fuel barrier properties, and PEMFC performance of Nafion membranes by incorporating carbon nanotubes, graphene oxide, and fullerene as additives.