Abstract

Platinum and platinum-based catalysts are some of the most effective catalysts used in fuel cells. However, electrocatalysts used for direct liquid fuel cells (DLFCs) and electrolyzers are high cost and suffer from several other problems, thus hindering their commercialization as power sources to produce clean energy. Common issues in electrocatalysts are low stability and durability, slow kinetics, catalyst poisoning, high catalyst loading, high cost of the catalytic materials, poisoning of the electrocatalysts, and formation of intermediate products during electrochemical reactions. The use of catalyst supports can enhance the catalytic activity and stability of the power sources. Thus, nickel foam and graphene foam with 3D structures have advantages over other catalyst supports. This paper presents the application of nickel foam and graphene foam as catalyst supports that enhance the activities, selectivity, efficiency, specific surface area, and exposure of the active sites of DLFCs. Selected recent studies on the use of foam in electrolyzers are also presented.

Highlights

  • Among the most commonly used catalyst supports are carbon black, carbon aerogels, carbon nanotubes, mesoporous carbon, graphene oxide, and graphene nanosheets [6,23,24], but these materials face problems, namely, their corrosion resistance [25,26] leads to particle detachment, Ostwald ripening, and agglomeration [27,28]

  • The use of nickel foam (NF) and graphene foam (GF) as catalyst supports for electro-oxidation in direct glycerol fuel cell (DGFC), direct ethylene glycol fuel cell (DEGFC), direct hydrazine fuel cell (DHFC), and direct ammonia fuel cell (DAFC) is still limited

  • A more consistent, active, and productive study of the high activity of the electro-oxidation reaction in Direct liquid fuel cells (DLFCs) is essential to address the issues that have been mentioned in this paper

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Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Efficient and clean alternative energy is needed to replace the increasingly used fossil fuel due to increasing energy demands, which has caused the reservoir of fossil fuels to be depleted and high CO2 emissions [1,2,3] These problems have led to the use of fuel cells, an alternative which can generate electricity from chemical energy without combustion [4]. The technical challenges in DLFCs are liquid fuel crossover, poor mass transport, sluggish reaction rates, cathode flooding, chemical safety, species and thermal management, the production of side products, and the high-cost of catalysts [8,10,16,17]. The sluggish reaction rate and other problems related to the electrochemical reactions in DLFCs are the main challenges to overcome so that the commercialization of fuel cells can be sped up, especially to produce the catalysts for large-scale applications [18,19]

Challenges in Conventional Catalyst Support and Future Perspective Using 3D
Methanol Electro-Oxidation Reaction
Oalmost
FESEM images
Ethanol Electro-Xxidation Reaction
Borohydride Electro-Oxidation Reaction
Urea Electro-Oxidation Reaction
Glucose Electro-Oxidation Reaction
Hydrogen Peroxide Electro-Oxidation and Electro-Reduction Reaction
Other Electro-Oxidation Reaction in DLFC
M Methanol
M Ethanol
M H2 O2
Selected Application of Foam in the Electrolyzers
Findings
Conclusions
Full Text
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