Graphene-Based Electrocatalytic Materials for Fuel Cells

Electrochemical energy systems known as fuel cells (FCs) cleanly and efficiently convert the chemical energy of fuels into electricity. Such a green technology is essential to address the future global energy demand owing to the depletion of fossil fuels and to reduce carbon emissions. Fuel cells require effective electrocatalysts to enable and accelerate electrochemical reactions, such as cathodic oxygen reduction reactions (ORR) and anodic oxidation reactions (AOR). For conventional fuel cell applications, noble metals like platinum (Pt) and palladium (Pd) are frequently utilized as electrocatalysts. However, the utilization of these two metals in fuel cells was constrained by their high price and resource scarcity. Additionally, the total effectiveness of the fuel cells is decreased by the catalytic poisoning of carbon monoxide (CO) at the surface and the catalytic degradation of these two metals. The CO poisoning at the surface of Pt and Pd is limited by alloying these metals with other transition metals, such as ruthenium (Ru), cobalt (Co), iron (Fe), nickel (Ni), etc., or by incorporating the carbon support materials such as carbon black (CB). However, the deterioration of these materials in acidic or alkaline environments compromises the durability and performance of the fuel cells. In 2004, the discovery of 2-dimensional (2D) graphene opened a new avenue for the material scientific community to explore in different fields. Graphene (G) or graphene-based electrocatalysts, which have many benefits over Pt and Pd-based materials, are thought to be possible candidates for fuel cell applications. This is caused by graphene's distinct structural characteristics and extraordinary physical attributes, which include a high theoretical surface area (2600 m2 g−1), high electrical and thermal conductivities, superior mechanical strength and corrosion resistance, good optical transparency, and strong flexibility. This chapter is structured into four main sections. The first section deals with the introduction of fuel cells, which includes a brief overview of the fuel cells, the role of electrocatalysts and support materials in the fuel cell, and the various degradations affecting the performance of fuel cells. In the subsequent sections, the synthesis and properties of graphene and graphene derivatives used in electrocatalytic applications are discussed. The advantages of graphene-based materials used as electrocatalysts in cathodic oxygen reduction and anodic oxidation of fuels in various fuel cells are also described. Apart from the conclusion, the final section outlines the challenges and future perspectives of graphene-based electrocatalysts in fuel cell applications.