Alternatives to conventional platinum-based catalysts in Polymer Electrolyte Membrane Fuel Cells

Abstract

With a total energy consumption of up to 5%, the aviation industry has an impact on world energy consumption and by 2050 it might account for one-fourth of the world’s total carbon emission. The principal fuel used in the aviation sector is currently liquid fossil fuel, which generates a range of greenhouse gases (GHGs). Global warming, natural disasters, and fossil-fuel shortages have sparked interest in environmentally friendly and renewable energy-based fuels around the world. The demand for environmentally friendly power technology for a variety of aircraft applications has risen considerably in recent years as the aviation sector expands to meet the needs of a growing global population [1]. The hydrogen fuel cell, which is a device that converts the chemical energy directly to electrical energy, seems to be an alternative solution to the problem [2].

Due to its cleanliness and abundance among the multiple clean power sources, hydrogen-derived energy is considered the future of energy generation in the aviation industry. However, depending on the fuel and electrolyte used, there are different types of fuel cells. The use of Proton Exchange Membrane (PEM) or the Polymer Electrolyte Membrane Fuel Cell (PEMFC), for onboard fuel generation is gaining importance. PEMFCs have many advantages over other fuel cells and their room temperature/close to room temperature operation makes it suitable for aviation applications. It also has qualities that make it acceptable for aeronautical use, including silent operation, the emission of significantly innocuous by-products, a solid electrolyte, and the absence of moving parts. However, there are a few hurdles such as the use of platinum catalyst, which accounts for half of the fuel cell's cost, it is readily poisoned by CO, necessitating the installation of a mechanism that eliminates CO in the fuel gas and the use of electrolyte membranes such as Nafion. As a result, the large-scale use of PEMFC is hampered [3]. Tremendous efforts have been devoted to the development of low-cost Platinum free catalysts to replace the existing Platinum Group Metals (PGM) catalyst.

This review is on the recent advances in non-noble metal catalysts suitable for PEM fuel cells to reduce the overall cost of the fuel cell system leading to its successful commercialization. Feasibility of replacing platinum-based catalysts, challenges associated with replacing the conventional catalysts, the effectiveness and performance evaluation of new catalysts [4] in comparison with the current platinum-based catalysts in PEM fuel cells are discussed.