Evaluation of Novel Fuel Cell Catalysts with Ultra-Low Noble Metal Contents towards Electrochemical Catalysis

Abstract

The conversion and storage technologies of sustainable energy have been thoroughly researched, considering the overconsumption of fossil fuels and the escalating environmental problems. The use of more environmentally benign energy vectors has helped fuel cells recently become one of the most promising technologies. These devices’ oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are vital processes, but their commercialization is severely constrained by slow kinetics. Consequently, creating highly effective ORR and OER bifunctional catalysts is crucial yet difficult. Pt-based catalysts have the best ORR activity but weak OER activity. The best commercial OER electrocatalysts are RuO2 and IrO2 based, although they have a subpar ORR characteristic. However, it is crucial to create electrocatalysts with low noble metal contents and high efficiencies and stabilities for OER and ORR applications. At the same time, the large-scale applications of these noble electrocatalysts are constrained due to their rarity, high cost, and poor stability. In this review paper, noble metal-based and free catalysts for ORR and OER have been reviewed.