Recent developments in copper-based, non-noble metal electrocatalysts for the oxygen reduction reaction

The high cost of Pt-based catalysts and the sluggish dynamics of the oxygen reduction reaction (ORR) severely hinder the rapid development of fuel cells. Therefore, the search for inexpensive, non-noble metal catalysts to substitute Pt-based catalysts has become a critical issue in the ORR research field. As an earth-abundant element, the use of Cu to catalyze the ORR has been explored with the ultimate target of finding a replacement for Pt-based catalysts in fuel cells. This review mainly focuses on recent research progress with Cu-based ORR catalysts and aims to aid readers' understanding of the status of development in this field. The review begins with a general update on the state of knowledge pertaining to ORR. This is followed by an overview of recent research based on Cu nanomaterial catalysts, which comprises Cu complexes, compounds, and other structures. Charting the development of Cu-based ORR catalysts shows that designing Cu-based materials to mimic active enzymes is an effective approach for ORR catalysis. By collecting recent developments in the field, we hope that this review will promote further development of Cu-based ORR catalysts and their application in fuel cells.