A Comprehensive Review on Materials Having High Oxygen Reduction Reaction (ORR) Activity

Several main energy conversion technologies need the improvement of extremely active, enduring, and economical catalysts for the cathodic oxygen reduction process. Some power conversion techniques including fuel cells and metal air batteries are efficient for the oxygen reduction process. The current improvements in platinum-based materials and platinum-free materials for fuel cell ORR catalysis are studied. Six primary types of contemporary ORR electrocatalysts are elaborated. Moreover, the efficiency of the resulting catalysts in respect of mass activity, kinetic current density, power density, and their inclusion into fuel cell processes, are also investigated. The benefits, drawbacks, performance of catalysts, and the need of rational design methods at the fuel-cell level are emphasized. Furthermore, the core issues, constraints, and possibilities are reviewed for developing inexpensive, more functional active, and stable electrocatalysts in the future.