Phyto- and zoomass-derived nanostructured carbon as efficient catalysts for oxygen reduction reaction in fuel cells: a review

The oxygen reduction reaction (ORR) plays a pivotal role in several energy storage and conversion technologies, including metal-air batteries, microbial fuel cells, and low-temperature hydrogen and alcohol fuel cells. Fuel cells, in particular, have gained significant traction as a feasible alternative energy source due to their efficiency, cleanliness, adaptability, and ability to reuse exhaust heat. However, the complex nature of ORR requires highly efficient electrocatalysts for optimal fuel cell performance. While Pt-based electrocatalysts are widely regarded as the most suitable for both the cathode and anode in fuel cells, their high cost, scarcity, and susceptibility to fuel crossover have driven the search for alternative ORR catalysts. In this context, carbon materials have emerged as promising candidates due to their low cost, long-term stability, and strong electrocatalytic activity. Recent advancements in biomass-derived carbon nanostructures align with the global push for sustainable energy and a pollution-free environment. This review examines carbon structures derived from the carbonization of plant and animal biomass and evaluates their performance as noble metal supports, non-noble metal electrocatalysts, and metal-free electrocatalysts for ORR.