Biomass derived hierarchical porous carbon materials as oxygen reduction reaction electrocatalysts in fuel cells

Porous carbon materials (PCM) hold great promise for multifarious applications (like energy conversion and storage devices, biological applications, photo-catalysis etc.) owing to their outstanding properties such as high surface area, accessible active sites, mass transport, diffusion etc. Interestingly, they appear as futuristic substitutes to replace the conventional and economically unviable Pt-based electrocatalysts for the oxygen reduction reaction in Fuel cells. PCM synthesized using biomass-derived sources have some clear advantages, vis-a-vis. their abundance in nature, characteristic sustainability, economic viability and environmental friendliness. Also, no harsh chemicals are being used for their synthesis, and they inherently contain variety of heteroatoms (N, P, S etc.) vital for the electrocatalytic activity. This review article will help researchers gain an in-depth understanding of bio-waste sources and composition; synthesis methods and their dependence on various parameters; templating methods and vital information like role of dopants and transition metals in influencing electrocatalytic activity, and will result in enabling biomass based PCM as electrocatalysts in future energy devices.