The development of effective catalysts for the oxygen reduction reaction (ORR) is a significant challenge in energy conversion systems, e.g., Zn–air batteries. Herein, green-algae- and gelatine-derived porous, nitrogen-rich carbons were extensively investigated as electrode materials for electrochemical catalytic reactions. These carbon-based catalysts were designed and optimized to create a metal-free catalyst via templating, carbonization, and subsequent removal of the template. The additional incorporation of graphene improved electronic conductivity and enhanced the electrochemical catalytic reaction. Porous carbons with heteroatoms were used as effective platinum-free ORR electrocatalysts for energy conversion; the presence of nitrogen in the carbon provided more active sites for ORR. Our catalyst also displayed notable durability in a rechargeable Zn–air battery energy system. More importantly, the nitrogen-containing porous carbons were found to have comparable ORR performance in alkaline media to commercially available electrocatalysts. The manuscript demonstrates that nitrogen atom insertion is an appropriate approach when aiming to eliminate noble metals from the synthesis route. N-doped carbons are competitive materials compared to reference platinum-based catalysts.

The new bifunctional catalysts for water splitting with excellent electrochemical performance in the hydrogen evolution reaction and oxygen evolution reaction.