Green algae and gelatine derived nitrogen rich carbon as an outstanding competitor to Pt loaded carbon catalysts

Abstract

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.

Nitrogen‐Rich Carbonaceous Materials for Advanced Oxygen Electrocatalysis: Synthesis, Characterization, and Activity of Nitrogen Sites

“…[194] Furthermore, Ilnicka et al prepared green algae and gelatine-derived nitrogen-rich carbon catalysts as ORR electrocatalysts, showing superior ORR performance in alkaline media compared to commercially available electrocatalysts. [201] While biomass can be easily transformed into novel carbon nanostructures with superior ORR activity, it usually contains little or no nitrogen, requiring thus a second N-source that may result in poor homogeneity of the final materials due to the absence of molecular mixing. [43,87] Meanwhile, fine structural control of carbons produced by this method is difficult to achieve.…”

Nanostructured carbon electrocatalysts for clean energy conversion and storage: A mini review on the structural impact

“…To expose more active sites, obtaining a high specific surface area, improving the catalyst structure, loading active particles on carbon-based substrates, or introducing functional groups are effective strategies. For example, the as-prepared, metal-free mesoporous carbons possessed a high density of N-containing active sites and a high specific surface area (Ilnicka et al, 2021). Zan et al (2021) prepared an ultrathin carbon nanosheet with a thickness of 1-2 nm, which can incredibly increase the specific surface area and obtain a larger current density.…”

“…Feng et al (2018) synthesized catalysts that have more than twice the current density of Pt/C electrodes at the same catalyst loading due to the super absorption properties of graphene layers and oxygen bubbles stabilizing ability of dendritic interstices. The porous structure provides similar properties, with strong interaction with O 2 bubbles (Lu et al, 2016;Ilnicka et al, 2021). In the porous nanosheet catalyst synthesized by 17.4% of the macropores were for substance transport, and 82.6% of the mesopores were for the diffusion of reactants and products.…”

The effect of nitrogen species on the catalytic properties of N-doped graphene

“…At the same time, very high concentrations of heteroatoms and a large amount of defects in the structure can contribute to a decrease in electronic conductivity and disadvantage the oxygen reduction reaction 22 . There are many nitrogen precursors that may be useful for synthesising N-doped carbon catalysts of high activity towards ORR, e.g., melamine 23 , 24 , urea 23 , 25 , adenine 23 , 26 , arginine 23 , 27 , or natural materials, such as green algae or gelatine 28 , 29 . We have demonstrated in our previous studies that such N-doped materials can be derived from amino acids 30 , chitin, and chitosan 31 , 32 , and provide high activity towards ORR.…”