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

Malgorzata Skorupska,Kinga Kowalska,Anna Ilnicka,Jerzy P Lukaszewicz,Piotr Kamedulski,Wojciech Zielinski,Magdalena Tyc

doi:10.1038/s41598-021-86507-5

Malgorzata Skorupska, Kinga Kowalska + Show 5 more

Open Access

https://doi.org/10.1038/s41598-021-86507-5

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Journal: Scientific Reports	Publication Date: Mar 29, 2021
Citations: 21	License type: open-access

Affiliation: Nicolaus Copernicus University

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.

Highlights

The development of effective catalysts for the oxygen reduction reaction (ORR) is a significant challenge in energy conversion systems, e.g., Zn–air batteries
High-resolution transmission electron microscopy (HRTEM) images reveal a majority of the pores that is spherical with a diameter of approximately 20 nm; these observations show geometry and size representative of the silica particles used as a template during synthesis (Fig. 1a,b)
The as-prepared, metal-free mesoporous carbons possessed a high density of N-containing active sites (N content 7.7 at.%) and a high specific surface area (880 m2 g−1)

Summary

Introduction

The development of effective catalysts for the oxygen reduction reaction (ORR) is a significant challenge in energy conversion systems, e.g., Zn–air batteries. Some studies seem to confirm this assumption, for example, the case in which this natural precursor was activated using KOH, though the resulting specific surface area was small In another example, algae were treated by a hydrothermal method to obtain N-doped carbon (but nonporous)[24]. It is essential to explore an approach to this sort of facile method to produce novel, N-rich, hierarchical porous carbons from algae and gelatine, with a unique three-dimensional (3D) structure, high specific surface area, and excellent catalytic activity for ORR. The current work addresses the research challenges mentioned above, i.e., a metal-free catalyst for oxygen reduction reactions in an alkaline medium was synthesized through the carbonization of green algae and gelatine These natural precursors were selected due to the content of nitrogen-rich peptides, which were the assumed source of nitrogen atoms embedded in the carbon matrix after thermal degradation. The developed method can provide simple but efficient, versatile approaches to low-cost production of N-rich porous carbons to be used as efficient, metal-free electrocatalysts for metal–air batteries

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