A Unique 3D Nitrogen-Doped Carbon Composite as High-Performance Oxygen Reduction Catalyst

Abstract

The synthesis and properties of an oxygen reduction catalyst based on a unique 3-dimensional (3D) nitrogen doped (N-doped) carbon composite are described. The composite material is synthesised via a two-step hydrothermal and pyrolysis method using bio-source low-cost materials of galactose and melamine. Firstly, the use of iron salts and galactose to hydrothermally produceiron oxide (Fe2O3) magnetic nanoparticle clusters embedded carbon spheres. Secondly, magnetic nanoparticles diffused out of the carbon sphere when pyrolysed in the presence of melamine as nitrogen precursor. Interestingly, many of these nanoparticles, as catalyst-grown carbon nanotubes (CNTs), resulted in the formation of N-doped CNTs and N-doped carbon spheres under the decomposition of carbon and a nitrogen environment. The composite material consists of integrated N-doped carbon microspheres and CNTs show high ORR activity through a predominantly four-electron pathway.

Green Synthesis of Three-Dimensional Hybrid N-Doped ORR Electro-Catalysts Derived from Apricot Sap

“…The pyrolysed composite material forms an integrated composite material with both carbon fibers (CFs) and CMS. A similar integrated structure was reported in our previous paper, where we hypothesised that the decomposition of melamine during pyrolysis causes disruption to the iron oxide magnetic nanoparticle clusters’ (FeMNPC) surface that is embedded in the carbon sphere to diffuse FeMNPC particles out of the sphere to catalyse the formation of N-doped carbon fibers (N-CFs) [ 50 ]. This hybrid carbon catalyst contains N-CFs and N-doped carbon microspheres (N-CMS) with magnetic nanoparticles, forming a unique 3D intergrated morphology.…”

“…The pyrolysed composite material forms an integrated composite material with both N-CF and N-microspheres ( Scheme 1 D). During pyrolysis, the decomposition of melamine caused disruption to the spheres’ surface and caused the FeMNPCs embedded within the sphere to diffuse out [ 50 ], which catalysed the formation of N-CF [ 53 ]. The synthesised hybrid material, which consists of both N-CF and N-CMS, formed a unique 3D integrated morphology.…”

“…As the integrated structures were only seen on the catalysts with transition metals ( Figure 1 B and Figure S2B in SI ), we deduce that both a transition metal oxide and a nitrogen precursor are needed for the synthesis of the integrated structure comprised of both N-CMS and N-CFs. Previously, we reported a 3D integrated structure of N-CMS and N-CFs using sugar galactose (N-GAL-Fe) [ 50 ]. A similar morphology was observed in N-APG-Fe, which demonstrates that the presence of galactose in the apricot sap also contributes significantly to the formation of the integrated structure.…”

Natural Okra Shells Derived Nitrogen‐Doped Porous Carbon to Regulate Polysulfides for High‐Performance Lithium–Sulfur Batteries

“…As shown in Figure b, the C 1s peak deconvoluted into three peaks at the positions of 284.4, 285.2, and 289.0 eV, which were assigned to C—C, C—N, and C—O bonding, respectively. Especially, the existence of C—N bonding denotes the successful doping of N atoms into the carbon lattice fringe, which can enhance the intrinsic electronic conductivity and reduce the energy barrier of ion penetration . In the bind of N 1s (Figure c), two components at 398.0 and 399.4 eV are assigned to pyridinic N and pyrrolic N, which can enhance the conductivity and active sites, consequently improving the LSB properties.…”

Nitrogen-Doped Carbon Nanoparticles for Oxygen Reduction Prepared via a Crushing Method Involving a High Shear Mixer

“…Fuel cells are regarded as a renewable energy technology and have been widely studued in recent years for their high energy density and zero emission [ 14 ]. However, advance in fuel cells is limited due to the sluggishness of the oxygen reduction reaction (ORR) in the cathode.…”