Optimizing Surface N‐Doping of Fe‐N‐C Catalysts Derived from Fe/Melamine‐Decorated Polyaniline for Oxygen Reduction Electrocatalysis

Abstract

The insufficient active site density and poor stability of iron and nitrogen co‐doped carbon (Fe‐N‐C) catalyst remain as great challenges for advanced oxygen reduction reaction (ORR). Surface N‐doping together with Fe species is considered as an efficient strategy to enhance the catalytic activity and stability of Fe‐N‐C. Here, we report a facile preparation of high performing Fe‐N‐C catalysts derived from Fe/melamine‐decorated polyaniline. The optimal catalyst displays much better ORR onset and half‐wave potentials (1.00 and 0.86 V) than that of the melamine‐free catalyst (0.97 and 0.83 V) and even the commercial Pt/C (0.99 and 0.83 V), respectively. It also shows a decent stability during 20 000 cycles of accelerated durability test (ADT) with only 15 mV loss in the half‐wave potential. Physical and electrochemical characterizations demonstrate that introduction of melamine could increase the percentage of surface pyrrolic N species and non‐crystalline Fe species, which would be responsible for the significant improvement in the catalytic performance toward ORR.

High-performance FeOx@CoOx/NC electrocatalysts for the oxygen reduction reaction in alkaline media

“…The four types of nitrogen are supposed to provide stability to the synthesized electrocatalyst. 1,28,32 The shiing of the d-band centre of FeO x downward to compensate for the distortion caused as a result of electronic interaction with cobalt oxides (CoO x ) and nitrogens is in agreement with the dband centre model. Enhanced electrocatalytic activity of the FeO x @CoO x /NC2 electrocatalyst is attributed to the cumulative electronic interaction of cobalt, iron and nitrogen sites, thereby modulating the chemisorption energy of O 2 and the reaction mechanism.…”

“…35 The superior catalytic activity and stability of FeO x @CoO x /NC2 can be attributed to the following key points. (1) Strong synergism between FeO x , CoO x and four types of nitrogen in nitrogendoped tubular carbon; (2) the introduction of four types of nitrogen as a result of decomposition of 1,10-phenanthroline induces uneven charge distribution in the carbon matrix, greatly facilitating the charge transfer; (3) greater number of active sites and exposed surface area of the synthesized electrocatalyst. 35 To assess the efficiency of the catalyst, all the electrochemical results were compared to those of commercial Pt/C under the same experimental conditions.…”

“…The cumulative global energy crisis encourages the development of electrochemical energy conversion technologies such as fuel cells and metal-air batteries due to their high-power density, low emission of gases, high efficiency and renewable source of reactants. 1 The upcoming energy crisis can be alleviated by the pivotal process of the cathodic oxygen reduction reaction (ORR). Porous structure catalysts are considered important for efficient electrocatalysis.…”

Probing Oxygen-to-Hydrogen Peroxide Electro-Conversion at Electrocatalysts Derived from Polyaniline

“…The comparison between the control material PANI-TS-TC ( Figure 5 a1,a2) and those containing the metallic species PANI-Ni-TS-TC ( Figure 5 b1,b2) and PANI-Co-TS-TC ( Figure 5 c1,c2) shows the presence of micro-structured particles of different shape and size. For polyaniline-based materials, it is known that the thermal treatment under an inert atmosphere of argon or nitrogen at 600–1200 °C will trigger the rearrangement of the different atoms to create new bonds of carbon–carbon (C-C, C=C, C-H) and carbon–nitrogen (pyridinic-N, pyrrolic-N, and graphitic-N) in a nanostructured network that has different levels of electrical conductivity, number of active sites and electrocatalytic kinetics [ 18 , 20 , 54 , 55 , 56 , 57 , 58 ]. In order to obtain a qualitative analysis of the nature of the structures formed with metallic species, in-depth analysis was conducted by EDX.…”

Synergistic melamine intercalation and Zn(NO3)2 activation of N-doped porous carbon supported Fe/Fe3O4 for efficient electrocatalytic oxygen reduction

“…30 It is found that the graphitization degree, porosity and conductivity of Fe/N/C catalysts are effectively improved by introducing melamine in the preparation process. [31][32][33] Besides, it can be seen that using melamine as ligand to prepare catalysts can signicantly enhance the ORR catalytic performance. 34 Most of these catalysts pyrolyze at high temperature, various active substances are produced besides the Fe-N x coordination active site, such as metallic Fe/Fe 3 C nanoparticles, Fe x O y or FeN x nanoparticles and so on.…”