Enhancement of ORR catalytic activity by multiple heteroatom-doped carbon materials

Abstract

Heteroatom-doped carbon matrices have been attracting significant attention due to their superior electrochemical stability, light weight and low cost. Hence, in this study, various types of heteroatom, including single dopants of N, B and P and multiple dopants of B-N and P-N with a carbon matrix were synthesized by an innovative method named the solution plasma process. The heteroatom was doped into the carbon matrix during the discharge process by continuous dissociation and recombination of precursors. The chemical bonding structure, ORR activity and electrochemical performance were compared in detail for each single dopant and multiple dopants. According to the Raman spectra, the carbon structures were deformed by the doped heteroatoms in the carbon matrix. In comparison with N-doped structures (NCNS), the ORR potential of PN-doped structures (PNCNS) was positively shifted from -0.27 V to -0.24 V. It was observed that doping with N decreased the bonding between P and C in the matrix. The multiple doping induced additional active sites for ORR which further enhanced ORR activity and stability. Therefore, PNCNS is a promising metal-free catalyst for ORR at the cathode in a fuel cell.

Synthesis of graphitic-N and amino-N in nitrogen-doped carbon via a solution plasma process and exploration of their synergic effect for advanced oxygen reduction reaction

“…[37][38] Recently, an emerging synthesis method, named solution plasma process (SPP), is specific for in situ heteroatom-doped carbon including synthesize N-doped [39][40][41][42] and/or B, P or Odoped carbon nanomaterials. [43][44] Previous findings from our group observed that crystallinity and graphitization of the synthesized carbon matrix increased significantly by introducing small amount of anthracene (C 14 H 10 ) as an additive in pure benzene. 45 We hypothesized that the addition of anthracene might promote the formation of graphitic-N. Herein, we applied pyridine and acrylonitrile as aromatic and linear C-N precursors, respectively, and further enhanced the amount of graphitic-N in N-doped carbon by the addition of anthracene.…”

α- and γ-Fe2O3 nanoparticle/nitrogen doped carbon nanotube catalysts for high-performance oxygen reduction reaction

“…The N-CNTs were synthesized by an annealing method [23], in which the activated CNTs were heated at 800°C with a rate of 5°C min −1 in N 2 /NH 3 (v/v = 2:1) gas and held for 3 h. The resulting black products were washed by ultrapure water and ethanol for three times. For the synthesis of the two different crystal ferric oxides supported N-doped CNTs nanocatalysts [8,24], 100 mg of activated CNTs were stirred at 600 rpm in ethanol-water (v/v = 5%) solution at room temperature for 1 h, followed by 10 min of ultrasonic treatment.…”

Fastest Formation Routes of Nanocarbons in Solution Plasma Processes

“…In such systems, the plasma enables unique reactions such as C–H activation reactions at the interface between the solution and plasma, whereas conventional plasma induces random decomposition reactions. We have fabricated graphene, heterographene, nanocarbon sheets, and nanocarbon spheres via solution plasma from organic solutions containing solvents such as benzene, toluene, pyridine, or pyrazine60616263646566676869707172. Moreover, the reaction rate is substantially higher than the rates of other synthesis methods such as chemical vapor deposition and pyrolysis synthesis.…”