Jackie Vigneron, Aurélie Habert, Virginie Jorda, Yann Leconte, Arnaud Etcheberry, Henri Perez, Mathieu Frégnaux, Pierre Bonville, Axelle Quinsac, Laboratoire Edifices Nanométriques (LEDNA), Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Energie (ex SIS2M) (NIMBE UMR 3685), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut Lavoisier de Versailles (ILV), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), DIM Nano-K, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)
This paper reports original results on the synthesis of Carbon/Nitrogen/Iron-based Oxygen Reduction Reaction (ORR) electrocatalysts by CO2 laser pyrolysis. Precursors consisted of two different liquid mixtures containing FeOOH nanoparticles or iron III acetylacetonate as iron precursors, being fed to the reactor as an aerosol of liquid droplets. Carbon and nitrogen were brought by pyridine or a mixture of pyridine and ethanol depending on the iron precursor involved. The use of ammonia as laser energy transfer agent also provided a potential nitrogen source. For each liquid precursor mixture, several syntheses were conducted through the step-by-step modification of NH3 flow volume fraction, so-called R parameter. We found that various feature such as the synthesis production yield or the nanomaterial iron and carbon content, showed identical trends as a function of R for each liquid precursor mixture. The obtained nanomaterials consisted in composite nanostructures in which iron based nanoparticles are, to varying degrees, encapsulated by a presumably nitrogen doped carbon shell. Combining X-ray diffraction and Mossbauer spectroscopy with acid leaching treatment and extensive XPS surface analysis allowed the difficult question of the nature of the formed iron phases to be addressed. Besides metal and carbide iron phases, data suggest the formation of iron nitride phase at high R values. Interestingly, electrochemical measurements reveal that the higher R the higher the onset potential for the ORR, what suggests the need of iron-nitride phase existence for the formation of active sites towards the ORR.