Facile synthesis of fully ordered L10-FePt nanoparticles with controlled Pt-shell thicknesses for electrocatalysis

• Published in: Nano research 2017-08, Vol.10 (8), p.2866-2880
• Main Authors: Hong, Yonghoon, Kim, Hee Jin, Yang, Daehee, Lee, Gaehang, Nam, Ki Min, Jung, Myung-Hwa, Kim, Young-Min, Choi, Sang-Il, Seo, Won Seok
• Format: Article
• Language: English
• Subjects: Acetic acid; Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Catalysis; Catalysts; Chemistry and Materials Science; Condensed Matter Physics; Electrocatalysis; Etching; Hydrochloric acid; Intermetallic compounds; Iron compounds; Materials Science; Nanoparticles; Nanotechnology; Oxidation; Platinum compounds; Research Article; Shells; Sodium hydroxide; Sonication; Synthesis
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-017-1495-5

We report a simple one-step approach for the synthesis of -4 nm uniform and fully L10-ordered face-centered tetragonal （fct） FePt nanoparticles （NPs） embedded in -60 nm MCM-41 （fct-FePt NPs@MCM-41）. We controlled the Pt-shell thickness of the fct-FePt NPs by treating the fct-FePt NPs@MCM-41 with acetic acid （HOAc） or hydrochloric acid （HC1） under sonicafion, thereby etching the surface Fe atoms of the NPs. The fct-FePt NPs deposited onto the carbon support （fct-FePt NP/C） were prepared by mixing the fct-FePt NPs@MCM-41 with carbon and subsequently removing the MCM-41 using NaOH. We also developed a facile method to synthesize acid-treated fct-FePt NP/C by using a HF solution for simultaneous surface-Fe etching and MCM-41 removal. We studied the effects of both surface-Fe etching and Pt-shell thickness on the electrocatalytic properties of fct-FePt NPs for the methanol oxidation reaction （MOR）. Compared with the non-treated fct-FePt NP/C catalyst, the HOAc-treated and HCl-treated catalysts exhibit up to 34% larger electrochemically active surface areas （ECASAs）; in addition, the HCl-treated fct-FePt NP （with -1.0 nm Pt shell）/C catalyst exhibits the highest specific activity. The HF-treated fct-FePt NP/C exhibits an ECASA almost 2 times larger than those of the other acid-treated fct-FePt NP/C catalysts and shows the highest mass activity （1,435 mA·mgPt^-1, 2.3 times higher than that of the commercial Pt/C catalyst） and stability among the catalysts tested. Our findings demonstrate that the surface-Fe etching for the generation of the Pt shell on fct-FePt NPs and the Pt-shell thickness can be factors for optimizing the electrocatalysis of the MOR.