Abstract
Nano-ordered intermetallic compounds have generated great interest in fuel cell applications. However, the synthesis of non-preciousearly transition metal intermetallic nanoparticles remains a formidable challenge owing to the extremely oxyphilic nature and very negative reduction potentials. Here, we have successfully synthesized non-precious Co3Ta intermetallic nanoparticles, with uniform size of 5 nm. Atomic structural characterizations and X-ray absorption fine structure measurements confirm the atomically ordered intermetallic structure. As electrocatalysts for the hydrazine oxidation reaction, Co3Ta nanoparticles exhibit an onset potential of −0.086 V (vs. reversible hydrogen electrode) and two times higher specific activity relative to commercial Pt/C (+0.06 V), demonstrating the top-level performance among reported electrocatalysts. The Co-Ta bridge sites are identified as the location of the most active sites thanks to density functional theory calculations. The activation energy of the hydrogen dissociation step decreases significantly upon N2H4 adsorption on the Co-Ta bridge active sites, contributing to the significantly enhanced activity.
Highlights
Adsorption than atomically disordered Pt3Ti, pure Pt, or Pt-Ru NPs for both formic acid and methanol oxidation reactions[28]
To prepare early transition metal intermetallic compounds, extremely strong reductants and high temperatures are usually adopted, which leads to significant agglomeration and unwanted particle growth[28,30,31,32,33]
We instead added surface treated carbon supports to the reaction solution before the co-reduction of metal salts
Summary
Adsorption than atomically disordered Pt3Ti, pure Pt, or Pt-Ru NPs for both formic acid and methanol oxidation reactions[28]. Hideki et al found that both 150-nm NbPt3 and 100-nm TaPt3 intermetallic particles showed significant enhancement in catalytic activity and stability compared with Pt NPs31,32 Despite these obvious advantages, the works of the related early transition metal nano-intermetallic compounds are preliminary (e.g., Pt3Ti28,29, Pt3V29, ZrPt330, NbPt331, TaPt332, and Pt3Y33) due to higher melting points, more oxyphilic nature and much more negative reduction potentials of these metals compared with late transition metals. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging and Xray absorption fine structure (XAFS) measurements reveal the ordered intermetallic crystal structure of Co3Ta. As an electrocatalyst for hydrazine oxidation reaction (HzOR), Co3Ta/C NPs exhibit outstanding performance for both activity and stability, including an ultralow onset potential (Eon) of −0.086 V (vs the reversible hydrogen electrode, RHE) and twofold improvement of specific activity relative to commercial Pt/C (+0.06V). The excellent performances on HzOR provide a potential application for Co3Ta NPs to be an anode catalyst in direct hydrazine fuel cells
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
