Ordered PtFeIr Intermetallic Nanowires Prepared through a Silica‐Protection Strategy for the Oxygen Reduction Reaction

Abstract

Developing efficient and stable Pt‐based oxygen reduction reaction (ORR) catalysts is a way to promote the large‐scale application of fuel cells. Pt‐based alloy nanowires are promising ORR catalysts, but their application is hampered by activity loss caused by structural destruction during long‐term cycling. Herein, the preparation of ordered PtFeIr intermetallic nanowire catalysts with an average diameter of 2.6 nm and face‐centered tetragonal structure (fct‐PtFeIr/C) is reported. A silica‐protected strategy prevents the deformation of PtFeIr nanowires during the phase transition at high temperature. The as‐prepared fct‐PtFeIr/C exhibited superior mass activity for ORR (2.03 A mgPt−1) than disordered PtFeIr nanowires with face‐centered cubic structure (1.11 A mgPt−1) and commercial Pt/C (0.21 A mgPt−1). Importantly, the structure and electrochemical performance of fct‐PtFeIr/C were maintained after stability tests, showing the advantages of the ordered structure.

Intermetallic Nanoarchitectures for Efficient Electrocatalysis

“…In particular, templating and protective layer coating methods have successfully produced multidimensional intermetallic nanoarchitecture from onedimensional (1D) nanostructures to three-dimensional (3D) skeletal nanomaterials. 11,[22][23][24][25][26][27]32 1D nanomaterials, including NWs, nanorods, and nanotubes, have emerged as promising electrocatalytic nanostructures owing to their high surface-area-to-volume ratio and electrical conductivity. In addition, their anisotropy enables multiple contacts with the surface of the electrode or support materials, ACS Nanoscience Au resulting in improved stability against aggregation of nanostructure or detachment from the electrode surface compared to the 0D nanocrystals.…”

“…11 In another Zhang and co-workers developed intermetallic PtFeIr NWs possessing an fct crystal structure (fct-PtFeIr/C) with a diameter of 2.6 nm using silica protective layers. 22 To form silica protective layers on the catalyst, the asprepared PtFeIr NWs with an alloy fcc phase (fcc-PtFeIr/C) was mixed with ethanol and ammonium hydroxide. Then, tetraethylorthosilicate (TEOS) was added to the mixture, and the mixture was stirred for 12 h. Finally, after the annealing process at 690 °C for 2 h and subsequent silica removal, the fct-PtFeIr/C was formed.…”

“…Thermally stable SiO 2 , MgO, and carbon-shell have been found suitable as protective layers. More importantly, the intermetallic nanoarchitectures, which refer to intermetallic catalysts with uniform size and controlled shape in nanoscale, have demonstrated unprecedented enhancement in catalytic performances. ,− Nanoarchitectures, including facet-controlled nanocrystals and multidimensional nanostructures, often expose well-defined crystallographic planes or highly strained surfaces from curved planes, undercoordinated defects, and grain boundaries. These structural features of intermetallic nanoarchitectures engender different binding strengths of reaction intermediates from typical intermetallic NPs, boosting catalytic performance.…”

Ordered intermetallic compounds combining precious metals and transition metals for electrocatalysis

“…( Chung et al, 2015 ; Liu et al, 2015 ) Third, the highly fct -ordered structure and strong d -interaction between Fe and Pt tends to be stable, especially the reaction of Fe and Pt in acidic solutions. ( Hu et al, 2020 ; Yang et al, 2022 ) However, it is worth noting that metal leaching occurs under high-potential electrochemical conditions. Previous simulation studies have shown that in the fct -PtFe structure, Fe and Pt interact strongly through spin-orbit coupling, and the hybridization of Fe 3 days and Pt 5 days states makes the chemical structure of fct -PtFe more stable.…”

Elucidating Electrocatalytic Oxygen Reduction Kinetics via Intermediates by Time Resolved Electrochemiluminescence

“…For this reason, the rotation electrode technique, including rotating disk electrode (RDE) and rotating ring disk electrode (RRDE), has been the most common way to obtain the intrinsic activities of ORR catalysts. [13][14][15][16] The Koutecky-Levich (K-L) equation describes current density of electrocatalysts on RDE (Eq. S1-3).…”