From rotating disk electrode to single cell: Exploration of PtNi/C octahedral nanocrystal as practical proton exchange membrane fuel cell cathode catalyst

Preparation of a Graphitized-Carbon-Supported PtNi Octahedral Catalyst and Application in a Proton-Exchange Membrane Fuel Cell

“…Therefore, the crystallite size will become larger with the crystal growth, resulting in the decrease of the number of active sites per unit mass, and thus, the ORR activities of PtNi/GC samples are lower than that of PtNi/BP2000 and decrease in turn with the increase of the graphitization degree. For similar reasons, their ORR activities also decrease slightly compared to PtNi/C octahedral samples synthesized by XC-72 carbon black in our previous work . However, their mass activities and specific activities are still 5 and 7 times higher than those of Pt/C (JM), indicating that PtNi alloying and highly active (111) facets still play important roles in the enhanced activities of these PtNi/GC octahedral catalysts.…”

“…The catalyst of 2 mg was added to a Nafion/methanol solution of 1 mL (the mass ratio of Nafion solution/methanol is 1:30) to obtain the catalyst ink. The composition of the three-electrode system, and the details of electrochemical tests of catalysts refer to our as-reported work . Cyclic voltammetry (CV), linear sweep voltammetry (LSV), and 2000 cycles of accelerated durability testing (ADT) were employed to estimate electrochemical activity and durability of catalysts.…”

“…In our previous investigations, a PtNi/C octahedral catalyst has been successfully prepared with Vulcan XC-72 as the support, and it exhibits enhanced ORR activity compared to the commercial Pt/C catalyst, but its electrochemical stability, especially the single-cell durability under high potential condition is not satisfactory as a result of poor corrosion resistance of XC-72 carbon. Some studies demonstrate that the graphite structure can help to reduce the corrosion-prone defect sites in the surface structure of the carbon support, thus effectively improving the corrosion resistance of the support. − Therefore, carbon nanotubes (CNTs) are first selected by us as the support to prepare the octahedral catalyst .…”

Size and Composition Dependence of Oxygen Reduction Reaction Catalytic Activities of Mo-Doped PtNi/C Octahedral Nanocrystals

“…There is consensus that larger and compositionally uniform PtNi octahedral catalysts are needed to overcome the cost and degradation issues. − The most widely applied synthetic protocols for oh-PtNi NPs involve the reduction of Pt­(acac) 2 and Ni­(acac) 2 using dimethylformamide (DMF) as the solvent and reducing agent. The synthesis has been typically carried out in a sealed vessel (autoclaves, pressure flasks or vials), and the reaction temperature has been generally above the boiling points of both the DMF (153 °C) and the acetylacetonate ligand (140 °C). − The low Ni-content of the resulting NP catalysts (to a large degree Pt 3 Ni octahedra), combined with the weak reductive power of DMF raised doubts about the rate of reduction of Ni­(acac) 2 from Ni II to Ni 0 under these conditions. , Alternatively, Pt-rich oh-PtNi NPs have been synthesized at temperatures above 200 °C using oleylamine and oleic acid as solvents and capping agents and with or without tungsten hexacarbonyl as the reducing and shape-directing agent. − Wu et al proposed the use of benzyl alcohol (BA) as both solvent and reducing agent to produce larger bimetallic oh-PtNi NP catalysts (11.8 ± 1.2 nm apex to opposite apex). However, these oh-PtNi NP catalysts were never studied for their oxygen electroreduction performance .…”

Efficient synthesis of Pt–Co nanowires as cathode catalysts for proton exchange membrane fuel cells

“…7 Although PtM alloy catalysts signicantly improve kinetic activity, 8 poor durability and stability on account of second phase metal degradation, atomic migration, and particle aggregation under corrosive electrochemical conditions have become major limitations. 9 Ultrathin PtM alloy nanowires (NWs) not only improve the electrocatalytic performance and utilization efficiency of Pt, but also make alloys difficult to dissolve and agglomerate in the fuel cell operating environment due to the ultrasmall size and the unique one-dimensional morphology, which can improve the durability of the catalyst. [10][11][12][13] In the last few years, the application of strong coordination capping ligands such as oleylamine (OAm) has generated a great interest.…”