The effect of supporting carbons on the solid-state chemistry of octahedral Pt3Ni electrocatalysts with various H2:CO ratios

The production of octahedral Pt₃Ni/C electrocatalysts with several carbon substrates (Ketjen black, Graphene, and Vulcan XC-72R) via solid-state chemistry was investigated. Different carbon substrates influenced the shape and alloy of Pt₃Ni nanoparticles, with octahedral morphology and alloy metal preferred to develop on Ketjen black and Graphene, whereas spherical shape and bi-metallic metal preferred to grow on Vulcan. In addition, the shape was determined to be controlled during the reduction process, where the H₂:CO ratio played a significant role in regulating octahedral morphology and executing the ORR activity. At an H₂:CO ratio of 1:3, the Pt₃Ni/Ketjen black had the greatest ORR activity for both mass activity (1.02 A mg_Pt^-1) and specific activity (5.09 mA cm^-2) which were 16.5 and 66.1 times greater than commercial Pt/C catalysts (0.062 A mg_Pt^-1 and 0.077 mA cm^-2). Whereas the H₂:CO composition that demonstrated the best ORR activity of Pt₃Ni onto Graphene and Vulcan XC-72R was 1:1. The catalysts were examined using an accelerated durability test (ADT) with 4000 voltage cycles, and it was discovered that the Pt₃Ni /Ketjen catalyst performed the best in terms of ORR stability and durability.