PtNi nanoparticles supported on electrochemically reduced porous graphene oxide for methanol oxidation reaction

Synthesis and Evaluation of PtNi Electrocatalysts for CO and Methanol Oxidation in Low Temperature Fuel Cells

“…In Figure 2, the Pt diffraction peaks are shifted towards the diffraction angle of hexagonal Ni instead to the higher angles where the cubic Ni signal is located. Studies about PtNi catalysts in the literature, prepared by simultaneous reduction of the platinum and nickel precursors [18,28,33,39,49,51,52,59], described fcc alloy structures with 2θ angles between those of pure cubic Pt and pure cubic Ni, then higher than those of Pt, according to a Pt lattice contraction, just the opposite found in this paper. This can be explained assuming that hexagonal Ni is spontaneously formed when depositing Ni alone in the present synthesis conditions, whereas cubic PtNi results from Pt and Ni codeposition.…”

“…This difference can be ascribed to the different Ni content and suggests that it can be increased with the amount of Ni. It is also interesting to remark that Wang et al [51] reported also onset potentials of about 0.1-0.2 V vs. SCE, which is about 0.15-0.25 V vs. Ag/AgCl/KCl sat , at a sweep rate of 50 mV s −1 in 0.5 M methanol +0.5 M H 2 SO 4 , for fcc PtNi alloys supported on electrochemically reduced porous graphene oxide. The best onset potentials and the maximum current densities were achieved for the Pt:Ni atomic ratio of 1:1, decaying for higher Pt relative contents and also for higher Ni relative contents.…”

“…Ni-containing Pt-based alloys have been synthesized and tested for the oxygen reduction reaction (ORR) [28,33,35,39,41,[47][48][49], and the CO [18,38], methanol [8,31,37,41,[50][51][52][53] and ethanol [8,22,29,[44][45][46] oxidation reactions, with generally better results than using Pt/C and the same alloys in the absence of Ni. The oxidation of ethylene glycol and glycerol on one-dimensional Pt 3 Ni nanowires and nanorods has been also studied [54], with the conclusion that it presented higher mass and specific activities than Pt/C.…”

“…In the latter core-shell structures, Ni did not appear to be in contact with the electrolyte. However, it is under discussion whether the surface Ni is being dissolved during the stability tests [28,33] and/or it is oxidized to highly conductive Ni(OH) 2 , which may help the desorption of CO by the bifunctional mechanism [38,51]. Recently, Glüsen et al [49], using dealloyed PtNi/C catalysts with a PtNi core and a Pt-rich shell, found that Ni was necessary in the core and detrimental in the shell for both, the activity and stability of the DMFC cathode.…”

“…Recently, Glüsen et al [49], using dealloyed PtNi/C catalysts with a PtNi core and a Pt-rich shell, found that Ni was necessary in the core and detrimental in the shell for both, the activity and stability of the DMFC cathode. Recent publications show the renewed interest in studying PtNi alloys for methanol oxidation [49,[51][52][53][54].…”