| Popis: |
Fuel cells (FC) are emerging technologies that will eventually sustain energy demands replacing fossil fuels. However, the Oxygen reduction reaction (ORR) behaves sluggishly in acidic medium, where actual commercialization of FC concentrates. An alternative is to use alkaline environment were the ORR have demonstrated great activity using less expensive metals, replacing the more frequent catalyst, Pt/C. In this study we focused our interests in PtNi-nanowires (NWs), based on the promotive results that Ni offers to Pt on it's d valency. Moreover, the addition of Ni will lower the cost of the catalyst. Preliminary results demonstrated current densities of ~ 5 mA/cm2 with an E1/2 = 0.85 V for the PtNi-NWs at 1,600 rpm and 0.100 (mgPt/cm2) in alkaline medium at (25.00 ± 0.01) °C. Additionally, the number of electrons was calculated using the Koutecký-Levich analysis with and without temperature-controlled instrumentation resulting in n= 3.79 ± 0.05 and n=3.99 ± 0.05, respectively. Furthermore, durability experiments demonstrated that the PtNi-NWs maintained optimal catalytic activity for ORR along 10,000 cycles. The initial reported E1/2 was of 0.817 V and after 10,000 cycles E1/2 = 0.812 V, this represents a remarkable 5mV change in the E1/2. Operando X-ray spectroscopy (XAS) electrochemical were completed to evaluate changes in electronic structure for Ni and Pt. Results showed that the white line of Pt L3 edge in the PtNi-NWs changed while the electrochemical potential was lowered to negatives values. Showing changes in the electronic structure of Pt. The results presented here suggest that PtNi-NWs is a sustainable catalyst for the ORR in alkaline medium and that it can be consider for future Alkaline Fuel Cells (AFCs) experiments. |
