Achieving enhanced durability in oxygen reduction catalysis with platinum nanowires on a TiO2–C composite support

Jicheng Shi, Han Deng, Jinhui Qiu, Hui Wu, Heng Yang, 王韶旭, Fen Xu

Platinum nanowires (PtNWs), with lengths on the micrometer scale and diameters of approximately 5–10 nm, were successfully synthesized on a TiO 2 -C composite support using a hydrothermal method. This method involved a reaction system comprising dimethylformamide (DMF), KOH, TiO 2 , acetylene black (BP2000), ethylene glycol, and HPtCl 6 ·6H 2 O. X-ray diffraction (XRD) revealed that the surface of the nanowires is predominantly composed of (111) and (200) crystal planes, corresponding to their most intense diffraction peaks. Accelerated degradation tests (ADT) demonstrated that the Pt/TiO 2 −C catalyst exhibits significantly higher structural stability compared to commercial Pt/C, a phenomenon attributed to the robust interaction between the TiO 2 anchoring sites dispersed within the continuous carbon phase and the Pt nanowires. Although the electrochemically active surface area of Pt/TiO 2 –C is only about one-third that of commercial Pt/C, its mass activity and specific activity are two times and six times greater than those of commercial Pt/C, respectively. In the cathode of an aluminum-air battery, which simulates a triple-phase (gas–liquid-solid) mass transfer environment, the cell loaded with Pt/TiO 2 -C exhibited slower voltage decay during galvanostatic discharge at 50 mA cm −2 , indicating improved durability. However, polarization curve results also indicate that at current densities exceeding 111 mA cm −2 , the discharge voltage of aluminum-air batteries utilizing a Pt/TiO 2 –C cathode is lower than that of commercial Pt/C. Therefore, while the PtNWs provide high stability due to their chain-like structure, their aspect ratio requires further optimization to mitigate the oxygen reduction reaction (ORR) mass transfer issues arising from the significant curling and entanglement of the nanowires.