In Situ Confined Synthesis of Ti4O7 Supported Platinum Electrocatalysts with Enhanced Activity and Stability for the Oxygen Reduction Reaction

摘要

Herein, an in situ confined synthesis of highly conductive titanium oxide supported Pt catalysts is successfully employed. The method involves crystallization and formation of TiO2 particles inside the inert silica shell introduced by using hexamethyldisilazane (HMDS). The conductivity of titania is found to be greatly enhanced by increased annealing temperature, whereas the inevitable decrease in the specific surface area was effectively inhibited by the confining silica shell derived from HMDS. The optimal catalyst (20Pt 850FHST), exhibited better oxygen reduction reaction (ORR) activity with a maximum current density of 0.049mAcm(-2) at 0.9V (vs. normal hydrogen electrode (NHE)) and an onset potential of 0.86V (vs. NHE). The prolonged cycling test demonstrated superior stability compared with Pt/C (JM 20). Moreover, X-ray absorption spectroscopy asserts that the increased electron population in the Pt 5d orbital, emanating from the strong metal-support interaction, improves the electrochemical performance in the ORR. The in situ HMDS-assisted synthesis can also be extended to other oxide-supported catalytic systems.