Influence of the velocity of Pt ablated species on the structural and electrocatalytic properties of Pt thin films

Platinum was deposited by pulsed laser deposition at different kinetic energy by varying the He background pressure in the deposition chamber. As a result, the porosity of the film varies from 5 to 86% as the He pressure is increased. This yields to an increase of the electrochemically active surface area and to an increased resistance to poisoning by CO, as evidenced by a 45 mV shift of the peak potential of the CO stripping peak towards less positive values. Similarly, the electrocatalytic activity of the films for the oxygen reduction reaction, as measured by the potential at half limiting diffusion current, is enhanced. However, a comparison between the intrinsic electrocatalytic activities of the films show that they have similar values (within a factor of 1.8) and do not significantly differ from that of a polycrystalline Pt disk, indicating that the increased activity for the ORR is mainly due to a geometric (electrochemically active surface area) effect.