How PM2.5 Affects Pt-Catalyzed Oxygen Reduction Reaction

The particulate matter of size less than 2.5 mu m (PM2.5) in haze not only affects human health but also reduces the efficiency of fuel cells. Herein, we report for the first time the underlying nature of the effects of representative water-soluble ions in simulated PM2.5 pollutions on the Pt/C-catalyzed oxygen reduction reaction (ORR) in acid media by combining simulated experiments, Tafel kinetics with density functional theory (DFT) calculations. The Cl- ion is discriminated as the major obstacle for the O-2 adsorption and reduction, which are correlated with both the catalyst active site blocking and negative electronic property. The adsorbed Cl- also leads to the change in the rate-determining step from the formation of OOH* to the protonation of O*, since it has an excessively weakening ability for the adsorption and protonation of the oxygen-containing reaction intermediates. These insights could guide the rational design and engineering of Pt/C ORR catalysts with the higher antipoisoning ability of PM2.5.