Construction of Pt/Powder Charcoal Electrocatalyst Utilizing MnO2 as an Additive to Improve the Stability for Oxygen Reduction Reaction

Pt/C catalyst is a crucial cathode material in proton exchange membrane fuel cells (PEMFCs), but its low stability limits its use in fuel cells. In this study, smaller Pt nanoparticles (NPs) were strongly anchored to the surface of regenerated decolorizing powder charcoal (PC) using MnO2 as an additive (Pt/M-PC), which was synthesized by the ethylene glycol reduction method. Benefiting from the strong anchored structure, the Pt/M-PC exhibits excellent stability. Notably, 77% of activity can be maintained by Pt/M-PC during the stability test of 12 h, which was higher than that of Pt/powder charcoal (Pt/PC, 68%). Moreover, Pt/M-PC (13.1 wt %) also showed higher mass activity than commercial Pt/C. XPS results showed that Pt NPs had a stronger interaction with PC when MnO2 was used as an additive, thereby decreasing the agglomeration degree of Pt NPs in the catalytic reaction due to the strong anchoring. In addition, the interaction between Pt NPs and PC increases the local electron density of Pt NPs, which is beneficial to improve the bonding strength of Pt NPs and oxygenated intermediates, ensuring the numbers of active sites and then enhancing the stability. As a result, this kind of metal oxide as additive may be an effective strategy for designing highly stable Pt-based catalysts.