Ionic Liquid-Derived Ultrafine Pt Nanoparticles with a Uniformly Dispersed State for Long-Life Oxygen Electroreduction

Ultrafine Pt nanoparticles (NPs) homogeneously anchored on hollow carbon nanoshells (Pt-IL-HCNs) via a wet-chemistry reduction of a new type of imidazolium-[PtCl6](2-) ionic liquid (IL) are reported. Confined [PtCl6](2-) in IL molecules effectively prevents the growth and spontaneous aggregation of the Pt NPs due to the electrochemical neutrality of the IL, resulting in a homogeneously dispersed state of Pt NPs. The Pt-IL-HCNs with a Pt loading of 22 wt % outperform the commercial Pt/C (40 wt %) in terms of oxygen reduction reaction (ORR) activity and durability. The half-wave potential of Pt-IL-HCNs is 51 mV more positive than that of the commercial Pt/C in 0.1 M HClO4. An electrochemical surface area of 97 m(2) mg(-1) Pt and specific mass activity of 475 mA mg(-1) Pt of Pt-IL-HCNS were found to be 5.6 and 2.7 times higher than those on the commercial Pt/C. Furthermore, this work demonstrates that unlike one-dimensional (1D) carbon nanotubes and two-dimensional (2D) reduced oxide graphene, the three-dimensional (3D) HCN support plays an indispensable role in preventing any stacking of Pt NPs, leading to significantly enhanced ORR activity and durability.

Automated summary

This study reports the homogeneous anchoring of ultrafine Pt nanoparticles (NPs) on hollow carbon nanoshells (Pt-IL-HCNs) through wet-chemistry reduction of a new type of imidazolium-[PtCl6](2-) ionic liquid (IL). The Pt-IL-HCNs exhibit superior oxygen reduction reaction (ORR) activity and durability compared to commercial Pt/C, with a higher half-wave potential and electrochemical surface area. The three-dimensional (3D) HCN support is found to play a crucial role in preventing stacking of Pt NPs, leading to significantly enhanced ORR performance.