Sulfur doping triggers charge redistribution at the heterointerface of Fe-N-C supported ultralow-Pt-loading electrocatalysts for efficient oxygen reduction

Development of low Pt-loading electrocatalyst with enhanced activity towards oxygen reduction reaction (ORR) is highly demanded for widespread penetration of clean energy technologies. Heterointerface regulation can effectively optimize the electronic structure and intrinsic activity of the carbon supported Pt-based electrocatalyst to reduce Pt consumption. Here, by judicious choice of a sulfur-doped Fe-N-C (Fe-NS-C) as support, we construct a novel Pt/Fe-N-C heterointerface with sulfur incorporation and develop a hybrid electrocatalyst (denoted as Pt@Fe-NS-C) with ultralow Pt-loading (1.51 wt%). The incorporation of sulfur triggers the charge redistribution at the heterointerface and reduces the electron transfer from Pt to Fe-NS-C, prompting the electron density around Pt sites and boosting the electrocatalytic performance towards ORR (half-wave potential: 0.903 V; mass activity of 1.28 A mg-1Pt at 0.9 V). In comparison, Pt species dispersed onto Fe-N-C without sulfur doping (Pt@Fe-N-C) are electron-deficient, which is not conductive to activate O2 and results in inferior ORR activity. Zinc-air battery fabricated with Pt@Fe-NS-C as the cathode catalysts shows a large peak power density and a specific capacity of 806.7 mAh g-1Zn. This work offers an effective way to tailor the heterointerface of hybrid or supported electrocatalyst with optimized electronic structures towards advanced electrocatalysis.