Sulfur dioxide-resistant platinum-based intermetallic nanocatalysts encaged by porous nitrogen-doped carbon for oxygen reduction reaction

Abstract

SO2, one of the considerable air pollutants, exhibits a stronger binding affinity with Pt when compared to O2, thereby inducing irreversible degradation of the Oxygen Reduction Reaction (ORR) catalyzed by Pt-based catalysts. Despite this detrimental phenomenon, scarce investigations have delved into the realm of contaminant-tolerant catalysts, and so far, no effective SO2-tolerant catalysts have been proposed. To meet this challenge, we designed and synthesized a core–shell structure catalyst equipped with a dual protection mechanism. This was achieved through the in-situ polymerization of aniline monomers, concomitantly reducing Pt2+. The resulting shell effectively hinders the transmission of SO2 to the active sites of Pt, while permitting the unimpeded transmission of O2. Simultaneously, the intermetallic core inhibits the adsorption of SO2. Therefore, this catalyst exhibits exemplary ORR activity coupled with exceptional resistance to SO2 resistance. In particular, the PtFe@FeNC/C-10 catalyst, optimized in terms of the quantity of added aniline, demonstrates a mass activity 1.84 times greater and a specific activity 4.03 times higher than that of commercial Pt/C catalysts. Following exposure to SO2-induced poisoning, the E1/2 value of the PtFe@FeNC/C-10 catalyst undergoes a decrease of only 51.7 mV, lower than that observed for the commercial Pt/C catalyst (92.0 mV). Moreover, the results of an accelerated durability test affirm the superior stability of PtFe@FeNC/C-10 in comparison to commercial Pt/C. This stability advantage is attributed to the protective carbon shell, which effectively prevents the detachment and agglomeration of Pt nanoparticles.