Pt nanoparticles on Ni-N-C support for oxygen reduction reaction with robust SO₂ tolerance

The irreversible degradation of platinum-based catalysts caused by strong sulfur dioxide (SO₂) adsorption poses a primary obstacle to the oxygen reduction reaction (ORR), limiting the practical application of proton exchange membrane fuel cells. Herein, we design and synthesize an anti-SO 2 poisoning Pt-based catalyst comprising Pt nanoparticles anchored on a single-atom Ni-N-HCNs support. The obtained catalyst (Pt/Ni-N-HCNs) exhibits exceptional tolerance to SO₂ poisoning, demonstrating a minimal negative shift of only 47.7 mV in the half-wave potential after contamination, compared to the 79.4 mV shift observed for commercial Pt/C. More importantly, Pt/Ni-N-HCNs catalyst demonstrates significantly enhanced ORR performance, with a mass activity of 0.58 A mg Pt −1 and a specific activity of 1.57 mA cm −2 , representing 1.2-fold and 2.7-fold improvements over commercial Pt/C, respectively. Density functional theory (DFT) calculations and XPS results reveal that the strong metal-support interaction (SMSI) induces the downshift of the d-band center of Pt, thereby weakening SO 2 adsorption and facilitating SO 2 removal. Furthermore, the Ni N site in Ni-N-HCNs support exhibits high activity for SO 2 oxidation, promoting the effective removal of SO 2 from adjacent Pt sites. Both effects synergistically enhance the resistance to SO 2 poisoning of the Pt/Ni-N-HCNs catalyst without sacrificing ORR performance. This work provides insights into the design of poison-resistant electrocatalysts and the development of energy conversion systems with high environmental applicability.