Modulating d–p Orbital Hybridization via Interstitial S-Doping, Boosting Oxygen Reduction Stability

Nonmetallic doping of platinum represents a pivotal strategy for enhancing the oxygen reduction reaction (ORR) performance in proton exchange membrane fuel cells (PEMFCs). Herein, we manufacture a high-stability PtS/SCoNC electrocatalyst by generation of a Pt–S bond via interstitial S-doping in a Pt lattice. The extended X-ray absorption fine structure (EXAFS) analysis revealed a characteristic peak of Pt–S coordination at 1.86 Å, which demonstrates the interstitial S atom doping in the Pt lattice. Further density functional theory (DFT) calculations show that S doping in both Pt and the substrate lowers reaction barriers via charge redistribution and reduces the Pt d-band center to weaken oxygen intermediate adsorption, as well as enhances the binding energy of PtS and substrates to inhibit the loss of active components. Moreover, the lower work function and higher ionization energy of PtS/SCoNC detected by ultraviolet photoelectron spectroscopy (UPS) confirm its rapid electron supply capability and stable active sites. Benefiting from the optimized electronic structure, enhanced bonding energy, and the appropriate orbital d-band center which is ascribed to the interstitial S doping, the PtS/SCoNC exhibits enhanced ORR stability and achieves a higher peak power density of 152.03 mW/cm2 in a zinc–air battery, surpassing the performance of commercial Pt/C (120.0 mW/cm2).