Synergistic electronic regulation of a PtCo alloy by N,S co-doped carbon for highly efficient oxygen reduction electrocatalysis

The sluggish kinetics of the oxygen reduction reaction (ORR) and the high cost of Pt-based catalysts remain critical challenges for the large-scale application of proton exchange membrane fuel cells and rechargeable zinc-air batteries. Herein, a microwave-ultrasound-assisted polyol reduction method combined with thermal annealing and acid etching is developed to construct uniformly dispersed PtCo alloy nanoparticles supported on N,S co-doped carbon (PtCo/NSC). The synergistic effects of PtCo alloying and N,S co-doping effectively regulate the electronic structure of Pt sites, enhance metal-support interactions, and promote the formation of highly dispersed Pt₃Co nanoparticles with an average size of 5.71 nm. The abundant defects and heteroatom-doped active sites in NSC provide strong anchoring capability and facilitate interfacial charge transfer. The optimized PtCo/NSC catalyst exhibits superior ORR activity in acidic media, achieving a half-wave potential of 0.936 V, a mass activity of 0.45 mA μg_Pt^-1, and a specific activity of 0.58 mA cm_Pt^-2, surpassing commercial Pt/C and related PtCo-based catalysts. Furthermore, PtCo/NSC demonstrates good durability with only a 6 mV decrease in half-wave potential after 10 000 accelerated durability cycles. When applied as the cathode catalyst in rechargeable zinc-air batteries, it delivers a high peak power density of 253.98 mW cm^-2, a specific capacity of 813.62 mAh g^-1, and stable cycling performance over 200 h. DFT calculations reveal that N,S co-doping induces a downward shift of the Pt d-band center, optimizes the adsorption/desorption of oxygen intermediates, and reduces the energy barrier of the rate-determining step, thereby accelerating the four-electron ORR process. This study provides an effective strategy for regulating the alloy composition and catalyst-support interactions, offering new insights into the design of high-performance Pt-based electrocatalysts for advanced energy conversion and storage applications.