Sodium thiosulfate-assisted synthesis of PtFeNC-S catalysts with dispersed Pt nanoparticles for enhancing oxygen reduction performance

The PtFeNC-S catalyst was obtained assisted bysodium thiosulfate. • PtFeNC-S exhibits excellent performance higher than that of Commercial PtC. • It can be attributed to the synergistic effects of FeN x sites, and C-S-C. • The catalytic mechanism is further clarified by DFT calculations. Reducing Pt loading is a promising strategy to scale up fuel cells and water electrolysis by optimizing catalyst design and active site distribution, achieving high efficiency with minimal precious metal. A Pt-loaded cathode catalyst (PtFeNC-S) was synthesized, in which Pt nanoparticles were uniformly distributed on the FeNC-S substrate using sodium thiosulfate, and it exhibited excellent oxygen reduction reaction (ORR) performance. TEM analysis reveals uniform dispersion of Pt nanoparticles (Pt NPs) with sizes of 2–5 nm, while XPS confirms the retention of FeN x active sites. The optimized PtFeNC-S catalyst exhibits a half-wave potential (E 1/2 ) of 0.86 V, 20 mV more positive than that of Commercial PtC (0.84 V), together with a kinetic current density of 11.95 mA cm −2 at 0.85 V and a Pt mass activity of 203.64 mA mg Pt −1 , substantially higher than that of Commercial PtC (3.92 mA cm −2 and 62.19 mA mg Pt −1 , respectively). Moreover, PtFeNC-S retains 88.8% of its initial current after 24 h of continuous operation, compared with 81.7% for Commercial PtC, and exhibits only a 13 mV decrease in E 1/2 after 10,000 accelerated durability cycles, lower than the 18 mV decrease observed for Commercial PtC. The high performance arose from both the uniform dispersion of Pt nanoparticles and the presence of C-S-C sites, along with FeN x sites that added further active centers for ORR. Density functional theory (DFT) calculations indicate that the downshift of d-band center for Pt was induced by synergistic interaction of Pt and FeN x sites, and S doping, thereby promoting OH desorption and augmenting ORR performance. The study presents a straightforward approach for synthesizing Pt catalysts that exhibit promising capabilities. Download: Download high-res image (251KB) Download: Download full-size image