Oxygen Reduction Reaction Performance Boosting Effect of Nitrogen/Sulfur Co-Doped Graphene Supported Cobalt Phosphide Nanoelectrocatalyst: pH-Universal Electrocatalyst

Herein, a novel noble metal-free hybrid of CoP@N,S-3D-GN in which cobalt phosphide (CoP) anchored onto the nitrogen and sulfur co-doped three-dimensional graphene(N,S-3D-GN) architecture is proposed to catalyze the oxygen reduction reaction (ORR) both in acidic and alkaline media. The facile cost-effective fabrication strategy including hydrothermal self-assembly of 3D-GN and subsequent low-temperature phosphidation is implemented. The obtained hybrids exhibit pH-universal electrocatalytic activity towards ORR thanks to facilitated mass diffusion, boosted charge transport, and abundance of electroactive sites as a result of the synergistic effect of co-doped heteroatoms and metal phosphide nanoparticles. The virtues of large specific surface area and 3D-interconnected microporous and mesoporous architecture, as well as tailoring of the surface with CoP and N,S-co-doping, facilitate the ORR catalytic activity and offer four-electron pathways both in acidic (n = 3.962) and alkaline media (n = 3.991). CoP@N,S-3D-GN offered long-term stability with 91.8% and 82.8% retention of initial current after 25,000 s in 0.1 M KOH and 0.1 M HClO4 electrolytes, respectively. The boosted electrocatalytic performance of CoP@N,S-3D-GN puts forward its up-and-coming usage of noble metal-free electrocatalysts alternative to platinum-group metals for ORR. This work paves the way for designing the next generation electrocatalysts for renewable energy systems due to the intriguing features including pH-universal catalytic activity, satisfactory durability, relatively low-cost and scalable production method.

Automated summary

The novel noble metal-free hybrid CoP@N,S-3D-GN showed excellent catalytic performance for the oxygen reduction reaction (ORR) in both acidic and alkaline media, thanks to the synergistic effect of co-doped heteroatoms and metal phosphide nanoparticles. It offered four-electron pathways and demonstrated long-term stability, showcasing potential as an alternative to platinum-group metals for ORR. This work lays the groundwork for designing the next generation of renewable energy systems' electrocatalysts with intriguing features such as pH-universal catalytic activity, satisfactory durability, relatively low cost, and scalable production methods.