Encapsulation of Janus-structured Ni/Ni2P nanoparticles within hierarchical wrinkled N-doped carbon nanofibers: Interface engineering induces high-efficiency water oxidation

[Display omitted] •A scalable strategy was developed to immobilize Ni/Ni2P within N-CNF.•Janus-structured Ni/Ni2P renders optimal electronic state and active sites.•Carbon nanosheet-grafted N-CNF leads to shortened distance for mass transport.•Strong coupling of Ni/Ni2P and carbon substrate enhances electrochemical stability.•Ni/Ni2P@N-CNF exhibits high-efficiency water oxidation performance in KOH medium. The exploration of efficient and economical electrocatalysts towards the oxygen evolution reaction (OER) is highly imperative for the development of OER-associated sustainable energy technologies. Interface engineering-enabled electronic regulation represents a powerful leverage to improve the intrinsic activity of earth-abundant electrocatalysts. Herein, we report a scalable hydroxycarbonate-assisted pyrolysis strategy to immobilize Janus-structured fine Ni/Ni2P nanoparticles onto hierarchical N-doped carbon nanosheet-grafted nanofibers (denoted as Ni/Ni2P@N-CNF hereafter) for high-efficiency electrocatalytic OER. The strong coupling of fine Ni/Ni2P hetero-nanoparticles with the superstructured carbon substrate renders Ni/Ni2P@N-CNF with regulated electronic state, sufficient anchored active sites, shortened distance for mass transport and enhanced structural stability. Consequently, the optimized Ni/Ni2P@N-CNF exhibits extraordinary electrocatalytic OER activity and durability in KOH medium. As a proof-of-concept demonstration, when pairing Ni/Ni2P@N-CNF with commercial Pt/C catalyst for overall water splitting, the assembled two-electrode electrolyzer outperforms the state-of-the-art RuO2‖Pt/C-equipped counterpart. The concept of interface engineering and carbon hybridization herein may provide new inspirations for the future design of affordable and efficient electrocatalysts for various sustainable energy conversions.