Nanosized Metal Phosphides Embedded in Nitrogen‐Doped Porous Carbon Nanofibers for Enhanced Hydrogen Evolution at All pH Values

Transition-metal phosphides (TMPs) have emerged as promising catalyst candidates for the hydrogen evolution reaction (HER). Although numerous methods have been investigated to obtain TMPs, most rely on traditional synthetic methods that produce materials that are inherently deficient with respect to electrical conductivity. An electrospinning-based reduction approach is presented, which generates nickel phosphide nanoparticles in N-doped porous carbon nanofibers (Ni₂ P@NPCNFs) in situ. Ni₂ P nanoparticles are protected from irreversible fusion and aggregation in subsequent high-temperature pyrolysis. The resistivity of Ni₂ P@NPCNFs (5.34 Ω cm) is greatly decreased by 10⁴ times compared to Ni₂ P (>10⁴ Ω cm) because N-doped carbon NFs are incorporated. As an electrocatalyst for HER, Ni₂ P@NPCNFs reveal remarkable performance compared to other previously reported catalysts in acidic media. Additionally, it offers excellent catalytic ability and durability in both neutral and basic media. Encouraged by the excellent electrocatalytic performance of Ni₂ P@NPCNFs, a series of pea-like M_x P@NPCNFs, including Fe₂ P@NPCNFs, Co₂ P@NPCNFs, and Cu₃ P@NPCNFs, were synthesized by the same method. Detailed characterization suggests that the newly developed method could render combinations of ultrafine metal phosphides with porous carbon accessible; thereby, extending opportunities in electrocatalytic applications.