Porous Multishelled Ni₂P Hollow Microspheres as an Active Electrocatalyst for Hydrogen and Oxygen Evolution

Tailoring the morphology and microstructure of electrocatalysts is important in improving catalytic performance. Herein, porous multishelled Ni 2 P hollow microspheres assembled by nanoparticles were prepared through a simple and economical self-templating approach followed by phosphorization. Compared with nanoparticles and hierarchical solid-interior microspheres, the synthesized multishelled, hollow microstructures of Ni 2 P exhibit significantly higher electrocatalytic activity for the hydrogen evolution reaction in a 1 M KOH electrolyte. Additionally, a NiOOH layer is formed on the surface of Ni 2 P during anodic polarization, as revealed by electron microscopy, X-ray photoelectron spectroscopy, and in situ Raman analysis. The Ni 2 P/NiOOH derivative outperforms the benchmark RuO 2 in catalyzing the oxygen evolution reaction. Furthermore, pairing the carbon fiber paper-supported multishelled Ni 2 P as both the anode and cathode results in superior overall alkaline water splitting performance, generating 10 and 20 mA cm –2 current densities at applied cell voltages of only 1.57 and 1.64 V, respectively, together with outstanding durability. These results suggest that further elaboration of the design of multishelled and hollow structured metal phosphides is desirable for application in hydrogen and oxygen evolution electrocatalysis.