Construction of FeP Hollow Nanoparticles Densely Encapsulated in Carbon Nanosheet Frameworks for Efficient and Durable Electrocatalytic Hydrogen Production.

Developing noble-metal-free based electrocatalysts with high activity, good stability, and low cost is critical for large-scale hydrogen production via water splitting. In this work, hollow FeP nanoparticles densely encapsulated in carbon nanosheet frameworks (donated as hollow FeP/C nanosheets), in situ converted from Fe-glycolate precursor nanosheets through carbonization and subsequent phosphorization, are designed and synthesized as an advanced electrocatalyst for the hydrogen evolution reaction. FeP hollow nanoparticles are transformed from intermediate Fe3 O4 nanoparticles through the nanoscale Kirkendall effect. The two-dimensional architecture, densely embedding FeP hollow nanoparticles, provides abundant accessible active sites and short electron and ion pathways. The in situ generated carbon nanosheet frameworks can not only offer a conductive network but also protect the active FeP from oxidation. As a result, hollow FeP/C nanosheets exhibit excellent electrocatalytic performance for the hydrogen evolution reaction in 0.5 m H2 SO4 with a quite low overpotential of 51.1 mV at 10 mA cm-2 , small Tafel slope of 41.7 mV dec-1 , and remarkable long-term stability. The study highlights the in situ synthesis of two-dimensional metal phosphide/C nanocomposites with highly porous features for advanced energy storage and conversion.