N-doped carbon coated FeNiP nanoparticles based hollow microboxes for overall water splitting in alkaline medium

Stable, earth-abundant and efficient electrocatalysts for overall water splitting are urgently needed. In this work, we have reported the synthesis of FeNiP/NC hollow microboxes (FeNiP/NC) based bifunctional electrocatalyst via the phosphorization process using rationally designed cube-type metal-organic framework (FeNi-MOF) as both the template and carbon source. The FeNiP/NC, which were obtained by assembling the uniform FeNiP nanoparticals together through N-doped carbon, manifests outstanding catalytic performances for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in KOH solution. Notably, FeNiP/NC displays exceptional activity when it was utilized as both anode and cathode toward overall water splitting with potential of 1.54 V at a current density of 10 mA cm(-2) in alkaline electrolyte, which is much better than FeP/NC and Ni2P/NC electrocatalyst. More importantly, the improvement of the catalytic activities of FeNiP/NC mainly benefits from the well dispersion of FeNiP nanoparticles on the surface of carbon support, the large active surface area and the doping of N and C derived from organic ligands. In addition, the enhanced electrocatalytic performance of FeNiP/NC for OER is closely related with the in-situ formed surficial MOOH (M = Fe, Ni) active sites, which has been confirmed by X-ray photoelectron spectroscopy (XPS) analysis. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.