Bimetallic FeCo phosphide nanoparticles anchored on N-doped carbon foam for wide pH hydrogen evolution reaction

Abstract

Transition metal phosphides (TMPs) have considered as excellent electrocatalysts with high reactivity for hydrogen evolution reaction (HER). While electro-catalytic properties of TMPs are restricted by uneven dispersion, small surface area, poor conductivity, and unsatisfied stability. Herein, a facile procedure was proposed to prepare a hierarchical structure of FeCoP nanoparticles anchored on N-doped carbon/multi-walled carbon nanotubes (NC/CNT) nanocomposites. With the increased porosity and conductive network of NC/CNT substrate, the as-synthesized NC/CNT-FeCoP provided abundant active sites for HER. Meanwhile, due to the synergistic effect between the dual metal centers and uniform distribution of bimetallic composites, the synthesized electrocatalyst can provide enhanced intrinsic activity. Therefore, the optimized NC/CNT-FeCoP delivered excellent HER activity in 1.0 M KOH and 0.5 M H2SO4 with overpotentials of 182 mV and 150 mV at 10 mA cm−2, respectively. Moreover, NC/CNT-FeCoP coupled two-electrode system needs a low cell potential of 1.68 V at 10 mA cm−2 for overall water splitting. First-principle calculations indicated that N-doped graphene substrate can adjust the electronic properties of surface metal site and consequently affect the H adsorption strength to yield an improved HER activity. Our work demonstrated that the combination of mesoporous conductive matrices with bimetallic phosphides could greatly improve the HER efficiency for electrocatalysis.