Self-supporting Co-MoOx@N-doped carbon/expanded graphite paper for efficient water splitting catalyst

Abstract

Molybdenum oxides are widely used as electrocatalysts due to their polymetallic oxidation state, abundant reactive sites and low production cost. However, the low electrical conductivity and easy agglomeration has limited their practical application. Here, MoO3 nanowires encapsulated with ZIF-67 polyhedra were grown in situ on expanded graphite paper (EGP) by a simple hydrothermal synthesis method, and then the precursors were pyrolyzed to obtain self-supported Co-MoOx@N-doped carbon/EGP composites. Thanks to the three-dimensional porous structure and the synergistic effect of Co and multi-valance MoOx, the as-prepared Co-MoOx@N-doped carbon/EGP exhibits the excellent performances of OER (η10 = 256 mV) and HER (η10 = 138 mV), and a small Tafel slope and good durability. Furthermore, the assembled water splitting device achieved a current density of 10 mA cm−2 at a low voltage of 1.62 V and the excellent stability after 24 h continuous water splitting.