Electrocatalyst nanoarchitectonics with molybdenum-cobalt bimetallic alloy encapsulated in nitrogen-doped carbon for water splitting reaction

The rational construction of highly efficient electrocatalysts comprising multiple components with distinctive bifunctionalities is still a challenge for the practical application due to their sluggish kinetics for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Here, a series of cobalt-molybdenum alloy nanorods encapsulated in N-doped carbon shells (CoMo@NC) is synthesized via an in-situ carbonization-reduction method using CoMoO4 as the precursor. The high conductivity, strain-induced effect, and synergistic interactions between N-doped carbon and bimetallic cores endow the optimized catalyst with outperforming catalytic performances for HER and OER in alkaline solution with low overpotentials (98 mV for HER and 336 mV for OER at 10 mA cm-2), as well as high durability. The overall water splitting device using the CoMo@NC sample achieved at 800 celcius treatment (CoMo@NC-800) as bifunctional catalyst could possess a low voltage of 1.67 V to drive a current density of 10 mA cm-2 and high durability. Furthermore, density functional theory calculations reveal that the pyridinic-N atoms of graphene anchored on CoMo alloy nanoparticles can efficiently modulate the electronic structure to generate optimal free energy of hydrogen adsorption (-0.029 eV), suggesting excellent HER intrinsic activity. This work may provide a facile avenue to achieve multiple metallic alloy-based nanomaterials for boosting electrochemical water splitting performance.