Boosting electrocatalytic hydrogen generation from water splitting with heterostructured MoS2/NiFe2O4 composite in alkaline media

Abstract

Design and synthesis of earth-abundant and robust bifunctional electrocatalysts have been greatly sought for commercialization of the technology for clean and renewable energy and replacement of the energy equipment based on fossil fuels. In this work, a facile hydrothermal approach is used to synthesize MoS2/NiFe2O4-based nanocomposite as a novel electrocatalyst for alkaline water splitting. Surface analysis was conducted using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Benefiting from the synergy of lamellar MoS2 and crystalline NiFe2O4, the obtained MoS2/NiFe2O4 composite shows excellent hydrogen evolution reaction (η10 = 190 mV, η50 = 279 mV) and oxygen evolution reaction (OER) (η50 = 350 mV, η100 = 360 mV) activity with high TOF (0.01 s−1@190 mV for HER and 0.24 s−1 @360 mV for OER) and displays good electrochemical stability. Explicitly, the electrocatalyst requires a cell voltage of 1.69 V to drive overall water splitting at a current density of 10 mA cm−2. Density functional theory (DFT) results demonstrated that the MoS2/NiFe2O4 composite electrocatalyst has smaller hydrogen adsorption free energy (|ΔGH*|) than pristine MoS2 and NiFe2O4, which demonstrates the effective adsorption and cleavage of water on the catalyst surface. This work thus presents an approach for the synthesis and rational design of metal oxide/metal sulfide hybrids as an electrocatalyst with high performance for overall water splitting.