Engineering sponge-like MoS2@Co(OH)2 hybrid structures as efficient non-precious metal catalysts for overall alkaline water splitting

Abstract

Efficient and durable catalysts are essential for sustainable energy conversion via electrochemical water splitting. MoS₂ is a promising candidate with abundant hydrogen adsorption sites, but its limited water dissociation kinetics hinder HER in alkaline media. Conversely, Co(OH)₂ exhibits superior water dissociation performance, but lacks hydrogen adsorption activity. To address these limitations, we present a top-down electrochemical synthesis approach for a porous MoS₂@Co(OH)₂ hybrid structure, enabling synergistic performance for bifunctional water splitting. SEM reveals a sponge-like morphology that facilitates mass transport and electrolyte accessibility. Hydrogen evolution requires only an overpotential of 226 mV to reach 10 mA/cm², due to the complementary roles of MoS₂ in facilitating hydrogen adsorption/recombination and Co(OH)₂ in accelerating water dissociation. XPS confirms Mo⁴⁺/Mo⁶⁺ and M-O-S species that can synergistically enhance adsorption-desorption. For OER, the hybrid catalyst reaches an overpotential of 341 mV at 10 mA/cm², with excellent stability over 24 h. In overall water splitting, the Faradaic efficiencies were 94 % for H₂ and 96 % for O₂. The cell voltage of 1.86V for M0.6@C1 ||M1@C1 accentuates MoS₂@Co(OH)₂ as a promising bifunctional electrocatalyst. The design strategy presented herein unveils a broadly applicable approach for designing hybrid surface architectures via electrochemical top-down synthesis for advanced energy conversion systems.