Self-Supported Super-Hydrophilic Interconnected Nanospikes and Particles of MoS2-Ni3S2/NF with Optimum d-Band Center for Anion Exchange Membrane Water Electrolyzer

Abstract

There is an imperative need for highly efficient electrocatalysts for cost-effective hydrogen production. Herein, a self-supported, hybrid composite as a bifunctional electrocatalyst is introduced. This is achieved by in situ growth of MoS₂-Ni₃S₂ on nickel foam (NF), designated as MoS₂-Ni₃S₂/NF, synthesized by a facile one-step hydrothermal synthesis method. MoS₂-Ni₃S₂/NF exhibits low overpotentials of only 187 and 146 mV for OER and HER, respectively, to achieve a current density of 10 mA cm⁻² in 1 M KOH. The practical application of the designed bifunctional electrocatalyst is verified by constructing the MoS₂-Ni₃S₂/NF || MoS₂-Ni₃S₂/NF symmetrical membrane electrode assembly (MEA) of 4 cm² working area for the anion exchange membrane water electrolyzer. The system shows continuous electrolysis for the monitored 48 h duration. For OER, an optimum d-band center of −1.66 eV for the heterostructure is calculated from the Density Functional Theory (DFT) studies. The factors like the unique structure of the electrocatalyst, enhanced hydrophilicity, improved electrochemically accessible number of sites (ECASs), and optimum d-band center, are expected to be the primary contributors to the system's improved performance. Thus, the present finding unveils a straightforward synthesis approach for creating a stable electrocatalyst for advancing commercial water electrolysis in the realm of renewable electrochemical energy conversion.