Efficient electrochemical water splitting using copper molybdenum sulfide anchored Ni foam as a high-performance bifunctional catalyst

Abstract

The necessity of developing a bifunctional catalyst for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has increased due to the urge to meet the future renewable energy requirements. This work demonstrated the use of copper molybdenum sulfide nanostructures on Ni foam (CMS/Ni) as a bifunctional catalyst for the HER and OER. Physicochemical characterizations such as X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopic analyses confirmed the formation of hierarchical CMS nanostructures on Ni foam using a hydrothermal method. The CMS/Ni electrocatalyst exhibits excellent electrocatalytic properties in an alkaline electrolyte (1 M KOH) with a low overpotential of about 213 and 350 mV for the HER and OER (to drive a current density of 50 mA cm⁻²) and Tafel slope values of 80 and 124 mV dec⁻¹, respectively. A lab-scale water electrolyzer is constructed using the CMS/Ni electrocatalyst (as anode and cathode), which requires a low voltage of 1.62 V (at a current density of 50 mA cm⁻²) for electrochemical water splitting reaction. The multi-current and long-term stability analysis suggested better electrocatalytic properties of the CMS/Ni electrode. Finally, a self-powered water electrolyzer system was constructed via integration of a solar cell with the fabricated CMS/Ni electrolyzer, which demonstrated potential application towards next-generation energy conversion and management systems.