Enhanced high-performance catalyst of α-MoO3/g-C3N4 composite for electrochemical water splitting and photocatalyst application

One of the active combinations for improving both photo-electrocatalytic performances by using transition metal oxide-based MoO₃ is a good electrocatalyst and carbon-based g-C₃N₄ is a good photocatalyst material. Moreover, it is essential for energy conversion and environmental applications due to rapid technological developments and the increasing energy crisis. In this study, we synthesize α-MoO₃/g-C₃N₄ composite by a one-step facile hydrothermal method. The physical characterizations are the crystalline structure, surface morphology, chemical composition, and optical properties of the catalyst investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), UV–Vis absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS) analysis. The photocatalytic degradation efficiency of ∼88 % is 50 mL of 10 mg/L organic rhodamine B dye degraded under visible light irradiation is attained in 70 min with stirring at 300 rpm speed by the 100 mg α-MoO₃/g-C₃N₄ composite. Furthermore, we demonstrate the overall hydrogen and oxygen evaluation reaction, that the electrocatalysts were deposited on a nickel foam substrate in an effective 0.5 M Na₂SO₄ electrolyte solution. These kinetic performances are examined using linear sweep voltammetry, chronoamperometry, chronopotentiometry, and electrochemical impedance spectroscopy analysis. The results showed that the α-MoO₃/g-C₃N₄ composite had a low overpotential of 187.6 mV and 139.3 mV, as well as a small Tafel slope of 126.2 mV/dec and 120.2 mV/dec for OER and HER, compared to bare α-MoO₃ and g-C₃N₄ catalysts, attained the 10 mA cm⁻² current density for 12 h of stability.