ZnCr-CO₃ LDH/ruptured tubular g-C₃N₄ composite with increased specific surface area for enhanced photoelectrochemical water splitting

Ruptured tubular structured graphitic-carbon nitride (RT g-C₃N₄) was prepared, followed by in-situ growth of carbonate-intercalated ZnCr layered double hydroxide (LDH) on its surface by the co-precipitation method. The fabricated composites contain varying amounts of the LDH. An increase in the specific surface area of the g-C₃N₄/LDH₃ composite (103.74 m²/g) was observed as compared to RT g-C₃N₄ (7.55 m²/g) and pristine LDH (11.26 m²/g). The formation, morphology and chemical composition of the pristine RT g-C₃N₄, pristine LDH and composites were examined by powdered-X-ray diffraction (p-XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) techniques. Optical measurements by ultraviolet-visible (UV) diffuse reflectance spectroscopy revealed that the band gap of the composites can be tuned by varying the LDH concentration in the composite. The ability towards the separation of photo-generated electron-hole pairs was examined by photoluminescence (PL) and the curves of transient photo-current with time. Mott-Schottky measurements were carried out to determine the flat band potential. Finally, the photoelectrocatalytic activity represented by measurements of transient photo-current with time (i-t curve), electrochemical impedance spectroscopy, and linear sweep voltammetry (i-v curve) was examined.