In situ synthesis of g-C3N4/Ti3C2Tx nano-heterostructures for enhanced photocatalytic H2 generation via water splitting

Abstract

Herein, we demonstrated the in situ synthesis of g-C₃N₄/Ti₃C₂T_x nano-heterostructures for hydrogen generation under UV visible light irradiation. The formation of the g-C₃N₄/Ti₃C₂T_x nano-heterostructures was confirmed via powder X-ray diffraction and supported by XPS. The FE-SEM images indicated the formation of layered structures of MXene and g-C₃N₄. HR-TEM images and SAED patterns confirmed the presence of g-C₃N₄ together with Ti₃C₂T_x nanosheets, i.e., the formation of nano-heterostructures of g-C₃N₄/Ti₃C₂T_x. The absorption spectra clearly showed the distinct band gaps of g-C₃N₄ and Ti₃C₂T_x in the nano-heterostructure. The increase in PL intensity and broadening of the peak with an increase in g-C₃N₄ indicated the suppression of electron–hole recombination. Furthermore, the nano-heterostructure was used as a photocatalyst for H₂ generation from water and methylene blue dye degradation. The highest H₂ evolution (1912.25 μmol/0.1 g) with good apparent quantum yield (3.1%) and an efficient degradation of MB were obtained for gCT-0.75, which was much higher compared to that of the pristine materials. The gCT-0.75 nano-heterostructure possessed a high surface area and abundant vacancy defects, facilitating the separation of charge carriers, which was ultimately responsible for this high photocatalytic activity. Additionally, TRPL clearly showed a higher decay time, which supports the enhancement in the photocatalytic activity of the gCT-0.75 nano-heterostructure. The nano-heterostructure with the optimum concentration of g-C₃N₄ formed a hetero-junction with the linked catalytic system, which facilitated efficient charge carrier separation also responsible for the enhanced photocatalytic activity.