TiO2/Nb2O5/carbon xerogel ternary photocatalyst for efficient degradation of 4-chlorophenol under solar light irradiation

Abstract This study examines the development of ternary photocatalysts based on titanium dioxide, niobium oxide, and carbon xerogel, aimed at increasing photocatalytic efficiency under solar light irradiation. The modifications proposed are focused on diminishing charge recombination and enhancing visible light sensitivity. The new photocatalyst was prepared using discarded titanium and niobium scraps and chips, whilst black wattle tannin was used as the carbon source. The X-ray diffractometry results show that the anatase form of titanium dioxide is present in the samples, whereas the niobium oxide presents itself in the amorphous structure. The incorporation of both carbon xerogel and niobium oxide into the TiO2 is confirmed by the infrared and energy dispersive spectroscopies. The diffuse reflectance results show that the materials containing carbon xerogel present a significantly higher visible light absorption, whilst the combined effect of the modifications proposed caused the gap energy of the ternary material to drop noticeably. The photocatalytic efficiency of the ternary material was superior to the ones found for the pure oxides and binary material, probably due to its lower value of bandgap and enhanced charge separation efficiency, as confirmed by the electrochemical impedance tests.