Anchoring spinel NiCr₂O₄ nanoparticles on tubular g-C₃N₄: Efficacious p-n heterojunction photocatalysts for removal of tetracycline hydrochloride under visible light

This study reports anchoring spinel NiCr₂O₄ nanoparticles over tubular g-C₃N₄ (TGC) through a facile process. The features of resultant photocatalysts were characterized via various analyses to perusal phase, optical, elemental, morphological, and electrochemical properties. Among the binary photocatalysts, the TGC/NiCr₂O₄ (20%) composite exhibited superior performance in the removal of tetracycline, which was 29.7 and 2.22-folds as much as the pristine g-C₃N₄ (abbreviated as GC) and TGC materials, respectively. Interestingly, the binary photocatalyst displayed tremendous activity in the visible-light degradation of cationic and anionic dye pollutants. The Mott-Schottky, EIS, photocurrent density, and PL analyses, along with scavenger tests confirmed the formation of a type II heterojunction between p-NiCr₂O₄ and n-TGC semiconductors, which resulted in effectual transfer and segregation of the photoinduced charges reinforced by the constructed electric field. The trapping results disclosed that the holes and superoxide anion radicals play major role in the photocatalytic degradation reaction. Considering the superior activity in visible-light-triggered degradation of different pollutants, high stability, and facile synthesis method, this binary photocatalyst is recommended as a sustainable photocatalyst for environmental applications.