One pot synthesis of multi-functional B doped g-C3N4-praseodymium oxide nanocomposites for colorimetric detection of Hg2+ ion and solar photocatalytic removal of toxic water pollutants

A novel praseodymium oxide-boron co-doped graphitic carbon nitride composite was synthesized via one-step solid-state thermal condensation of urea, orthoboric acid and praseodymium nitrate precursors. The prepared composites were characterized by various methods. All the prepared composites demonstrated multi-functional activities towards peroxidase-mimetic based colorimetric detection of Hg2+ ions and superior photocatalytic efficiency towards photodegradation of textile colorants, photoreduction of hexavalent chromium and nitro aromatics like para-nitro phenol (PNP) and para-nitro aniline (PNA). The superior photocatalytic activity can be attributed to the formation of type II heterojunction which facilitates charge separation and increases the lifetime of photogenerated charge pairs. As evident from the scavenger studies, these charge pairs are involved in the formation of superoxide and hydroxyl radicals. The superior activity of the optimum composite can be attributed to the porous flaky morphology, decreased optical band gap, heterojunction mediated charge separation, and praseodymium oxide's conductive nature. A linear range of about 0.25–800 nM of Hg2+ ions can be detected with a limit of detection (LOD) of 42.4 nM using the colorimetric strategy. The as-synthesized composite is thus a unique, efficient, economically viable, and excellent candidate for detecting and degrading various hazardous water pollutants.