CeO2 quantum dots decorated g-C3N4 nanosheets: A potential scaffold for fluorescence sensing of heavy metals and visible-light driven photocatalyst

Herein, we report the synthesis of g-C3N4/CeO2 heterostructure using a facile co-precipitation method. The as-synthesized g-C3N4/CeO2 heterostructure was examined by several techniques in order to understand the morphology, thermal, structural, optical and compositional properties. A strong interfacial contact was observed between g-C3N4 nanosheets and CeO2 quantum dots (QDs) as CeO2 QDs were deposited on g-C3N4 nanosheets with slight agglomeration. The as-synthesized heterostructure was successfully applied as a probe for the fluorescence sensing of heavy transition metals (Cu(II), Hg(II) and Ag(I)) and a visible light active photocatalyst for the decomposition of tetracycline (TC) in an aqueous phase. The g-C3N4/CeO2 heterostructure exhibited remarkable selectivity towards the sensing of Cu(II), Hg(II) and Ag(I) heavy metal ions because of strong binding affinity of these metal ions towards nitrogen and oxygen containing functional moieties present in g-C3N4/CeO2 heterostructure. Furthermore, a good linearity was observed between the relative FL intensity and concentration of Cu(II), Hg(II) and Ag(I) ions with detection limit estimated to be 26.2 µM, 17.5 µM and 14.9 µM, respectively. The high selectivity for these ions was due to their strong binding affinity towards nitrogen and oxygen containing functional groups in g-C3N4/CeO2 heterostructure. Moreover, the removal efficiency of 77.95% was acquired for degradation of tetracycline in 160 min using g-C3N4/CeO2 heterostructure under optimized conditions. The photocatalytic results of the heterostructure could be accredited to the reduction in the recombination of excited carriers across the interface of the heterojunction. Therefore, the present work provides an effective strategy for the preparation of fluorescent photocatalytic materials that can be utilized for the FL detection of harmful heavy metal ions as well as degradation of pollutants in an aqueous phase.