Facile sono-design of 3D flower-like NiO–CuFe2O4 nano-heterostructure as an efficient and magnetically separable catalyst for photodegradation of organic dyes

Abstract

The magnetic flower-like NiO–CuFe2O4 p-p heterostructure nanophotocatalysts with various weight percentages of NiO were prepared to study the photodegradation of the different organic dyes under simulated sunlight illumination. To design these novel nanocomposites, co-precipitation, and ultrasound-assisted hydrothermal approaches were utilized. Different characterization techniques including XRD, FESEM, EDX, BET-BJH, DRS, PL, EIS, VSM and pHpzc were applied over the as-prepared nanophotocatalysts. Also, Mott Schottky analysis was also used to confirm the formation of p-p heterojunction structure in NiO–CuFe2O4 nanocomposites. The p-p heterostructured NiO–CuFe2O4 nanophotocatalyst with the composition of 40 wt% NiO and 60 wt% CuFe2O4 (NiO(40)-CuFe2O4(60)), as the optimum and solar-light-responsive nanophotocatalyst, exhibited considerable photocatalytic performance toward the photodegradation of different dye pollutants. Surprisingly, the removal and mineralization efficiency of MG reached 88.7% and 73.4% in the reaction time of 120 min, respectively. The enhanced photo-activity of NiO(40)-CuFe2O4(60) nanocomposite compared to pure NiO and CuFe2O4 could be attributed to its high light absorption capacity in the solar light region and effective separation of photo-induced charge carriers, ball flower-like morphology, higher specific surface area (42 m2/g), larger pore volume (0.127 cm3/g), lower band gap energy, and appropriate created p-p heterojunction structure, which effectively lessoned the recombination processes of the photo-induced electron-hole pairs. Besides, some other operation parameters, including catalyst loading, initial dye concentration, and initial solution pH were examined in this study. The reusability study was performed in four sequential cycles that the negligible reduction of 7.4% in the photocatalytic degradation efficiency has illustrated the excellent chemical and optical stability of this magnetically separable photocatalyst. Eventually, the degradation mechanism of malachite green under solar light irradiation over NiO(40)-CuFe2O4(60) nanophotocatalyst was suggested.