Tailoring the optical and structural properties of spinel nickel ferrite by simultaneous Sr2+ and Ce3+ doping philosophy to enhance the photocatalytic efficiency

Abstract

Herein, Sr and Ce co-doped spinel nickel ferrites (SCNF) were synthesized using a simple coprecipitation technique. Annealing of prepared precipitates was carried out at high temperature in a controlled muffle furnace. Additionally, SCNF composites with carbon nanotubes (CNTs) were also prepared through ultrasonication. The prepared photocatalyst samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy. XRD results confirmed the cubic spinel structure with the Fd3m space group of as-prepared spinel ferrites. Mott-Schottky analysis was carried out to determine the conduction band (CB) and valence band (VB) positions of the prepared doped and un-doped powder photocatalyst samples. The optical analysis results demonstrated a reduced band gap of 2.45 eV for the co-doped NF. Ciprofloxacin was used as a model drug to evaluate the photodegradation performance of the as-prepared nickel ferrite-based semiconductor photocatalyst samples. Among the tested samples, the SCNF/CNTs composite showed the highest degradation efficiency, achieving 91.3 % degradation within 120 min with a rate constant of 0.02094 min⁻¹. The key influential factors on photodegradation proficiency, such as the effect of drug concentration, photocatalyst dosage, pH effect, radical scavengers, and reusability of photocatalyst, were also studied in detail and discussed in this article. It was observed that the optimal conditions for the photodegradation of ciprofloxacin using the SCNF/CNTs photocatalyst were 5 ppm concentration, 15 mg catalyst dose, and pH 7.