Photocatalytic reduction of 4-nitrophenol over eco-friendly Ni_xCu_xFe₂O₄ without an additional reducing agent in water

Organic pollutants such as 4-nitrophenol (4-NP) pose serious environmental extortions due to their chemical stability for which efficient catalytic materials are indispensable in treating them. In this regard, the present work involves the synthesis of two different types of ferrites (NiFe₂O₄, and CuFe₂O₄), and a combination of Ni_xCu_xFe₂O₄ with various ratios that systemically work as efficient photocatalysts without any additional reducing agents is reported. The structural, and morphological properties of NiFe₂O₄, CuFe₂O₄, and NiCuFe₂O₄ were characterized by XRD, FT-IR, SEM, and HRTEM techniques. Then, the catalytic role of individual ferrite catalysts was evaluated towards catalytic reduction of 4-NP under visible light. The progress dye reduction was examined via UV–vis spectrophotometry. The effect of various concentrations, and reduction time were investigated. The kinetic rate constants determined for NiFe₂O₄, CuFe₂O₄, and Ni_xCu_xFe₂O₄ revealed that Ni and Cu in bimetallic ferrites promoted the reduction reaction under visible light. The results demonstrated that the photo-reduction efficiency of the Ni_0.7Cu_0.3Fe₂O₄ catalyst over 4-NP (conc. 10 ppm) to 4-AP was determined as 82 % under 120 miniutes with good recyclability up to six cycles. The mechanism of photocatalytic reduction of ferrites without the use of a reducing agent was studied. Such facile and productive ferrite materials could be employed as efficient photocatalysts for the reduction of toxic organic contaminants in environmental treatment.