A novel bentonite–cobalt doped bismuth ferrite nanoparticles with boosted visible light induced photodegradation of methyl orange: synthesis, characterization and analysis of physiochemical changes

In this work, pure and bentonite-Co-doped multiferroic Bi1-xBentxFe1-yCoyO3 (x = 0.00 – 0.03, y = 0.00 – 0.15) bismuth ferrite (BFO) nanoparticles (NPs) were synthesised using a cost-effective solvothermal process without using any mineraliser. A meticulous investigation has been made on the structural, magnetic, electric and visible light-driven photocatalytic properties of bentonite–cobalt-doped BFO NPs. The XRD patterns showed a well-arranged rhombohedral crystalline structure with space group R3c. The structural phase transformation has been observed from R3c to orthorhombic with the pnma group for Bi1-xBentxFe1-yCoyO3 samples. The SEM analysis confirmed the presence of components with villiform aggregates and new dense nanometric spots with an average crystal size of about 14 nm. The values of the dielectric constant of BFO NPs have been increased with bentonite–Co doping and are maximum (340 at 1 kHz) for x = 0.03 and y = 0.05 at 100 Hz. The saturation magnetisation value of 0.47 emu/g for BFO increases with bentonite-Co-doped BFO NPs to a maximum value of 1.79 emu/g for the Bi0.97Bent0.03Fe0.85Co0.15O3 sample. The energy band gap value of Eg = 2.99 eV for BFO decreases with bentonite–Co doping, and minimum value, Eg = 2.59 eV for the x = 0.03, y = 0.15 sample. The percentage degradation efficiency of undoped BFO NPs (64%) increased after bentonite–Co doping to 92% for the removal of methyl orange. The improved ferroelectric, magnetic and photocatalytic properties of bentonite–Co-doped BFO NPs offer new application in multiferroic-based energy storage devices as well as the removal of toxic dyes (methyl orange) from water.