Green photoluminescence, supercapacitor and cytotoxic properties of nickel doped haematite nanoparticles

Fe${}_2$O${}_3$: Ni (1–9 mol.%) nanoparticles (NPs) were synthesized using the co-precipitation method and calcined at $500{}^{\circ }$C for 12 h. The crystallite size, phase, crystallinity, and structural parameters were analyzed via powder X-ray diffraction. The Bragg reflections confirmed that the synthesized NPs crystallize in a pure hexagonal crystal structure with space group R-3c. Surface morphology analysis revealed agglomerated NPs of irregular sizes and shapes. Energy Dispersive X-ray Analysis confirmed the presence of Fe, O, and Ni elements, as well as the purity of the sample. Both the direct band gap energy and crystallite size decreased with increasing dopant concentration. Detailed studies were conducted on the photoluminescence and anticancer properties. The CIE coordinates indicated a color tuning from blue to green in the visible region. CIE coordinates and CCT values ranging between 2860 to 9547 k demonstrated that the synthesized nanophosphor material meets the requirements of display technology. Additionally, anticancer properties were investigated using HeLa cells and compared with the standard drug cisplatin for biomedical applications. Electrochemical investigations revealed super capacitance values ranging from 93.43 to 149.13 F/g at a scan rate of 10 mV/s with increasing Ni${}^{2+}$ concentration. Therefore, the synthesized Ni${}^{2+}$-doped hematite NPs show great promise in display technology, the biomedical field, and as supercapacitors in energy storage devices.