Defect-engineered white-light emission in Zn-substituted Ni1-xZnxFe2O4–rGO hybrid spinels

The Zn-substituted Nickel Ferrite-rGO (NiFe 2 O 4 –rGO) nanocomposites were prepared to investigate its intrinsic defect-mediated optical emission tuning without external dopants. Formation of spinel structure with lattice distortions due to cation redistribution was confirmed by P-XRD. Uniform nanoscale distribution on rGO sheets was ascertained by HRSEM. The UV–Vis diffuse reflectance analysis revealed non-linear bandgap modification with Zn content, consistent with strain-induced electronic structure modification. The PL spectra revealed broad visible emissions dominated by intrinsic defects, with Zn substitution systematically modifying intensity and recombination dynamics. The CIE chromaticity plots revealed near-white emission, particularly for intermediate Zn content. This research illustrates that precise Zn 2+ substitution itself allows for structural and photoluminescent behavior control, with a defect-engineered pathway to white-light emission. Ni 1-x Zn x Fe 2 O 4 –rGO is a cost-effective, tunable optoelectronic material system. • Zn 2+ was substituted into NiFe 2 O 4 –rGO to tune structural and optical properties. • UV–Vis revealed bandgap tuning via Zn 2+ substitution and lattice strain effects. • PL showed defect-mediated visible emissions with near-white chromaticity. • HRSEM color mapping confirmed uniform Zn, Ni, Fe, O, and C distribution. • CIE plots confirmed white-light proximity for intermediate Zn compositions.