Wastewater from many sectors that contains hazardous organic pollutants exacerbates environmental contamination. Consequently, outstanding photocatalytic substances that can successfully degrade hazardous substances are needed to provide pollution-free water. From this perspective, zinc oxide/g-C₃N₄-based composites are desirable due to their low cost, strong reactivity, and environmental friendliness. So, in the current investigation, sequences of Mn/g-C₃N₄/ZnO (Mn/GZ) and Ni/g-C₃N₄/ZnO (Ni/GZ) nanocomposites (NCs) containing different concentrations (wt.%) of g-C₃N₄ were made via the co-precipitation process. The chemical makeup and morphological characteristics of the produced composites were ascertained via the techniques of transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), Fourier transform infrared (FTIR), photoluminescence (PL), and UV spectrophotometry. Methyl orange (MO) and Eriochrome Black T (EBT) dyes were used as target pollutants to assess the composite materials’ photocatalytic effectiveness. Compared to g-C₃N₄/ZnO and g-C₃N₄, the produced Mn/GZ and Ni/GZ NCs displayed better photocatalytic activity. The improved photocatalytic efficiency of the Ni/GZ and Mn/GZ NCs might be credited to synergistic interactions at the g-C₃N₄ and ZnO interface that result in a more efficient separation and conduction of photo-induced charges. Furthermore, the Ni/Mn atoms act as the facilitators to improve electron–hole pair separation and conduction in NCs. The nanocomposites were found to be incredibly stable, with consistently high dye decoloration efficiency over five catalytic cycles. Hence, Ni/GZ and Mn/GZ could potentially be very effective and adaptable photocatalysts for the photocatalytic decoloration of wastewater pollutants.

Cobalt-doped potassium hexa-titanate (Co_x:K₂Ti₆O₁₃ (x = 0.05, 0.10, 0.15 mole%)) ceramics were synthesized by the solid-state reaction method. The XRD patterns confirmed single-phase development in a monoclinic symmetry of various samples, and they were used for different structural calculations of Co_x:K₂Ti₆O₁₃ ceramics. The dielectric constant, tanδ, electrical modulus, and ac conductivity of Co-doped K₂Ti₆O₁₃ were studied in the temperature range of 100–500 °C. Anomalies were observed in graphs of the dielectric constant versus temperature, showing the transition phase in the studied samples. Dielectric peaks at transition temperature decreased with an increasing frequency, and the peaks shifted toward higher temperatures, illustrating the relaxation of the dielectric materials. The composition with x = 0.10 showed low dielectric loss and a higher dielectric constant and can be utilized for high-temperature dielectric material. Small doping of cobalt improved the ac conductivity of K₂Ti₆O₁₃ ceramics due to the increase in the spin–phonon interaction and dominant electron hopping conduction; however, the conductivity diminished with substantial doping because of the contraction of the tunnel space and ambushing of conduction electrons. The uniqueness of this study is in the high dielectric optimization of lead-free ceramic Co_x:K₂Ti₆O₁₃ and the discovery of positive temperature coefficients of the resistivity of these ceramic samples.