Abstract

This study explores the enhancement of photocatalytic performance in 2D ZnO-stearic acid (SA) composites through copper (II) doping. Materials containing 1–10 mol% Cu (II) were synthesized by coprecipitation and characterized using X-ray photoelectron spectroscopy, electron paramagnetic resonance, UV–visible and vibrational spectroscopies, as well as X-ray diffraction. These analyses confirmed the formation of single-phase composites with structures resembling the ZnO-SA precursor, but exhibiting discrete Zn/Cu doping, forming Zn1-xCuOx-SA materials. Scanning electron microscopy and Energy dispersive X-ray spectroscopy analysis revealed layered structure and the elemental compositions of the samples. High-resolution transmission electron microscopy (HR-TEM) images confirm the layered morphology of the Zn0.95Cu0.05O-SA sample, underscoring its two-dimensional material characteristics. Absorption band edge of the undoped hybrid ZnO is centered in the UVA zone, while copper-doped samples expanded into the visible range. Photoluminescence (PL) spectra exhibit multiple emission peaks related to defects within ZnO host. An intensity slight decrease in PL intensity is observed with increasing copper concentration, indicated a low recombination rate. Photoelectrochemical testing showed that Cu doping reduces charge recombination and increases current density, thereby improving photocatalytic degradation of pollutants such as indigo carmine and 4-chlorophenol under simulated sunlight. The optimally doped Zn0.95Cu0.05O-SA displayed significant efficiency improvements, degrading contaminants up to four times faster than the undoped composite and maintaining consistent performance over multiple cycles. Additional testing linked these photocatalytic improvements to enhanced charge separation and electron/hole transfer facilitated by Cu2+ ions, thereby boosting photocatalytic activity.