Visible light-driven Nd-ZnSe: Structural insights and enhanced photocatalytic degradation of Congo red dye

Abstract

In this study, cubic zinc blende ZnSe and Nd-doped ZnSe (Zn_1−xNd_xSe; x = 0.05) nanomaterials were synthesized using a co-precipitation protocol to investigate their photocatalytic performance for Congo Red (CR) dye degradation. The pH of the growth medium was adjusted to 3.0, 5.0, and 7.0 in an acidic medium using hydrazine hydrate as the reducing agent to study its impact on the synthesis conditions of the semiconductor chalcogenide. The cubic structure was confirmed through structural analysis, which revealed a decrease in particle size with increasing pH. The optimal growth condition was identified based on morphological analysis. Optical studies showed a reduced band gap (2.46 eV at pH 5) due to Nd doping, facilitating visible light absorption and enhancing photodegradation activity. The neodymium doped ZnSe NPs demonstrated exceptional photocatalytic efficacy for the degrading Congo Red dye under sunlight, achieving 94.3% degradation within 80 min. Adsorption kinetics followed the first-order and Elovich models, while the Temkin isotherm provided the best fit for the synthesized catalyst, indicating strong dye-catalyst interactions. After four cycles of stability testing, the catalyst maintained over 95% efficiency, demonstrating its remarkable durability and potential for sustainable wastewater treatment.