Photocatalytic detoxification of azo dyes and electrochemical detection of Pb²⁺ and Li⁺ using green-synthesized calcium-activated Ag nanocatalysts
Year: 2026
Type: article
Abstract: ABSTRACT The increasing demand for sustainable technologies to address environmental pollution and energy challenges has stimulated the development of multifunctional nanomaterials with superior photocatalytic and electrochemical properties. In this study, 3%, 6%, 9%, and 12% calcium-doped silver nanoparticles (Ca:Ag NPs) were prepared for the first time using a simple co-precipitation method. The morphological, structural, optical, photocatalytic and electrochemical properties of the prepared nanoparticles were systematically investigated using various analytical techniques. The successful synthesis of Ca:Ag NPs and the incorporation of calcium into the silver lattice were confirmed by XRD, SEM, TEM, XPS, and EDAX. UV–Visible spectroscopy revealed enhanced optical absorption and a reduction in the effective band gap with increasing calcium concentration, indicating improved photocatalytic performance. The photocatalytic activity of the prepared Ca:Ag NPs was evaluated through the degradation of the azo dyes Acid Orange (AO) and Congo Red (CR) under UV irradiation. The degradation efficiency increased progressively with irradiation time (0–120 min), demonstrating the excellent photocatalytic activity of the prepared nanocatalysts. The photodegradation efficiencies of Congo Red reached 65.3%, 66.35%, 85.35%, 68.70% for 3%, 6%, 9%, and 12% Ca:Ag NPs and photodegradation efficiencies of Acid Orange reached 40.8%, 58.70%, 66.4%, 59.15% respectively, after 120 min of UV irradiation. Among the investigated samples, 9% Ca:Ag NPs exhibited the highest photocatalytic activity, owing to the optimized calcium concentration, which effectively suppressed electron–hole recombination and intensified the generation of reactive oxygen species. The electrochemical performance of the synthesized Ca:Ag NPs was investigated using CV, EIS, and DPV. The enhanced electrochemical response is attributed to calcium-induced improvements in electron transport and the reversible Ag/Ag⁺ redox processes occurring at the nanoparticle surface. The Nyquist plot obtained from EIS exhibited a small semicircular diameter with a charge-transfer resistance of approximately 71.8 Ω, indicating efficient electron transfer kinetics and low interfacial resistance. Furthermore, the fabricated sensor demonstrated excellent sensing performance toward Pb²⁺ and Li⁺ ions, exhibiting sensitivities of 0.0062 A and 0.0043 A, respectively. Overall, the synthesized calcium-doped silver nanoparticles (Ca:Ag NPs) exhibited outstanding photocatalytic degradation of azo dyes and excellent electrochemical sensing performance for heavy metal ions, highlighting their potential as multifunctional nanomaterials for environmental remediation and chemical sensing applications.
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,920
OpenAlex ID: W7222982065