Mini-review on Synthesis and Characterization of Metal/Silver Iodides Nanostructures and Their Applications to Optical Sensors

Currently, metal/silver iodide (AgI) nanomaterials are considered one of the most promising material candidates for future optical sensor applications because of their inherent optical, electronic, and photoactive properties. The integration of AgI is beneficial because it has a wide bandgap of about 2.8–3.0 eV, a high refractive index, and a high light absorption in the ultraviolet-visible region that improves the sensor's performance. With the incorporation of metal nanoparticles such as silver (Ag) and gold (Au), AgI possesses photochromic characteristics, plasmonic behavior, and surface-enhanced Raman spectroscopy as well as localized surface plasmon resonance properties, which offer higher sensitivity for real-time and label-free sensing. These nanocomposites are analyzed by gas sensing, sensing application of biology, sensing of pH, sensing of environmental pollution, and the application of optical imaging, where receptor-colorable properties enhance quantities of analyte especially in a high noise background. However, there are some drawbacks to their synthesis and application. The major limitations include instability of the environment, difficulties in reproduction when synthesizing, and challenges in mass production. Specifically, future work will involve investigating new approaches to creating layers of protection, solid-state stabilizers, and low-cost synthesis techniques for the purpose of enhanced stability and scalability. Besides, the scope of their uses in diagnostics, environment monitoring, and biomedical imaging will assure a steady position of metal/AgI nanocomposites as the materials for enhanced optical detection in the creation of future high-performance sensing systems. Received: 17 January 2025 | Revised: 9 April 2025 | Accepted: 5 August 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Nazia Nusrat: Conceptualization, Investigation, Writing – original draft. Humaira Aslam: Methodology, Validation, Investigation, Writing – review & editing. Ali Umar: Methodology, Formal analysis, Visualization. Jehanzaib Sohail: Software, Formal analysis, Data curation, Visualization. Aman Ullah: Methodology, Software. Shumaila Ayuab: Validation, Writing – original draft. Ayesha Siddiq: Investigation, Data curation. Shehla Honey: Conceptualization, Resources, Writing – review & editing, Supervision, Project administration. Misbah Ullah Khan: Conceptualization, Resources, Writing – review & editing, Supervision, Project administration.