Analytical investigation of co-precipitated SnO2–CuO nanocomposite: synthesis, characterization, and performance assessment

Abstract

In this work, SnO2–CuO composites were synthesized in a 1:1 ratio using the co-precipitation method and calcined at varying temperatures from 300 to 600 °C. X-ray diffraction (XRD) confirmed a phase transition from semicrystalline to crystalline with increasing temperature, accompanied by crystallite growth from 8 nm to 13 nm and a corresponding decrease in micro strain and dislocation density. Scanning electron microscopy (SEM) revealed morphological evolution from block-like structures at lower temperatures to fine-grained particles at higher temperatures, indicating improved crystallinity. UV–visible analysis shows a redshift in absorption peaks, suggesting band gap narrowing that can enhance conductivity, while FTIR spectra exhibited a reduction in O–H bond intensity with increasing temperature. Electrical characterization demonstrated superior conductivity at higher calcination temperatures, with impedance analysis showing distinct calcination temperature-dependent behavior. The sample calcined at 500 °C displayed a pronounced semi-circular arc in the Nyquist plot, lower dielectric constant and loss, and minimal AC conductivity attributed to p–n junction formation and strong interfacial interactions. This paper demonstrates a full correlation between calcination temperature, microstructure, crystallinity, dielectric behavior, and electrical properties, finding that 500 °C is the suitable temperature for calcination of SnO2–CuO nanostructures suggesting its potential suitability for future gas sensing applications for gas sensing application.