Influence of Precursor Molar Concentration on the Morphology and Electrochemical Performance of Tin oxide Nanoparticles

Despite extensive studies on Tin oxide nanoparticles for energy storage applications, the role of precursor molar concentration as a simple and scalable parameter to simultaneously tune morphology, electronic structure, and electrochemical performance remains insufficiently explored. In this work, Tin oxide nanoparticles were synthesized via a co-precipitation method using precursor concentrations of 0.3, 0.4, and 0.5 M to systematically investigate this relationship. The results reveal that increasing molar concentration leads to a significant growth in crystallite size from ~5 nm to ~15 nm, accompanied by a reduction in optical band gap from 2.92 eV to 2.70 eV, indicating enhanced defect states and improved charge transport properties. Morphological evolution from relatively smaller particles to agglomerated secondary nanostructures at higher concentrations provides improved interparticle connectivity, which is beneficial for electrochemical applications. Electrochemical analysis demonstrates that all samples exhibit electrical double-layer capacitive behaviour with good reversibility. Notably, the 0.5 M sample delivers a maximum specific capacitance of 131 Fg-1 (CV) and 26 Fg-1 (GCD), compared to 79 Fg-1 and 14 Fg-1 for the 0.3 M sample. The enhanced performance is attributed to the combined effect of increased crystallite size, reduced band gap, and favorable morphological features facilitating efficient ion diffusion and electron transport. This study establishes a direct correlation between precursor molar concentration and the resulting physicochemical and electrochemical properties of SnO2 nanoparticles, demonstrating a simple yet effective strategy for optimizing electrode materials for high-performance supercapacitor applications.