Enhancing Supercapacitor Performance with Zero-Dimensional Tin–Niobium Oxide Heterostructure Composite Spheres: Electrochemical Insights

The development of advanced tin and niobium bimetallic composite electrode materials is crucial for enhancing the performance of supercapacitors. In this paper, we present a novel bimetallic composite material consisting of zero-dimensional spherical-like SnNb2O6 nanocomposites synthesized through the reaction of tin oxide (SnO2) and niobium pentoxide (Nb2O5) precursors, alongside comparative materials. The morphology of the spherical agglomerates comprising Sn/Nb oxide particles that were nucleated on the SnNb2O6 surface was characterized using field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM). The as-prepared heterostructures of the SnNb2O6 composites were analyzed for elemental composition, including Sn3d, Nb3d, and O1s; moreover, chemical oxidative state analysis was performed through X-ray photoelectron spectroscopy (XPS). Additionally, cyclic voltammetry curves exhibited pseudocapacitive redox behavior for the SnNb2O6 composites, while the galvanostatic charge-discharge (GCD) performance demonstrated a maximum specific capacitance of 294.8 F/g at 1 A/g. Moreover, SnNb2O6 composite electrodes demonstrated rapid charge–discharge kinetics and excellent cycling stability, with a capacitance retention of 95.7% over 10,000 cycles. This study elucidated the synthesis of tin–niobium oxide-based composites, demonstrating their potential for high-performance supercapacitors.