Enhanced electrochemical behavior of C@CdS Core-Shell heterostructures

•C@CdS core shell structures are prepared by hydrothermal method.•The variations in the quantity of carbon nanospheres exerted discernible influence on the size, morphology and electrochemical characteristics of the resultant nanospheres.•A reduction in the quantity of carbon spheres led to an enhanced uniformity of CdS shell.•The sample with least amount of carbon demonstrated optimized optical and electrochemical properties showing high potential for solar cells. The current work presents hydrothermally synthesized carbon@cadmium sulfide core–shell nanostructures with varying carbon nanosphere concentrations. The series is prepared to investigate the shell thickness depending on the concentration of precursors and consequently impacting the optical and electrochemical properties of the core–shell structures. XRD analysis reveals enhanced crystallinity with reduced carbon. SEM & TEM confirm uniform spherical core–shell structures, with optimal uniformity at lower carbon levels. UV–vis spectroscopy demonstrates visible range absorption and reduced band gap with decreased carbon. Electrochemical analysis exhibits diffusion-controlled behavior and Warburg impedance, making the low-carbon sample most suitable for solar cells. Core-shell structures outperform pure carbon samples in absorbance and impedance spectroscopy, showcasing potential for solar cell applications.