Improved ion-diffusion assisted uniform growth of 1D CdS nanostructures for enhanced optical and energy storage properties

The defect-free growth of 1D CdS nanostructure faces serious setback since other techniques heavily bank on high-temperature growth, use of organic solvents, catalyst, seed layer, and expensive electrodes. Over and above, the organic ligand passivates the surface defect states that obstruct the optical pathway of 1D nanostructures; and make them unsuitable for device applications. Amidst all these shortcomings, low-cost ion-diffusion is one such technique which is simple, reproducible and eco-friendly for the synthesis of defect-free pure CdS nanotubes (NTs) through AAO membrane; reported here with strong merits, unlikely not possible with the conventional approaches. Aligned CdS NTs with tapered diameter at the bottom were fabricated for its possible incorporation into nanoscale photonic devices. The synthesized NTs showed strong photoluminescence (PL) near-band-edge emission and third order multiphonon LO mode in resonant Raman scattering (RRS); due to its small crystalline grain size. In addition, the well-aligned hollow CdS NTs on AAO membrane proved to be an excellent energy electrode material with a specific capacitance of 1207 F g⁻¹ at a scan rate of 5 mV s⁻¹ in 6 mol L⁻¹ KOH with 10⁻⁴ mol L⁻¹ of K₃Fe(CN)₆ as redox additive electrolyte.