Woolen bun shaped CdS microspheres enfolded 1D nanowires for the superior photooxidation of dyes: A comparative case study

• Woolen bun shape microsphere morphology of CdS nanowires is prepared.
• Hexagonal lengthy CdS nanowires (8–10 μm × 50–80 nm) exhibit best photoactivity.
• Significant quenching (>80%) in CdS nanowires photoemission at 380 nm excitation.
• Photodegradation of dyes by CdS nanowires > nanorods > nanospheres under sunlight.
• Quantitative decomposition of rhodamine B to CO2 via many intermediate products.

Woolen bun shaped CdS microspheres (2–5 μm) wrapped by highly crystalline one dimensional CdS nanowires (length = 8–10 μm and diameter ∼80 nm) are synthesized via anodic alumina membrane to achieve the best photoactivity for the decomposition of rhodamine B (50 μM) and methylene blue (20 μM) dyes using sunlight (50 mW cm−2) irradiations. The higher number of surface exposed molecules for improved interactions with dye molecules in CdS nanowires led to its excellent photocatalytic performance over its spherical [cubic (∼12 nm) and hexagonal (∼15 nm) phase] and rod like (170 nm × 10 nm) morphology. Though of having less surface area (35.55 < 76 m2g−1) than nanorods, the crystalline structure with least surface defects, higher spectral response to absorb more light for multiple generation of charge carriers (e−–h+), and their superior delocalization for better charge separation as evidenced from its maximum (>80%) photoluminescence quenching and higher photoexcited charge carrier relaxation lifetime (3.6 ns) seems to be the cause of its outstanding performance. Many intermediate products and nearly linear increase in CO2 production are quantified during rhodamine B degradation by CdS nanowires under different time periods of sunlight irradiation.

Woolen bun shaped microspheres (2–5 μm) coiled with crystalline 1D CdS nanowires (8–10 μm × 80 nm; L × W) exhibits the best photoactivity for the complete decomposition of dyes using sunlight irradiation. Highly crystalline structure with least surface defects, higher spectral response for generation of charge carriers, better delocalization and higher number of its surface molecules for better interactions with dye molecules led to a drastic improvement in their photocatalytic activity relative to other CdS morphologies.Figure optionsDownload high-quality image (256 K)Download as PowerPoint slide