Noninjection ultralarge-scaled synthesis of shape-tunable CdS nanocrystals as photocatalysts

CdS nanocrystals with a wide variety of shapes including spheres, tetrahedra, and branched and flower-like structures have been conveniently tuned by only changing the amount of trioctylphosphine ( TOP) used in a noninjection synthetic approach, in which CdO and S powder were directly used as reactants in paraffin media. The noninjection approach could be facilely scaled up to tens of grams scale in one batch reaction. The shape-controlled growth mechanism could be explained by the TOP-concentration-dependent nuclei structure and monomer concentration. This is further confirmed by the effects of the amount of oleic acid and the Cd/S ratio on the morphology of the obtained CdS nanocrystals. All the CdS nanocrystal samples with different morphologies exhibit good photocatalytic activity for degradation of dyes. The observed lower photocatalytic activity of the sphere-shaped CdS nanocrystals could be ascribed to the higher PL emission efficiency relative to those with other morphologies, which results in low electron-hole separation efficiency. Our reported preparation approach can satisfy the requirements of industrial production bearing the advantage of low-cost, reproducibility and scalability.