CHEM01200604009 Sreejith Kaniyankandy - Homi Bhabha ...

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6.2.2. Reduction of Graphene Oxide
1gm of as prepared Graphene Oxide were dispersed in 1 litter of 1M NaOH and sonicated for
1 hour. This solution was cooled to 0 ○ C. To this solution 2gm of NaBH 4 was added with
vigorous stirring. This above solution was maintained at 0 ○ C for 2h and heated to 50 ○ C for
2h [6.20].
6.2.3. Synthesis of CdTe Decorated Graphene
The CdTe QDs were prepared by colloidal methods as reported earlier [6.21]. Briefly, 10
mmol of CdCl 2 . 2.5H 2 O was added to the above solution of reduced graphene (1g/l). To this,
mercaptopropionic acid (MPA) was added with mole ratio of MPA:Cd = 2.4:1. The solution
was then purged with nitrogen gas (N 2 ). The tellurium precursor NaHTe, was prepared by
the reaction between NaBH 4 and tellurium powder in N 2 purged water at 0°C for 8 hours.
Part of this solution was added to the Cd precursor solution with the ratio of Cd:Te = 1: 0.5.
The above mixed solution was then refluxed for 4hours. The solution was then concentrated
at reduced pressure by a Butchi Rotavapor to 1/3 of the original volume and isopropyl
alcohol was added to the concentrated solution to precipitate the graphene-quantum dots
composites. The collected composites were re-dissolved in nanopure water and precipitated
with isopropyl alcohol, this process was repeated for 3 times to remove the precursors and
clean the composites. Synthesis of CdTe quantum dots for the comparison of dynamics have
been carried out by the same procedure as described above without the addition of exfoliated