10.1039/c5nr00656b
Electronically coupled hybrid structures by graphene oxide directed self-assembly of Cu 2-x S nanocrystals
GO was synthesized from graphite powder using a modified Hummers method, and dispersed in water.11 In a typical macroemulsion preparation, 150 μL of the GO solution in water (initial concentration ~ 4 mg mL-1) was diluted with 150 μL of deionized water (1:1 v/v). The solution was sonicated for about 20 minutes in order to exfoliate the GO sheets that are initially stacked in the dispersion. To this, 50 μL of diluted hydrochloric acid (HCl, 1 M) were added dropwise and mixed with the solution. The addition of HCl is needed for the later stabilization of the macroemulsion. Thereafter, a toluene solution containing the Cu2-xS NCs (200 μL) was added to the diluted GO solution. Upon addition of the toluene solution an emulsion was formed in the vial by manual shaking. Subsequently, the emulsion was sonicated in order to decrease droplet size, leading to the formation of a macroemulsion having a milky appearance. Pure toluene/GO macroemulsions (in the absence of Cu2-xS NCs) were prepared in an analogous way, but using pure toluene instead of Cu2-xS NCs in toluene. The reference Cu2-xS NCs samples were prepared by diluting the original NC's solution two times, in order to obtain similar NC's concentration. 
The synthesis of 5 nm Cu2-xS NCs was performed according to a previous report.8 Typically, the synthesis was performed by mixing 1.25 mmol of ammonium diethyldithiocarbamate, 10 mL of dodecanethiol and 17 mL of oleic acid in a three-neck flask. The solution was degassed at 120 degC for 1 h. Under nitrogen a suspension composed of 1 mmol of copper(II) acetylacetonate and 3 mL of oleic acid was injected followed by heating up to 180 degC, and kept at this temperature for 10-20 min. After cooling to room temperature the NC solution was transferred to a glove box and washed twice with anhydrous solvents before being redispersed in toluene. The NC dispersion was kept in the glovebox until utilization for the formation of hybrid GO/Cu2-xS NCs structures.
GO solution in water
initial concentration
~ 4 mg mL-1
mg mL-1
deionized water
150 μL
μL
GO solution in water
diluted
150 μL
μL
150 μL of the GO solution in water (initial concentration ~ 4 mg mL-1) was diluted with 150 μL of deionized water
1:1 v/v
v/v
solution
sonicated
about 20 minutes
minutes
hydrochloric acid (HCl
1 M
M
diluted hydrochloric acid (HCl
added
50 μL
μL
Cu2-xS NCs
200 μL
μL
original NC's solution
diluting
two times
times
Cu2-xS NCs
synthesis
5 nm
nm
ammonium diethyldithiocarbamate
mixing
1.25 mmol
mmol
dodecanethiol
mixing
10 mL
mL
oleic acid
mixing
17 mL
mL
solution
degassed
120 degC
degC
solution
degassed
1 h
h
nitrogen a suspension
copper(II) acetylacetonate
1 mmol
mmol
nitrogen a suspension composed
oleic acid
3 mL
mL
solution
heating
up to 180 degC
degC
solution
kept at this temperature
10-20 min
min