NBEXP0006

Aim
To obtain AFM images of sample... & establish average graphene sheet height and size/dimensions.

Multi-Mode AFM


Several other images were taken and the results were similar. No individual graphene oxide flakes could be observed; there was some indication that fluid has formed about features on mica surface. The solvent may not have dried or samples may have been kept in air for too long and liquid had condensed on the flakes. Also, the tip seems to have required replacement.

Of the features that have been observed they are >10nm in height. Graphene oxide may have agglomerated in solution, or the concentration of GO in solution may have been too high to allow single sheets to be visible.

19181555


Most common height: 12nm Average height: 13nm Max. height: 64nm

09181611


Most common height: 6nm Average height: 7nm Max. height: 33nm

09181635


Most common height: 7nm Average height: 11nm Max. height: 53nm

09181650
Images not worth processing

Discussion
Graphene sheets can be resolved using mica as a substrate and by drying ethanol in vacuum for several hours. The concentration used was 1mg/mL, which was probably too high. Concentration should instead be 0.1mg/mL or possibly even 0.01mg/mL to allow imaging of individual flakes. Higher-resolution AFM must be used to obtain more accurate measurements of flake height and dimension.

Conclusion
Future AFM studies must be performed on the multimode AFM at concentrations of 0.1mg/mL or possibly 0.01mg/mL.