NBEXP010901

=Photocurrent measurement of graphene/TiO2 films=

Results
[|NBEXP010901 potentiostat data] media type="googlespreadsheet" key="t0CXWndT9UepT06c9nyJYig" width="500" height="300" Minitab analysis of photocurrent. Values are the average of all current measurements during 'on' light pulse. Beginning and end of pulse were determined by holding cursor over beginning and end of pulse — as-selected values are highlighted (in grey) in the linked spreadsheet.

Discussion
We are not sure of the cause of the slope in the excel chart — it could be an artifact of the instrument or a chemical reaction. Futher investigation is required to clarify this.

The chart itself is quite noisy. The potentiostat software was not set at the correct sensitivity level (selected sensitivity was too low as higher photocurrents were expected), which is something to bear in mind for future measurements.

Regardless of the chart slope and the high noise, the Minitab analysis revels that there is a statistically significant increase in the photocurrent with graphene concentration (error bars do not overlap), with the exception of the 0.7mg sample. This film may have been of poor quality. However, we do not yet know whether the photocurrent increase is due to enhanced charge collection by graphene, or from the photogeneration of graphene itself (no pure graphene sample was tested.)

Conclusion
Adding graphene to TiO2 nanoparticle films enhances the UV-generated photocurrent by ~2.3x. Whether the enhancement effect is due to improved charge transport by graphene or additional photogeneration by graphene itself (or some other mechanism) is unknown.

Log
17:00 Performed minitab analysis 17:33 Added discussion & conclusion **
 * 2009-09-07