Once lyophilized form is prepared then it seems that water is already removed completely. So, just to clean your material surface you can degassed simply overnight at 40 degree under vacuum conditions so after that your material surface is fully activated.

Dear Sandeep

Thanks for your response. I did it on 100 degree overnight in vacuum last time, but i got the surface area negative which is quite unrealistic.

That's why I told to degas it at lower temperature so surface property remains intact and 100 degree under under vacuum will be very harsh condition to degas such material. As material is already lypholized so no need to put it in harsh condition.

When you mention " surface area negative " - you are trying to measure surface area using nitrogen BET? BET pretty much does not work on unreduced graphene oxide. If you slowly heat your sample for 48 hours or more (for example 48 hours at 80 deg C) you should be about to mostly reduce the GO without exfoliating it. (if you heat to 600 deg C rapidly, this will exfoliate. Highly exothermic reaction) You can monitor weight of the sample to identify when it is fully reduced, or run a DSC.

Dear Dr Claire

Yes, I have tried to measure the surface area using nitrogen BET for graphene oxide and its derivative gels. The degassing was performed on 100 degree C for overnight ( 12 hrs) after which i got the surface area in negative.