Hello, the change in electrochemical performance of the CV is caused by the reaction of the binder of the prepared screen printing electrode with the carbon material at a different temperature, rather than the transition of the carbon material itself with temperature. It is hoped that it will help you .

Thank you Haifeng.. even I did not notice any appreciable change in crystallite size with change in curing temperature..can you please provide me some references where I can get some insights into these sort of reactions..?

The curing temperature certainly changes the carbon phase.With temperature, carbon changes its phase from amorphous to flakes/ribbons of nanocrystalline graphite (See book edited by Igor V. Barsukov..., "New carbon based materials for electrochemical energy storage systems"). The morphology is very crucial for any application. According to your electrode preparation and curing temperature of carbon (yielding different crystallite size of carbon (carbon phase)) will have different charge transfer resistance as well as solution resistance response (Please check the electrochemical impedance spectroscopy for it)  and thus consequently your CV response will have the impact. 

http://pubs.rsc.org/en/content/articlehtml/2009/cs/b813846j

http://www.sciencedirect.com/science/article/pii/S0378775306003442