I have difficulties in understanding the question. I don't know the "exact role." I think that Na2CO3 is a base in alcohol solution and after release of CO2 forms alcoholate anion, RO-, which is easier to oxidize.

thanks for your answer.

For a primary alcohol the addition of a base helps removing the alpha hydrogen and facilitates the oxidation of the carbon bound to the catalyst

Thanks, Baldassarre Venezia for your guide.

It provides the alkaline medium for the reaction.