I'm guessing you're increasing the cell to twice its size.

What you have to do is reduce by half the coordinates in the reciprocal space. For example, if before increasing the size of the cell the point K had coordinates (1,0,0) in the supercell the same point will have coordinates (0.5,0,0).

Hi Jhon W. González ,

Thanks for the suggestion. unfortunately, It didn't work !!

Thank you

You need to scale all the points in the k-space, but you must be careful because it's not a obvious transformation.

The best option is to use a program like xcrysden to choose them visually.

I would suggest to use

https://www.materialscloud.org/work/tools/seekpath

together with xcrysden.

Remember that band structure should be done with the primitive cell, so the first step should do the band structure for graphene, if your results reproduce those from the literature, then you could try to do the band structure for a supercell.

Regards