I suppose you apply a square potential wave in the system with negative potential and zero potential. During the negative part, ions are adsorbed on the surface of electrode. When you cut the potential, the electrode is not attractive enough to carry so many ions, and the ions will move from the surface to the bulk. This movement cause some additional current. For details, you can refer to Cottrell equation.

have you chosen chrnonoamperometry with a fixed imposed potential?

Yes mam, -1 to 2 V

If you change the sign of the applied potential it is not unreasonable to expect the sign of the resulting current to change as well. This of course depends on the open circuit potential, but if your applied potential alternates between values above and below your OCP, the current should alternate between positive and negative values. The explanation given by Sihan Zhang (2 days ago) will probably also apply either enhancing or dampening this behavior.

Dear Ramyashree M S,

since you've applied a potential interval of -1 to 2V/Ag/AgCl, you'll get this result, chronoamperometry you the disturbance signal under anodic (when the disturbance is 2volt) and cathodic (-volt) current. the ideal is to apply once a fixed potential 2 volt and the other time -1 volt and you'll see the result quite different.

Thank you so much 👍