I am using Pt wire as a quasi reference and counter electrode (separate), and glassy carbon as a working electrode. I am getting this unusual reversible peak at between -1.5 and -1 V see attached the CV.

There were no electroactive species introduced in the electrolyte. I tried several times with various reference (Ag wire, Pt wire) and working (Au, GC, Pt), still, the peak remains there with a slight change in potential.