In Rev. Sci. Intrum. 1995, 66 (1), 97-100, on page 98, the authors describe using a -1.1 V vs carbon (but I use vs Pt) in H2SO4 ( I use 50 mM) to electrochemically etch PtO2 off Pt. Hope this helps!
well actually you go to turn back cave if you get in the chamber with the portal in 3 rooms it will be there then go in the portal and get to the end where you'll find a griseous orb ( platinum orb)...