The following is a example method to prepare a platinum counter electrod for a DSSC from Pt(0).
Chloroplatinic acid is produced by dissolving Pt(0) platinum metal in aqua regia. Brownish red crystals can be isolated by evaporating this solution to a syrup.
Pt NPs applied as the counter electrodes (CNS-CEs) for dye-sensitized solar cells ( DSSCs), Chloroplatinic acid precursor to platinum nanoparticles (Pt NPs).
You can try thermal decomposition of PtCl2. Dissolve small amount of PtCl2 in isopropyl alcohol, applied uniformly few drops of the solution on ITO, dry and repeat 3 to 5 times. Then anneal at 450oC for 0.5-1 h.