Thermal Decomposition of Platinum Chlorides and Application to the Pt-coated Electrodest

Abstract

The thermal decomposition of platinum chlorides was investigated by TG and DTA and characteristics of the Pt-coated electrodes were discussed. Both crystals and aqueous solutions of H₂PtCl₆.6H₂0 and PtCl₄.5H₂0 were decomposed firstly into PtCl₂ and finally into Pt^o of which forming temperatures were 330°C and 530°C, respectively. On the other hand, the TG curve showed that Pt(IV) was reduced to Pt^o at about 400°C when Pt(IV) was dissolved in butyl alcohol (n-BuOH). Titanium/Pt electrodes with large roughness were tentatively prepared by applying H₂PtCl₆-n-BuOH solution on Ti bases and heating even at lower temperature (300°C). The roughness was, however, lowered gradually as the heating temperature was risen. When the electrodes were prepared at higher temperature, the Ti/Pt joining points were better sintered and the exposed Ti, surface was also better protected against corrosion by formation of titanium(IV) oxide, so that the lifetime of the electrodes could be prolonged. Other organic reagents were examined as the solvents and it was concluded that the thermal decomposition of Pt(IV) in the organic reagents takes place readily via the redox reaction of a Pt(II)-complex.