Colloidal platinum sols: anion effects on coagulation behaviour

Abstract

The concentration of added electrolyte required to induce coagulation of a platinum sol has been determined for a range of electrolytes. It has been found that, for electrolytes in which the anion contains lone-electron-pair substituents, sol stability is significantly enhanced compared with that observed when similar but non-electron-pair-containing anions are used. It is proposed that the lone electron pairs enable anion adsorption on negative platinum surfaces despite the Coulombic repulsions present.