Foreign ion effect on the reduction of C-60 fullerene films in aqueous solutions

C-60 fullerene films were reduced in aqueous solutions of potassium and sod ium ions, and the effect of positively charged Bronsted acids was investiga ted on these reduction processes. Ammonium, hydronium (hydrogen) and hydrat ed aluminium ions were used as proton donors. It was established that their overall effect is different due to their different proton donating abiliti es. However, their primary effect can be summarized as disturbing the reduc tion process. Their addition shifted the reduction potential to lower value s, and changed the shape of the voltammograms, but allowed the formation of nearly the same product. It is supposed that they are not inserted into th e reduced films in significant amounts. That is why their effect is called a foreign ion effect. Under special conditions, however, films could be pro duced that probably contained aluminium ions as dopants, i.e. produced a sa lt of C-60 with a trivalent cation. (C) 2001 Elsevier Science B.V. All righ ts reserved.