Preparation of ultrafine ruthenium oxide particles with ammonium hydrogencarbonate

Ruthenium oxide precursors were prepared from ruthenium chloride in aqueous solution. The addition of ammonium hydrogencarbonate to the ruthenium chloride aqueous solution results in complete precipitation of the ruthenium oxide precursors. The solution pH value can be kept constant around neutrality because the acidic products are neutralized with ammonium hydrogencarbonate to form gaseous carbon dioxide. The neutrality of the solution should be important for the continuance of the precipitation reaction. The particle size of the ruthenium oxide precursors was controlled by the amount of ammonium hydrogencarbonate and the addition of diethylene glycol. Ammonium hydrogencarbonate enhances the hydrolysis and the subsequent dehydrative polycondensation as a catalyst while diethylene glycol inhibits them. Ultrafine particles of crystalline RuO2 were obtained with the calcination of the precursors at 600 degrees C.