Hexaboride Ceramics as PEMFC Electrode Catalysts Supports

Abstract

Metal hexaborides demonstrate the unusual ability to spontaneously deposit noble metals from solution without the need for separate reducing agents or pretreatments. A range of deposition thicknesses are possible and uniform and strongly adherent 30 nm thick metal films on lanthanum hexaboride sputter- coated glass are easily and quickly achieved. Full and uniform coverages of hexaboride powders are obtained even with deposits only ca. 1 nm thick. Cyclic voltammetry for 4 wt% Pt on a roughly 1 m2/g EuB6 powder show electrochemically active Pt surface area, derived from the area under the hydrogen absorption curve, to be 39 m2/g Pt and is exceptional considering the low hexaboride support surface area. This result suggests that the entire support area is covered with Pt (approximately 1 nm thick) and that the entire Pt surface is electrochemically active.