Polybetaine-stabilized nanosized platinum particles, their preparation and their use as electrocatalysts in fuel cells

摘要

Polybetaine-stabilized nanosize platinum particles, a process for preparing them and their use for electrocatalysts in fuel cellsSoluble nanosize particles which have a diameter of from 0.5 to 3 nm, preferably from 1 to 2 nm, comprise platinum alone or platinum and other metals of the platinum group and are embedded in a protective colloid which comprises polymeric betaines and can be degraded by hydrolysis. The betaine is preferably a carbobetaine of the formula -N+R1R2-(-CH2-)n-CO2-, a phosphobetaine of the formula -N+R1R2-(-CH2-)n-PO3- or, preferably, a sulfobetaine of the formula -N+R1R2-(-CH2-)n-SO3-, where R1 and R2 may, independently of one another, be identical or different and are alkyl radicals having from 1 to 6 carbon atoms and n is 1, 2 or 3. Also described are a process for preparing the nanosize particles and catalysts produced therefrom and also their use for fuel cells.