Intermetallic Pd(3)X (X= Ti and Zr) nanocrystals for electro-oxidation of alcohols and formic acid in alkaline and acidic media

Two highly active and stable Pd-based intermetallic nanocrystals with early d-metals Pd(3)Ti and Pd(3)Zr have been developed. The nanocrystals are synthesized by co-reduction of the respective salts of Pd and Ti/Zr. Hard X-ray photoemission Spectroscopy (HAXPES) analysis of the nanocrystals indicates that the electronic properties of Pd are modified significantly, as evident from the lowering of the d-band center of Pd. The intermetallic nanocrystals dispersed in Vulcan carbon, Pd(3)Ti/C and Pd(3)Zr/C, exhibit improved electrocatalytic activity towards methanol and ethanol oxidation in an alkaline medium (0.5 M KOH), compared to those of commercially available catalysts such as Pd/C, Pt/C, and Pt(3)Sn/C. In addition, Pd(3)Ti/C and Pd(3)Zr/C show significantly higher activity towards the oxidation of formic acid in an acidic medium (0.5 M H(2)SO(4)), compared to those of Pd/C and Pt/C. The modification of the d-band center of Pd as a result of the alloying of Pd with the early d-metals Ti and Zr may be responsible for the enhanced catalytic activity.