Coordination complex synthesis of noble metals in the preparation of nanoparticles supported on MWCNTs used as electrocatalysts

Abstract Coordination complex salts were synthesized in an aqueous solution and used as precursors to prepare metallic and bimetallic nanoparticles supported on multiwalled carbon nanotubes (MWCNTs) to be applied as electrocatalysts on methanol electrooxidation. The precursors were obtained by the reaction between (NH 4 ) 2 PtCl 6 , (NH 4 ) 2 PdCl 6 , (NH 4 ) 3 RuCl 6 and HAuCl 4 with tetraoctylammonium bromide (TOAB). These were obtained as (TOA) n MCl y salts (where “M” = Pt, Pd, Ru or Au) and were characterized by FT-IR and TGA analysis. The precursors were used to prepare metallic and bimetallic nanoparticles of Pt, Pt–Pd, Pt–Ru, as well as Pt–Au coated on MWCNT (Pt–M/MWCNTs, where M = Pd, Ru or Au). Materials were characterized by TEM, XRD and TGA. The electrocatalytic properties of the Pt–M/MWCNTs electrodes for the methanol oxidation were determined by cyclic voltammetry (CV) and chronoamperometry (CA). The bimetallic nanoparticles presented a higher electrocatalytic activity and stability than the Pt/MWCNTs electrocatalyst, attributed to the addition of “M” which not only led to a smaller average particle size and higher dispersion of Pt of the metallic nanoparticles on MWCNTs but also promoted an elevated electronic transfer between bimetallic nanoparticles.