Carbon nanotubes-supported PtAu-alloy nanoparticles for electro-oxidation of formic acid with remarkable activity

PtAu-alloy nanoparticles supported on multi-walled carbon nanotubes (MWCNTs) were successfully prepared by simultaneous reduction of H2PtCl6·6H2O and HAuCl4·3H2O with sodium borohydride as a reducing reagent and sodium citrate as a stabilizing reagent. The morphology and composition of the composite catalyst were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The results show that the PtAu alloy nanoparticles with an average diameter of about 3.5 nm and narrow size distribution are supported on MWCNTs. Electrocatalytic oxidation of formic acid at the PtAu/MWCNTs nanocomposite electrode was investigated in a solution containing 0.50 M H2SO4 as a supporting electrolyte and 0.50 M formic acid by cyclic voltammogram and chronoamperometry. The results demonstrate that the PtAu/MWCNTs catalyst exhibits higher activity and stability for electro-oxidation of formic acid than the commercial Pt/C catalyst, reflecting by its lower onset potential (−0.05 V), oxidation mainly occurring in low potential range of −0.05 ± 0.65 V and higher peak current density of 3.12 mA cm−2. The result of CO stripping voltammetry discloses that gold in the PtAu/MWCNTs nanocomposite enhances the catalytic activity and stability.

Research highlights▶ Electro-oxidation of HCOOH over PtAu at lower potential, higher peak current. ▶ The stability of the PtAu catalyst is high. ▶ Au in the PtAu catalyst promotes utilization of Pt.