Pt/Ni Catalyst Supported by Composite of Graphene and Polyaniline Microtubes Boosting Methanol Electrochemical Oxidation

Abstract

The development of durable and efficient anode electrocatalysts is crucial for direct methanol fuel cells. In this paper, polyaniline (PANI) microtubes are firstly prepared by removing the polystylene (PS) core from PANI coated electrospun PS. The catalyst of PtNi/PANI@rGO is built by two steps: graphene oxide (GO) is mixed with PANI microtubes to obtain PANI@GO and then PANI@GO is used as a support material to load PtNi nanoparticles by reductive reaction while GO is reduced into rGO. The morphology, electronic structure and chemical structure of the catalysts are characterized by SEM, TEM, XPS and Raman spectroscopy, respectively. The electrochemical analysis of electrochemical impedance spectroscopy, cyclic voltammetry and chronoamperometric measurement are performed to analyze the electrocatalytic performance. The electrochemical results indicate that as-synthesized PtNi/PANI@rGO has the high activity toward methanol oxidation, and its mass activity is 1.7, 1.3 and 4.1 times higher than that of PtNi/PANI, PtNi/rGO and commercial Pt/C catalysts, respectively. The PANI microtubes not only improve the electron transfer kinetic but also help avoid the accumulation of graphene layers. The doping of Ni into Pt changes the surface electronic structure to elevate the catalytic activity and helps effectively improve the resistance to CO poisoning.