Small-sized and high-dispersed WN from [SiO4(W3O9)4]4- clusters loading on GO-derived graphene as promising carriers for methanol electro-oxidation

The small size and high dispersion of cocatalysts on supports are essential to increase the chance to contact with a Pt catalyst for promoting the synergistic effect. In this paper, we report the synthesis of the small-sized WN nanoparticles (NPs) loading on GO-derived graphene (denoted as graphene for simplicity) by using heteropoly acid H-4[SiO4(W3O9)(4)] (SiW12) clusters as a W source. The SiW12 clusters are anchored on the polyethyleneimine (PEI)-modified GO through a hydrothermal process. After the nitridation with NH3, the small-sized and well dispersed WN NPs of 2-3 nm are obtained. The ternary Pt-WN/graphene catalysts are fabricated by an EG reduction method. The intimate contact and intensive interaction between Pt and WN are verified by TEM, XRD, XPS and XAFS tests. Due to the above characteristics, the Pt-WN/graphene catalyst exhibits a remarkably enhanced activity and durability toward methanol electrocatalytic oxidation. The mass activity of Pt-WN/graphene (531.5 mA mg(Pt)(-1)) is 2.45, 2.88 and 3.70 times that of Pt/graphene, Pt/C(JM) and Pt/Vulcan catalysts, respectively. Furthermore, the ternary PtWN/ graphene catalyst shows excellent resistance to CO poisoning and good stability. The high activity of Pt-WN/graphene is mainly attributed to the enhanced synergistic effect benefited from the intimate contact and intensive interaction of Pt with WN NPs.