Simultaneous tunable structure and composition of PtAg alloyed nanocrystals as superior catalysts

Abstract

PtAg alloyed nanostructural catalysts were firstly prepared by co-reduction of AgNO₃ and H₂PtCl₆ precursors in growth solution using a seed-mediated method. By simply changing the molar ratio of the metal precursors, the morphologies of the porous alloyed nanocrystals can be tuned from multipetals to multioctahedra. Simultaneously, the alloy composition can be varied from Pt₇₆Ag₂₄ to Pt₆₆Ag₃₄. The catalytic properties of the prepared PtAg alloyed nanocrystals with a tunable structure and composition were tentatively examined by choosing the reduction of 4-nitrophenol with NaBH₄. The reaction rate normalized to the concentration of catalysts was calculated to be 318.9 s⁻¹ mol⁻¹ L and 277.4 s⁻¹ mol⁻¹ L for Pt₇₀Ag₃₀ and Pt₆₆Ag₃₄ porous catalysts, which is much higher than the pure Pt catalysts. Moreover, PtAg nanostructures can also serve as efficient electrocatalysts toward the methanol oxidation reaction, especially for Pt₇₀Ag₃₀ and Pt₆₆Ag₃₄ porous nanocrystals. The electrocatalytic activity and the durability were both highly enhanced compared to the commercial Pt/C catalyst. In addition, we also investigated the enhancement mechanism.