Although aqueous synthesis of nanocrystals is advantageous in terms of the cost, convenience, environmental friendliness, and surface cleanness of the product, nanocrystals of Pt and non-noble metal alloys are difficult to obtain with controlled morphology and composition from this synthesis owing to a huge gap between the reduction potentials of respective metal salts. This huge gap could now be remedied by introducing a sulfite into the aqueous synthesis, which is believed to resemble an electroless plating mechanism, giving rise to a colloid of Pt-M (M=Ni, Co, Fe) alloy nanowires with an ultrasmall thickness (ca. 2.6 nm) in a high yield. The sulfite also leads to the formation of surface M-S bonds and thus atomic-level Pt/M-S(OH) interfaces for greatly boosted hydrogen evolution kinetics under alkaline conditions. An activity of 75.3 mA cm-2 has been achieved with 3 μg of Pt in 1 m KOH at an overpotential of 70 mV, which is superior to previously reported catalysts.
Keywords: aqueous synthesis; bimetallic alloys; hydrogen evolution reaction; platinum; ultrathin nanowires.
© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.