Microwave-assisted optimization of platinum-nickel nanoalloys for catalytic water treatment

• Pt/Ni nanoalloys are synthesized using microwave-assisted polyol reduction.
• The surface composition of nanoalloys is varied from Pt-rich to Ni-rich.
• The reactivity-composition relationship of nanoalloys shows a volcano curve.
• The highest reactivity in p-nitrophenol reduction is found with Pt:Ni ≈ 1:1.
• The service life of nanoalloys is extended by affixing them on graphene sheets.

Blending noble metal catalysts with inexpensive transition metals can reduce material cost in catalytic water treatment by improving the catalytic reactivity. An important challenge is, however, to synthesize a series of alloy nanoparticles with varied compositions so that the screening of catalytic reactivity can be performed rapidly for a contaminant of interest. Here, we report a facile approach for the rapid synthesis of bimetallic nanoalloys using cycle-controlled microwave-assisted polyol reduction, with an option of fixing the nanoalloys directly on graphene supports in a one-pot operation. Using Pt and Ni as the model noble and promoter metals, we show that Pt/Ni nanoparticles with diameters ranging from 2.8 to 4 nm can be readily synthesized within minutes. The surface Ni percentage of the nanoparticles are varied from 0 to 100%, which serves as a model system for nanoalloy screening. Using the model contaminant p-nitrophenol, we further show that the reactivity-composition relationship has a classic volcano shape as the Sabatier principle predicts. The highest reactivity is found with a surface Ni percentage of approximately 50%.

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