One-pot synthesis of Ag–Au bimetallic nanoparticles with Au shell and their high catalytic activity for aerobic glucose oxidation

PVP-protected Agcore/Aushell bimetallic nanoparticles of enough small size, i.e., 1.4 nm in diameter were synthesized in one-vessel using simultaneous reduction of the corresponding ions with rapid injection of NaBH4, and characterized by HR-TEM. The Agcore/Aushell bimetallic nanoparticles show a high and durable catalytic activity for the aerobic glucose oxidation, and the catalyst can be stably kept for more than 2 months under ambient conditions. The highest activity (16,890 mol-glucose h−1 mol-metal−1) was observed for the bimetallic nanoparticles with Ag/Au atomic ratio of 2/8, the TOF value of which is several times higher than that of Au nanoparticles with nearly the same particle size. The higher catalytic activity of the prepared bimetallic nanoparticles than the usual Au nanoparticles can be ascribed to: (1) the small average diameter, usually less than 2.0 nm, and (2) the electronic charge transfer effect from adjacent Ag atoms and protecting PVP to Au active sites. In contrast, the Ag–Au alloy nanoparticles, synthesized by dropwise addition of NaBH4 into the starting solution and having the large mean particle size, showed a low catalytic activity.

Synthesis of Agcore/Aushell bimetallic nanoparticles with size of 1.6 nm using rapid injection of NaBH4.Figure optionsDownload high-quality image (81 K)Download as PowerPoint slideResearch highlights
► Agcore/Aushell bimetallic nanoparticles (BNPs) of less than 2 nm in diameter were prepared with rapid injection of NaBH4.
► The catalytic activity on glucose oxidation of the BNPs is several times higher than that of pure Au nanoparticles.
► The prepared BNPs exhibit not only a high instantaneous catalytic activity but also a high long-time catalytic stability.
► A possible activation mechanism through electronic charge transfer in the BNPs is proposed.