Facile and Green Synthesis of Carbon-Supported Nanoparticle Catalysts By Physical Vapor Deposition on Soluble Powder Substrate

Abstract

Recently, Nanoparticles supported on high surface area carbon (NP/C) have attracted increasing interest for application in electrical energy generation and storage systems. NPs/C can be prepared by the chemical and/or physical reduction of metal ions. Typically, impregnation is widely used for preparing supported NPs. Meanwhile, fine metal NPs have been prepared by the physical vapor deposition (PVD) of corresponding metals, in the absence of metal complexes. PVD on liquid substrates, such as ionic liquids (ILs), vegetable oils, and liquid N2-cooled acetone has been reported for the preparation of NPs with a tunable composition and size distribution. However, these approaches require expensive reagents, such as metal ion complexes, solvents, and stabilizing or reducing agents, which often exhibit potential environmental and biological hazards. In this study, we present a novel, facile and totally green approach toward the synthesis of NPs/C catalyst by using the α-D-glucose (Glu). This strategy consists of: 1) The deposition of NPs on α-D-glucose powder (NP/Glu) by PVD; and 2) Transfer of the NPs from Glu to carbon supports using a mixture of NP/Glu, high surface area carbon support, and solvent. PVD is employed for the facile preparation of various types of NPs, including noble metals, alloys, and transition-metal oxides. The prepared NPs are expected to exhibit a finite size and narrow size distribution. Moreover, our NPs will not contain surfactants, which often impede catalytic reactions. This strategy can be extended to prepare NPs on a range of supports, such as carbon nanotubes (CNTs), graphene oxide (GO), and TiO2, thereby demonstrating its generality. As only the target materials and Glu are required in our procedure, it can be considered environmentally friendly, with the NPs being devoid of hazardous chemicals. In this strategy, Glu act as not only carrier for the transport of NPs from the bulk materials to the support materials but also stabilizer through their OH moieties of the Glu surfaces, which prevent the agglomeration of NPs during the synthesis process. Furthermore, the prepared NPs/C exhibited an improvement in activity for various electrochemical reactions, mainly attributed to their high surface area.