One-Pot Environmentally Friendly Approach toward Highly Catalytically Active Bimetal-Nanoparticle-Graphene Hybrids

Abstract

A one-pot universal approach with simple metal sputtering onto room temperature ionic liquids has been developed to prepare bimetal-nanoparticle (NP)-graphene hybrids, and the process is environmentally friendly and completely free of additives and byproducts. The graphene-supported bimetallic NPs have an Ag-based core and an Au/Pd-rich shell, demonstrated by the scanning transmission electron microscopy. The X-ray absorption near-edge spectroscopy using synchrotron radiation reveals the occurrence of charge redistribution at both the Ag@Au and Ag@Pd core-shell interfaces. The as-prepared Ag@Au and Ag@Pd bimetal-NP-graphene hybrids are highly catalytically active for reduction of 4-nitrophenol, whose catalytic activity is superior to the corresponding monometallic hybrids. The catalytic superiority is ascribed to the electronic structure modification and morphological irregularity of the graphene-supported bimetallic NPs.

Small and uniform Pd monometallic/bimetallic nanoparticles decorated on multi-walled carbon nanotubes for efficient reduction of 4-nitrophenol

“…The promotion in j is due to the increased surface density of Pd NPs upon increasing Pd sputtering time, which can generate more catalytically active sites. The optimized j value is very high compared with those of hybrid nanocatalysts reported in literatures [13,23,24]. The absence of a capping layer results in the bare surface of Pd NPs, which is in favor of direct contact with the reactant and thus electron transfer in the catalytic reaction [22,24].…”

“…Reduction of 4-nitrophenol, with an excess of NaBH 4 in aqueous solution, could be a model reaction to evaluate the activity of many nanocatalysts [13,[22][23][24][25]. The UV-vis absorption spectra of an aqueous mixture of 4-nitrophenol and NaBH 4 shows a characteristic peak at about 400 nm arising from the nitro compound [13,[22][23][24][25], which can be monitored to track the 4-nitrophenol reduction.…”

“…The UV-vis absorption spectra of an aqueous mixture of 4-nitrophenol and NaBH 4 shows a characteristic peak at about 400 nm arising from the nitro compound [13,[22][23][24][25], which can be monitored to track the 4-nitrophenol reduction. Upon addition of pristine MWCNTs, the characteristic peak remain unchanged with time, indicating that the nanosupport itself is not catalytically active.…”

“…It is a one-step, universal and environmental-friendly approach totally free of additive agents and byproducts [12,13]. In particular, a PdAu alloyed target is used to straightforwardly prepare PdAu bimetallic NPs decorated on multi-walled CNTs (MWCNTs …”

15. Nanocarbon materials for heterogeneous catalysis

“…Similar examples utilizing, e.g., Pd, Pt, Ag, as well as alloys and mixtures thereof, for C-C coupling reactions, selective oxidations, or reductions are frequently reported [11,[130][131][132][133]. In general, the performance of such graphene-supported systems is explained by the exceptionally high surface area, conductivity, and by the intimate interaction of metal nanoparticles with surface functional groups.…”