Synthesis of high performance Ni3C-Ni decorated thermally expanded reduced graphene oxide (TErGO/Ni3C-Ni) nanocomposite: A stable catalyst for reduction of Cr(VI) and organic dyes.

A high performance thermally expanded reduced graphene oxide (TErGO) nanocomposite decorated with Ni3C-Ni nanoparticles (TErGO/Ni3C-Ni) has been successfully synthesized by using a facile and eco-friendly approach. The morphology, textural features, surface composition and stability of TErGO/Ni3C-Ni nanocomposite are investigated by various physicochemical characterizations which revealed the uniform dispersion of crystalline metal nanoparticles inside TErGO matrix. The composite has been exhibited a large surface area and pore volume of 121 m2 g-1 and 0.791 cm3 g-1, respectively. The TErGO/Ni3C-Ni exhibited remarkable catalytic performance surpassing most metal-based catalysts with various kind of support matrices reported in recent literature. The reduction of Cr(Ⅵ) to Cr(Ⅲ) was achieved within 1 min with an excellent rate constant of 2.74 min-1 and phenomenally higher specific removal rate (SRR) of 0.29 mg Cr(VI) min-1. mg-1 of TErGO/Ni3C-Ni. While it also proved an excellent reducing catalyst for organic dyes via NaBH4 with full reduction achieved within 30 s. Moreover, as prepared nanocatalyst possesses excellent stability and recyclability with easy magnetic separation.

Regional selective construction of nano-Au on Fe3O4@SiO2@PEI nanoparticles by photoreduction.

A magnetically separatable catalyst Fe3O4@SiO2@PEI@Au (gold) nanoparticle was successfully constructed by a novel regional selective photoreduction method. Based on the photolysis mechanism of a type II photoinitiator, through controlling the distribution of polyethylene imine (PEI), Au nanoparticles about 10 nm, which are only on the surface of the Fe3O4@SiO2@PEI nanoparticle, could be photoreduced due to the PEI acting as a coordinating agent, capping agent, and photoreducing agent simultaneously. The small size Au nanoparticles endow the catalyst with a high catalytic performance toward the reduction of 4-nitroaniline to 4-aminophenol by NaBH4. In addition, magnetic Fe3O4@SiO2@PEI@Au nanoparticles could easily be recovered and could be reused at least six times still keeping catalytic efficiency higher than 95%, which contributes to their high stability and magnetization. Furthermore, compared to another reported approach, this method showed great regional selectivity of reducing metal nanoparticles by controlling the distribution of the PEI. Taking advantage of the regional selectivity of the photoreducing method could also be used to fabricate other metal nanoparticles as catalysts for various reactions.