Abstract: Disclosed herein is a multi-layered composite thin film material formed from graphene quantum dots (GQDs) and metal nanocrystals in a layer-by-layer design, wherein the metal nanocrystals can be selected from the group consisting of Ru, Rh, Os, Ir, Pd, Au, Ag and Pt. In a preferred embodiment, the multi-layered composite thin film material is prepared via a facile, green, and easily accessible layer-by-layer (LbL) self-assembly strategy. In this strategy, positively charged GOQDs and negatively charged metal nanocrystals are alternately and uniformly integrated with each other in a “face-to-face” stacked fashion under substantial electrostatic attractive interaction, and then the obtained GOQDs/metal composite thin film is calcined into GQDs/metal composite thin film. The composite thin film material disclosed herein may be used to catalyse a wide range or reactions, including selective reduction of aromatic nitro compounds in water and electrocatalytic oxidation of methanol at ambient conditions.

Abstract: Disclosed herein is a multi-layered composite thin film material formed from graphene quantum dots (GQDs) and metal nanocrystals in a layer-by-layer design, wherein the metal nanocrystals can be selected from the group consisting of Ru, Rh, Os, Ir, Pd, Au, Ag and Pt. In a preferred embodiment, the multi-layered composite thin film material is prepared via a facile, green, and easily accessible layer-by-layer (LbL) self-assembly strategy. In this strategy, positively charged GOQDs and negatively charged metal nanocrystals are alternately and uniformly integrated with each other in a “face-to-face” stacked fashion under substantial electrostatic attractive interaction, and then the obtained GOQDs/metal composite thin film is calcined into GQDs/metal composite thin film. The composite thin film material disclosed herein may be used to catalyse a wide range or reactions, including selective reduction of aromatic nitro compounds in water and electrocatalytic oxidation of methanol at ambient conditions.

Abstract: Provided is a nanoparticulate composite with two layers. One of the layers comprises one or more metals, which are a paramagnetic metal, a ferromagnetic metal, or a superparamagnetic metal. This layer also contains one or more suitable dopants. The other layer comprises one or more metals of gadolinium, manganese (II), and iron (III), in the form of an oxide or a fluoride. This layer may contain one or more lanthanide dopants. The nanoparticulate composite may be used as a contrast agent, in particular in magnetic resonance imaging.

Abstract: Provided is a nanoparticulate composite with two layers. One of the layers comprises one or more metals, which are a paramagnetic metal, a ferromagnetic metal, or a superparamagnetic metal. This layer also contains one or more suitable dopants. The other layer comprises one or more metals of gadolinium, manganese (II), and iron (III), in the form of an oxide or a fluoride. This layer may contain one or more lanthanide dopants. The nanoparticulate composite may be used as a contrast agent, in particular in magnetic resonance imaging.

Abstract: The present invention refers to a composite material including at least one upconversion particulate material that under near infrared (NIR) irradiation emits visible light of a wavelength between 380 and 740 nm, and at least one semiconductor particulate material that can absorb the visible light emitted by the at least one upconversion particulate material and upon absorbance generates reactive species, wherein the at least one upconversion particulate material and the at least one semiconductor particulate material are physiologically acceptable. The upconversion particulate material can comprises NaYF4 doped with a one rare earth metal. The bright fluorescence emitted from rare earth-doped NaYF4 upconversion particles is in the visible region of the electromagnetic spectrum and may be absorbed by a biocompatible photocatalysts such as TiO2 to produce reactive species. This allows the composite to be used for in vivo applications.