Controlling the luminescence emission from palladium grafted graphene oxide thin films via reduction

A novel Co-based MOF/Pd composite: synergy of charge-transfer towards the electrocatalytic oxygen evolution reaction

A novel Co-based MOF/Pd composite (LEEL-037/Pd-C) presented an electronic transference (Co 3d orbital → linkers π* → Pd 5S orbital) promoting an enhanced OH⁻ adsorption, thus improving the oxygen evolution reaction (OER) in alkaline medium.

Palladium Nanoparticles Supported on Graphene Oxide as Catalysts for the Synthesis of Diarylketones

Three palladium catalysts supported on graphene oxide (GO) and on its composite with TiO2 (GO-TiO2) were prepared and characterized. The presence of Pd NPs of different diameters (4–89 nm) and size distributions was evidenced by TEM measurements. GO-supported palladium efficiently catalysed the carbonylative coupling of iodobenzenes with aryl boronic acids forming relevant diarylketones at 1 atm CO. The highest activity and recyclability were obtained for Pd/GO-TiO2. The emission behaviour of Pd/GO and Pd/GO-TiO2 catalysts indicated structural changes occurring during the catalytic reaction.

Large magnetization modulation in ZnO-based memory devices with embedded graphene quantum dots

Magnetization modulation in oxide-based resistive random-access memories facilitates their application in multifunctional memory devices and spintronics. However, the small magnetization modulation in oxide films hinders their practical applications. In this paper, we report a significant enhancement in the magnetization modulation of ZnO films upon embedding graphene quantum dots (GQDs). The magnetization-modulation ratio is greater than 500% in the ZnO-GQD hybrid films under applied biases of only 0.23/-0.20 V. This magnetization-modulation ratio is the highest value reported to date in pure or magnetic-ion-doped metal-oxide films. Further analyses indicate that the exchange of oxygen between the GQDs and ZnO, under a reversible electric field, plays an important role in enhancing the magnetization modulation. This work provides a new direction for the application of GQDs.

Facile approach to synthesize highly fluorescent multicolor emissive carbon dots via surface functionalization for cellular imaging

Luminescent nanomaterials are encouraging scaffolds for diverse applications such as chemical sensors and biosensors, imaging, drug delivery, diagnostics, catalysis, energy, photonics, medicine, and so on. Carbon dots (CDs) are a new class of luminescent carbonaceous nanomaterial that have appeared recently and reaped tremendous scientific interest. Herein, we have exploited a simple approach to prepare tuneable and highly fluorescent CDs via surface functionalization. The successful synthesis of CDs is manifested from several investigations like high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The CDs exhibit excellent water solubility and with increasing nitrogen content fluorescence quantum yield increases whereas cell toxicity decreases. The CD synthesized at high temperature (180 °C) shows very high quantum yield (more than 56%). The tuneable optical properties of CDs are systematically studied using UV-vis and fluorescence spectroscopy. The cell viability evaluation and in vitro imaging study reveals that the synthesized CDs can be employed as a potential fluorescent probe for bio-imaging without further modification.

A Reduced Graphene Oxide Based Radio Frequency Glucose Sensing Device Using Multi-Dimensional Parameters

A reduced graphene oxide (RGO) based glucose sensor using a radio frequency (RF) signal is demonstrated. An RGO with outstanding electrical property was employed as the interconnector material between signal electrodes in an RF electric circuit, and it was functionalized with phenylbutyric acid (PBA) as a linker molecule to bind glucoses. By adding glucose solution, the fabricated sensor with RGO and PBA showed detecting characteristics in RF signal transmission and reflection. Frequency dependent electrical parameters such as resistance, inductance, shunt conductance and shunt capacitance were extracted from the RF results under the equivalent circuit model. These parameters also provided sensing characteristics of glucose with different concentrations. Using these multi-dimensional parameters, the RF sensor device detected glucose levels in the range of 1–4 mM, which ordinarily covers the testing range for diabetes or medical examination. The RGO based RF sensor, which fits well to a linear curve with fine stability, holds considerable promise for biomaterials detection, including glucose.

High-rate and long-life of Li-ion batteries using reduced graphene oxide/Co3O4 as anode materials

A new one-step microwave method was designed for synthesis of rGO/Co₃O₄, and the Li-ion battery showed high capacity and long life.

All-solid-state flexible asymmetric micro supercapacitors based on cobalt hydroxide and reduced graphene oxide electrodes

All-solid-state flexible asymmetric micro supercapacitor was prepared based on Co(OH)₂ and electrochemically reduced graphene oxide via photolithography and electrodeposition.

Graphene oxide-phosphor hybrid nanoscrolls with high luminescent quantum yield: synthesis, structural, and X-ray absorption studies

Highly luminescent graphene oxide (GO)-phosphor hybrid thin films with a maximum quantum yield of 9.6% were synthesized via a simple chemical method. An intense luminescence emission peak at 537 nm and a broad emission peak at 400 nm were observed from the GO-phosphor hybrid films. The maximum quantum yield of the emissions from the hybrid films was found to be 9.6%, which is 48 times higher than that of pristine GO films. The GO-phosphor hybrids were prepared via spin-coating and subsequent postannealing of the films, resulting in scrolling of the GO sheets. The resulting GO nanoscrolls exhibited a length of ∼2 μm with nanoscale interior cavities. Transmission electron microscopy and selected-area electron diffraction analyses revealed that the lattice structure of the tubular scrolls is similar to that of carbon nanotubes. While pristine GO films are p-type, in the GO-phosphor hybrids, the Fermi level shifted upward and fell between the HOMO-LUMO gap due to phosphor attachment via C-N bonding. The highly luminescent GO-phosphor hybrids will find important applications in graphene-based optoelectronic devices.