Graphene quantum dots (GQDs) are great promising in various applications owing to the quantum confinement and edge effects in addition to their intrinsic properties of graphene, but the preparation of the GQDs in bulk scale is challenging. We demonstrated in this work that the micrometer sized graphene oxide (GO) sheets could react with Fenton reagent (Fe(2+)/Fe(3+)/H(2)O(2)) efficiently under an UV irradiation, and, as a result, the GQDs with periphery carboxylic groups could be generated with mass scale production. Through a variety of techniques including atomic force microscopy, X-ray photoelectron spectroscopy, gas chromatography, ultraperformance liquid chromatography-mass spectrometry, and total organic carbon measurement, the mechanism of the photo-Fenton reaction of GO was elucidated. The photo-Fenton reaction of GO was initiated at the carbon atoms connected with the oxygen containing groups, and C-C bonds were broken subsequently, therefore, the reaction rate depends strongly on the oxidization extent of the GO. Given the simple and efficient nature of the photo-Fenton reaction of GO, this method should provide a new strategy to prepare GQDs in mass scale. As a proof-of-concept experiment, the novel DNA cleavage system using as-generated GQDs was constructed.

An arbitrary unknown quantum state cannot be precisely measured or perfectly replicated. However, quantum teleportation allows faithful transfer of unknown quantum states from one object to another over long distance, without physical travelling of the object itself. Long-distance teleportation has been recognized as a fundamental element in protocols such as large-scale quantum networks and distributed quantum computation. However, the previous teleportation experiments between distant locations were limited to a distance on the order of 100 kilometers, due to photon loss in optical fibres or terrestrial free-space channels. An outstanding open challenge for a global-scale "quantum internet" is to significantly extend the range for teleportation. A promising solution to this problem is exploiting satellite platform and space-based link, which can conveniently connect two remote points on the Earth with greatly reduced channel loss because most of the photons' propagation path is in empty space. Here, we report the first quantum teleportation of independent single-photon qubits from a ground observatory to a low Earth orbit satellite - through an up-link channel - with a distance up to 1400 km. To optimize the link efficiency and overcome the atmospheric turbulence in the up-link, a series of techniques are developed, including a compact ultra-bright source of multi-photon entanglement, narrow beam divergence, high-bandwidth and high-accuracy acquiring, pointing, and tracking (APT). We demonstrate successful quantum teleportation for six input states in mutually unbiased bases with an average fidelity of 0.80+/-0.01, well above the classical limit. This work establishes the first ground-to-satellite up-link for faithful and ultra-long-distance quantum teleportation, an essential step toward global-scale quantum internet.Comment: 16 pages, 3 figure

Biochemical and biomedical applications of graphene oxide (GO) critically rely on the interaction of biomolecules with it. It has been previously reported that the biological activity of the GO-enzyme conjugate decreases due to electrostatic interaction between the enzymes and GO. Herein, the immobilization of horseradish peroxidase (HRP) and oxalate oxidase (OxOx) on chemically reduced graphene oxide (CRGO) are reported. The enzymes can be adsorbed onto CRGO directly with a tenfold higher enzyme loading than that on GO, and maximum enzyme loadings reach 1.3 and 12 mg mg(-1) for HRP and OxOx, respectively. Significantly, the more CRGO is reduced, the higher the enzyme loading. The CRGO-HRP conjugates also exhibit higher enzyme activity and stability than GO-HRP. Excellent properties of the CRGO-enzyme conjugates are attributed to hydrophobic interaction between the enzymes and the CRGO. The hydrophobic interaction mode of the CRGO-enzyme conjugates can be applied to other hydrophobic proteins, and thus could dramatically improve the performance of immobilized proteins. The results indicate that CRGO is a potential substrate for efficient enzyme immobilization, and is an ideal candidate as a macromolecule carrier and biosensor.

Heterogeneous oxidation of gas-phase SO 2 on different iron oxides was investigated in situ using a White cell coupled with Fourier transform infrared spectroscopy (FTIR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results revealed that adsorbed SO 2 could be oxidized on the surface of most iron oxides to form a surface sulfate species at ambient temperature. Additional support for this hypothesis was provided by X-ray photoelectron spectroscopy (XPS) measurements and ion chromatogram (IC) analysis. The spectroscopic results further revealed that the surface hydroxyl species on the iron oxides was the key reactant for this heterogeneous oxidation. Furthermore, the bidentate sulfate species were the predominant surface species with R-Fe 2 O 3 , R-FeOOH, and Fe 3 O 4 , while the monodentate surface Fe(III)sulfato complexes were available in the case of γ-Fe 2 O 3 . Using the BET area as the reactive surface area, the samples showed the varied reactivity in the order of R-FeSome preliminary experiments indicated a significant acceleration during SO 2 uptake on the surface of R-Fe 2 O 3 in the presence of oxygen. In contrast, no significant formation of sulfate was seen on the surface of R-Fe 2 O 3 prereduced by H 2 at 523 K at the absence of O 2 , suggesting that the concentration of adsorbed oxygen over catalyst surfaces may be the key factor contributing to the oxidizing activities. On the basis of these results, the atmospheric implications of these studies on SO 2 uptake on Fe-rich mineral aerosol were discussed.

Bulk-scale production of individual graphene sheets is still challenging although several methodologies have been developed. We report here a rapid and cost-effective approach to reduction of graphene oxide (GO) using hydroxylamine as a reductant. We demonstrated that the reduction of GO with hydroxylamine could take place quickly under a mild condition, and the as-produced graphene sheet showed high electrical conductivity, fair crystalline state, and admirable aqueous dispersibility without using any stabilizing reagents. A mechanism for removal of epoxide and hydroxyl groups from GO by hydroxylamine has been proposed. Comparing with other reported methods, the reduction of GO with hydroxylamine should be a preferable route to bulk-scale production of the graphene because it is simple, efficient, and cost-effective.

Due to the high peroxidase-like activity and small lateral size of graphene quantum dots (GQDs), the covalently assembled GQDs/Au electrode exhibits great performance and stability in H(2)O(2) detection. It is better or comparable to some enzyme-immobilized electrodes, and thus could be useful in sensing H(2)O(2) changes in biological systems.

The unstable nature of perovskites has severely limited their practical applications. Here, we report on ultrastable CsPbBr3 nanocrystals (NCs) with a thick (∼25 nm) polymer coating prepared via an effective postsynthetic strategy. The thick poly­(maleic anhydride-alt-1-octadecene) (PMAO) with long hydrophobic alkyl chains bounded with the surface ligands of perovskite NCs acts as a protection layer to effectively prevent perovskite degradation from the external environment. The photoluminescence (PL) for the thick PMAO-coated CsPbBr3 NCs maintains more than 90% of its initial emission intensity under continuous ultraviolet illumination of 144 h, whereas that of the pristine NCs is decreased to ∼6%. After exposure in air for 40 days, only a very little PL degradation appears for the thick polymer-coated NCs as compared to the dramatic decrease in the PL emission for the pristine NCs. Upon immersion into water for 24 h, the perovskite NCs maintain 60% of its initial PL intensity, whereas the PL emission for the pristine NCs is completely quenched within only a few minutes. Moreover, there is no any side effect on the luminescent properties of perovskite NCs by the transparent polymer coating and the PL quantum yields are obviously improved due to the surface defect passivation of NCs. The resulting thick PMAO-coated CsPbBr3 NCs are combined with a commercially available red-emitting phosphor on a blue InGaN chip to fabricate a high-performance warm white light-emitting diode with a high power efficiency of 56.6 lm/W.

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