Dual-Hole Excitons Activated Photoelectrolysis in Neutral Solution.

II-VI semiconductors exhibit unique behaviors that can generate dual-holes ("heavy and light"), but the application in photocatalysis is still missing. Herein, an empirical utilization of light/heavy holes in a hybrid metal cluster-2D semiconductor nanoplatelets is reported. This hybrid material can boost the hole-transfer at the surface and suppress the recombination. Different roles are enacted by light-holes and heavy-holes, in which the light-holes with higher energy and mobility can facilitate the slow kinetics of water oxidation and further reduce the onset voltage, while the massive heavy-holes can increase the resulting photocurrent by about five times, achieving a photocurrent of 2 mA cm-2 at 1.23 V versus RHE under AM 1.5 G illumination in nonsacrificial neutral solution. These strategies can be the solutions for photoelectrolysis and be beneficial for sustainable development in solar conversion.

Antiferromagnetic iron nanocolloids: a new generation in vivo T1 MRI contrast agent.

A novel T1 agent, antiferromagnetic α-iron oxide-hydroxide (α-FeOOH) nanocolloids with a diameter of 2-3 nm, has been successfully prepared. These nanocolloids, together with a post synthetic strategy performed in mesoporous silica, are a great improvement over the low T1-weighted contrast common in traditional magnetic silica nanocomposites. The intrinsic antiferromagnetic goethite (α-FeOOH) shows very low magnetization (M(z)) of 0.05 emu g(-1) at H = 2 T at 300 K (0.0006 emu g(-1) for FeOOH/WMSN-PEG), which is 2 orders of magnitude smaller than any current ultrasmall iron oxide NPs (>5 emu g(-1)) reported to date, hence ensuring the low r2 (∝ Mz) (7.64 mM(-1) s(-1)) and r2/r1 ratio (2.03) at 4.7 T. These biodegradable α-FeOOH nanocolloids also demonstrate excellent in vitro cellular imaging and in vivo MR vascular and urinary trace imaging capability with outstanding biocompatibility, which is exceptionally well secreted by the kidney and not the liver as with most nanoparticles, opening up a new avenue for designing powerful antiferromagnetic iron T1 contrast agents.

Homogeneous, surfactant-free gold nanoparticles encapsulated by polythiophene analogues.

The synthesis of nanocrystal-polymer nanocomposites is reported, in which 2-(2-ethoxyethoxy)ethoxy modified polythiophene serves as the protecting group for dispersion and homogeneous size distribution of the nanoparticles, showing potential of this polymer-based material in optoelectronics and microelectronics.

Ag@Au nanoprism-metal organic framework-based paper for extending the glucose sensing range in human serum and urine.

In this work, we present a Ag@Au nanoprism-metal-organic framework-paper based glucose sensor for rapid, sensitive, single-use and quantitative glucose determination in human serum. To achieve painless measurement of glucose with a non-invasive detection methodology, this biosensor was further tested in human urine. In this approach, a new hybrid-Ag@Au nanoprism loaded in close proximity to micrometer sized coordination polymers as phosphorescent luminophores significantly enhanced the emission intensity due to metal-enhanced phosphorescence and worked as reaction sites to support more dissolved oxygen. Reports of enhanced phosphorescence intensity are relatively rare, especially at room temperature. The true enhancement factor of Ag@Au-phosphorescent metal-organic frameworks on paper was deduced to be 110-fold, making it a better optical type glucose meter. The results demonstrate the validity of the intensity enhancement effect of the excitation of the overlap of the emission band of a luminophore with the surface plasmon resonance band of Ag@Au nanoprisms. Ag@Au nanoprisms were used not only to improve the detection limit of glucose sensing but also to extend the glucose sensing range by enhancing the oxygen oxidation efficiency. The oxidation of glucose as glucose oxidase is accompanied by oxygen consumption, which increases the intensity of the phosphorescence emission. The turn-on type paper-based biosensor exhibits a rapid response (0.5 s), a low detection limit (0.038 mM), and a wide linear range (30 mM to 0.05 mM), as well as good anti-interference, long-term longevity and reproducibility. Finally, the biosensor was successfully applied to the determination of glucose in human serum and urine.

En route to white-light generation utilizing nanocomposites composed of ultrasmall CdSe nanodots and excited-state intramolecular proton transfer dyes.

One single material that emits white light is of paramount interest for the development of white light-emitting diodes (WLEDs). Here we report a novel nanocomposite, in which a new type of excited-sate intramolecular proton transfer (ESIPT) molecule, namely 5-(1,2-dithiolan-3-yl)-N-(2-{[4-(3-hydroxy-4-oxo-4H-chromen-2-yl)phenyl](methyl)amino}ethyl)pentanamide (HF-N-LA), is anchored onto the surface of ultrasmall CdSe quantum dots through dithiol functionality. Authentic white light with a CIE coordinate of (0.33, 0.33) could then be generated by confluence of 440 nm emission from CdSe and 570 nm proton-transfer tautomer emission from HF-N-LA. Moreover, linear color tunability could be achieved simply by altering relative amount of the two species, i.e., number of HF-N-LA onto CdSe, in one single nanocomposite, thus opening an innovative route toward applying nanocrystals in the field of WLEDs.

2D self-bundled CdS nanorods with micrometer dimension in the absence of an external directing process.

In the absence of an external direction-controlling process, exclusive self-bundled arrays of CdS nanorods are formed using a facile solution-based method involving trioctylphosphine (TOP) and tetradecylphosphonic acids (TDPA) as cosurfactants. CdS self-bundled arrays with an area of as large as 2.0 microm(2) could be obtained. A detailed mechanistic investigation leads us to conclude that the matching in nanorod concentration, intrinsic properties of CdS, and the hydrocarbon chains of the surfactants between adjacent CdS rods play key roles in the self-assembly. In sharp contrast to the defect dominant emission in solutions, the self-bundled CdS nanorods exhibit optical emission nearly free from the defect-states, demonstrating their potential for applications in luminescence and photovoltaic devices.