Direct Electrosynthesis of Metal Nanoparticles on Ti3C2Tx-Mxene during Hydrogen Evolution.

Herein, we propose a simple yet effective method to deposit metal nanoparticles on Ti3C2Tx-MXene via direct electrosynthesis. Without using any reducing reagent or annealing under reducing atmosphere, it allows the conversion of metal salts (e.g., PtCl4, RuCl3·yH2O, IrCl3·zH2O, AgNO3, and CuCl2·2H2O) to metal nanoparticles with a small particle size (ca. 2 nm). Under these circumstances, it was realized that the support effect from Ti3C2Tx-MXene (electron pushing) is quite profound, in which the Ti3C2Tx-MXene support will act as an electron donor to push the electron to Pt nanoparticles and increase the electron density of Pt nanoparticles. It populates the antibonding state of Pt-Pt bonds as well as the adsorbate level that leads to a "weakening" of the ΔGH* in the optimal position. This rationalizes the outstanding activity of Pt/Ti3C2Tx-MXene (5 wt %, η10 = 16 mV) for the hydrogen evolution reaction (HER). In addition, this direct electrosynthesis method grants the growth of two or multiple types of metal nanoparticles on the Ti3C2Tx-MXene substrate that can perform dual or multiple functions as desired. For instance, one can prepare an electrocatalyst with Pt (2.5 wt %) and Ru nanoparticles (2.5 wt %) on the Ti3C2Tx-MXene support from the same synthetic method. This electrocatalyst (Pt_Ru/Ti3C2Tx-MXene) can display good electrocatalytic HER performance in both acid (0.5 M H2SO4) and alkaline electrolytes (1.0 M KOH).

Dipole Engineering through the Orientation of Interface Molecules for Efficient InP Quantum Dot Light-Emitting Diodes.

InP-based quantum dot (QD) light-emitting diodes (QLEDs) provide a heavy-metal-free route to size-tuned LEDs having high efficiency. The stability of QLEDs may be enhanced by replacing organic hole-injection layers (HILs) with inorganic layers. However, inorganic HILs reported to date suffer from inefficient hole injection, the result of their shallow work functions. Here, we investigate the tuning of the work function of nickel oxide (NiOx) HILs using self-assembled molecules (SAMs). Density functional theory simulations and near-edge X-ray absorption fine structure put a particular focus onto the molecular orientation of the SAMs in tuning the work function of the NiOx HIL. We find that orientation plays an even stronger role than does the underlying molecular dipole itself: SAMs having the strongest electron-withdrawing nitro group (NO2), despite having a high intrinsic dipole, show limited work function tuning, something we assign to their orientation parallel to the NiOx surface. We further find that the NO2 group─which delocalizes electrons over the molecule by resonance─induces a deep lowest unoccupied molecular orbital level that accepts electrons from QDs, producing luminescence quenching. In contrast, SAMs containing a trifluoromethyl group exhibit an angled orientation relative to the NiOx surface, better activating hole injection into the active layer without inducing luminescence quenching. We report an external quantum efficiency (EQE) of 18.8%─the highest EQE among inorganic HIL-based QLEDs (including Cd-based QDs)─in InP QLEDs employing inorganic HILs.

Mapping thalamic-anterior cingulate monosynaptic inputs in adult mice.

The anterior cingulate cortex (ACC) is located in the frontal part of the cingulate cortex, and plays important roles in pain perception and emotion. The thalamocortical pathway is the major sensory input to the ACC. Previous studies have show that several different thalamic nuclei receive projection fibers from spinothalamic tract, that in turn send efferents to the ACC by using neural tracers and optical imaging methods. Most of these studies were performed in monkeys, cats, and rats, few studies were reported systematically in adult mice. Adult mice, especially genetically modified mice, have provided molecular and synaptic mechanisms for cortical plasticity and modulation in the ACC. In the present study, we utilized rabies virus-based retrograde tracing system to map thalamic-anterior cingulate monosynaptic inputs in adult mice. We also combined with a new high-throughput VISoR imaging technique to generate a three-dimensional whole-brain reconstruction, especially the thalamus. We found that cortical neurons in the ACC received direct projections from different sub-nuclei in the thalamus, including the anterior, ventral, medial, lateral, midline, and intralaminar thalamic nuclei. These findings provide key anatomic evidences for the connection between the thalamus and ACC.

Polychromatic fluorescent MoS2 quantum dots: fabrication and off-on sensing for fluorine ions in water.

Recently, MoS2 quantum dots (QDs) have receive widespread attention as a promising luminescent material. However, so far, little effort has been made on the multicolor emission of MoS2 QDs. Herein, an in situ iodine doping strategy is presented and used to synthesize tunable-photoluminescent (PL) MoS2 QDs. By fine iodine doping, the PL of the MoS2 QDs (I-MoS2 QDs) can be tuned in the range from 423 nm to 529 nm, which exceeds the as-reported emission wavelength range. Studies using controlled experiments and density functional theory (DFT) reveal that the change in electronic state of MoS2 QDs is responsible for the changing PL due to iodine doping. As-synthesized I-MoS2 QDs combined with Fe3+ is developed as a "turn-off-on" fluorescence sensor for F- ions in water. The fluorescence probe has a fine linear response to F- ions in the concentration range of 2.5-80 µM, and the limit of detection is 1.4 µM (S/N = 3).

The Impact of Financial Deepening on Carbon Reductions in China: Evidence from City- and Enterprise-Level Data.

This study extends the limited evidence of the China context by establishing a panel fixed-effect model to identify the nexus between financial deepening and carbon emissions. Using newly compiled city-level (287 prefecture-level and above cities) and enterprise-level (resource enterprises listed on the Chinese A-shares) datasets from 2007 to 2019, this study quantitatively evaluated finance deepening and analysed the impact of financial deepening on carbon emissions in China, with a particular consideration of green innovation. Our results document that financial deepening contributes to carbon reductions, as shown by the considerably decreased carbon dioxide (CO2) emissions. Both the city-level and enterprise-level estimates argue that financial deepening has a promoting effect on green innovation. Stimulating green innovation is identified as an important mechanism through which financial deepening can contribute to carbon reductions. Policy implications are presented based on the empirical results.

Boride-derived oxygen-evolution catalysts.

Metal borides/borates have been considered promising as oxygen evolution reaction catalysts; however, to date, there is a dearth of evidence of long-term stability at practical current densities. Here we report a phase composition modulation approach to fabricate effective borides/borates-based catalysts. We find that metal borides in-situ formed metal borates are responsible for their high activity. This knowledge prompts us to synthesize NiFe-Boride, and to use it as a templating precursor to form an active NiFe-Borate catalyst. This boride-derived oxide catalyzes oxygen evolution with an overpotential of 167 mV at 10 mA/cm2 in 1 M KOH electrolyte and requires a record-low overpotential of 460 mV to maintain water splitting performance for over 400 h at current density of 1 A/cm2. We couple the catalyst with CO reduction in an alkaline membrane electrode assembly electrolyser, reporting stable C2H4 electrosynthesis at current density 200 mA/cm2 for over 80 h.

Nitrogen-doped MoS2 quantum dots: Facile synthesis and application for the assay of hematin in human blood.

Nitrogen-doped MoS2 quantum dots (N-MoS2 QDs) were synthesized via a facile hydrothermal approach, and exhibited high fluorescence quantum yield (QY, 14.9%), excellent photostability, biocompatibility and water solubility. A novel method with good selectivity and sensitivity was established to assay hematin using N-MoS2 QDs as a fluorescent probe based on inner filter effect (IFE). Fluorescent quenching of N-MoS2 QDs has a fine linear dependence with the concentration of hematin in the range of 0.5-15 µmol/L and a limit of detection of 0.32 µmol/L (S/N = 3). By the detection method, average concentration of hematin in real health human erythrocytes was measured as 22.5 ± 3.9 µmol/L. And, recoveries range varied from 94 to 108% through standard recovery experiment. The N-MoS2 QDs probe shows excellent photostability, low cytotoxicity and anti-interference ability for hematin assay, which may become a promising method for the test of hematin in human blood.

Contagious itch can be induced in humans but not in rodents.

Itch contagion has been reported in human when people watch someone scratching in a video. The basic mechanism of contagious itch induced by scratching video is still being investigated. A recent study has reported that adult mice showed itch like responses after watching itch-like video or mice showing itching responses. However, such contagious itch behaviors failed to be reproduced by another study by repeating the same experiments of viewing itching mice. It is unclear if contagious itch induced by seeing itching video may be reproducible. In the present study, we used a four-iPad paradigm to repeat these experiments, and found that mice showed no significant itch-like responses after watching itching video of mice. To test if mice actually can see the video, we placed mirrors at the same location. Interestingly, mice showed altered activities in the open field with the mirrors. Finally, in healthy subjects, we found that viewing human itch video did cause itch sensation or responses. Our results indicate that the mouse model may not appropriate for studying contagious itch in humans.