Electronic Structure Modulation Via Iron-Incorporated NiO to Boost Urea Oxidation/Oxygen Evolution Reaction

The urea-assisted water splitting not only enables a reduction in energy consumption during hydrogen production but also addresses the issue of environmental pollution caused by urea. Doping heterogeneous atoms in Ni-based electrocatalysts is considered an efficient means for regulating the electronic structure of Ni sites in catalytic processes. However, the current methodologies for synthesizing heteroatom-doped Ni-based electrocatalysts exhibit certain limitations, including intricate experimental procedures, prolonged reaction durations, and low product yield. Herein, Fe-doped NiO electrocatalysts were successfully synthesized using a rapid and facile solution combustion method, enabling the synthesis of 1.1107 g within a mere 5 min. The incorporation of iron atoms facilitates the modulation of the electronic environment around Ni atoms, generating a substantial decrease in the Gibbs free energy of intermediate species for the Fe-NiO catalyst. This modification promotes efficient cleavage of C-N bonds and consequently enhances the catalytic performance of UOR. Benefiting from the tunability of the electronic environment around the active sites and its efficient electron transfer, Fe-NiO electrocatalysts only needs 1.334 V to achieve 50 mA cm-2 during UOR. Moreover, Fe-NiO catalysts were integrated into a dual electrode urea electrolytic system, requiring only 1.43 V of cell voltage at 10 mA cm-2.

The simultaneous adsorption, activation and in situ reduction of carbon dioxide over Au-loading BiOCl with rich oxygen vacancies

The main process of carbon dioxide (CO₂) photoreduction is that excited electrons are transported to surface active sites to reduce adsorbed CO₂ molecules. Obviously, electron transfer to the active site is one of the key steps in this process. However, current catalysts for CO₂ adsorption, activation, and electron reduction occur in different locations, which greatly reduce the efficiency of photocatalysis. Herein, through a spontaneous chemical redox approach, the plasmonic photocatalysts of Au-BiOCl-OV with enhanced interfacial interaction were fabricated for visible light CO₂ reduction through the simultaneous adsorption, activation and in situ reduction of CO₂ without a sacrificial agent. By loading gold (Au) on the oxygen vacancy (OV), Au and BiOCl-OV formed a direct and tight interface contact, whose fine structure was confirmed by SEM, TEM, EPR and XPS, which not only effectively boosts the light utilization efficiency and the light carrier separation ability, but also can simultaneously adsorb, activate and in situ reduce carbon dioxide for highly efficient visible light photocatalysis. Thanks to the synergistic influence of Au and OV, Au-BiOCl-OV exhibits excellent photocatalytic performance without sacrificial agent and outstanding stability with a high CO and CH₄ production yield, reaching 4.85 μmol g^-1 h^-1, which were 2.8 times higher than C-Au-BiOCl-OV (obtained by traditional NaBH₄ reduction). This study proposes a new strategy for the production of high-performance collaborative catalysis in photocatalytic CO₂ reduction.

Valley Polarization and Valleyresistance in a Monolayer Transition Metal Dichalcogenide Superlattice

A significant, fundamental challenge in the field of valleytronics is how to generate and regulate valley-polarized currents in practical ways. Here, we discover a new mechanism for producing valley polarization in a monolayer transition metal dichalcogenide superlattice, in which valley-resolved gaps are formed at the supercell Brillouin zone boundaries and centers due to intervalley scattering. When the incident energy of the electron lies in the gaps, the available states are valley polarized, thus providing a valley-polarized current from the superlattice. We show that the direction and strength of the valley polarization may be further tuned by varying the potential applied to the superlattice. The transmission can have a net valley polarization of 55% for a four-period heterostructure. Moreover, two such valley filters in series may function as an electrostatically controlled giant valleyresistance device, representing a zero-magnetic field counterpart to the familiar giant magnetoresistance device.

Enhanced Schottky effect of a 2D-2D CoP/g-C3N4 interface for boosting photocatalytic H2 evolution

As emerging noble metal-free co-catalysts, transition metal phosphides have been employed to improve photocatalytic H2 production activity. Herein, the metallicity of CoP, as a representative phosphide, and the Schottky effect between CoP and g-C3N4 are confirmed via theoretical calculations. Then, a 2D/2D structure is designed to enlarge the Schottky effect between the interfaces, for which the apparent quantum efficiency of the photocatalytic H2 evolution is 2.1 times that of corresponding 0D/2D heterojunctions. The morphology, microstructure, chemical composition, and physical nature of pristine CoP, g-C3N4, and the composites are characterized in order to investigate the dynamic behavior of photo-induced charge carriers between CoP and g-C3N4. Based on the measurements, it is proposed that the efficient electron collecting effect of CoP can be attributed to the superior interfacial contact and Schottky junction between the CoP and g-C3N4 interfaces. Furthermore, the excellent electrical conductivity and low overpotential of CoP make water reduction easier. This work demonstrates that the construction of a 2D/2D structure based on a suitable Fermi level is crucial for enhancing the Schottky effect of transition metal phosphides.

[The preliminary study of stimulus input temporal changes on the visual cortex of rats at different ages]

Objective: To observe the impact of the input temporal changes on visual cortex of rats cells and the change of the synaptic efficacy, for the study of visual developmental plasticity mechanism. Methods: Experimental research. The brain slice of ten 14d healthy Wistar rats and ten 21d healthy Wistar rats were recorded with whole cell recording technique, using single stimulation and combined stimulate model, to observe the visual cortex of rats neurons changes in synaptic activity. Change the stimulus input sequence, and observe the visual cortex of rats changes of synaptic efficacy. Using the paired t test to compare the change of excitatory postsynaptic potential (EPSC) of visual cortex. Result: The difference between single stimulation and combined stimulate about EPSC was statistically significant, which was decreased (14.3±7.4) % (n=15) in single stimulation and (53.4±17.5) % (n=20) in combined stimulation for P14 rats which were long-term depression (t_s2=3.9, t_s1+s2=2.2; P<0.05) , and was increased (27.5±11.4) % (n=16) in single stimulation and (34.6±10.3) % (n=10) in combined stimulation for P20 rats which were long-term potentiation (t_s2=2.3, t_s1+s2=3.5; P<0.05) . Rats in different development period have a specific time window for input temporal changes. Combined stimulation patterns produced by the neuron cell reaction were not just an accumulation of simple response caused by single stimulation. For P14 rats, its time window was of about ±0.5ms. However, for P20 rats, scope of time window reduced to ±0.1ms. Conclusions: Different development period of rats, change the stimulation pattern can cause the change of the visual cortex synapses reaction, and stimulate the temporal change within a specific time window to producenonlinear results. (Chin J Ophthalmol, 2016, 52: 936-940).

One-step synthesis, electronic structure, and photocatalytic activity of earth-abundant visible-light-driven FeAl2O4

The development of inexpensive visible-light-driven photocatalysts is an important prerequisite for realizing the industrial application of photocatalysis technology. In this paper, an earth-abundant FeAl₂O₄ photocatalyst is prepared via facile solution combustion synthesis. Density functional theory and the scanning Kelvin probe technique are employed to ascertain the positions of the energy bands and the Fermi level. Phenol is taken as a model pollutant to evaluate the photocatalytic activity of FeAl₂O₄. The scavenger experiment results, ˙OH-trapping fluorescence technique, and electron spin resonance measurements confirm that the superoxide anion radical is the main active species generated in the photocatalytic process, which also further corroborates the proposed electronic structure of FeAl₂O₄. The degradation experiments and O₂ temperature programmed desorption results over various samples verify that the crystallinity degree is a more important factor than the oxygen adsorption ability in determining photocatalytic activity.

Hypothalamic obesity in weanling rats

Bilateral hypothalamic lesions were placed in the ventromedial nuclei of 15 male weanling rats. Nine male littermates were used as controls. Food intake, body weight, and nose-occipital (N-O) length were followed for 90 days. Rats were killed on the 90th postoperative day and stomach weight, body fat content, and femur length were then measured. Although the daily food intake and the rate of body weight gain of the rats with lesions were comparable to those of their controls, all 15 operated rats became obese and their N-O and femur lengths were significantly shorter. It is concluded that hypothalamic obesity of weanling rats is associated with growth impairment.