Space-Confined Growth of MoS₂ Nanosheets within Graphite: The Layered Hybrid of MoS₂ and Graphene as an Active Catalyst for Hydrogen Evolution Reaction

Since the electrocatalytic activity of layered molybdenum disulfide (MoS₂) for hydrogen evolution reaction (HER) closely depends on its exposed edges, the morphology and size of the material are critically important. Herein, we introduce a novel solvent-evaporation-assisted intercalation method to fabricate the hybrid of alternating MoS₂ sheets and reduced graphene oxide layers, in which the nanosize of the MoS₂ nanosheets can be effectively controlled by leveraging the confinement effect within the two-dimensional graphene layers. Significantly, the resulting MoS₂/reduced graphene oxide (RGO) composite shows excellent catalytic activity for HER characterized by higher current densities and lower onset potentials than the conventional pre-exfoliated RGO supported MoS₂ nanosheets. Further experiments on the effect of oxidation degree of graphene, the crystallinity of MoS₂, and the exposed active site density on the HER performance of the MoS₂/RGO composites show that there is an optimum condition for the catalytic activity of HER due to a balance between the numbers of exposed active sites of MoS₂ and the internal conductive channels provided by graphene

Close-Packed Colloidal SiO₂ as a Nanoreactor: Generalized Synthesis of Metal Oxide Mesoporous Single Crystals and Mesocrystals

We report a generalized “immobilized crystallization in silica nanoreactor” (ICSR) strategy for the synthesis of an extensive series of well-defined and high-quality metal oxide mesoporous single crystals (SnO₂, TiO₂, and CeO₂ MSCs) and mesoporous mesocrystals (CeO₂ and ZrO₂ MMCs) with varying morphologies, sizes, and phases. Close-packed colloidal SiO₂ is used as a nanoreactor, a peculiar reaction medium in which immobilized nucleation and crystallization have been systematically studied. High hydrophilicity of residual Si-OH groups facilitates surface adsorption and pore filling of precursor solution, leading to spontaneous nucleation and subsequent crystal growth in the reactor template. The silica template merely serves a faithful negative replication without interfering in the crystallization process but with an added advantage of avoiding crystal aggregation without the need for surfactant. The universality of the ICSR strategy is demonstrated by synthesizing MSCs and MMCs of different materials and different pore sizes. The great value of the as-obtained MSCs and MMCs is exemplified by a case study on the conspicuous gas-sensing activities of the SnO₂ MSCs. With 3D-connected mesopores and a single-crystalline framework, the highest gas-sensing activity is achieved when high-energy facets are maximally exposed. Overall, this work has provided insights and strategies for the rational fabrication of MSC and MMC materials and opened unprecedented opportunities for studying their structure–property relationship

Elevated expression of FTH1P3 increased the uveal melanoma cell proliferation and migration.

<p>(A) The expression of FTH1P3 in the uveal melanoma cell line MUM-2B treated with pcDNA-FTH1P3 was detected with qRT-PCR. (B) The cell proliferation was meaured by CCK-8 assay. Ectopic expression of FTH1P3 promoted the MUM-2B cell proliferation. (C) Elevated expression of FTH1P3 increased the MUM-2B cell cycle. (D) Wound healing assay was performed to determine the cell migration. (E) The relative ratio of wound closure per field was shown. *p<0.05, **p<0.01 and ***p<0.001.</p

Mesoporous TiO₂ Single Crystals: Facile Shape‑, Size‑, and Phase-Controlled Growth and Efficient Photocatalytic Performance

In this work, we have succeeded in preparing rutile and anatase TiO₂ mesoporous single crystals with diverse morphologies in a controllable fashion by a simple silica-templated hydrothermal method. A simple in-template crystal growth process was put forward, which involved heterogeneous crystal nucleation and oriented growth within the template, a sheer spectator, and an excluded volume, i.e., crystal growth by faithful negative replication of the silica template. A series of mesoporous single-crystal structures, including rutile mesoporous TiO₂ nanorods with tunable sizes and anatase mesoporous TiO₂ nanosheets with dominant {001} facets, have been synthesized to demonstrate the versatility of the strategy. The morphology, size, and phase of the TiO₂ mesoporous single crystals can be tuned easily by varying the external conditions such as the hydrohalic acid condition, seed density, and temperature rather than by the silica template, which merely serves for faithful negative replication but without interfering in the crystallization process. To demonstrate the application value of such TiO₂ mesoporous single crystals, photocatalytic activity was tested. The resultant TiO₂ mesoporous single crystals exhibited remarkable photocatalytic performance on hydrogen evolution and degradation of methyl orange due to their increased surface area, single-crystal nature, and the exposure of reactive crystal facets coupled with the three-dimensionally connected mesoporous architecture. It was found that {110} facets of rutile mesoporous single crystals can be considered essentially as reductive sites with a key role in the photoreduction, while {001} facets of anatase mesoporous single crystals provided oxidation sites in the oxidative process. Such shape- and size-controlled rutile and anatase mesoporous TiO₂ single crystals hold great promise for building energy conversion devices, and the simple solution-based hydrothermal method is extendable to the synthesis of other mesoporous single crystals beyond TiO₂

FTH1P3 was a direct target gene of miR-224-5p.

<p>(A) MiRDB (<a href="http://mirdb.org/cgi-bin/custom.cgi" target="_blank">http://mirdb.org/cgi-bin/custom.cgi</a>) was used to search the target gene of miR-224-5p. FTH1P3 may be a target gene of miR-224-5p. (B) The expression of miR-224-5p was measured by qRT-PCR. (C) Overexpression of miR-224-5p decreased the luciferase activity of FTH1P3-WT, but it has not decreased the luciferase activity of FTH1P3-Mut. (D) Overexpression of miR-224-5p decreased the FTH1P3 expression in the MUM-2B cell.</p

miR-224-5p expression level was downregulated in uveal melanoma cell lines and samples and inversely correlated with FTH1P3.

<p>(A) The expression level of miR-224-5p in the uveal melanoma cell lines (C918, MUM-2B, OCM-1A and MUM-2C) and melanocyte cell line (D78) was determined by qRT-PCR. (B) The miR-224-5p expression was lower in the uveal melanoma samples than in the no-tumor samples. (C) The expression of miR-224-5p in the uveal melanoma tissues was inversely correlated with FTH1P3 expression. ***p<0.001.</p

Doping of Vanadium into Bismuth Oxide Nanoparticles for Electrocatalytic CO₂ Reduction

Electrocatalytic reduction of carbon dioxide (CO2) to formate is an effective solution to address the continuous increase in CO2 in the atmosphere. Here, we report a vanadium-doped (V-doped) bismuth oxide (Bi2O3) electrocatalyst synthesized using a facile one-step hydrothermal method for highly efficient electrochemical reduction of CO2 to formate. The doping of V can tune the intrinsic crystal and electronic structure of Bi2O3, that is, causing partial amorphization in the Bi2O3 nanosheet and decreasing electron density around Bi active sites. The partial amorphous region can provide more reactive sites; meanwhile, the electron-deficient environment around Bi enhances the adsorption of CO2. The synergistic crystal and electronic structure modulation in the V-doped Bi2O3 provides excellent electrocatalytic CO2RR performance with a high formate selectivity of 94.2% and a high partial current density of 45.03 mA cm–2 at −1.1 V (vs RHE)

Cobalt-Embedded Nitrogen Doped Carbon Nanotubes: A Bifunctional Catalyst for Oxygen Electrode Reactions in a Wide pH Range

Electrocatalysts for the oxygen reduction and evolution reactions (ORR/OER) are often functionally separated, meaning that they are only proficient at one of the tasks. Here we report a high-performance bifunctional catalyst for both ORR and OER in both alkaline and neutral media, which is made of cobalt-embedded nitrogen doped carbon nanotubes. In OER, it shows an overpotential of 200 mV in 0.1 M KOH and 300 mV in neutral media, while the current density reaches 50 mA cm^–2 in alkaline media and 10 mA cm^–2 in neutral media at overpotential of 300 mV. In ORR, it is on par with Pt/C in both alkaline and neutral media in terms of overpotential, but its stability is superior. Further study demonstrated that the high performance can be attributed to the coordination of N to Co and the concomitant structural defects arising from the transformation of cobalt-phthalocyanine precursor

Mechanisms of the Water–Gas Shift Reaction Catalyzed by Ruthenium Carbonyl Complexes

Density functional theory (DFT) is employed to study the water–gas shift (WGS) reaction in the gas phase for two complexes, Ru₃(CO)₁₂ and Ru­(CO)₅. Here we report four mechanisms of ruthenium carbonyl complexes catalyzed for WGS reaction. The energetic span model is applied to evaluate efficiency of the four catalytic pathways. Our results indicate that mechanism C and D show a good catalytic behavior, which is in agreement with results from the literature. The mechanism C and D not only include the important intermediate Ru₃(CO)₁₁H^– but also exclude the energy-demanding OH^– desorption and revise an unfavorable factor of the previous mechanism. Two complexes along mechanisms B have the highest turnover frequency (TOF) values. The trinuclear carbonyl complexes-Ru₃(CO)₁₂ is preferred over mononuclear carbonyl Ru­(CO)₅ by comparing TOF due to the fact that metal–metal cooperativity can enhance activity to the WGS reaction. In this work, the nature of interaction between transition states and intermediates is also analyzed by the detailed electronic densities of states, and we further clarify high catalytic activity of ruthenium carbonyl complexes as well. Our conclusions provide a guide to design catalysts for the WGS reaction

Enhanced Charge Collection for Splitting of Water Enabled by an Engineered Three-Dimensional Nanospike Array

Photoelectrochemical (PEC) water splitting is a promising method of converting solar energy to hydrogen fuel from water using photocatalysts. Despite much effort in preparing mesoporous thin films on planar substrates, relatively little attention has been paid to their deposition on three-dimensional (3D) substrates, which could improve electron collection and enhance light-trapping. Here, we report the first synthesis of hierarchically branched anatase TiO₂ nanotetrapods, achieved by dissolution and nucleation processes on a ZnO nanotetrapods template. When used as a photoanode for efficient PEC water splitting, the unique branched anatase TiO₂ nanotetrapods yielded a photocurrent density of 0.54 mA cm^–2 at applied potential of 0.35 V vs RHE, much higher than that of commercial TiO₂ nanoparticles under otherwise identical conditions. Moreover, when the nanotetrapods were deposited on an ordered, purposely engineered 3D F-doped tin oxide (FTO) nanospike array, the photocurrent density was upgraded to 0.72 mA cm^–2. This large photocurrent enhancement can be attributed to the ultrahigh contact surface area with the electrolyte, which is bequeathed by the hierarchically branched TiO₂ nanotetrapods with a skin layer of vertically aligned ultrathin nanospines, as well as the short charge transport distance and enhanced light-trapping due to the peculiar 3D FTO nanospike array we have engineered by design