Influence of Electronic Modulation of Phenanthroline-Derived Ligands on Separation of Lanthanides and Actinides.

The solvent extraction, complexing ability, and basicity of tetradentate N-donor 2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-1,10-phenanthroline (CyMe4-BT- Phen) and its derivatives functionalized by Br, hydroxyphenyl, nitryl were discussed and compared. It was demonstrated that four BTPhen ligands are able to selectively extract Am(lll) over Eu(lll). It was notable that the distribution ratio of 5-nitryl-CyMe4-BTPhen for Eu(lll) was suppressed under 0.02, which was much lower compared to DEu(lll) = 1 by CyMe4-BTPhen. The analysis of the effect of the substituent on the affinity to lanthanides was conducted by UV/vis and fluorescence spectroscopic titration. The stability constants of various ligands with Eu(lll) were obtained by fitting titration curve. Additionally, the basicity of various ligands was determined to be 3.1 ± 0.1, 2.3 ± 0.2, 0.9 ± 0.2, 0.5 ± 0.1 by NMR in the media of CD3OD with the addition of DClO4. The basicity of ligands follows the order of L1 > L2 > L3 > L4, indicating the tendency of protonation decreases with the electron-withdrawing ability increase.

Fabrication of 2D-2D Heterojunction Catalyst with Covalent Organic Framework (COF) and MoS2 for Highly Efficient Photocatalytic Degradation of Organic Pollutants.

In this work, for the first time, we fabricated a novel covalent organic framework (COF)-based 2D-2D heterojunction composite MoS2/COF by a facile hydrothermal method. The results of photocatalytic degradation of TC and RhB under simulated solar light irradiation showed that the as-prepared composite exhibited outstanding catalytic efficiency compared with pristine COFs and MoS2. The significantly enhanced catalytic efficiency can be ascribed to the formation of 2D-2D heterojunction with a well-matched band position between COF and MoS2, which can effectively restrain the recombination of charge carriers and increase the light absorption as well as the specific surface area. Moreover, the fabricated 2D-2D layered structure can effectively increase the contact area with an intimate interface contact, which greatly facilitates the charge mobility and transfer in the interfaces. This study reveals that artful integration of organic (COFs) and inorganic materials into a single hybrid with a 2D-2D interface is an effective strategy to fabricate highly efficient photocatalysts.

Fabrication of Hierarchical Co9S8@ZnAgInS Heterostructured Cages for Highly Efficient Photocatalytic Hydrogen Generation and Pollutants Degradation.

In the present study, a hierarchical Co9S8@ZnAgInS heterostructural cage was developed for the first time which can photocatalytically produce hydrogen and degrade organic pollutants with high efficiency. First, the Co9S8 dodecahedron was synthesized using a metal-organic framework (MOFs) material, ZIF-67, as a precursor, then two kinds of metal sulfide semiconductors were elaborately integrated into a hierarchical hollow heterostructural cage with coupled heterogeneous shells and 2D nanosheet subunits. The artfully designed hollow heterostructural composite exhibited remarkable photocatalytic activity without using any cocatalysts, with a 9395.3 µmol g-1 h-1 H2 evolution rate and high degradation efficiency for RhB. The significantly enhanced photocatalytic activity can be attributed to the unique architecture and intimate-contact interface between Co9S8 and ZnAgInS, which promote the transfer and separation of the photogenerated charges, increase light absorption, and offer large surface area and active sites. This work presents a new strategy to design highly active semiconductor photocatalysts by using MOF materials as precursors and coupling of metal sulfide semiconductors to form hollow architecture dodecahedron cages with an intimate interface.

Comparison of three methods for collecting interstitial fluid from subcutaneous tissue in mini pigs.

Interstitial fluid, owing to its similarity to blood components and higher sensitivity and specificity, finds widespread application in disease diagnosis and tumor marker detection. However, collecting interstitial fluid, particularly from the deep subcutaneous connective tissue, remains challenging.•This study aimed to compare three different collection methods - push-pull perfusion, multi-filament nylon thread implantation, and tissue centrifugation - for collecting interstitial fluid from the subcutaneous connective tissue layer of mini-pigs. High-performance ion chromatography was employed to analyze the conventional cation components in the samples and compare ion composition analysis between the different methods.•Results indicated that while the distribution of conventional cations in the interstitial fluid collected by the three methods was generally consistent, there were slight variations in the detection rates and concentrations of different ions. Hence, suitable collection methods should be selected based on the ions or collection sites of interest.

Differences in the catalytic properties of Fe isotopes.

The significant differences in the catalytic properties caused by different 'isotopic catalysts' were discovered for the first time. The commonly purchased Fe2O3 is a 'mixture' of different Fe isotopic oxides which means the catalytic effect of Fe2O3 is theoretically a synthetical result of all isotopic compounds. In this work, the differences in catalytic properties of α-Fe2O3 with natural abundance ratio and separated isotopic α-Fe2O3 (α-54Fe2O3, α-56Fe2O3, and α-58Fe2O3) catalyzing thermal decomposition of ammonium perchlorate (AP) were investigated, and are mainly attributed to the difference in the charge distribution of the nuclei of different iron isotopes. The result suggests that isotope effects in different isotopes when utilized as catalysts are caused by nuclear morphology and the nuclear charge distribution. This study will serve as a base as well as an initiation for future studies of the isotopic catalyst.

Formation of a PVP-protected C/UO2/Pt catalyst in a direct ethanol fuel cell.

In order to solve the problem that UO2 in direct ethanol fuel cell anode catalysts is easily lost in acidic solution, resulting in the degradation of catalytic performance, this paper prepared a C/UO2/PVP/Pt catalyst in three steps by adding polyvinylpyrrolidone (PVP). The test results by XRD, XPS, TEM and ICP-MS showed that PVP had a good encapsulation effect on UO2, and the actual loading rates of Pt and UO2 were similar to the theoretical values. When 10% PVP was added, the dispersion of Pt nanoparticles was significantly improved, which reduced the particle size of Pt nanoparticles and provided more ethanol electrocatalytic oxidation reaction sites. The test results by electrochemical workstation showed that the catalytic activity as well as the stability of the catalysts were optimized due to the addition of 10% PVP.

Efficient and selective capture of thorium ions by a covalent organic framework.

The selective separation of thorium from rare earth elements and uranium is a critical part of the development and application of thorium nuclear energy in the future. To better understand the role of different N sites on the selective capture of Th(IV), we design an ionic COF named Py-TFImI-25 COF and its deionization analog named Py-TFIm-25 COF, both of which exhibit record-high separation factors ranging from 102 to 105. Py-TFIm-25 COF exhibits a significantly higher Th(IV) uptake capacity and adsorption rate than Py-TFImI-25 COF, which also outperforms the majority of previously reported adsorbents. The selective capture of Py-TFImI-25 COF and Py-TFIm-25 COF on thorium is via Th-N coordination interaction. The prioritization of Th(IV) binding at different N sites and the mechanism of selective coordination are then investigated. This work provides an in-depth insight into the relationship between structure and performance, which can provide positive feedback on the design of novel adsorbents for this field.

Research on UO2 modification of a direct ethanol fuel cell Pt/C catalyst.

Radioactive UO2 powder was prepared by hydrothermal method and a set of Pt-xUO2/C catalysts were synthesized by impregnation method for solving the problem of low activity and easy poisoning of anode Pt/C catalysts for a direct ethanol fuel cell. XRD, TEM, EDS, XPS and ICP-MS characterization showed the successful loading of Pt and UO2 onto the carbon carrier. Electrochemical workstation and single cell test results confirm that the catalytic performance of Pt-10% UO2/C is significantly better than Pt/C-eg. It is speculated that the synergistic effect of Pt and U enhances the catalytic activity and UO2 improves the resistance to CO poisoning by releasing O2 stored in the lattice space, while the α-particles released by 235U can also generate radiolysis product OH and promote the oxidative desorption of CO from the Pt surface.

Improved performance of self-reactivated Pt-ThO2/C catalysts in a direct ethanol fuel cell.

A novel self-reactivated catalyst Pt-ThO2/C was prepared for the first time by selecting radioactive material ThO2 as the catalytic additive to address the low activity and toxicity of the anode Pt/C catalyst in a direct ethanol fuel cell. The catalytic activity and resistance to CO poisoning of Pt-6.67 wt%ThO2/C were found to be superior to those of Pt/C-NaBH4 in electrochemical workstation and single-cell tests. It is speculated that the exist of ThO2 not only improves the catalytic activity via the synergistic effect of Pt and Th, but also produces a large amount of radiolysis products, OH radicals, due to 232Th which oxidatively desorbs CO from Pt-COads and solves the CO poisoning problem.

The mechanism of Co oxyhydroxide nano-islands deposited on a Pt surface to promote the oxygen reduction reaction at the cathode of fuel cells.

With the rapid development of fuel cell technology, the low reduction rate of oxygen on Pt-based cathodes is generally considered the main obstacle. Pt/transition metal alloys (Pt-Ms) or Pt/transition metal oxides (Pt-MO x ) can be formed by doping transition metal atoms into the lattice of the Pt layer or depositing onto the surface of the Pt layer to intensify the catalytic activity of the electrodes. In this work, a stepwise solution chemical reduction method for high dispersion of cobalt oxyhydroxide (-OCoOH) deposited onto the facet of Pt as nano-islands and the mechanism of promoting the oxygen reduction reaction (ORR) at the cathode have been investigated by density functional theory (DFT) calculation. As a result, the electrocatalytic activity of Pt with nano-island -OCoOH structure was 3.6 times that of the Pt/C catalyst, which indicated that promoting the desorption of the first O atom and weakening the adsorption capacity of the interfacial junction Pt for the second O atom from adsorbed oxygen attributed to the migration of d-band center in Pt and the existence of the Co hydroxyl group.

Porous MOF-808@PVDF beads for removal of iodine from gas streams.

The removal of radioiodine from the exhaust gas streams produced in spent fuel reprocessing plants is of paramount importance for the nuclear fuel cycle's security. Here, millimeter-sized poly(vinylidene fluoride) (PVDF) composites containing zirconium-based metal-organic frameworks, MOF-808, were synthesized by a facile phase inversion method to adsorb the volatile iodine. MOF-808@PVDF composites have inherited the crystallinity and pore accessibility of MOF-808, as well as its outstanding iodine capture performance. The MOF-808@PVDF composite beads containing 70 wt% MOFs, exhibited ultrahigh iodine adsorption capacity, 1.42 g g-1 at 80 °C, much higher than other millimeter-sized adsorbents reported in the literature. Raman mapping suggests that the negative iodine ions were formed at the early stage of iodine adsorption, while the close-packed iodine molecules were subsequently trapped in the frames. Using dynamic adsorption, the influences of iodine concentration, operating temperature and humidity were analyzed to evaluate its application potential in industrial conditions. The iodine adsorption capacity could reach 1.36 g g-1 at 80 °C, 100 °C and 120 °C in flow gas. And the elevated temperature (120 °C) is beneficial to accelerating the mass transfer of iodine vapor, as well as slightly inhibiting the competitive adsorption of water molecules under humidity. Besides, only one-third of the loaded iodine was released in nitrogen purging after saturated adsorption. The remaining majority was trapped firmly by the beads due to their strong interactions with the frameworks. This work highlights the millimeter-sized MOF-808@polymer composite beads with ultrahigh iodine adsorption capacity, providing experimental references for their application in radioiodine removal from hot and moist streams.

Switching Xe/Kr adsorption selectivity in modified SBMOF-1: a theoretical study.

The separation of Xe/Kr mixtures in used nuclear fuel (UNF) has attracted lots of attention, but no report on the adsorption and separation of Kr from mixed Kr/Xe at room temperature can be found. From grand canonical Monte Carlo (GCMC) simulation, it is found that by replacing the metal center Ca of SBMOF-1 with Mg, due to the appropriate pore size, the adsorption selectivity (S Kr/Xe) was extremely high (250 000) and the adsorption capacity for Kr on Mg-SBMOF-1 modified with -NH2 was increased by 300% to 1.020 from 0.248 mmol g-1. Based on the calculations of density functional theory (DFT), we found that the stronger electron-donating ability of a functional group will increase the polarizability of the ligand, and thus increase the adsorption capacity to Kr. In addition, the analysis of electronic structures with independent gradient model (IGM) and energy decomposition analysis (EDA) indicates that van der Waals forces will be responsible for the interaction of Mg-SBMOF-1 and Kr gas. Among them, the interaction of Mg-SBMOF-1 and Kr gas is mainly an induction force, while that of modifications with -CH3 and -NH2 is mainly a dispersion force. The present theoretical study represents the first report of the separation of Kr from Xe with MOF adsorption at room temperature. We hope this work may promote the experimental synthesis of Mg-SBMOF-1 for efficient separation of Kr and Xe.