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Abstract The grand challenge of “net-zero carbon” emission calls for technological breakthroughs in energy production. The traveling wave reactor (TWR) is designed to provide economical and safe nuclear power and solve imminent problems, including limited uranium resources and radiotoxicity burdens from back-end fuel reprocessing/disposal. However, qualification of fuels and materials for TWR remains challenging and it sets an “end of the road” mark on the route of R&D of this technology. In this article, a novel approach is proposed to maneuver reactor operations and utilize high-temperature transients to mitigate the challenges raised by envisioned TWR service environment. Annular U-50Zr fuel and oxidation dispersion strengthened (ODS) steels are proposed to be used instead of the current U-10Zr and HT-9 ferritic/martensitic steels. In addition, irradiation-accelerated transport of Mn and Cr to the cladding surface to form a protective oxide layer as a self-repairing mechanism was discovered and is believed capable of mitigating long-term corrosion. This work represents an attempt to disruptively overcome current technological limits in the TWR fuels. Impact statement After the Fukushima accident in 2011, the entire nuclear industry calls for a major technological breakthrough that addresses the following three fundamental issues: (1) Reducing spent nuclear fuel reprocessing demands, (2) reducing the probability of a severe accident, and (3) reducing the energy production cost per kilowatt-hour. An inherently safe and ultralong life fast neutron reactor fuel form can be such one stone that kills the three birds. In light of the recent development findings on U-50Zr fuels, we hereby propose a disruptive, conceptual metallic fuel design that can serve the following purposes at the same time: (1) Reaching ultrahigh burnup of above 40% FIMA, (2) possessing strong inherent safety features, and (3) extending current limits on fast neutron irradiation dose to be far beyond 200 dpa. We believe that this technology will be able to bring about revolutionary changes to the nuclear industry by significantly lowering the operational costs as well as improving the reactor system safety to a large extent. Graphical abstract

The diffusion of stubborn oils and organic pigments has become a severe environmental pollution problem. Promisingly, the combination of superhydrophobicity and photocatalysis is expected to provide an efficient, economical and simple solution. In this paper, a kind of superhydrophobic and super-lipophilicity polyurethane (PU)-based sponge was reported by a strategy of undergoing ferric tetroxide loading (Fe3O4@PU), polydopamine fixation (PDA-Fe3O4@PU), octadecylamine grafting (ODA-Fe3O4@PU) and molybdenum disulfide loading (MoS2-ODA-Fe3O4@PU) successively. The results show that the MoS2-ODA-Fe3O4@PU sponge exhibits outstanding superhydrophobicity (with maximum water contact angle of 161.64°), excellent oil absorption capacity (60–109 wt/wt), robust stability in extreme environments and great oil/water separation ability. In addition, the MoS2-loaded sponge demonstrates desirable outcomes in decomposing methyl orange and methylene blue under light source, and a dual-functional purification system with a heterogeneous polyurethane-based sponge (the upper part is MoS2-ODA-Fe3O4@PU and the bottom part is MoS2@PU) endowed with superhydrophobicity and photocatalysis can purify water by separating oils and decomposing methylene blue simultaneously.

Doped halide pervoskites as highly efficient light emitters have recently fascinated the research community, while the influence of halogen atoms X (X = Cl, Br, I) on the hybrid energy levels and p...

Cesium lead halide perovskite nanocrystals (NCs) have emerged as promising luminescent materials for a range of applications. However, the creation of highly luminescent violet-emitting CsPbCl3 NCs mostly relies on doping of a limited number of small-sized metal ions or post-synthetic surface treatment of NCs. Alkaline-earth (AE) metals (e.g., Ca2+, Sr2+, and Ba2+) have been proposed to be able to substitute Pb2+ in halide perovskites, yet it remains incompletely understood whether AE metal ions can be incorporated into the perovskite lattice or can be merely situated at the surface. Here, we explore the possibility of using AE metal ions for the suppression of the formation of trap centers, which leads us to develop a one-pot synthetic passivation strategy to boost the violet-emitting efficiency of CsPbCl3 NCs through the creation of a Ca2+/Sr2+ involved passivation layer. The photoluminescence quantum yield of violet emission reaches 77.1% by incorporating an optimal amount of Ca2+. A wide range of opti...

Electrochemical studies of LaF3 in molten FLiNaK salt were performed on inert working electrodes. An additional reduction reaction prior to the decomposition of FLiNaK melt was observed when LaF3 was dissolved in and the reduction product was later recognized as lanthanum metal by SEM analysis. This phenomenon is very surprising and interesting considering the standard reduction potential of La (III) is more cathodic than that of K (I) and Na (I). The present study corrected the previous study [ 1 ] and will provide a new insight on the electrochemical and thermodynamic investigation of other lanthanides in molten FLiNaK salt.

A high-temperature flow loop system was designed to study the effects of buffers agents, temperature and flow conditions on the release of aluminum corrosion products in post-LOCA scenarios. Inductively coupled plasma-Optical Emission Spectrometry (ICP-OES) and X-ray photoelectron spectroscopy techniques are used to characterize the aluminum release in solution and the oxide layers formed on the surface. Aluminum release in trisodium phosphate solution is significantly less than in sodium tetraborate solution under same operating conditions. Flow accelerated aluminum release is evident, and power law correlations between the aluminum release rate and mass transfer coefficient are developed, allowing transfer of data between different flow systems.

The mechanochemical route is a facile and fast way and has received much attention for developing versatile advanced functional materials. Herein, we reported a mechanochemical synthesis for incorporating divalent manganese ions (MnII) into a two-dimensional (2D) hybrid perovskite (C4H9NH3)2PbCl4. The mild external stimuli originating from the grinding at room temperature enabled the formation of MnII-doped 2D hybrid perovskites, and rapidly changed the luminescence characteristics. The photoluminescence analyses show that the violet and orange emissions are attributed to (C4H9NH3)2Pb1– x Mn x Cl4 band-edge emission and the T1→6A1 transition of Mn2+ resulting from an efficient energy transfer process, respectively. Site preference and distribution of the doped Mn2+ cations on the locations of Pb2+ were analyzed. The formation energy calculated by the density functional theory (DFT) indicates that the Mn2+ ions can rapidly enter the crystal lattice due to the unique 2D crystal structure of the hybrid perovskite. Such a case of mechanochemical synthesis for the 2D hybrid perovskite motivates many novel emerging materials and the related applications.

Two-dimensional (2D) nanomaterials have attracted great attention in next generation electronic and optoelectronic technologies due to the unique layered structure and excellent physical and chemical properties. However, the mechanism of transmission along the vertical direction of 2D semiconductor materials has not been investigated. Here, we use first-principles calculations to explore the bandgap energies along different directions, and fabricate a vertical, a lateral and a mixture-structured black phosphorus field effect transistor (BPFET) to study the electrical characteristics along different directions under variable temperatures. The variable temperature test indicates that the mixture-structured device performs more like a lateral device, while the conductance along the vertical direction is hard to be tuned by temperature and electrical field. The unchanged conductance under electric field and variable temperatures allows the vertical device to act as a fixed resistor, promising possible application for the prospective electronic and optoelectronic devices.

In this work, the spin-resolved transport properties of the Fe doped SnS2 monolayer devices have been investigated. The results show that the doping systems have the transport properties of negative differential resistance, large magnetoresistance effect and near 100% spin polarization effect when the magnetization directions of two electrodes are in parallel. Moreover, the mechanisms for the properties also have been discussed. The original reason of these results could be due to the half-metallic of the doping system. Our results imply that Fe doped SnS2 monolayer is a promising candidate for the future spintronic devices.

Monolayer MoS2 has emerged as an active and non-precious electrocatalyst for electrochemical hydrogen production. The atomic thinness and ultrahigh surface-to-volume ratio of the chemical vapor deposition (CVD)-grown monolayers result in an ideal material to facilitate efficient electrochemical hydrogen evolution and explore the mechanism at the atomic level. However, the active sites of pristine monolayer MoS2 are reported to locate at the edges, leaving the basal planes inert, which limits their hydrogen evolution reaction performance. Here, we synthesize monolayer MoS2 hexagonal flakes with high surface coverage and abundant highly distributed S vacancies as active reaction sites directly by CVD. The catalytic performance of the hexagonal MoS2 flakes presented here is superior to that of the existing as-grown MoS2, exhibiting a current density of 100 mA cm−2 at −353 mV versus the reversible hydrogen electrode (RHE) with an extraordinarily low onset potential of only 41 mV. And an outstanding exchange current density of 0.091 mA cm−2 stands as the highest ever reported for all kinds of non-precious-metal doped MoS2 catalysts. It is proved by a variety of tests that abundant S vacancies are distributed in the highly crystalline basal plane of hexagonal MoS2, which leads to a remarkably improved catalytic efficiency compared with that of the triangular one. The monolayer MoS2 is further evidenced to have excellent long-term stability and high durability, maintaining a stable performance for nine months in air and retaining the initial performance after 6000 cyclic voltammetry scans. On-site defect engineering of monolayer MoS2 for excellent hydrogen evolution reaction (HER) performance enriches insights into the structure–performance relationship in 2D materials and provides new opportunities for the design of highly active catalysts.

Doping has been established as a powerful approach for endowing lead halide perovskite nanocrystals (NCs) with novel properties. However, our fundamental understanding of the local structure of dopants, doping efficiency and luminescence properties of these NCs is still very sparse. Here, we provide the first experimental evidence regarding the local structure of rare earth ions in CsPbCl3 NCs, based on the analysis of extended X-ray absorption fine structure spectroscopy. Our result suggests that Yb3+ occupies the Pb2+ crystallographic sites in CsPbCl3 NCs. We further demonstrate a strategy to examine the determinant of the doping efficiency in lanthanide-doped lead halide perovskite NCs, which enables us to uncover the important role of structural defects in affecting the doping efficiency. A broad range of experimental characterization techniques including steady-state and time-resolved luminescence spectra, X-ray absorption spectra, and positron annihilation lifetime spectra, coupled with first-principles calculations, help us identify that the doping efficiency is associated with structural defects in NCs and that the formation of a higher-concentration of defects favors incorporation of a higher-concentration of dopants into the lattice. Importantly, we demonstrate that the concept of defect-assisted doping is not limited to the model system of Yb3+-doped CsPbCl3 NCs, but can be used as a guideline to rationally tune the doping efficiency of lanthanide-doped halide perovskite NCs. We also show that lanthanide-doped CsPbCl3 NCs demonstrate anomalous decay of the band-edge emission, which we propose is due to the existence of shallow trapping states near the conduction band. Our results greatly deepen the understanding of the structural and photophysical properties of lanthanide-doped lead halide perovskite NCs, and highlight the possibility to use the chemistry of defects to tailor the doping efficiency of halide perovskite NCs.

In order to promote the work of prevention and management of coal mine water disaster in China, it took Panlong coal mine, Xiayukou coal mine and Xiangshan coal mine in Hancheng mining area as object of study, which were compared from 7 classification factors of hydrogeological type, time and scale of water inrush. Ordovician limestone water inrush and water inrush from old and empty areas were then thought out to be the major types of water disaster in Hancheng mining area.

Endochondral ossification is the major process of long bone formation, and chondrogenesis is the final step of this process. Several studies have indicated that bone morphogenetic proteins (BMPs) are required for chondrogenesis and regulate multiple growth plate features. Abnormal BMP pathways lead to growth plate defects, resulting in osteochondrodysplasia. The SPARC-related modular calcium binding 2 (SMOC2) gene encodes an extracellular protein that is considered to be an antagonist of BMP signaling. In this study, we generated a mouse model by knocking-in the SMOC2 mutation (c.1076 T > G), which showed short-limbed dwarfism, reduced, disorganized, and hypocellular proliferative zones and expanded hypertrophic zones in tibial growth plates. To determine the underlying pathophysiological mechanism of SMOC2 mutation, we used knock-in mice to investigate the interaction between SMOC2 and the BMP–SMAD1/5/9 signaling pathway in vivo and in vitro. Eventually, we found that mutant SMOC2 could not bind to COL9A1 and HSPG. Furthermore, mutant SMOC2 inhibited BMP signaling by competitively binding to BMPR1B, which lead to defects in growth plates and short-limbed dwarfism in knock-in mice.

Zero-dimensional (0D) hybrid metal halides have emerged as a new generation of luminescent phosphors owing to their high radiative recombination rates, which, akin to their three-dimensional cousins, commonly demonstrate thermal quenching of luminescence. Here, we report on the finding of antithermal quenching of luminescence in 0D hybrid metal halides. Using (C9NH20)2SnBr4 single crystals as an example system, we show that 0D metal halides can demonstrate antithermal quenching of luminescence. A combination of experimental characterizations and first-principles calculations suggests that antithermal quenching of luminescence is associated with trap states introduced by structural defects in (C9NH20)2SnBr4. Importantly, we find that antithermal quenching of luminescence is not only limited to (C9NH20)2SnBr4 but also exists in other 0D metal halides. Our work highlights the important role of defects in impacting photophysical properties of hybrid metal halides and may stimulate new efforts to explore metal halides exhibiting antithermal quenching of luminescence at higher temperatures.

Previously study showed that SMOC, a matricellular protein, inhibits BMP signaling downstream of its receptor via activation of mitogen-activated protein kinase (MAPK) signaling. In our study, exome sequencing revealed a missense mutation (c.1076T>G, p.Leu359Arg) in EC domain of SMOC2 in a Chinese family with multiple epiphyseal disease (MED). The pathogenicity of this SMOC2 variant was verified by Smoc2L359R/L359R knock-in mice. Of note, decreasing phosphorylation of SMAD1/5/9 was detected in growth plates and primary chondrocytes from Smoc2L359R/L359R mice. Furthermore, binding affinity of mutant SMOC2 with collagen IX and HSPG in the extracellular matrix of cartilage were reduced while binding affinity with BMPRIB was intact. In addition, in contrast to previously results, that SMOC2 cannot antagonize BMP activity in the presence of a constitutively activated BMP receptor. These results support that SMOC2 with p.Leu359Arg variant act as an antagonist of canonical BMP pathway by competitively binding with BMP receptors.

Direct electrolytic reduction (DER) of UO 2 utilizes a molten LiCl-Li 2 O electrolyte operating at 650 °C.Productive processes at the cathode are UO 2 and Li 2 O reduction (followed by metallothermic reduction of UO 2 by Li metal). Non-productive reduction current has been observed that could be attributed to impurities produced from interaction of the salt with water. Cyclic voltammetry (CV) scans of molten mixtures of LiCl containing Li 2 O, LiOH, and/or Li 2 O 2 indicate that LiOH is the primary cause of reduction current preceding UO 2 and Li 2 O reduction. LiOH reduction appears as a broad soluble-soluble transition and forms a pre-reduction plateau characteristic of micro-electrode reactions. Electrochemical response to LiOH in the salt is reduced with addition of Li 0 , providing a practical approach to eliminating LiOH from LiCl-Li 2 O salt before the DER process. Generation of H 2 gas was detected while heating Li 0 with LiCl-Li 2 O-LiOH, consistent with a reaction mechanism where LiOH reduction causes formation of Li 2 O and H 2 .

Although the activity coefficients and diffusion coefficients of LaCl3 in molten LiCl KCl salt have been extensively studied, the data on the electrochemical properties of La(III)/La reaction in the melt are very scarce. Among the few measurements, up to five orders of magnitude discrepancies for the reaction rate constant k 0 have been reported. In the present study, potentiodynamic polarization measurements at different LaCl3 concentrations (1–6 wt%) and temperatures (723–823 K) are conducted to obtain accurate values of the exchange current density i 0 and charge transfer coefficient α . The data are analyzed using non-simplified electrode kinetic equations through the optimization fitting procedures, and conventional Tafel and linear polarization (LP) methods. The concentration dependence of i 0 obtained from the optimization fitting method is examined, showing agreement with the theoretical correlation i 0 = n F k 0 c ( 1 − α ) . The corresponding values of k 0 are 1.76–3.22 × 10−5 cm s−1 in 723–823 K.

In a molten salt nuclear reactor system, the redox potential must be controlled for mitigating corrosion of structural materials. The paper presented a critical review on the available knowledge of redox potential control in molten fluoride salt systems. The major phenomena that affect the redox potential and material corrosion are fission, TF production by transmutation, and salt contamination with metal fluorides or other oxidizing impurities. Redox potential control methodologies include gas sparging, contacting the salt with a reducing metal, and adding soluble salt redox buffers to the salt. Redox potential measurement technologies include electrochemical sensors and optical spectroscopy. The paper also analyzed the current technology issues and recommended near future studies.

Cyclic voltammetry (CV) analysis was performed to determine the behavior of Dysprosium (Dy) and Lanthanum (La) in molten FLiNaK salt (LiF-NaF-KF: 46.5–11.5–42 mol%) and to understand the mechanism driving the electrochemical reactions. The goals of these experiments are to understand the behavior of contaminants and nuclear fission products related to the Fluoride Salt-cooled High-Temperature Reactor (FHR) concept, and to generate a reliable source of electrochemical properties in fluoride salts. The tests were performed at 600–650–700 °C for Dy and 650–700–750 °C for La in a glassy carbon crucible contained within an inert argon atmosphere. A platinum wire quasi-reference electrode exhibited stable potential throughout experiments and allowed for thermodynamic reference between test species and known redox couple (F2/F−). The electrochemical reduction of Dy and La (assumed three-electron, single-step transfer) maintained quasi-reversibility at the solid tungsten electrode for scan rates of 160 mV/s and below during CV. For scan rates of 200 mV/s and above, significant deviation from reversibility was evidenced by increasing separation between anodic and cathodic peaks. For Dy3+, the diffusion coefficient was calculated as D [cm2/s] = 0.0538∗exp(−6193/T(K)) and the activation energy Ea = 51.5 kJ/mol. The diffusion coefficient of La3+ was calculated as D [cm2/s] = 14.252∗exp(−15285/T(K)) and the activation energy Ea = 127 kJ/mol. The apparent potential of the La3+/La0 redox reaction was determined as E0∗[V vs. K+/K] = −0.368 + 0.001119∗T[K] and for the Dy3+/Dy0 reaction as E0∗[V vs. K+/K] = 0.0626 + 0.00088∗T[K].

Engineering oxygen coordination environments of cations in oxides has received intense interest thanks to the opportunities for the discovery of novel oxides with unusual properties. Herein, the synthesis of stoichiometric layered BaBiO2.5 by a nontopotactic phase transformation of perovskite BaBiO3 is presented. By analyzing the synchrotron X-ray diffraction data by the maximum-entropy method/Rietveld technique, it was found that Bi is involved in an unusual chemical bonding situation with four oxygen atoms featuring one ionic bond and three covalent bonds, which results in an asymmetric coordination geometry. Photophysical characterization revealed that this peculiar structure shows near-infrared luminescence differing from that of conventional Bi-containing compounds. Experimental and theoretical results led to the proposal of an excitonic nature of the luminescence. This work highlights that synthesizing materials with uncommon Bi-O bonding and Bi coordination geometry provides a pathway to the discovery of systems with new functionalities. This could inspire interest in the exploration of a range of materials containing heavier p-block elements with prospects for finding systems with unusual properties.

All-inorganic perovskites have emerged as a new class of phosphor materials owing to their outstanding optical properties. Zero-dimensional inorganic perovskites, in particular the Cs4PbBr6-related systems, are inspiring intensive research owing to the high photoluminescence quantum yield (PLQY) and good stability. However, synthesizing such perovskites with high PLQYs through an environment-friendly, cost-effective, scalable, and high-yield approach remains challenging, and their luminescence mechanisms has been elusive. Here, we report a simple, scalable, room-temperature self-assembly strategy for the synthesis of Cs4PbBr6/CsPbBr3 perovskite composites with near-unity PLQY (95%), high product yield (71%), and good stability using low-cost, low-toxicity chemicals as precursors. A broad range of experimental and theoretical characterizations suggest that the high-efficiency PL originates from CsPbBr3 nanocrystals well passivated by the zero-dimensional Cs4PbBr6 matrix that forms based on a dissolution–cr...

The activity coefficients of lanthanides in liquid bismuth at different concentrations and temperatures were calculated based on the assessed expression of Gibbs energy by the method of CALPHAD (CALculation of PHAse Diagrams). The temperature- and concentration-dependent correlations of the activity coefficients of eight lanthanides were developed which make it possible to calculate the activity coefficient for any concentration up to the solubility limit in the temperature range of 873–973 K. Based on the correlations developed, the change of the activity with concentration was analyzed and discussed. This research provided calculated fundamental properties of lanthanides in liquid bismuth over a wide range of concentration and temperature for the FHR primary coolant cleanup system development. The method used in this study can be extended to investigate other liquid metal binary or ternary systems.

Reliable measurement of exchange current density i 0 is important for systems using molten salts as electrolyte or/and coolant. The values of i 0 of Gd(III)/Gd reaction in LiCl-KCl eutectic at different GdCl3 concentrations (1–9 wt%) and temperatures (723–823 K) are reported. The values are determined by optimization fitting method using the non-simplified electrode kinetics equation, and other three commonly used methods including Tafel method, linear polarization (LP) method, and electrochemical impedance spectroscopy (EIS) method. Results show that significant errors can be introduced by using the three conventional methods in the mass-transfer involved case as they are based on the simplified electrode kinetics equations with an assumption of no mass-transfer effect. The optimization fitting method shows more reliable results but has limitations at 1 wt% Gd concentration. The standard rate constant k 0 values determined by the optimization fitting are 4.93–9.13 × 10−5 cm/s in the studied temperature range and the activation energy is 30.5 kJ/mol.

The fluoride molten salt such as FLiNaK and FLiBe is one of the coolant candidates for the next generation nuclear reactor concepts, for example, the fluoride salt cooled high temperature reactor (FHR). For mitigating corrosion of structural materials in molten fluoride salt, the redox condition of the salts needs to be monitored and controlled. This study investigates the feasibility of applying the Eu3+/Eu2+ couple for redox control. Cyclic voltammetry measurements of the Eu3+/Eu2+ couple were able to obtain the concentrations ratio of Eu3+/Eu2+ in the melt. Additionally, the formal standard potential of Eu3+/Eu2+ was characterized over the FHR's operating temperatures allowing for the application of the Nernst equation to establish a Eu3+/Eu2+ concentration ratio below 0.05 to prevent corrosion of candidate structural materials. A platinum quasi-reference electrode with potential calibrated by potassium reduction potential is shown as reliable for the redox potential measurement. These results show that the Eu3+/Eu2+ couple is a feasible redox buffering agent to control the redox condition in molten fluoride salts.

Three-dimensional porous sponge has been demonstrated as an outstanding candidate in oil/water separation due to its hydrophobicity and oleophilicity that originates from the synergistic effect of rough structure and low surface energy, but the separation process has not been illuminated clearly. This paper presents the study of the synthesis of oil/water separation sponge, mechanism of separation process and establishment of kinetic model, via the combination among dopamine chemistry, covalent modification, theoretical analysis, experimental results and mathematical model. Results show that both the dopamine deposition time and the octadecyltrimethoxysilane hydrolysis system significantly affect the hydrophobicity of the modified-melamine sponge and that the oil/water separation process is composed of six scenarios with different physical state. Furthermore, with the experimental results, established iso-potential separation model and the height-quantized model, we conclude that the time-dependent separation patterns and kinetics are subjected to the modulation of the viscosity of the separated substance and the immersion depth of the sponge.

Experiments were conducted to investigate the aluminium corrosion in the simulated containment pool environment following a loss-of-coolant accident at a nuclear power plant. The results show an identical power law correlation between the corrosion rate and mass transfer coefficient for different flow systems. Aluminium corrosion is inhibited by the silicon leached from the insulation materials, and the inhibition efficiency increases with the silicon concentration due to the increase of Al 2 SiO 5 or SiO 2 content in the passivation layer. The concurrent corrosion of copper and iron has little influence on aluminium corrosion while the presence of zinc significantly retards the aluminium corrosion.