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CO2, a predominant anthropogenic greenhouse gas, emerges as a primary factor in climate change due to the increasing utilization of fossil fuels, necessitating immediate efforts for the development and implementation of strategies like carbon capture and storage (CCS) to mitigate emissions, considering the ongoing dependence on unsustainable energy and transportation resources. The research endeavours to meet the critical requirement for effective CO2 capture through the exploration of novel sorbent materials, with a specific focus on molecularly precise nanoclusters (NCs), aiming to enhance understanding of the catalytic mechanisms in CO2 reduction and design stable, high‐performance sorbents with controllable properties. Advancing the field, the study delves into the synthesis and examination of molecularly precise nanoclusters (NCs), an emerging domain in nanoscience, with a particular emphasis on well‐defined nanoclusters like thiolate‐protected Au, Ag, and Cu NCs. This strategy provides a distinctive foundation for attaining atomic‐level understanding of electrocatalytic CO2 reduction mechanisms, offering a more precise and customized synthesis to overcome challenges associated with polydispersity in conventional nanoparticles. The study highlights the exceptional catalytic activity of specific Au NCs like Au25 in converting CO2 to CO. It surpasses thermodynamic limits. The study also investigates the influence of surface properties, electrostatic, and steric stability on preventing nanocluster aggregation. It emphasizes the potential of molecularly precise nanoclusters as catalysts for CO2 reduction. Additionally, it suggests avenues for advanced sorbent development with improved performance and stability. [ABSTRACT FROM AUTHOR]

Titanium nitride is an exciting plasmonic material, with optical properties similar to gold. However, synthesizing TiN nanocrystals is highly challenging and typically requires solid‐state reactions at very high temperatures (800–1000°C). Here, the synthesis of TiN nanocrystals is achieved at temperatures as low as 350°C, in just 1 h. The strategy comprises molten salt, Mg as reductant and Ca3N2 as nitride source. This brings TiN from the realm of solid‐state chemistry into the field of solution‐based synthesis in regular, borosilicate glassware. [ABSTRACT FROM AUTHOR]

Molten salts (MSs) thermal energy storage (TES) enables dispatchable solar energy in concentrated solar power (CSP) solar tower plants. CSP plants with TES can store excess thermal energy during periods of high solar radiation and release it when sunlight is unavailable, such as during cloudy periods or at night. This capability allows these plants to provide reliable, dispatchable power, ensuring a continuous electricity supply to the grid. This paper examines the challenges and opportunities of utilizing higher‐temperature molten salt formulations to enhance power cycle efficiency. Drawing on existing literature, performance analysis of existing power plants, and novel simulation results, we project the expected technological improvements by the end of this decade. By using 15 h of TES and a higher temperature MS formulation, with heat transfer fluid hot temperatures of 700°C, and a power cycle 350 bar 700°C of efficiency 48%, the annual electricity production from a 115 MW power plant in Daggett, California is 688 GWh, the total installed cost is $684 m while the 25‐year LCOE is 6.37 c/kWh. [ABSTRACT FROM AUTHOR]

Strong metal‐support interaction (SMSI) plays a vital role in tuning the geometric and electronic structures of metal species. Generally, a high‐temperature treatment (>500 °C) in reducing atmosphere is required for constructing SMSI, which may induce the sintering of metal species. Herein, we use molten salts as the reaction media to trigger the formation of high‐intensity SMSI at reduced temperatures. The strong ionic polarization of the molten salt promotes the breakage of Ti−O bonds in the TiO2 support, and hence decreases the energy barrier for the formation of interfacial bonds. Consequently, a high‐intensity SMSI state is achieved in TiO2 supported Ir nanoclusters, evidenced by a large number of Ir−Ti bonds at the interface, at a low temperature of 350 °C. Moreover, this method is applicable for triggering SMSI in various supported metal catalysts with different oxide supports including CeO2 and SnO2. This newly developed SMSI construction methodology opens a new avenue and holds significant potential for engineering advanced supported metal catalysts toward a broad range of applications. [ABSTRACT FROM AUTHOR]

Solid solutions are garnering substantial attention in the realm of solar energy utilization due to their tunable electronic properties, encompassing band edge positions and charge‐carrier mobilities. In this study, we designed and synthesized Co1‐xZnxFe2xGa2–2xO4 (0

Intercalation of layered materials offers an effective approach for tunning their structures and generating unprecedented properties. The multiple van der Waals (vdW) gap combined with long‐range ordering guests can change the interaction of layered host materials and electromagnetic field. Herein, a chemical‐scissor intercalation protocol medicated by molten salt is proposed for tailing the electromagnetic properties of transitional metal dichalcogenides (TMDCs). NbS2 is functional intercalated by heteroatoms (Fe, Co, Ni). The intercalated NbS2 with superlattice exhibit improved dielectric properties due to the reduced Brillouin zone size and the local electron distribution. Both the computational and experimental investigations indicate enhanced electron transport and additional polarized centers caused by intercalation. Overall, this work shows the great potential of structure editing of vdW materials, whilst intercalation via the chemical scissor in molten salts is considered a feasible intercalation strategy to further enrich their applications. [ABSTRACT FROM AUTHOR]

MXene‐supported noble metal alloy catalysts exhibit remarkable electrocatalytic activity in various applications. However, there is no facile one‐step method for synthesizing these catalysts, because the synthesis of MXenes requires a strongly oxidizing environment and the preparation of platinum nanoalloys requires a strongly reducing environment and high temperatures. Hence, achieving coupling in one step is extremely challenging. In this paper, a straightforward one‐step molten salt method for preparing MXene‐supported platinum nanoalloy catalysts is proposed. The molten salt acts as the reaction medium to dissolve the transition metals and platinum ions at high temperatures. Transition metal ions oxidize the A‐site element from its MAX precursor at high temperatures, and the resulting transition metals further reduce platinum ions to form alloys. By coupling Al oxidation and platinum ion reduction using a molten salt solvent, this method directly converts Ti3AlC2 to a Pt‐M@Ti3C2Tx catalyst (where M denotes the transition metal). It further offers the possibility of extending the Pt‐M phase to binary, ternary, or quaternary platinum‐containing nanoalloys and converting the Al‐containing MAX phase to Ti2AlC and Ti3AlCN. Due to the strong interfacial interaction, the as‐prepared Pt‐Co@Ti3C2Tx is superior to commercial Pt/C (20 wt.%) in the hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

2D materials are of interest in various applications such as energy conversion, storage, and sensing. These materials are prepared by bottom‐up or top‐down methods that are difficult to control and suffer from low yield. Synthesis in molten salt is suggested as an alternative in which the balance between exfoliation and solubility is explored. It is demonstrated that when a pellet of 2D material is insoluble in molten salt (graphite in any salt), it is exfoliated. For low solubility (MoS2 in NaCl/KCl), the 2D material nucleates and grows into a small flowerlike structure composed of thin MoS2 sheets through Ostwald ripening. For high solubility in the molten salt (MoS2 in CsCl), it forms larger flowers. Herein, the molten salt treatment of high and low surface area MoS2 (micron‐size particles and a single large pellet, respectively) is compared. The particles yielded facet MoS2 crystals through dissolution–nucleation–recrystallization process and the pellet yielded flowers. Herein, methods for synthesizing 2D materials with controllable size and shape are promoted by simple molten salt treatment that opens an avenue to the development of soluble (MoS2) and non‐soluble (graphite) materials with different morphologies in a simple and affordable way. [ABSTRACT FROM AUTHOR]

The formation of lithiophobic inorganic solid electrolyte interphase (SEI) on Li anode and cathode electrolyte interphase (CEI) on the cathode is beneficial for high‐voltage Li metal batteries. However, in most liquid electrolytes, the decomposition of organic solvents inevitably forms organic components in the SEI and CEI. In addition, organic solvents often pose substantial safety risks due to their high volatility and flammability. Herein, an organic‐solvent‐free eutectic electrolyte based on low‐melting alkali perfluorinated‐sulfonimide salts is reported. The exclusive anion reduction on Li anode surface results in an inorganic, LiF‐rich SEI with high capability to suppress Li dendrite, as evidenced by the high Li plating/stripping CE of 99.4% at 0.5 mA cm−2 and 1.0 mAh cm−2, and 200‐cycle lifespan of full LiNi0.8Co0.15Al0.05O2 (2.0 mAh cm−2) || Li (20 µm) cells at 80 °C. The proposed eutectic electrolyte is promising for ultrasafe and high‐energy Li metal batteries. [ABSTRACT FROM AUTHOR]

The hot corrosion behaviour of the γ‐Y2Si2O7 ceramic exposed to NaVO3 or V2O5 molten salt was studied at 1000–1300°C. YVO4 was identified as the corrosion product due to the chemical interaction of the two corrosive agents with the γ‐Y2Si2O7 ceramic. Although YVO4 produced in the two corrosion reactions had the same crystallographic structure, they had different morphologies. YVO4 produced by the corrosion of NaVO3 with the γ‐Y2Si2O7 ceramic showed a rod‐like shape, whereas it was particle‐shaped in the corrosion reaction of V2O5 with the γ‐Y2Si2O7 ceramic. Additionally, the degradation of γ‐Y2Si2O7 ceramic by V2O5 was more severe than that by NaVO3, and the thickness of the corrosion layer significantly increased with temperature. In this study, a model describing the formation of the corrosion product was established, and the formation of YVO4 with different morphologies in the two corrosion reactions was explained based on the growth characteristics of the YVO4 crystals. [ABSTRACT FROM AUTHOR]

A series of WS2/Co9S8 nanoparticles (NPs) supported on N, S co‐doped mesoporous carbons were prepared via the molten salts process. Glucose, WCl6 and CoCl2 were used as carbon, tungsten and cobalt precursors, respectively. Thiourea were utilized as nitrogen and sulfur precursor. The common inorganic salts were the porogens, which can be removed and recycled. The molar ratio of the precursors can affect the porosities of the catalysts, which can further determine the electrocatalytic performance. The sample of G2.5TWCo shows the best HER performance due to the high electrochemically active surface area and low electrochemical impedance. [ABSTRACT FROM AUTHOR]

Mixed‐anion compounds widen the chemical space of attainable materials compared to single anionic compounds, but the exploration of their structural diversity is limited by common synthetic paths. Especially, oxychlorides rely mainly on layered structures, which suffer from low stability during photo(electro)catalytic processes. Herein we report a strategy to design a new polar 3D tetrahedral framework with composition Zn4Si2O7Cl2. We use a molten salt medium to enable low temperature crystallization of nanowires of this new compound, by relying on tetrahedral building units present in the melt to build the connectivity of the oxychloride. These units are combined with silicon‐based connectors from a non‐oxidic Zintl phase to enable precise tuning of the oxygen content. This structure brings high chemical and thermal stability, as well as strongly anisotropic hole mobility along the polar axis. These features, associated with the ability to adjust the transport properties by doping, enable to tune water splitting properties for photoelectrocatalytic H2 evolution and water oxidation. This work then paves the way to a new family of mixed‐anion solids [ABSTRACT FROM AUTHOR]

CsCl‐type intermetallic compounds TiM (M=Co, Fe) were obtained by deoxidizing trigonal ilmenite‐type MTiO3 with a reducing agent CaH2 in molten LiCl at 600 °C. X‐ray diffraction, nitrogen adsorption, scanning electron microscopy, and transmission electron microscopy with energy‐dispersive X‐ray, and X‐ray photoelectron spectroscopy analyses revealed the formation of nanoscale layered structures, which enhanced specific surface areas (approximately 20 m2/g) in the intermetallic compounds. In the initial deoxidation stage, Li2TiO3‐like compounds were observed as an intermediate, suggesting the substitution of M in MTiO3 by Li from the molten LiCl. Compound MTiO3 has a layered structure perpendicular to the c axis of the trigonal structure, suggesting that the layered structures may originate from the crystal structure of the precursors. Formation of the Li2TiO3‐like intermediate may help maintain the original layered structure during deoxidation and the subsequent alloying at temperatures as low as 600 °C. [ABSTRACT FROM AUTHOR]

The molten‐salt oxidation method (MSO) can be applied for disposal of spent cationic exchange resins (CERs) after the treatment of nuclear industry wastewater. In this work, the oxidation decomposition of resins in carbonate molten salt in N2 and air atmospheres was investigated. The SEM morphology and FTIR spectrograms indicated that the addition of air obviously prompted the oxidation decomposition of the benzene ring, S−O bond and S−C bond in residues and the decomposition efficiency of resins reached 98.69 % at 800 °C. The XPS analysis showed the conversion of sulfur species in residues. The peroxide and superoxide ions in carbonate molten salt prompted the decomposition of thiophene sulfur and resulted in the formation of sulfate. The retention rate of sulfur in spent salt was 84.36 % at 800 °C. This work provided more theoretical guidance for the treatment of resins and technical support for the sustainable development of nuclear industry. [ABSTRACT FROM AUTHOR]

Poly (triazine imide) photocatalysts prepared via molten salt methods emerge as promising polymer semiconductors with one‐step excitation capacity of overall water splitting. Unveiling the molecular conjugation, nucleation, and crystallization processes of PTI crystals is crucial for their controllable structure design. Herein, microscopy characterization was conducted at the PTI crystallization front from meso to nano scales. The heptazine‐based precursor was found to depolymerize to triazine monomers within molten salts and KCl cubes precipitate as the leading cores that guide the directional stacking of PTI molecular units to form aggregated crystals. Upon this discovery, PTI crystals with improved dispersibility and enhanced photocatalytic performance were obtained by tailoring the crystallization fronts. This study advances insights into the directional assembling of PTI monomers on salt templates, placing a theoretical foundation for the ordered condensation of polymer crystals. [ABSTRACT FROM AUTHOR]

This paper demonstrates the availability of electro‐codeposition (i.e., the simultaneous occurrence of electrophoretic deposition of nanoparticles and electrochemical deposition of metal ions) in molten salts without the assistance of stirring of the bath. In molten NaCl–KCl–AlCl3–MoO3 system containing TiB2 nanoparticles at 710°C, the electro‐codeposition of TiB2 nanoparticles and Mo(VI) ions has been achieved, and a (Ti, Mo)B2 coating has been prepared. [ABSTRACT FROM AUTHOR]

Functional carbon materials are useful for energy storage, catalysis, and pollutant adsorption, and are in high demand, for which biomass has become a valuable raw material. Molten salt carbonization and activation (MSCA) is a promising approach to converting biomass to functional biocarbon and reducing or neutralizing carbon impact on the environment. It uses a single thermal treatment and features high‐efficiency conversion, rapid production, and low resource and processing costs. More importantly, in this process, the unmatched purely ionic environment at high temperatures can lead to in situ activation (pore generation) of the biocarbon and introduce desired ions into the carbon to enable unique functionalities. The obtained biocarbon possesses a fairly large specific surface area (SSA), balanced pore structure, and specific surface oxygen‐containing groups for diverse applications. This review explains the fundamental and technological aspects of MSCA of biomass, focusing on the approaches, salt compositions (mixtures), processing conditions, and products. The properties of the obtained biocarbon are analyzed and compared in the context of practical applications. Areas for further investigation are also explored with the hope of this molten salt route becoming optimized and industrialized for a circular economy. [ABSTRACT FROM AUTHOR]

A molten salts strategy was developed to synthesize Co2P nanoparticles (NPs) embedded N, P co‐doped mesoporous carbon. No solvent was introduced in the synthesis process. Moreover, the common inorganic salts were utilized as the templates, which could be removed and recycled by water washing. The characterization results exhibited that the final products consisted of Co2P NPs and carbon. The amounts of the salts determined the porosities of the as‐obtained sample, which further effect the activities for electrocatalytic hydrogen evolution reaction (HER). The optimal sample of GUCo‐0.2NaCl showed the best HER performance among these as‐obtained electrocatalysts, including small Tafel slope and low overpotential. [ABSTRACT FROM AUTHOR]

Summary: Molten salts as thermal energy storage (TES) materials are gaining the attention of researchers worldwide due to their attributes like low vapor pressure, non‐toxic nature, low cost and flexibility, high thermal stability, wide range of applications etc. This review presents potential applications of molten salts in solar and nuclear TES and the factors influencing their performance. Ternary salts (Hitec salt, Hitec XL) are found to be best suited for concentrated solar plants due to their lower melting point and higher efficiency. Two‐tank direct energy storage system is found to be more economical due to the inexpensive salts (KCl‐MgCl2), while thermoclines are found to be more thermally efficient due to the power cycles involved and the high volumetric heat capacity of the salts involved (LiF‐NaF‐KF). Heat storage density has been given special focus in this review and methods to increase the same in terms of salt composition changes are discussed in the paper. Methods of concatenating energy storage systems with nuclear power plants are also discussed with different types of nuclear reactors like MHTGR, PAHTR, VHTR, etc. Nanomodifications of molten salts are done to improve heat transfer properties and efficiency of the transfer. The best dopants for such modifications were found to be TiO2, SiO2, MWCNTs, etc. Future challenges for large scale deployment of molten salts viz., high volume expansion ratio, low thermal conductivity, incongruent melting, corrosion, etc., are listed and discussed. Corrosion of molten salts and its mitigation has been discussed in detail for developing next‐generation storage systems and its remedies are also discussed. [ABSTRACT FROM AUTHOR]

We developed a molten salts process to prepare Co9S8 nanoparticles (NPs) entrapped, S, N co‐doped carbons. Cobalt chloride was used as the cobalt source. The melamine‐formaldehyde (MF) resin provided the carbon source and nitrogen source, and thiourea provided sulfur source. In addition, common inorganic salts were added as templates to generate pores. The characterization results showed that the prepared materials contained high contents of N, S and Co, and were mesoporous composites. At the same time, the porosity of electrocatalyst depended on the type of salt and the mass ratio of precursor to salt, which further affected the electrocatalytic activity of hydrogen evolution reaction (HER). The best prepared catalyst showed excellent HER performance. The onset overpotential of the catalyst was low (33 mV) and had a small Tafel slope (61.1 mV dec−1), in addition to good stability in alkaline media. [ABSTRACT FROM AUTHOR]

Summary: Molten salts are of great interest in the energy industry as coolants and heat transfer fluids due to their superior heat transfer properties and high operating temperatures. Due to these high temperatures and the corrosive properties of many molten salts, it can be difficult to perform fluid flow and heat transfer experiments of molten salt components in laboratory settings. Instead, surrogate fluids that operate at lower temperatures and match relevant dimensionless parameters of molten salts are suggested for such experiments. In this work, we examine two well‐known surrogate fluids, water and Dowtherm A, and introduce two heat transfer fluids, Freezium 60 and Zitrec S‐25, as candidate molten salt surrogates. We compare these fluids to common fluoride‐, chloride‐, and nitrate‐based molten salts by considering temperature ranges over which their Prandtl numbers match. A model example at matched Prandtl and Reynolds number is used to determine the effects of using such surrogates on friction factor, pressure drop, Nusselt number, and pumping and heating power in a theorized experiment, and potential distortions based on Prandtl number mismatches are discussed. This article describes a distortion calculation methodology and quantifies the largest Prandtl number distortions encountered for various molten salt and surrogate pairs using a linearly scaled technique. Distortions between the fluids are seen to be small, but uncertainties in salt thermophysical properties motivate further research to understand the magnitude of such distortions and their subsequent effects on experimental outcomes. [ABSTRACT FROM AUTHOR]

Summary: This work aims to design a small (5 kW) renewable energy plant, which can supply fully dispatchable electricity to the grid at a cost, inclusive of dispatchability, better than using wind or solar photovoltaic and batteries, specific for remote areas where the solar irradiance is significant, but plagued by clouds. A beam down point concentrator is coupled to a two‐tank thermal energy storage system and natural gas heater, to produce constant power by using a Stirling engine. Considered as a conventional combustion fuel plant, the fuel conversion efficiency on the typical day of every month of the typical year is 82%‐222%, an average of 124%. This means that replacing an oil generator with the proposed device would permit an 83% reduction of CO2 emissions. [ABSTRACT FROM AUTHOR]

Persistent luminescent nanocrystals (PLNCs) in the sub‐10 nm domain are considered to be the most fascinating inventions in lighting technology owing to their excellent performance in anti‐counterfeiting, luminous paints, bioimaging, security applications, etc. Further improvement of persistent luminescence (PersL) intensity and lifetime is needed to achieve the desired success of PLNCs while keeping the uniform sub‐10 nm size. In this work, the concept of molten salt confinement to thermally anneal as‐synthesized ZnGa2O4:Cr3+ (ZGOC) colloidal NCs (CNCs) in a molten salt medium at 650 °C is introduced. This method led to significantly monodispersed and few agglomerated NCs with a much improved photoluminescence (PL) and PersL intensity without much growth in the size of the pristine CNCs. Other strategies such as i) thermal annealing, ii) overcoating, and iii) the core–shell strategy have also been tried to improve PL and PersL but did not improve them simultaneously. Moreover, directly annealing the CNCs in air without the assistance of molten salt could significantly improve both PL and PersL but led to particle heterogeneity and aggregation, which are highly unsuitable for in vivo imaging. We believe this work provides a novel strategy to design PLNCs with high PL intensity and long PersL duration without losing their nanostructural characteristics, water dispersibility and biocompatibility. [ABSTRACT FROM AUTHOR]

Inspired by the spongy bone structures, three‐dimensional (3D) sponge‐like carbons with meso‐microporous structures are synthesized through one‐step electro‐reduction of CO2 in molten carbonate Li2CO3−Na2CO3−K2CO3 at 580 °C. SPC4‐0.5 (spongy porous carbon obtained by electrolysis of CO2 at 4 A for 0.5 h) is synthesized with the current efficiency of 96.9 %. SPC4‐0.5 possesses large electrolyte ion accessible surface area, excellent wettability and electronical conductivity, ensuring the fast and effective mass and charge transfer, which make it an advcanced supercapacitor electrode material. SPC4‐0.5 exhibits a specific capacitance as high as 373.7 F g−1 at 0.5 A g−1, excellent cycling stability (retaining 95.9 % of the initial capacitance after 10000 cycles at 10 A g−1), as well as high energy density. The applications of SPC4‐0.5 in quasi‐solid‐state symmetric supercapacitor and all‐solid‐state flexible devices for energy storage and wearable piezoelectric sensor are investigated. Both devices show considerable capacitive performances. This work not only presents a controllable and facile synthetic route for the porous carbons but also provides a promising way for effective carbon reduction and green energy production. [ABSTRACT FROM AUTHOR]

Besides widely used surface passivation, engineering the film crystallization is an important and more fundamental route to improve the performance of all‐inorganic perovskite solar cells. Herein, we have developed a urea‐ammonium thiocyanate (UAT) molten salt modification strategy to fully release and exploit coordination activities of SCN− to deposit high‐quality CsPbI3 film for efficient and stable all‐inorganic solar cells. The UAT is derived by the hydrogen bond interactions between urea and NH4+ from NH4SCN. With the UAT, the crystal quality of the CsPbI3 film has been significantly improved and a long single‐exponential charge recombination lifetime of over 30 ns has been achieved. With these benefits, the cell efficiency has been promoted to over 20 % (steady‐state efficiency of 19.2 %) with excellent operational stability over 1000 h. These results demonstrate a promising development route of the CsPbI3 related photoelectric devices. [ABSTRACT FROM AUTHOR]

The corrosion mechanisms of T24, T92, VM12, and AISI 304 steels are studied under the influence of NaCl–KCl, NaCl–Na2SO4, and KCl–K2SO4 salt mixtures in a dry air atmosphere at 650°C for 15 days. NaCl–KCl was the most aggressive deposit and AISI 304 stainless steel exhibited the highest corrosion resistance. There was no relation between the Cr content of the ferritic steels and their corrosion resistance in NaCl–KCl. In contrast, the resistance of high‐Cr steels was better when exposed to NaCl–Na2SO4 and KCl–K2SO4. The high‐Cr and the low‐Cr steels were more susceptible to NaCl–Na2SO4 and to KCl–K2SO4, respectively. [ABSTRACT FROM AUTHOR]

Summary: To combat the serious agglomeration and growth of the active materials, huge volume expansion and sluggish kinetics of metal oxides in the process of Li+ insertion/extraction, constructing hybrid nanostructures aiming to anchor active materials has been pursued. However, it is still limited in terms of capacity decay and complex preparation process. Herein, the hybrid MoO2/C is synthesized through a novel molten‐salt‐assisted approach, in which isolated small MoO2 nanoparticles were anchored on the well‐developed coal‐based porous carbon framework. The novel MoO2/C electrodes demonstrate enhanced electrochemical performance as Li+ battery anodes with a higher capacity of 960 mAh g−1 at 200 mA g−1, which is attributed to the synergistic effect for the uniform dispersion of MoO2 nanoparticles and coal‐based porous carbon layer with abundant active contact sites, which is better by far than the currently reported MoO2‐based electrode. Meanwhile, the hybrid MoO2/C exhibited improved extrinsic capacitive characteristics. Therefore, the hybrid MoO2/C constructed by the simple low cost strategy can be a prospective Li‐ion battery anode. [ABSTRACT FROM AUTHOR]

Most of the photocatalytic materials are prepared by wet chemical methods and calcination methods. These preparation methods usually have the problems of slow reaction speed and low crystallinity of products, which seriously restrict the development of photocatalytic technology. Molten salt method (MSM) has attracted much attention of researchers because of its unique advantages in optimizing the synthesis route of photocatalyst. Herein, the application of molten salt technology in the preparation of photocatalytic materials in recent years is summarized. The advantages of MSM in photocatalytic synthesis, such as promoting crystallization, adjusting morphology, accelerating the construction of heterostructure, stabilizing single atom, doping auxiliary elements and adjusting defect position, are also discussed in detail. It is indicated that MSM has important application potential in the preparation of photocatalytic materials. Meanwhile, the research achievements and existing problems of MSM are summarized, and suggestions for further application of MSM in photocatalyst's preparation are put forward. [ABSTRACT FROM AUTHOR]

The high temperature corrosion characteristic of Super304H, TP347H, and HR3C steel in an ultra‐supercritical coal‐fired boiler with service time of 17,973 h was investigated. The samples were analyzed by XRD, SEM, and EDS. The results showed that corrosion scales were composed and could be divided into three layers, including outer layer with composite reaction of alkalis and sulfate, middle layer with oxidation, and penetrated inner layer with oxidation and sulfidation. In addition, spalling of corrosion scales in the Super304H and TP347H samples was observed with the reasons of low Cr content and thermal expansion difference between different corrosion layers. [ABSTRACT FROM AUTHOR]

Non‐noble electrocatalyst for the oxygen evolution reaction (OER) is essential for water electrolysis and electrochemical conversion of CO2. Integrating electrochemical fixation of CO2 and electrochemical metallurgy to prepare advanced OER electrocatalyst is a promising solution to promote carbon neutrality and renewable energy. Herein, the electrochemical reduction of CO2 and Fe2O3 are combined in molten salts to prepare cathodic Fe3C‐based electrocatalyst and anodic oxygen at 600 °C with enhanced current efficiency. The resulting Fe3C‐based electrocatalyst outperforms precious electrocatalyst towards the OER operation in 1 M KOH due to a dynamic structural evolution to form an interface of Fe3C‐FeOOH. [ABSTRACT FROM AUTHOR]

The massive release of the greenhouse gas CO2 has resulted in numerous environmental issues. In searching for advanced technologies for CO2 capture/conversions, recent advances in electrochemical reduction of CO2 in molten salts shed a light on potential solutions to CO2 mitigation. Electro‐reduction of CO2 in molten salts exhibits features like high selectivity and efficiency towards sustainable carbons and fuels, low toxicity, and possibility to combine with in situ CO2 capture. In this Minireview, we highlight the tuning of the products in this process and mainly discuss two categories of electrolyte, carbonate‐based molten salts (CMS) and those based on halides (HMS). Depending on the synthetic conditions, fuels such as CO or hydrocarbons (in the presence of hydrogen source, i. e. LiOH, NaOH, or KOH in the electrolyte) as well as high‐value nanostructured carbons including carbon nanotubes, carbon nanofibers, carbon nano‐onions, and graphene can be obtained with high efficiency. The synthesis parameters are compared, and the applications of as‐obtained carbons are briefly summarized. Additionally, some perspectives on this technology are also discussed. [ABSTRACT FROM AUTHOR]

In the present work, the possibility for obtaining tantalum powders by means of the electrochemical pulverization (secondary reduction) in the molten electrolytes KBr‐NaBr and KI‐NaI was demonstrated. The powders were analyzed using the X‐ray diffraction, BET, ICP, and laser light scattering. It was revealed that the obtained powders have a chemical purity of 99.98 wt %, which corresponds to the qualification of high‐purity tantalum. The maximum specific surface area of the powder was 17.84 m2/g, and the prevailing particle sizes were in the range from 1.9 to 4.5 μm. The dependence of the predominant particle size on the anion sublattice size was established. The smallest particles were found to be obtained in the systems based on alkali chlorides, the largest in iodide systems. [ABSTRACT FROM AUTHOR]

Nine selected alloys are exposed in molten KCl–LiCl (eutectic composition) at 1073 K for 167 h under argon atmosphere to predict the long‐term corrosion behavior of these structural materials. The corrosive attack of each alloy is assessed with gravimetric methods, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy measurements. The corrosion rate of each alloy is calculated in accordance with ASTM G1‐03. Low chromium containing alloys as HAYNES 242, Hastelloy B‐3, and Hastelloy N revealed minor or no significant corrosive attack after molten chloride exposure. Alloy 600, Alloy 617, HAYNES 625, Hastelloy X, HAYNES 230, and HAYNES 188 with a chromium content wCr > 8% show severe corrosive attack with complete chromium depletion along the near‐surface layer and partially along grain boundaries. The results show that chromium forms chromium oxide with impurities of oxygen and water vapor at low oxygen partial pressures. This initiates an accelerated corrosion of the alloying elements in the matrix of Ni, Cr, Mo, Fe, and Co, due to chlorine formation. The influence of the composition of nickel‐base alloys on the corrosion resistance is discussed based on the comparison of the gravimetric measurements and thermodynamic calculations. [ABSTRACT FROM AUTHOR]

A study of graphene "in situ" formed during the chemical interaction of glucose with molten aluminium under a layer of molten alkaline halides in air at temperatures of 750–850°C is presented. By means of Raman and X‐ray photoelectron spectroscopy and electron microscopy, it is shown that graphene films synthesize in the aluminium. The number and defectiveness of graphene layers inside aluminium matrix depends on synthesis temperature– at 750°C two‐layer graphene and at 850°C three‐layer graphene form. The most defective graphene films synthesized at 750°C with the formation of five‐ and seven‐membered rings in plane of the graphene grid; the number of defects of graphene films is less for composite obtained at higher temperature. The evaluated defectiveness of graphene not exceed 14%; it evidences the formation of perfect graphene in aluminium matrix. The compressive stress value is the smallest for the sample obtained at 750°C and increases with temperature and plastic deformation because of differences in the crystal lattice parameters and their thermal expansion coefficients of aluminium and graphene. This fact explains the relation of defects number in graphene with temperature and plastic deformation. No aluminium carbide and graphene oxide were formed during synthesis inside aluminium matrix because of formation of defect‐free perfect graphene with high chemical stability. The absence of aluminium carbide was proven by means Raman spectroscopy, X‐ray photoelectron, transmission electron microscopy, and corrosion test with distilled water. It allows to propose aluminium‐graphene composites for numerous practical applications as a constructive material. [ABSTRACT FROM AUTHOR]

The current Si production process is based on the high‐temperature (1700 °C) reduction of SiO2 with carbon that produces large amounts of CO2. We report an alternative low‐temperature (850 °C) process based on the reduction of SiO2 in molten CaCl2 that does not produce CO2. It utilizes an anode material (Ti4O7) capable of sustained oxygen evolution. Two types of this anode material, dense Ti4O7 and porous Ti4O7, were tested. The dense anode showed a better performance. The anode stability is attributed to the formation of a protective TiO2 layer on its surface. In situ periodic current reversal and ex situ H2 reduction could be used for extending the lifetime of the anodes. The findings show that this material can be applied as a recyclable anode in molten CaCl2. Si wires, films, and particles were deposited with this anode under different cathodic current densities. The prepared Si film exhibited ≈30–40 % of the photocurrent response of a commercial p‐type Si wafer, indicating potential use in photovoltaic cells. [ABSTRACT FROM AUTHOR]

The current Si production process is based on the high‐temperature (1700 °C) reduction of SiO2 with carbon that produces large amounts of CO2. We report an alternative low‐temperature (850 °C) process based on the reduction of SiO2 in molten CaCl2 that does not produce CO2. It utilizes an anode material (Ti4O7) capable of sustained oxygen evolution. Two types of this anode material, dense Ti4O7 and porous Ti4O7, were tested. The dense anode showed a better performance. The anode stability is attributed to the formation of a protective TiO2 layer on its surface. In situ periodic current reversal and ex situ H2 reduction could be used for extending the lifetime of the anodes. The findings show that this material can be applied as a recyclable anode in molten CaCl2. Si wires, films, and particles were deposited with this anode under different cathodic current densities. The prepared Si film exhibited ≈30–40 % of the photocurrent response of a commercial p‐type Si wafer, indicating potential use in photovoltaic cells. [ABSTRACT FROM AUTHOR]

The current Si production process is based on the high‐temperature (1700 °C) reduction of SiO2 with carbon that produces large amounts of CO2. We report an alternative low‐temperature (850 °C) process based on the reduction of SiO2 in molten CaCl2 that does not produce CO2. It utilizes an anode material (Ti4O7) capable of sustained oxygen evolution. Two types of this anode material, dense Ti4O7 and porous Ti4O7, were tested. The dense anode showed a better performance. The anode stability is attributed to the formation of a protective TiO2 layer on its surface. In situ periodic current reversal and ex situ H2 reduction could be used for extending the lifetime of the anodes. The findings show that this material can be applied as a recyclable anode in molten CaCl2. Si wires, films, and particles were deposited with this anode under different cathodic current densities. The prepared Si film exhibited ≈30–40 % of the photocurrent response of a commercial p‐type Si wafer, indicating potential use in photovoltaic cells. [ABSTRACT FROM AUTHOR]

Manganite perovskite oxides exhibit a wide range of properties relevant for catalysis, energy conversion and spintronics. Such behaviors can be deeply modified at the nanoscale where confinement and surface effects may prevail. Interesting properties could then emerge from manganite perovskite nanocrystals, although their synthesis remains a challenge. The present study reports a versatile synthesis of manganite perovskite nanocrystals by using molten salts as high temperature liquids in the 600–750 °C range. Through X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning and transmission electron microscopies, we show that many substitutions on the A perovskite site are within reach by applying the approach to La2/3Sr1/3MnO3, La2/3Ca1/3MnO3 and La1/3Pr1/3Ca1/3MnO3 cubic‐shape nanocrystals with diameter of 20, 22 and 38 nm, respectively. The magnetic properties of these nanocrystals are then investigated at 5 K, highlighting the coexistence of a ferromagnetic phase typical of the bulk, with disordered and non‐magnetic domains, which presumably arise from the nanoscale and surface effects. Manganese oxide perovskites are obtained for the first time as highly crystalline, well‐faceted nanocrystals. High temperature liquid‐phase syntheses in molten salts thus offer a nice playground to assess the impact of the nanoscale on the properties of these materials, as exemplified by the magnetic properties of three different manganites. [ABSTRACT FROM AUTHOR]

Two iron nitrides γ‐FeN0.13 and ε‐Fe3N1.51 were synthesized electrochemically in a molten salt system KCl–LiCl at 450 °C. For the electrochemical formation of γ‐FeN0.13, which crystallizes in Fm3m with a = 367.46(7) pm, either Li3N or KNO3 can be added to the salt mixture as nitrogen source. An addition of Li3N corresponds to anodic polarization (anodic electrolysis) of the working electrode and KNO3 to cathodic polarization (cathodic electrolysis). The chosen applied voltages were 0.8 V and 1.4 V, respectively. Electrochemical synthesis employing a pure α‐iron foil as working electrode results in thicker layers than using an iron rod, independent of the polarization of the working electrodes. Cathodic electrolysis delivers a higher layer thickness compared to anodic electrolysis. Anodic electrolysis of a pure α‐iron foil at 2.2 V and a duration of 3 h provides ε‐Fe3N1.51 as bulk material. Structural refinements by the Rietveld method result in a hexagonal unit cell with parameters of a = 478.06(3) pm and c = 441.82(3) pm indicating the high nitrogen content in agreement with an elemental analysis. γ‐FeN0.13 and ε‐Fe3N1.51 can be synthesized electrochemically in LiCl–KCl salt melts. With this method it is possible to produce these nitrides at lower temperatures and without the use of harmful and corrosive gases, which is an advantage over conventional synthesis methods. Furthermore, rather high nitrogen contents are achieved in the products. [ABSTRACT FROM AUTHOR]

Application of nanostructured silicon (nSi) is significantly retarded by challenges in the production of affordable nSi. We herein report a high‐yield (ca. 100 %) and low‐energy (2 kWh Kg‐nSi−1) nanostructuring of industrial microsized silicon (mSi) through a closed‐loop electrochemical Mg alloying/dealloying in molten MgCl2/NaCl/KCl at 773 K. The resulting nSi unexpectedly shows a salt‐unwetted character, allowing an automatic separation from the melts. Thus water washing and accompanying oxidation of the nSi can be avoided. The final product has a nanoporous structure and comprises Si nanorods (ca. 30 nm in diameter) with an ultrathin oxide coating. It can be used for Li storage giving a combination of high initial coulombic efficiency, high specific capacity, and long cycling stability. This nanostructuring process consumes very few chemicals except for the mSi and produces almost zero waste. Bulk silicon can be nanostructured in a comparatively low‐energy and environmentally benign approach of electrochemical Mg alloying/dealloying in molten salts at moderate temperatures. For lithium storage, the nanostructured Si exhibits a combination of high initial Coulombic efficiency, high specific capacity, and long cycling stability. [ABSTRACT FROM AUTHOR]

Recycle of thorium is an essential process in the thorium‐uranium closed fuel cycle of molten salt reactor (MSR). Pyrochemical treatment of spent nuclear fuel using chloride molten salts as medium has been considered as a promising method. In this article, we performed molecular dynamics simulations on the ThCl4LiCl molten salts using a polarizable force field parameterized by us from first‐principles calculations. The microscopic structures and macroscopic properties at different compositions were investigated using the developed force field to understand the structure/property relationship in the mixture. The differences between ThCl4LiCl and ThF4LiF MSs are compared to understand the behaviors of Th4+ in the fluoride‐chloride mixed media. In the molten fluorides, the coordination number of Th4+ is larger, and the resulting more shared anions lead to lower ThF dissociation barrier and shorter lifetime of the Th4+ first solvation shell. Our results also indicate the Pauling's structural rules for crystals can be used to rationalize the local structures in molten salts. © 2018 Wiley Periodicals, Inc. Molecular dynamics simulations were performed on the ThCl4LiCl MSs using a polarizable force field parameterized by us from first‐principles calculations. The microscopic structures and macroscopic properties at different compositions were investigated to understand the structure/property relationship in the mixture. [ABSTRACT FROM AUTHOR]

Production of silicon film directly by electrodeposition from molten salt would have utility in the manufacturing of photovoltaic and optoelectronic devices owing to the simplicity of the process and the attendant low capital and operating costs. Here, dense and uniform polycrystalline silicon films (thickness up to 60 µm) are electrodeposited on graphite sheet substrates at 650 °C from molten KCl-KF-1 mol% K2SiF6 salt containing 0.020-0.035 wt% tin. The growth of such high-quality tin-doped silicon films is attributable to the mediation effect of tin in the molten salt electrolyte. A four-step mechanism is proposed for the generation of the films: nucleation, island formation, island aggregation, and film formation. The electrodeposited tin-doped silicon film exhibits n-type semiconductor behavior. In liquid junction photoelectrochemical measurement, this material generates a photocurrent about 38-44% that of a commercial n-type Si wafer. [ABSTRACT FROM AUTHOR]

Silicon is an extremely important technological material, but its current industrial production by the carbothermic reduction of SiO2 is energy intensive and generates CO2 emissions. Herein, we developed a more sustainable method to produce silicon nanowires (Si NWs) in bulk quantities through the direct electrochemical reduction of CaSiO3, an abundant and inexpensive Si source soluble in molten salts, at a low temperature of 650 °C by using low-melting-point ternary molten salts CaCl2-MgCl2-NaCl, which still retains high CaSiO3 solubility, and a supporting electrolyte of CaO, which facilitates the transport of O2− anions, drastically improves the reaction kinetics, and enables the electrolysis at low temperatures. The Si nanowire product can be used as high-capacity Li-ion battery anode materials with excellent cycling performance. This environmentally friendly strategy for the practical production of Si at lower temperatures can be applied to other molten salt systems and is also promising for waste glass and coal ash recycling. [ABSTRACT FROM AUTHOR]

Silicon is an extremely important technological material, but its current industrial production by the carbothermic reduction of SiO2 is energy intensive and generates CO2 emissions. Herein, we developed a more sustainable method to produce silicon nanowires (Si NWs) in bulk quantities through the direct electrochemical reduction of CaSiO3, an abundant and inexpensive Si source soluble in molten salts, at a low temperature of 650 °C by using low-melting-point ternary molten salts CaCl2-MgCl2-NaCl, which still retains high CaSiO3 solubility, and a supporting electrolyte of CaO, which facilitates the transport of O2− anions, drastically improves the reaction kinetics, and enables the electrolysis at low temperatures. The Si nanowire product can be used as high-capacity Li-ion battery anode materials with excellent cycling performance. This environmentally friendly strategy for the practical production of Si at lower temperatures can be applied to other molten salt systems and is also promising for waste glass and coal ash recycling. [ABSTRACT FROM AUTHOR]

Capacitive carbons are attractive for energy storage on account of their superior rate and cycling performance over traditional battery materials, but they usually suffer from a far lower volumetric energy density. Starting with expanded graphene, a simple, multifunctional molten sodium amide treatment for the preparation of high-density graphene with high capacitive performance in both aqueous and lithium battery electrolytes is reported. The molten sodium amide can condense the expanded graphene, lead to nitrogen doping and, what is more important, create moderate in-plane nanopores on graphene to serve as ion access shortcuts in dense graphene stacks. The resulting high-density graphene electrode can deliver a volumetric capacitance of 522 F cm−3 in a potassium hydroxide electrolyte; and in a lithium-ion battery electrolyte, it exhibits a gravimetric and volumetric energy density of 618 W h kg−1 and 740 W h L−1, respectively, and even outperforms commercial LiFePO4. [ABSTRACT FROM AUTHOR]

This concept paper describes a new electrochemical method for the graphitization of amorphous carbons. The graphitization is achieved by a simple cathodic polarization of the carbons at merely ≈1100 K in molten CaCl2. This electrochemical process is applicable to both graphitizable and non-graphitizable carbons, generating porous graphitic structures of high-crystallinity nanosheets. The transformation of carbon blacks, microspheres, and fibers to porous graphites, hollow graphite spheres, and pipes with porous shells have been demonstrated and the potential graphitization mechanism discussed. [ABSTRACT FROM AUTHOR]

An electrochemical cell utilizing a molten salt eutectic electrolyte (ZnCl2-KCl) is investigated as a new low-cost energy storage technology. Using Zn as the anode, a broad range of candidate cathode materials (Al, Ag, Bi, C, Cu, a Ni alloy, Sn, and Pb) are characterized by open-circuit potential, chronoamperometry, and electrochemical impedance spectroscopy methods. Cells employing the molten metal cathodes Sn, Bi, and Pb deliver markedly high current densities independent of their standard reduction potentials. Molten Pb (at 330 °C), for example, gave 25 times higher current density than solid Pb (at 315 °C). Additionally, ZnCl2-KCl is employed for the first time in an energy storage application and it affords an operating temperature >100 °C lower than other liquid metal battery technologies. Thermal properties of this relatively air-stable molten salt electrolyte allow for a second mode of energy storage, that is, thermal. The combination of an inexpensive Zn anode, low-temperature eutectic electrolyte, and a molten metal cathode offers a simple and promising electrochemical system for dual-mode (thermal-electrochemical) large-scale energy storage. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Nanocrystalline Li1.14Ni0.18Mn0.62O2 cathode materials are synthesized by a molten salt method using KCl as the molten agent. The influence of the sintering temperature and the mass ratio of KCl to Li1.14Ni0.18Mn0.62O2 on the structure and electrochemical performance are investigated. The sintering temperature can markedly affect the formation of the layered structure and the content of stacking faults. The amount of KCl influences the cation ordering of the materials. The ratios of Li+/Ni2+ replacement for the materials obtained at 800 °C with a KCl amount of R=4, 8, and 12 [ R= m(KCl)/ m(Li1.14Ni0.18Mn0.62O2)] are 16.51, 8.39, and 4.46 %, respectively. A lower steric hindrance-related to a better cationic ordering-is obtained when the amount of KCl is increased, which is in agreement with the tendency of the Li+ diffusion coefficient. This study demonstrates a new approach to control the Li+/Ni2+ replacement in lithium-rich layered cathode materials to improve their electrochemical performance. [ABSTRACT FROM AUTHOR]

Crystalline Si nanoparticles are prepared by reduction of SiCl4 with metallic magnesium in the molten salt of AlCl3 at 200 °C in an autoclave. AlCl3 not only acts as molten salt, but also participates in the reaction. The related experiments confirm that metallic Mg reduces AlCl3 to create nascent Al which could immediately reduce SiCl4 to Si, and the by-product MgCl2 would combine with AlCl3 forming complex of MgAl2Cl8. As anode for rechargeable lithium ion batteries, the as-prepared Si delivers the reversible capacity of 3083 mAh g−1 at 1.2 A g−1 after 50 cycles, and 1180 mAh g−1 at 3 A g−1 over 500 cycles. [ABSTRACT FROM AUTHOR]

We herein describe a straight forward procedure to increase the performance of piatinum-on-aiumina catalysts in methanol steam reforming by applying an alkali hydroxide coating according to the "solid catalyst with ionic liquid layer" (SCILL) approach. We demonstrate by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed desorption (TPD) studies that potassium doping plays an important role in the catalyst activation. Moreover, the hygroscopic nature and the basicity of the salt modification contribute to the considerable enhancement in catalytic performance. During reaction, a partly liquid film of alkali hydroxides/carbonates forms on the catalyst/alumina surface, thus significantly enhancing the availability of water at the catalytically active sites. Too high catalyst pore fillings with salt introduce a considerable mass transfer barrier into the system as indicated by kinetic studies. Thus, the optimum interplay between beneficial catalyst modification and detrimental mass transfer effects had to be identified and was found on the applied platinum-on-alumina catalyst at KOH loadings around 7.5 mass%. [ABSTRACT FROM AUTHOR]