Porous liquids: an integrated platform for gas storage and catalysis

Porous liquids (PLs) represent a new frontier in materials design, combining the unique features of fluidity in liquids and permanent porosity in solids. By engineering well-defined pores into liquids via designed structure modification techniques, the greatly improved free volume significantly enhances the gas transport and storage capability of PL sorbents. Triggered by the promising applications of PLs in gas separation, PLs are further explored in catalysis particularly to integrate the gas storage and catalytic transformation procedure. This emerging field has demonstrated promising progress to advance catalytic procedures using PLs as catalysts, with performance surpassing that of the pure liquid and porous host counterparts. In this perspective article, the recent discoveries and progress in the field of integrated gas storage and catalysis by leveraging the PL platforms will be summarized, particularly compared with the traditional homogeneous or heterogeneous catalytic procedures. The unique features of PLs endow them with combined merits from liquid and solid catalysts and beyond which will be illustrated first. This will be followed by the unique techniques being utilized to probe the porosity and active sites in PLs and the structural evolution during the catalytic procedures. The catalytic application of PLs will be divided by the reaction categories, including CO2-involving transformation, O2-involving reaction, H2S conversion, hydrogenation reaction, and non-gas involving cascade reactions. In each reaction type, the synthesis approaches and structure engineering techniques of PLs, structure characterization, catalytic performance evaluation, and reaction mechanism exploration will be discussed, highlighting the structure-performance relationship and the advancement benefiting from the unique features of PLs.

Operando probing and adjusting of the complicated electrode process of multivalent metals at extreme temperature

Nearly half of the elements in the periodic table are extracted, refined, or plated using electrodeposition in high-temperature melts. However, operando observations and tuning of the electrodeposition process during realistic electrolysis operations are extremely difficult due to severe reaction conditions and complicated electrolytic cell, which makes the improvement of the process very blind and inefficient. Here, we developed a multipurpose operando high-temperature electrochemical instrument that combines operando Raman microspectroscopy analysis, optical microscopy imaging, and a tunable magnetic field. Subsequently, the electrodeposition of Ti-which is a typical polyvalent metal and generally shows a very complex electrode process-was used to verify the stability of the instrument. The complex multistep cathodic process of Ti in the molten salt at 823 K was systematically analyzed by a multidimensional operando analysis strategy involving multiple experimental studies, theoretical calculations, etc. The regulatory effect and its corresponding scale-span mechanism of the magnetic field on the electrodeposition process of Ti were also elucidated, which would be inaccessible with existing experimental techniques and is significant for the real-time and rational optimization of the process. Overall, this work established a powerful and universal methodology for in-depth analysis of high-temperature electrochemistry.

Recent Advances in Electrochemical-Based Silicon Production Technologies with Reduced Carbon Emission

Sustainable and low-carbon-emission silicon production is currently one of the main focuses for the metallurgical and materials science communities. Electrochemistry, considered a promising strategy, has been explored to produce silicon due to prominent advantages: (a) high electricity utilization efficiency; (b) low-cost silica as a raw material; and (c) tunable morphologies and structures, including films, nanowires, and nanotubes. This review begins with a summary of early research on the extraction of silicon by electrochemistry. Emphasis has been placed on the electro-deoxidation and dissolution-electrodeposition of silica in chloride molten salts since the 21st century, including the basic reaction mechanisms, the fabrication of photoactive Si films for solar cells, the design and production of nano-Si and various silicon components for energy conversion, as well as storage applications. Besides, the feasibility of silicon electrodeposition in room-temperature ionic liquids and its unique opportunities are evaluated. On this basis, the challenges and future research directions for silicon electrochemical production strategies are proposed and discussed, which are essential to achieve large-scale sustainable production of silicon by electrochemistry.

Molecular Dynamics Simulation of Thin Silicon Carbide Films Formation by the Electrolytic Method

Silicon carbide is successfully implemented in semiconductor technology; it is also used in systems operating under aggressive environmental conditions, including high temperatures and radiation exposure. In the present work, molecular dynamics modeling of the electrolytic deposition of silicon carbide films on copper, nickel, and graphite substrates in a fluoride melt is carried out. Various mechanisms of SiC film growth on graphite and metal substrates were observed. Two types of potentials (Tersoff and Morse) are used to describe the interaction between the film and the graphite substrate. In the case of the Morse potential, a 1.5 times higher adhesion energy of the SiC film to graphite and a higher crystallinity of the film was observed than is the case of the Tersoff potential. The growth rate of clusters on metal substrates has been determined. The detailed structure of the films was studied by the method of statistical geometry based on the construction of Voronoi polyhedra. The film growth based on the use of the Morse potential is compared with a heteroepitaxial electrodeposition model. The results of this work are important for the development of a technology for obtaining thin films of silicon carbide with stable chemical properties, high thermal conductivity, low thermal expansion coefficient, and good wear resistance.

An iron-base oxygen-evolution electrode for high-temperature electrolyzers

High-temperature molten-salt electrolyzers play a central role in metals, materials and chemicals production for their merit of favorable kinetics. However, a low-cost, long-lasting, and efficient high-temperature oxygen evolution reaction (HT-OER) electrode remains a big challenge. Here we report an iron-base electrode with an in situ formed lithium ferrite scale that provides enhanced stability and catalytic activity in both high-temperature molten carbonate and chloride salts. The finding is stemmed from a discovery of the ionic potential-stability relationship and a basicity modulation principle of oxide films in molten salt. Using the iron-base electrode, we build a kiloampere-scale molten carbonate electrolyzer to efficiently convert CO₂ to carbon and oxygen. More broadly, the design principles lay the foundations for exploring cheap, Earth-abundant, and long-lasting HT-OER electrodes for electrochemical devices with molten carbonate and chloride electrolytes.

Molten salt electrosynthesis of Cr2GeC nanoparticles as anode materials for lithium-ion batteries

The two-dimensional MAX phases with compositional diversity are promising functional materials for electrochemical energy storage. Herein, we report the facile preparation of the Cr₂GeC MAX phase from oxides/C precursors by the molten salt electrolysis method at a moderate temperature of 700°C. The electrosynthesis mechanism has been systematically investigated, and the results show that the synthesis of the Cr₂GeC MAX phase involves electro-separation and in situ alloying processes. The as-prepared Cr₂GeC MAX phase with a typical layered structure shows the uniform morphology of nanoparticles. As a proof of concept, Cr₂GeC nanoparticles are investigated as anode materials for lithium-ion batteries, which deliver a good capacity of 177.4 mAh g^-1 at 0.2 C and excellent cycling performance. The lithium-storage mechanism of the Cr₂GeC MAX phase has been discussed based on density functional theory (DFT) calculations. This study may provide important support and complement to the tailored electrosynthesis of MAX phases toward high-performance energy storage applications.

Germanium Nanowires via Molten-Salt Electrolysis for Lithium Battery Anode

Germanium (Ge)-based materials can serve as promising anode candidates for high-energy lithium-ion batteries (LIBs). However, the rapid capacity decay caused by huge volume expansion severely retards their application. Herein, we report a facile and controllable synthesis of Ge nanowire anode materials through molten-salt electrolysis. The optimal Ge nanowires can deliver a capacity of 1058.9 mAh g^-1 at 300 mA g^-1 and a capacity above 602.5 mAh g^-1 at 3000 mA g^-1 for 900 cycles. By in situ transmission electron microscopy and in situ X-ray diffraction, the multiple-step phase transformation and good structural reversibility of the Ge nanowires during charge/discharge are elucidated. When coupled with a lithium-rich Li_1.2Mn_0.567Ni_0.167Co_0.067O₂ cathode in a full battery, the Ge nanowire anode leads to a relatively stable capacity with a retention of 84.5% over 100 cycles. This research highlights the significance of molten-salt electrolysis for the synthesis of alloy-type anode materials toward high-energy LIBs.

Anode electrolysis of sulfides

Traditional sulfide metallurgy produces harmful sulfur dioxide and is energy intensive. To this end, we develop an anode electrolysis approach in molten salt by which sulfide is electrochemically split into sulfur gas at a graphite inert anode while releasing metal ions that diffuse toward and are deposited at the cathode. The anodic splitting dictates the "sulfide-to-metal ion and sulfur gas" conversion that makes the reaction recur continuously. Using this approach, Cu₂S is converted to sulfur gas and Cu in molten LiCl-KCl at 500 °C with a current efficiency of 99% and energy consumption of 0.420 kWh/kg^-Cu (only considering the electricity for electrolysis). Besides Cu₂S, the anode electrolysis can extract Cu from Cu matte that is an intermediate product from the traditional sulfide smelting process. More broadly, Fe, Ni, Pb, and Sb are extracted from FeS, CuFeS₂, NiS, PbS, and Sb₂S₃, providing a general electrochemical method for sulfide metallurgy.

Electrochemical Mechanism of Molten Salt Electrolysis from TiO2 to Titanium

Electrochemical mechanisms of molten salt electrolysis from TiO2 to titanium were investigated by Potentiostatic electrolysis, cyclic voltammetry, and square wave voltammetry in NaCl-CaCl2 at 800 °C. The composition and morphology of the product obtained at different electrolysis times were characterized by XRD and SEM. CaTiO3 phase was found in the TiO2 electrochemical reduction process. Electrochemical reduction of TiO2 to titanium is a four-step reduction process, which can be summarized as TiO2→Ti4O7→Ti2O3→TiO→Ti. Spontaneous and electrochemical reactions take place simultaneously in the reduction process. The electrochemical reduction of TiO2→Ti4O7→Ti2O3→TiO affected by diffusion was irreversible.

Recent Advancement of the Current Aspects of g-C3 N4 for its Photocatalytic Applications in Sustainable Energy System

Being one of the foremost enticing and intriguing innovations, heterogeneous photocatalysis has also been used to effectively gather, transform, and conserve sustainable sun's radiation for the production of efficient and clean fossil energy as well as a wide range of ecological implications. The generation of solar fuel-based water splitting and CO₂ photoreduction is excellent for generating alternative resources and reducing global warming. Developing an inexpensive photocatalyst can effectively split water into hydrogen (H₂ ), oxygen (O₂ ) sources, and carbon dioxide (CO₂ ) into fuel sources, which is a crucial problem in photocatalysis. The metal-free g-C₃ N₄ photocatalyst has a high solar fuel generation potential. This review covers the most recent advancements in g-C₃ N₄ preparation, including innovative design concepts and new synthesis methods, and novel ideas for expanding the light absorption of pure g-C₃ N₄ for photocatalytic application. Similarly, the main issue concerning research and prospects in photocatalysts based g-C₃ N₄ was also discussed. The current dissertation provides an overview of comprehensive understanding of the exploitation of the extraordinary systemic and characteristics, as well as the fabrication processes and uses of g-C₃ N₄ .

Nanoscale electrodeposition: Dimension control and 3D conformality

Electrodeposition with a long history has been considered one of the important synthesis techniques for applying various applications. It is a feasible route for fabricating nanostructures using diverse materials due to its simplicity, cost-effectiveness, flexibility, and ease of reaction control. Herein, we mainly focus on the nanoscale electrodeposition with respect to dimension control and three-dimensional (3D) conformality. The principles of electrodeposition, dimensional design of materials, and uniform coatings on various substrates are presented. We introduce that manipulating synthesis parameters such as precursors, applied current/voltage, and additives affect the synthesis reaction, resulting in not only dimensional control of materials from three-dimensional structures to zero-dimensional atomic-level but also conformal coatings on complicated substrates. Various cases regarding morphology control of metal (hydro)oxides, metals, and metal-organic frameworks according to electrodeposition conditions are summarized. Lastly, recent studies of applications such as batteries, photoelectrodes, and electrocatalysts using electrodeposited materials are summarized. This review represents significant advances in the nanoscale design of materials through methodological approaches, which are highly attractive from both academic and commercial aspects.

Study of the structure of a multicomponent salt melt using molecular dynamics modeling

The composition of the electrolyte is critical in the electrodeposition of high-purity silicon. In this work, molecular dynamics modeling of the preparation of liquid salt melt KF-KCl-KI and a detailed study of its structure based on the method of statistical geometry have been performed. Partial radial distribution functions reflect the size of the ions under consideration and the averaged structure of the generated ionic subsystems. Halogen subsystems have domed angular distributions of nearest geometric neighbors, a wide range of face types of combined polyhedra, and fifth order rotational symmetry. The shape of the distribution of distances to the nearest neighbors of a given type depends on the amount of these ions in the melt. Small-scale thermal fluctuations in the halogen subsystems are predominantly represented by small triangular faces in combined polyhedra. The electrodeposition of silicon was carried out in a homogeneous salt melt, in which each halogen ion had from one to three close contacts with halogen ions of any other type. The simulations performed provide a fundamental understanding of the structure of the electrolyte molten salts used to produce solar silicon.

Growth of LaCoO3 crystals in molten salt: effects of synthesis conditions

Herein, several typical reaction media for the synthesis of LaCoO₃ (LCO) crystals were examined by X-ray absorption spectroscopy (XAS).

Sustainable Carbons and Fuels: Recent Advances of CO2 Conversion in Molten Salts

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.

Preparation of V–4Cr–4Ti Alloys from Mixed Oxides via Electro-Deoxidation Process in Molten Salt

V–4Cr–4Ti alloys exhibit important advantages as a candidate structural materials for fusion reactor first-walls and blanket applications. V–4Cr–4Ti alloys were prepared by direct electrochemical reduction of the solid mixture of V2O3, Cr2O3 and TiO2 in the molten CaCl2–NaCl eutectic at 1073 K. The influence of cell voltage, sintering temperature and electrolysis time on the electrolysis process are reported. The microstructure and phase compositions of the products were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) during the electrolysis process. The results showed that V–4Cr–4Ti alloys can be obtained at the voltage of 3.1 V and the time of 0.5 h. Cr2O3 was first reduced to Cr metal, while V2O3 and TiO2 was reduced to low-valence oxide of vanadium and titanium. The reduction rate increases with increasing cell voltage, with much perovskite oxide formed during the electrolysis process.

Silicon Electrochemistry in Molten Salts

Silicon electrochemistry has the potential to advance sustainable energy solutions by offering environmentally friendly and secure technologies that can contribute to the low-carbon economy. Electrochemical methods use electrons directly as reducing agents, eliminating the need for harmful chemicals and offering simpler, one-step, process control. Silicon itself is the second most abundant element in the earth's crust, is nontoxic, and is a robust material offering high efficiencies in solar photovoltaics. As such, silicon currently dominates the solar energy market and could continue to do so for the next few decades. This review summarizes recent achievements in the molten salt electrochemistry of silicon, highlighting subjects of technological significance such as the production of silicon by silica electro-deoxidation, the formation of photoactive layers, silicon electrorefining, and the synthesis of semiconductors as well as nanostructures for energy storage applications. The review highlights future opportunities and challenges such as the production of highly pure silicon, the creation of carbon-free anodes for oxygen production, and silicon electrodeposition from gaseous precursors.

In situ electrochemical conversion of CO2 in molten salts to advanced energy materials with reduced carbon emissions

Fixation of CO₂ on the occasion of its generation to produce advanced energy materials has been an ideal solution to relieve global warming. We herein report a delicately designed molten salt electrolyzer using molten NaCl-CaCl₂-CaO as electrolyte, soluble GeO₂ as Ge feedstock, conducting substrates as cathode, and carbon as anode. A cathode-anode synergy is verified for coelectrolysis of soluble GeO₂ and in situ-generated CO₂ at the carbon anode to cathodic Ge nanoparticles encapsulated in carbon nanotubes (Ge@CNTs), contributing to enhanced oxygen evolution at carbon anode and hence reduced CO₂ emissions. When evaluated as anode materials for lithium-ion batteries, the Ge@CNTs hybrid shows high reversible capacity, long cycle life, and excellent high-rate capability. The process contributes to metallurgy with reduced carbon emissions, in operando CO₂ fixation to advanced energy materials, and upgraded conversion of carbon bulks to CNTs.

Interactions of molten salts with cathode products in the FFC Cambridge Process

Molten salts play multiple important roles in the electrolysis of solid metal compounds, particularly oxides and sulfides, for the extraction of metals or alloys. Some of these roles are positive in assisting the extraction of metals, such as dissolving the oxide or sulfide anions, and transporting them to the anode for discharging, and offering the high temperature to lower the kinetic barrier to break the metal-oxygen or metal-sulfur bond. However, molten salts also have unfavorable effects, including electronic conductivity and significant capability of dissolving oxygen and carbon dioxide gases. In addition, although molten salts are relatively simple in terms of composition, physical properties, and decomposition reactions at inert electrodes, in comparison with aqueous electrolytes, the high temperatures of molten salts may promote unwanted electrode-electrolyte interactions. This article reviews briefly and selectively the research and development of the Fray-Farthing-Chen (FFC) Cambridge Process in the past two decades, focusing on observations, understanding, and solutions of various interactions between molten salts and cathodes at different reduction states, including perovskitization, non-wetting of molten salts on pure metals, carbon contamination of products, formation of oxychlorides and calcium intermetallic compounds, and oxygen transfer from the air to the cathode product mediated by oxide anions in the molten salt.

Electrodeposition of crystalline silicon films from silicon dioxide for low-cost photovoltaic applications

Crystalline-silicon solar cells have dominated the photovoltaics market for the past several decades. One of the long standing challenges is the large contribution of silicon wafer cost to the overall module cost. Here, we demonstrate a simple process for making high-purity solar-grade silicon films directly from silicon dioxide via a one-step electrodeposition process in molten salt for possible photovoltaic applications. High-purity silicon films can be deposited with tunable film thickness and doping type by varying the electrodeposition conditions. These electrodeposited silicon films show about 40 to 50% of photocurrent density of a commercial silicon wafer by photoelectrochemical measurements and the highest power conversion efficiency is 3.1% as a solar cell. Compared to the conventional manufacturing process for solar grade silicon wafer production, this approach greatly reduces the capital cost and energy consumption, providing a promising strategy for low-cost silicon solar cells production.

The photovoltaics market has been dominated by crystalline silicon solar cells despite the high cost of the silicon wafers. Here Zou et al. develop a one-step electrodeposition process in molten salt to produce high-purity solar-grade silicon films, delivering power conversion efficiency of 3.1%.

Extraction of Co and Li2CO3 from cathode materials of spent lithium-ion batteries through a combined acid-leaching and electro-deoxidation approach

Recycling of the spent LIBs to extract Li and Co not only offers raw materials for batteries but also lays a sustainable way for battery development. Herein, we adopt a route combining hydrometallurgical and pyro-electrochemical routes to extract Li₂CO₃ and Co powder from the spent LIBs of cell phones. The LiCoO₂-based cathode materials were firstly dissolved in H₂SO₄ solution containing H₂O₂ as the reductant, and the optimal conditions for attaining a high extraction rate of 99% were studied. After that, the precipitated Co(OH)₂ was calcinated in air under 500 °C to generate Co₃O₄ which was thereafter electrochemically converted into Co powder and oxygen in molten Na₂CO₃-K₂CO₃. Overall, the hybrid method employing both hydro- and pyro-route provides an effective pathway to recover both Li₂CO₃ and Co powder from spent LIBs.

Fabrication of Lanthanum Strontium Manganite Ceramics via Agar Gel Casting and Solid State Sintering

Fabricating lanthanum strontium manganite (LSM) ceramics with certain shapes is important for the design and construction of high-temperature energy conversion and storage devices. Here, we describe a low-cost and environmentally friendly method for fabricating LSM ceramics via agar gel casting and high temperature sintering. This new approach uses temperature tuning to fabricate LSM gel bodies, not only by manufacturing in the secondary process but also by remolding and recycling during the gel casting process. The effect of the sintering temperature on the properties of LSM ceramics was investigated as well. As a result, the porosity and compressive strength of LSM ceramics sintered at 1000 °C are ~60% and 5.6 MPa, respectively. When the sintering temperature increases to 1200 °C, the porosity decreases to ~28%, whereas the compressive strength increases to 25 MPa, which is able to meet the requirement of cathode-supported SOFCs (solid oxide fuel cells).

In Situ Pyrolysis Concerted Formation of Si/C Hybrids during Molten Salt Electrolysis of SiO2@Polydopamine

Aiming to enhanced productivity and improved functionality of electrolytic silicon from electroreduction of solid silica in molten salts, we herein report a one-pot electrochemical preparation of Si/C hybrids via pyrolysis-cum-electrolysis (PCE) of SiO₂@polydopamine (SiO₂@PDA) in molten NaCl-CaCl₂ at 800 °C. The obtained hybrids, denoted Si@C@Si, are composed of outmost silicon thin layers due to electrodeposition, sandwiched N-doped carbon hollow spheres derived from pyrolysis of PDA, and encapsulated silicon nanoparticles stemming from direct electrodeoxidation of SiO₂. The PCE protocol shows intriguing merits on accelerated electroreduction of SiO₂ and retarded generation of inconvenient SiC. The preparation conditions of Si@C@Si are optimized by varying electrolysis time and applied voltage, with the optimal conditions being identified as PCE at 2.6 V for 2 h. When evaluated as an anode for lithium-ion batteries, the obtained Si@C@Si exhibits a reversible specific capacity of 904 mAh g^-1 after 100 galvanostatic charge/discharge cycles at 500 mA g^-1. The proposed PCE method is highlighted as an intensified Si extraction method for advanced lithium-ion batteries, promising practical applications.

Minimising oxygen contamination through a liquid copper-aided group IV metal production process

This paper demonstrates for the first time the fabrication of Zr-Cu alloy ingots from a Hf- free ZrO₂ precursor in a molten CaCl₂ medium to recover nuclear-grade Zr. The reduction of ZrO₂ in the presence of CaO was accelerated by the formation of Ca metal in the intermediate stage of the process. Tests conducted with various amounts of ZrO₂ indicate that the ZrO₂ was reduced to the metallic form at low potentials applied at the cathode, and the main part of the zirconium was converted to a CuZr alloy with a different composition. The maximum oxygen content values in the CuZr alloy and Zr samples upon using liquid Cu were less than 300 and 891 ppm, respectively. However, Al contamination was observed in the CuZr during the electroreduction process. In order to solve the Al contamination problem, the fabrication process of CuZr was performed using the metallothermic reduction process, and the produced CuZr was used for electrorefining. The CuZr alloy was further purified by a molten salt electrorefining process to recover pure nuclear-grade Zr in a LiF-Ba₂ZrF₈-based molten salt, the latter of which was fabricated from a waste pickling acid of a Zr clad tube. After the electrorefining process, the recovered Zr metal was fabricated into nuclear-grade Zr buttons through arc melting following a salt distillation process. The results suggest that the removal of oxygen from the reduction product is a key reason for the use of a liquid CaCu reduction agent.

Microplasma Anode Meeting Molten Salt Electrochemistry: Charge Transfer and Atomic Emission Spectral Analysis

Molten salt electrolysis is normally conducted with solid anode, such as noble metal or graphite, which has defects such as high cost or emission of carbon oxide. Herein, we report that a microplasma based on atmospheric-pressure glow discharge could act as a kind of gaseous anode for electrolysis in molten salt. When the Ag/Ag⁺ redox couple was chosen as the research object, the microplasma anode could initiate charge-transfer reactions in the molten salt and Ag could be electrodeposited with current efficiency of above 90%. The microplasma anode has also shown excellent anticorrosive performance in both chloride and carbonate molten salt. Furthermore, the microplasma anode could potentially serve as an excitation source of atomic emission spectrometry (AES), making it possible to determine the concentration of Ag ions in the molten salt in situ and in real-time. With properties such as being carbon-free and having corrosion resistance and extensive utilization for analysis, the microplasma anode has opened a new direction for molten salt electrochemistry.

Spontaneous colloidal metal network formation driven by molten salt electrolysis

The molten salt-based direct reduction process for reactive solid metal outperforms traditional pyrometallurgical methods in energy efficiency. However, the simplity and rapidity of this process require a deeper understanding of the interfacial morphology in the vicinity of liquid metal deposited at the cathode. For the first time, here we report the time change of electrode surface on the sub-millisecond/micrometre scale in molten LiCl-CaCl₂ at 823 K. When the potential was applied, liquid Li-Ca alloy droplets grew on the electrode, and the black colloidal metal moved on the electrode surface to form a network structure. The unit cell size of the network and the number density of droplets were found to depend on the applied potential. These results will provide important information about the microscale mixing action near the electrode, and accelerate the development of metallothermic reduction of oxides.

Electrochemical and surface plasmon insulin assays on clinical samples

Diabetes is a complex immune disorder that requires extensive medical care beyond glycemic control. Recently, the prevalence of diabetes, particularly type 1 diabetes (T1D), has significantly increased from 5% to 10%, and this has affected the health-associated complication incidences in children and adults. The 2012 statistics by the American Diabetes Association reported that 29.1 million Americans (9.3% of the population) had diabetes, and 86 million Americans (age ≥20 years, an increase from 79 million in 2010) had prediabetes. Personalized glucometers allow diabetes management by easy monitoring of the high millimolar blood glucose levels. In contrast, non-glucose diabetes biomarkers, which have gained considerable attention for early prediction and provide insights about diabetes metabolic pathways, are difficult to measure because of their ultra-low levels in blood. Similarly, insulin pumps, sensors, and insulin monitoring systems are of considerable biomedical significance due to their ever-increasing need for managing diabetic, prediabetic, and pancreatic disorders. Our laboratory focuses on developing electrochemical immunosensors and surface plasmon microarrays for minimally invasive insulin measurements in clinical sample matrices. By utilizing antibodies or aptamers as the insulin-selective biorecognition elements in combination with nanomaterials, we demonstrated a series of selective and clinically sensitive electrochemical and surface plasmon immunoassays. This review provides an overview of different electrochemical and surface plasmon immunoassays for insulin. Considering the paramount importance of diabetes diagnosis, treatment, and management and insulin pumps and monitoring devices with focus on both T1D (insulin-deficient condition) and type 2 diabetes (insulin-resistant condition), this review on insulin bioassays is timely and significant.

A novel route to synthesize carbon spheres and carbon nanotubes from carbon dioxide in a molten carbonate electrolyzer

Carbon dioxide is readily converted into carbon spheres (CSs) and carbon nanotubes (CNTs) in a molten carbonate electrolyzer.

Effect of BaCO3 addition on the CO2-derived carbon deposition in molten carbonates electrolyzer

Atmospheric carbon dioxide is facilely transformed into carbon materials in Ba-containing or Ba-free carbonates eutectic.

Toward Cost-Effective Manufacturing of Silicon Solar Cells: Electrodeposition of High-Quality Si Films in a CaCl2 -based Molten Salt

Electrodeposition of Si films from a Si-containing electrolyte is a cost-effective approach for the manufacturing of solar cells. Proposals relying on fluoride-based molten salts have suffered from low product quality due to difficulties in impurity control. Here we demonstrate the successful electrodeposition of high-quality Si films from a CaCl₂ -based molten salt. Soluble Si^IV -O anions generated from solid SiO₂ are electrodeposited onto a graphite substrate to form a dense film of crystalline Si. Impurities in the deposited Si film are controlled at low concentrations (both B and P are less than 1 ppm). In the photoelectrochemical measurements, the film shows p-type semiconductor character and large photocurrent. A p-n junction fabricated from the deposited Si film exhibits clear photovoltaic effects. This study represents the first step to the ultimate goal of developing a cost-effective manufacturing process for Si solar cells based on electrodeposition.

Facile electrosynthesis of silicon carbide nanowires from silica/carbon precursors in molten salt

Silicon carbide nanowires (SiC NWs) have attracted intensive attention in recent years due to their outstanding performances in many applications. A large-scale and facile production of SiC NWs is critical to its successful application. Here, we report a simple method for the production of SiC NWs from inexpensive and abundantly available silica/carbon (SiO₂/C) precursors in molten calcium chloride. The solid-to-solid electroreduction and dissolution-electrodeposition mechanisms can easily lead to the formation of homogenous SiC NWs. This template/catalyst-free approach greatly simplifies the synthesis procedure compared to conventional methods. This general strategy opens a direct electrochemical route for the conversion of SiO₂/C into SiC NWs, and may also have implications for the electrosynthesis of other micro/nanostructured metal carbides/composites from metal oxides/carbon precursors.

Quantitative Analysis of Oxygen Gas Exhausted from Anode through In Situ Measurement during Electrolytic Reduction

Quantitative analysis by in situ measurement of oxygen gas evolved from an anode was employed to monitor the progress of electrolytic reduction of simulated oxide fuel in a molten Li2O–LiCl salt. The electrolytic reduction of 0.6 kg of simulated oxide fuel was performed in 5 kg of 1.5 wt.% Li2O–LiCl molten salt at 650°C. Porous cylindrical pellets of simulated oxide fuel were used as the cathode by loading a stainless steel wire mesh cathode basket. A platinum plate was employed as the anode. The oxygen gas evolved from the anode was exhausted to the instrumentation for in situ measurement during electrolytic reduction. The instrumentation consisted of a mass flow controller, pump, wet gas meter, and oxygen gas sensor. The oxygen gas was successfully measured using the instrumentation in real time. The measured volume of the oxygen gas was comparable to the theoretically calculated volume generated by the charge applied to the simulated oxide fuel.