Sacrificial Material Research Articles

Molecular Intercalation Enables Phase Transition of MoSe2 for Durable Na-Ion Storage.

1T-MoSe2 is recognized as a promising anode material for sodium-ion batteries, thanks to its excellent electrical conductivity and large interlayer distance. However, its inherent thermodynamic instability often presents unparalleled challenges in phase control and stabilization. Here, a molecular intercalation strategy is developed to synthesize thermally stable 1T-rich MoSe2, covalently bonded to an intercalated carbon layer (1TR/2H-MoSe2@C). Density functional theory calculations uncover that the introduced ethylene glycol molecules not only serve as electron donors, inducing a reorganization of Mo 4d orbitals, but also as sacrificial guest materials that generate a conductive carbon layer. Furthermore, the C─Se/C─O─Mo bonds encourage strong interfacial electronic coupling, and the carbon layer prevents the restacking of MoSe2, regulating the maximum 1T phase to an impressive 80.3%. Consequently, the 1TR/2H-MoSe2@C exhibits an extraordinary rate capacity of 326mAhg-1 at 5Ag-1 and maintains a long-term cycle stability up to 1500 cycles, with a capacity of 365mAhg-1 at 2Ag-1. Additionally, the full cell delivers an appealing energy output of 194Whkg-1 at 208Wkg-1, with a capacity retention of 87.3% over 200 cycles. These findings contribute valuable insights toward the development of innovative transition metal dichalcogenides for next-generation energy storage technologies.

Results of experimental simulation of interaction between corium of a nuclear reactor and sacrificial material (Al<sub>2</sub>O<sub>3</sub>) with a lead layer

<abstract> <p>This paper presents the results of an experimental study of the interaction of a candidate sacrificial material (SM) for a light water reactor melt trap with corium at the Lava-B test-bench. The candidate sacrificial material is a combination of aluminum oxide and a lead layer. The idea of using such a combination of SM is based on the fact that when the lead layer interacts with corium, there will be an increase in the intensity of heat removal from the corium, as well as the chemical interaction between the corium and SM due to the high heat-conducting properties of lead. This approach will improve the efficiency of corium localization in the melt trap compared to the current set of sacrificial material. Experiments have shown active melting and boiling of lead during its interaction with corium. This is confirmed both by the readings of thermocouples and by the X-ray diffraction phase analysis of the deposit material formed on the walls of the melt receiver (MR) of the Lava-B bench, sampled after the experiment. The experiment results show that the lead layer reduces the rate of increase in the temperature of the corium and increases the rate of erosion of the ceramic part of the SM. With these circumstances, it is possible to conclude that the use of aluminum oxide with a lead layer is promising in practice.</p> </abstract>

A thermo-chemo-mechanical model for material extrusion of frontally polymerizing thermoset polymers

The material extrusion of thermoset polymers that undergo frontal polymerization produces three-dimensional structures with complex freestanding shapes without the use of sacrificial support material. In this technique, a gelled monomeric ink is extruded from a nozzle and undergoes rapid curing by a self-energized reaction front. Between extrusion and complete curing, the material experiences large deformations, viscous dissipation, rapid heating, and solidification. A mathematical model for these processes is developed in the current study to guide the selection of process parameters for achieving defect-free prints and high dimensional stability. A thermo-chemo-mechanical theory is presented to model the extruded viscoelastic filament and its transition to a fully cured thermoset polymer. Additionally, a computational model is developed to simulate the 3D printing of common structures. Numerical examples are included for linear and curvilinear extrusions to illustrate the role of printing parameters like the extrusion, front, and printer head velocities. Comparisons with experiments, including some new experiments, for archetypal geometries demonstrate the utility of the model in the identification of process parameters for defect-free prints.

Effect of Alloy Elements on the Performance of Al Sacrificial Anode

Al-Bi-Ga alloy is a good sacrificial anode material, but research on its electrochemical performance in seawater, freshwater, and soil is limited. This article focuses on Al-Bi-Ga-Pb-In and Al-Bi-Ga-Sn-In alloys. The working potential, current efficiency, and corrosion morphology of aluminum alloys under constant current conditions were studied through electrochemical performance testing, microstructure observation, and composition detection. The influence of alloy elements (Bi, Ga, Pb) on the electrochemical performance of aluminum alloys was analyzed. The results indicate that the dissolution morphology of Al-Bi-Ga-Sn-In is better than that of Al-Bi-Ga-Pb-In, and the distribution of Bi element in Al-Bi-Ga-Sn-In is more extensive. The destruction of the oxide film on the surface of aluminum alloy is more uniform, exhibiting better dissolution morphology; As the Bi content increases, the corrosion rate shows a trend of first increasing, then decreasing, and then increasing. The current efficiency first decreases and then increases, usually stopping and rebounding around 4.5%; Ga can increase the corrosion rate and reduce the surface impedance value; When the Ga content is greater than 0.10%, the corrosion rate significantly increases; As the Ga content increases, the current efficiency first decreases and then increases, then stops decreasing and rebounds around 0.2%.

Redox-active electrolytes as a viable approach for the one-step assembly of metal-ion capacitors

The assembly of metal-ion capacitors is a very challenging task; the use of traditional metallic electrodes or sacrificial materials induces technical problems during cell assembly or affects its normal operation. Here, we report an efficient, one-step method for assembling metal-ion capacitors using redox-active electrolytes with thiocyanate-based salts. The addition of a redox-active salt compensates for the charge on the positive electrode while enabling the insertion of metal ions into the structure of the negative electrode. The proposed approach reduces assembly time and cost and results in increased specific energy compared to that from the traditional two-step assembled hybrid systems. Furthermore, we demonstrate that the proposed approach can be successfully implemented for sodium-ion and potassium-ion hybrid capacitors. Our results are supported by operando techniques and can potentially facilitate further research on metal-ion capacitors and applications of these devices.

Investigating the Use of Mg-3Pb Alloy for Cathodic Protection of Mg Alloys

Magnesium alloys possess many interesting properties, including high strength-to-weight ratios, good castability, and excellent biocompatibility. However, its use has been limited because they are also highly reactive and susceptible to corrosion in aqueous environments. As a result, the development of effective corrosion protection strategies for Mg alloys represents a significant challenge for many industrial applications, particularly in the aerospace, automotive, and biomedical industries.Sacrificial cathodic protection is a commonly used strategy to enhance the durability of metallic materials. This method involves the use of an active metal (known as the sacrificial anode) in galvanic contact with the metal to be protected from corrosion, which acts as the cathode. Due to their low corrosion potential, Mg alloys have traditionally served as sacrificial anodes to protect more noble metals such as steel, aluminum, and zinc. However, the growing interest in Mg alloys for industrial applications has led to the development of effective corrosion protection alternatives for Mg alloy components. Among them, the use of Mg alloy coatings as the anode material for the sacrificial protection of other Mg alloys is an interesting strategy. This approach offers several advantages such as minimized galvanic corrosion due to their comparable electrochemical behavior, as well as enhanced adhesion between the anode and the substrate.One of the key requirements for a metallic material to be used as a sacrificial anode is that its electrode potential must be more negative than that of the metal being protected. Additionally, the anode material must be chemically stable in the environment in which it will be located. These conditions are largely dependent on the composition of the anode material. Although recent studies have aimed to enhance the cathodic protection properties of Mg alloys for their use in industrial applications, such work remains restricted. This is due to the limited number of alloying elements with lower standard reduction potentials than Mg that are stable in solution, thereby decreasing the anode corrosion potential. In addition, Mg exhibits enhanced hydrogen evolution rates with increasing anodic polarization, which contradicts expectations of standard electrochemical kinetics and leads to significantly increased rates of self-dissolution. This phenomenon is termed anomalous hydrogen evolution (HE).This work investigates the potential of Mg-3Pb alloy as possible sacrificial anode material for the corrosion protection of three industrially important Mg alloys: AZ31, AM60, and AZ91. For that purpose, a Mg-3Pb alloy was casted in-house and its microstructural characteristics and electrochemical behavior were studied. Furthermore, galvanic corrosion between the Mg-3Pb alloy and the industrially relevant Mg alloys, AZ31, AM60, and AZ91, was evaluated in 0.1 M NaCl solution. The choice of Pb as an alloying element was motivated by its extremely low exchange current density for the HE reaction (i0,H2,Pb) on the order of 10-12 A/cm2. This was expected to result in reduced HE rates under cathodic polarization, which shifts the corrosion potential (Ecorr) to more negative values, and during anodic polarization, hindering anomalous HE and reducing self-dissolution.The microstructural characterization of the Mg-3Pb alloy revealed that it consisted of large α-Mg grains with the presence of a small amount of secondary phases, including Al, Si, Mn, Fe-containing intermetallics and oxide particles. Additionally, scanning electron microscopy revealed the occurrence of remarkable Pb segregation at grain boundaries.Electrochemical measurements showed that the Ecorr associated with the Mg-3Pb alloy was consistently lower than those of the AZ31, AM60, and AZ91 alloys during 24 hours of immersion in the test solution. Moreover, potentiodynamic polarization confirmed that the Mg-3Pb alloy exhibited the lowest cathodic kinetics. In terms of anomalous HE, which is directly related to the self-dissolution rate of the Mg alloy anode material, galvanostatic polarization at different anodic current densities showed that the HE current densities were linear with respect to the applied current density. Additionally, the charge associated with the HE was in the range of 40–50% of the applied anodic charge, which is consistent with previous findings for high purity Mg.Finally, ZRA measurements indicated that the galvanic current of the Mg-3Pb alloy remained anodic for 24 hours of immersion with no polarity reversal, indicating that the Pb-containing alloy served as sacrificial anode for the AZ31, AM60, and AZ91 alloys.In conclusion, the use of Mg-3Pb alloy in cathodic protection systems for Mg alloys has proved to be a viable option in 0.1 M NaCl solution, offering new possibilities for its use in various applications.Funding: This work was supported by the State Research Agency (MICINN), the Spanish National Research Council (CSIC) and European Regional Development Fund (ERDF) under the project RYC2019-027006-I (AEI/FEDER/UE).

Neodymium Metal Production Via Chloride Based Molten-Salt Electrolysis

The extraction and purification of metals such as aluminum has relied on the electrowinning process for decades. The Hall-Héroult process, developed in 1885, utilizes a molten salt electrolyte to electrochemically produce aluminum metal (Al) and carbon dioxide (CO2).1–3 Similar molten salt techniques exist for a variety of other metals including the rare earth metal Neodymium (Nd). Neodymium has seen significant increases in demand from increased production of wind turbines, electric vehicles, and hard disk drives that use neodymium–iron–boron (Nd–Fe–B) permanent magnets. 4,5 The current procedure for neodymium processing uses a neodymium and lithium fluoride molten salt electrolyte with a sacrificial carbon anode to convert neodymium oxide (Nd2O3) and carbon to neodymium metal and CO2.4,6 As an unfortunate byproduct of the fluoride containing molten salt, perfluorocarbons (PFCs) can also be produced simultaneously. The formation of PFCs combined with the emission of other greenhouse gases (CO,CO2) makes the current process dangerous and undesirable from an environmental standpoint. Due to this, few places currently produce neodymium metal and virtually none is produced in the United States, creating supply chain risks with dire consequences.5 An alternative molten salt process has been proposed where rather than directly converting neodymium oxide to neodymium metal, the oxide is first converted to chloride salt form by reaction with hydrochloric acid. The neodymium salt is then dissolved into a chloride salt based melt and neodymium is electroplated via the below set of reactions.7,8 Cathode: 2NdCl3 + 6e- → 2Nd(solid) + 6Cl- Anode: 6Cl- → 3Cl2 + 6e- Overall: 2NdCl3 → 2Nd(solid) + 3Cl2 This process has several distinct advantages. The chlorine reaction eliminates the need for a sacrificial anode material as well as the production of carbon dioxide. The chloride based molten salt also eliminates the formation of PFCs. The chlorine is then recycled to make more hydrochloric acid for use in converting neodymium oxide to chloride.This talk focuses on recent advances to improve purity and lower energy consumption (kWh/kg). We evaluate anode and cathode behavior during this neodymium chloride molten salt process. Over-potential and stability of various anode materials are investigated in order to minimize energy consumption and ensure long life of process materials. A new stable analytic cathode is demonstrated which is lowers chlorine over-potential by more than 200 mV at current density of 250 mA/cm2.The effect of various plating conditions such as current density and substrate material are investigated to determine impact on deposit quality, coulombic efficiency, and metal purity. Highly porous Nd deposits are known to form in chloride molten salt but are undesirable due to the energy required to separate out the high volume fraction of salt remaining in the solid sponge. Effects of temperature and electrolyte composition on deposit morphology are investigated and improvements toward densifying the sponge to minimize post electrolysis purification are reported. This proof of concept work aims to develop a safe, sustainable and environmentally friendly path towards large scale production of rare earth elements. Reactor design and cathode efficiency results are based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy under the Advanced Manufacturing Office, Award Number DE-EE0009434. Anode design work was supported through the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government. Portions of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. T. R. Beck, Electrochem. Soc. Interface, 23, 36–37 (2014).G. G. Botte, Electrochem. Soc. Interface, 23, 49–55 (2014).W. E. Haupin, J. Chem. Educ., 60, 279–282 (1983).M. F. Chambers and J. E. Murphy, Electrolytic production of neodymium metal from a molten chloride electrolyte.B. Sprecher, R. Kleijn, and G. J. Kramer, Environ. Sci. Technol., 48, 9506–9513 (2014).V. S. Cvetković et al., Met. 2020, Vol. 10, Page 576, 10, 576 (2020).R. Akolkar, J. Electrochem. Soc., 169, 043501 (2022).D. Shen and R. Akolkar, J. Electrochem. Soc., 164, H5292–H5298 (2017).

Engineering Block Copolymer-Derived Porous Carbon Nanofibers as Anodes for Sodium Ion Batteries

For decades, lithium-ion batteries have seen widespread usage in a variety of applications from consumer electronics such as smartphones to the more recent developments of electric vehicles. As the usage of lithium for batteries increases, one growing concern is the finite amount that could be found within the Earth’s crust. An alternative that is being considered is sodium-ion batteries due to how plentiful sodium is in the Earth’s crust and similar chemical properties to lithium. One of the main challenges of sodium-ion batteries is the development of anode materials because sodium does not intercalate well with graphite, which is one of the most used materials in lithium-ion batteries. One promising development for anode materials is the use of hard carbon derived from the pyrolysis of polymers such as polyacrylonitrile (PAN) which can have various morphologies and potential for doping. Our work will focus on carbon nanofibers which show high 1-dimensional transport capabilities. With the addition of a sacrificial material such as polymethylmethacrylate (PMMA) that will be removed entirely during the pyrolysis step, PAN/PMMA can be made into porous carbon nanofibers to further increase ion transport. When a PAN/PMMA blend is used, the pores are very random with a high degree of variation of pore characteristics, however studies have shown that the creation of a PAN-b-PMMA block copolymer would allow for more uniform pore structures. Our work intends to study the effects of pore structures on the electrochemical characteristics of porous carbon nanofiber anodes for sodium-ion batteries. The cycling stability data of coin cells made using hard carbon nanofibers derived from electrospun PAN (Nonporous), PAN/PMMA (Random Porous), and PAN-b-PMMA (Uniform Porous), shows their respective discharging specific capacities (mAh/g) at 0.1 A/g average at about 80, 116, and 175. A slight increase can be seen with the addition of random, nonuniform pores to the PAN hard carbon, however, with the highly uniform and controlled pores resulting from the pyrolysis of the PAN-b-PMMA block copolymer, a very significant increase in the discharging specific capacity can be seen.

Experimental and numerical investigation on low‐velocity impact response of sandwich structure with functionally graded core

AbstractThe present research investigates optimizing the impact resistance of functionally graded sandwich structures using experimental and numerical approaches. The low‐velocity impact (LVI) responses of functionally graded sandwich composite (FGSC) with different configurations with skin material jute/rubber/jute (JRJ) and core material having epoxy and sea sand by volume fraction of sea sand at 0%, 10%, 20%, and 30%. Sandwich structures were impacted with LVI (5.89, 10.92, and 15.18 m/s), with the impactor dropped from heights of 0.5, 1, and 1.5 m with precompressed spring loads. FGSC samples are considered a deformable body, and the impactor is modeled as a rigid body using commercially accessible dynamic explicit software. The burn‐out test and weight method were used to test the core's gradience; both methods' results substantially matched, and the variance in gradation could be observed. The proposed sandwich structure characteristics are examined by energy absorption, peak force, energy loss percentage, and coefficient of restitution. Results showed that SC30S provides greater energy absorption and superior damage resistance when tested on LVI. To evaluate the accuracy of experimental findings in predicting the indentation behavior of the sandwich structure, the finite element analysis was used to compare with the experimental results. According to the examination of these proposed FGSC overall performance, they could potentially be employed as sacrificial materials for LVI applications like claddings to shield major structural components. The systematic approach used in this work serves as a standard for choosing and using FGSC effectively for LVI applications.Highlights Low‐velocity impact behavior of sandwich structures was investigated. Combining flexible skin and epoxy core enhances energy absorption. Based on impact energy levels, impact damage areas were determined. Examined sandwich structure advantages in structural and aerospace uses. In terms of time and cost, the numerical analysis method would be useful.

Facile and green sculptured engineering of 3D hierarchical porous metals via gaseous oxidation-reduction and their use in efficient oxygen evolution reactions

Hierarchical porous metals (HPMs) are advanced functional materials used in various applications. However, the current fabrication methods require extra sacrificial materials and generate chemical waste. Here, a facile gaseous oxidation-reduction (GOR) approach was developed to directly transform commercial metals into HPMs. Taking cobalt (Co) as a typical example, a series of hierarchical porous Co foils (HPCF) with controlled porous structures were successfully sculptured. Larger micron-sized pores were formed spontaneously by utilizing different oxidation rates between grain and grain boundaries for the oxidation, and nanoscale pores originated from volume contraction and spontaneous rearrangement of the metal atoms during reduction. This straightforward GOR approach avoids multiple processes and harsh chemical etching and generates water vapor as the only processing byproduct, making it a facile, green process, suitable for large-scale fabrication. When HPCF were used as self-supporting electrodes for the oxygen evolution reaction, DFT calculations and in situ spectroscopy indicated that abundant vacancy defects contained within the hierarchical pores enhanced *OH adsorption and promoted the reconstruction of highly active CoOOH nanosheets. As a result, the CoOOH/HPCF electrode demonstrated outstanding performance of 190 mV at 10 mA cm−2 and exceptional durability of 500 h at 100 mA cm−2, outperforming most reported nonprecious metal oxygen evolution reaction electrodes.

Experimental study of the interaction between molten corium and new sacrificial material for ex-vessel melt retention

Ex-vessel melt Retention (EVR) is one of the important countermeasures to address the issue of basement melt penetration in the course of a hypothetical severe accident in a nuclear power plant. Specifically designed sacrificial material plays a pivotal role in EVR and therefore the verification of the material selection is required. A new experiment platform has been established to carry out experiments on the interaction of molten corium and new sacrificial materials. This paper gives an introduction to the platform and a pre-experiment based on it. Fe2O3 and ZrO2 are used in the test, and the result shows that this platform was capable to reveal the interaction between two kinds of material under a specific condition. Besides, heat balance analysis of the pre-experiment is also presented to help understand the melting process of the molten corium.

Corrosion Studies of Temperature-Resistant Zinc Alloy Sacrificial Anodes and Casing Pipe at Different Temperatures.

In order to solve the problem of external corrosion of deep well casing in oil and gas fields, a new type of high-temperature-resistant zinc alloy sacrificial anode material was used. The temperature and corrosion resistance of the new anode material and TP140 casing were investigated by simulating the high-temperature working conditions of a deep well in an oil field using high-temperature and high-pressure corrosion tests and electrochemical tests. The results showed that at 100-120 °C, the corrosion rate of TP140 protected by a sacrificial anode was only one-tenth of that under unprotected conditions, and the minimum corrosion rate of TP140 protected by a sacrificial anode at 100 °C was 0.0089 mm/a. The results of the dynamic potential polarization curve showed that the corresponding corrosion current density of TP140 first increased and then decreased with the increase in temperature. The self-corrosion potential in sacrificial anode materials first increased and then decreased with the increase in temperature, and the potential difference with TP140 gradually decreased.

Li2C2O4 with 3D confinement as simultaneous sacrificial material and activation reagent of biomass-derived carbon for advanced lithium-ion capacitors

Inappropriate pore size distribution and the lack of a suitable lithium-cation source in the device are the key issues limiting the industrial application of biowaste carbon-based lithium-ion capacitors (LICs) to achieve both high energy density and power density for energy storage. Herein, the Li2O nanowires, decomposed from Li2C2O4 under three-dimensional confinement provided by wasted feather-derived carbon, are introduced as a sacrificial material for self-prelithiation activated carbon materials (prAC) cathode preparation with a high practical specific capacity of 1376 mAh/g. Accompanied by the in-situ formation of Li2O, the volume of mesopores increases significantly to 0.319 cm3/g (32.1 vol% of the total pore volume) by activation with CO2 yielded by the decomposition of Li2C2O4. The assembled prAC/graphite LIC demonstrates a high energy density of (122 Wh/kg at 220 W/kg) and a high power density (13 kW/kg at 30 Wh/kg), as well as a superior lifespan of 10,000 cycles at 1 A/g.

Recent Advances and Trends in Photoelectrochemical Hybrid Water Electrolysis

The replacement of fossil fuels is urgently needed for carbon neutrality and sustainable development. Hydrogen is represented as a next-generation energy source, and among the various methods to obtain hydrogen, water electrolysis using catalysts has been studied steadily. Among them, photoelectrochemical water electrolysis using solar energy is a promising method, but it has problems such as high overvoltage, durability of photoelectrodes under aqueous electrolyte environment, and photocorrosion. Therefore, recently, there has been increasing interest in hybrid water electrolysis, which improves efficiency by reducing the high overvoltage of water electrolysis by adding sacrificial materials. In this article, we review various photoelectrochemical hybrid water electrolysis studies and their limitations.

Preparation of a scaffold for a vascular network channel with spatially varying diameter based on sucrose

In the past few decades, although tissue engineering has made significant progress and achieved many accomplishments, there are still some key problems that remain unsolved. One of the urgent research challenges in this field is how to prepare large-scale tissue engineering scaffolds with spatially complex structures. In this work, a sacrificial template process using sucrose as the sacrificial material and a gelatin/microbial transglutaminase mixed solution as the bio-scaffold material is proposed to fabricate a bio-scaffold with multi-level branching and spatially complex vascular network channels that mimic the structure and function of the human vascular network. To validate the feasibility of the fabrication process and the rationality of the process parameters, the morphological characteristics, connectivity of vascular network channels, shaping accuracy, and mechanical properties of the bio-scaffold were tested and analyzed. The results showed that the bio-scaffold fabricated using this process had a complete morphology and excellent connectivity. The diameter of the sucrose sacrificial template showed a linear relationship with the feeding speed, and the average diameter error rate between the sucrose sacrificial template and the vascular network channels inside the bio-scaffold was less than 8%. The mechanical properties of the bio-scaffold met the requirements for large-scale tissue defect repair. To evaluate the effect of the bio-scaffold on cell activity, human umbilical vein endothelial cells (HUVECs) were seeded into the vascular network channels of the bio-scaffold, and their attachment, growth, and proliferation on the surface of the vascular network channels were observed. To further assess the biocompatibility of the bio-scaffold, the bio-scaffold was implanted subcutaneously in the dorsal tissue of rats, and the tissue regeneration status was compared and analyzed through immunohistochemical analysis. The results showed that the vascular network channels within the bio-scaffold allowed uniform cell attachment, growth, with fewer dead cells and high cell viability. Moreover, clear cell attachment and growth were observed within the vascular network channels of the bio-scaffold after implantation in rats. These results indicate that the fabricated bio-scaffold meets the basic performance requirements for the repair and regeneration of large-scale tissue defects, providing a new approach for oxygen and nutrient transport in large-scale tissues and opening up new avenues for clinical applications.

Achieved advanced wastewater phosphate removal via improved ionic interference resistance in a migration-electric-field assisted electrocoagulation (MEAEC) system with modified-biochar pseudocapacitor electrode

The capacitive deionization-assisted electrocoagulation system has promising application potential in advanced phosphate removal of its low electricity consumption and sacrificial anode material. Phosphate removal in wastewater is crucial since excess phosphate might lead to eutrophication. However, the complex ion composition in raw wastewater can influence the effective phosphate removal by competing with the precipitable metal ions during electrocoagulation. In this study, a novel migration electric-field assisted electrocoagulation (MEAEC) with an assisted capacitive electrode made of N-doped and Fe-La co-modified biochar (LFNB) to achieve specific phosphate electro-adsorption for effective advanced phosphate removal. The LFNB-MEAEC achieved ultrahigh phosphate removal with the effluent of 0.1 mg/L in synthetic and raw municipal wastewater and met the first Grade A standard of total phosphate in the discharge standard of pollutants for municipal wastewater treatment plant (DSPMWTP) in China. The commonly observed coexisting ions in wastewater and a pH range of 2–12 did not significantly fluctuate the phosphate removal of LFNB-MEAEC. Cyclic voltammetry and charging-discharging tests confirmed the high phosphate affinity and excellent durability of LFNB in ion-interference circumstances. The MEAEC assisted with selective-adsorption capacitive electrodes and provided an effective and practical method for advanced phosphate removal from low-phosphorus-contaminated wastewater. The MEAEC with a selective-adsorbed capacitive electrode improved phosphate removal by 21 % (from 74 ± 1.7% to 95 ± 1.0%), reduced the energy consumption by 65.7% (0.012 kWh m−3-wastewater), and saved the sacrificial anode material by 67.5% (from 200 to 65 g m−3-wastewater) than those of MEAEC without phosphate-selective electrode in the same period (Sacrificial anode working time 200 s).

(Invited) Rare Earth Metal Production Via Chloride Based Molten-Salt Electrolysis

The extraction and purification of metals such as aluminum has relied on the electrowinning process for decades. The Hall-Héroult process, developed in 1885, utilizes a molten salt electrolyte to electrochemically produce aluminum metal (Al) and carbon dioxide (CO2) from aluminum oxide (Al2O3) and carbon.1–3 Similar molten salt techniques have been developed for a variety of other metals including the rare earth metal Neodymium (Nd). Neodymium is of particular interest recently with significant increases in demand being driven by the increased production of technologies such as wind turbines, electric vehicles, and hard disk drives that require neodymium in the form of neodymium–iron–boron (Nd–Fe–B) permanent magnets. 4,5 The current procedure for neodymium processing uses a neodymium and lithium fluoride molten salt electrolyte with a sacrificial carbon anode to convert neodymium oxide (Nd2O3) and carbon to neodymium metal and CO2.4,6 As an unfortunate byproduct of the fluoride containing molten salt, perfluorocarbons (PFCs) can also be produced simultaneously. The formation of PFCs combined with the emission of a significant amount of other greenhouse gases (CO,CO2) make the current process for neodymium electrowinning is dangerous and undesirable from an environmental standpoint. However rare earth metal production remains profitable enough that illegal processing operations make up a significant portion of the world’s supply of rare earth elements like neodymium. 7,8 Due to this, few places currently produce neodymium metal and virtually none is produced in the United States, creating supply chain risks with dire consequences.5 An alternative molten salt process has been proposed in which the fluoride salts have been replaced with chloride salts consisting of lithium chloride (LiCl) and potassium chloride (KCl). Rather than directly converting neodymium oxide to neodymium metal, the oxide is first converted to chloride salt form by reaction with hydrochloric acid. The neodymium salt is then dissolved into the LiCl-KCl molten salt and neodymium is electroplated via the below set of reactions.9,10 Cathode: 2NdCl3 + 6e- → 2Nd(solid) + 6Cl- Anode: 6Cl- → 3Cl2 + 6e- Overall: 2NdCl3 → 2Nd(solid) + 3Cl2 This process has several distinct advantages. Utilizing the chlorine reaction eliminates the need for a sacrificial anode material as well as the production of carbon dioxide. The chloride based molten salt also eliminates the formation of PFCs. The chlorine produced could then be recycled to make more hydrochloric acid for use in converting neodymium oxide to chloride.This talk focuses on recent advances to improve purity and lower energy consumption (kWh/kg). Our work evaluates anode and cathode behavior during this neodymium chloride molten salt process in order to determine its viability. Overpotential and stability of various anode materials are investigated in order to minimize energy consumption and ensure long life of process materials. The effect of various plating conditions such as current density and substrate material are investigated to determine impact on deposit quality, coulombic efficiency, and metal purity. Additional purification techniques such as vapor distillation procedures are developed to ensure a product that is viable for industrial use. This proof of concept work aims to develop a safe, sustainable and environmentally friendly path towards large scale production of rare earth elements. Reactor design and cathode efficiency results are based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy under the Advanced Manufacturing Office, Award Number DE-EE0009434. Anode design work was supported through the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government. Portions of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. T. R. Beck, Electrochem. Soc. Interface, 23, 36–37 (2014).G. G. Botte, Electrochem. Soc. Interface, 23, 49–55 (2014).W. E. Haupin, J. Chem. Educ., 60, 279–282 (1983).M. F. Chambers and J. E. Murphy, Electrolytic production of neodymium metal from a molten chloride electrolyte.B. Sprecher, R. Kleijn, and G. J. Kramer, Environ. Sci. Technol., 48, 9506–9513 (2014).V. S. Cvetković et al., Met. 2020, Vol. 10, Page 576, 10, 576 (2020).H. Vogel, B. Friedrich, H. Vogel, and B. Friedrich, Int. J. Nonferrous Metall., 6, 27–46 (2017).J. C. K. Lee and Z. Wen, Nat. Sustain. 2018 110, 1, 598–605 (2018).R. Akolkar, J. Electrochem. Soc., 169, 043501 (2022).D. Shen and R. Akolkar, J. Electrochem. Soc., 164, H5292–H5298 (2017).

A mist-based crosslinking technique for coaxial bioprinting of hollow hydrogel fibers

In this paper, a mist-based method for coaxial three-dimensional bioprinting of ionically crosslinking hydrogel hollow fibers is presented. Unlike current techniques of coaxial bioprinting that utilize the crosslinker in liquid or sacrificial form, the developed method introduces the core crosslinking agent in mist form. The use of mist as a core flow provides adequate pressure and sufficient crosslinking to maintain the tubular shape of a hollow fiber. Through controlled exposure of crosslinker, the developed system prevents poor resolution and layer adhesion caused by the accumulation of liquid crosslinker on the printbed. Furthermore, it eliminates additional processing steps, such as partial crosslinking of the hydrogel prior- or removal of sacrificial material post-printing. The printability and mechanical properties of hollow fiber scaffolds printed using various mist and hydrogel concentrations are studied. It is shown that mist concentration influences the gelation rate of the hollow fiber, impacting the shape fidelity, layer adhesion, and mechanical properties of the printed structures. Moreover, the effects of printing parameters, including the mist core pressure and hydrogel flowrate, on the diameter and wall thickness of the hollow fiber are investigated. Finally, scaffolds printed and crosslinked using mist exhibit over 90% cell viability. The developed mist-based coaxial system enables direct printing of continuous hollow fibers.

Sacrificial biomaterials in 3D fabrication of scaffolds for tissue engineering applications.

Three-dimensional (3D) printing technology has progressed exceedingly in the area of tissue engineering. Despite the tremendous potential of 3D printing, building scaffolds with complex 3D structure, especially with soft materials, still exist as a challenge due to the low mechanical strength of the materials. Recently, sacrificial materials have emerged as a possible solution to address this issue, as they could serve as temporary support or templates to fabricate scaffolds with intricate geometries, porous structures, and interconnected channels without deformation or collapse. Here, we outline the various types of scaffold biomaterials with sacrificial materials, their pros and cons, and mechanisms behind the sacrificial material removal, compare the manufacturing methods such as salt leaching, electrospinning, injection-molding, bioprinting with advantages and disadvantages, and discuss how sacrificial materials could be applied in tissue-specific applications to achieve desired structures. We finally conclude with future challenges and potential research directions.

Recent advances in 3D printing sacrificial templates for fabricating engineered vasculature

AbstractFabricating engineered vasculature within biological scaffolds is one of the most common strategies to maintain high cell viability before implantation. Many studies have been conducted from the aspects of the manufacturing process, materials science, and cell biology to fabricate engineered vasculature with the aim of enhancing the integration between scaffold and host. Among them, the method of combining three‐dimensional (3D) printing and sacrifice‐based technique has attracted extensive attention. Taking advantage of 3D printing, the method of separating the printed sacrificial template from the biological scaffold to form a 3D channel has become a widely used approach to advance the engineered vasculature. With the development of 3D printing techniques and material science, numerous sacrificial materials have shown their potential in fabricating engineered vasculature. However, several issues remain in this multimethod design, including, but not limited to, the printing process, removal method of sacrificial material, and cell seeding method. This review aims to summarize recent strategies for 3D printing sacrificial templates for fabricating engineered vasculature. The pros and cons of sacrificial materials used in these studies are analyzed. Future perspectives are proposed to fabricate biomimetic‐engineered vasculature. Flexible fabrication processes and materials should be advanced to support the 3D printing of sacrificial templates.