Ti Foam Research Articles

Three-dimensional Zn foam coated with zeolitic imidazolate frameworks as stable zinc-ion battery anode

Zinc-ion batteries (ZIBs) offer several advantages including low cost, safety, and high volumetric capacity. However, the potential of ZIBs is hindered by dendrite Zn growth, by-products, and hydrogen evolution resulting in poor lifespan. Herein, this study adopts three-dimensional Zn foams coated with zeolitic imidazolate framework (ZIF) as an anode for ZIBs for the first time. NaCl is selected as a spacer and mixed with Zn powder to vary the pore and strut size of Zn foams. The optimal condition for ZIF coating is investigated taking into account corrosion and electrical resistance as well as hydrogen evolution. The ZIF layer leads to the homogeneous Zn deposition and suppresses the hydrogen evolution and the by-product formation of zinc hydroxide sulfate. A Zn foam with a spacer size of >300 μm, which shows the most stable behavior during stripping/plating tests in a beaker cell, is also employed in symmetric coin-cell tests. Its excellent lifespan characteristic is demonstrated at 1 and 3 mA/cm2 for 1-h intervals over a duration of 300 h. Furthermore, ZIF-coated Zn foam and MnO2-filled Ti foam are assembled in full cells to evaluate the ZIB performance. The full cells show a capacity retention of 75.7 % over 100 cycles, demonstrating the potential of ZIF-coated Zn foam as a ZIB anode. This work provides a solution to practical anodes for ZIBs by maximizing the inherent structural advantages of Zn foam with the adequate coating of ZIF.

Fabrication of customized open-cell titanium foams by direct foaming for biomedical applications

Titanium (Ti) foams offer a promising alternative for bone reconstruction and repair due to their high porosity and lower stiffness compared to solid metals, which improves in vivo osseointegration by reducing the stress shielding effect and allowing bone ingrowth. In this work, customized Ti foams were successfully fabricated for the first time at room temperature using a direct foaming method. Ti powder suspension with a water-soluble surfactant and environmentally friendly thickener was foamed by mechanical stirring. Then, 3D-printed moulds were utilized to achieve near-net shape foams, which were subsequently consolidated by sintering, thus avoiding the need for complex processing of molten Ti. The resulting Ti foams exhibited a cancellous-like open-cell structure, high porosity (> 80%), and a five times higher effective surface area than a 3D Ti mesh with a primitive cubic-based cell fabricated by additive manufacturing. In addition, the Ti foams exhibited similar mechanical properties to cancellous bone and facilitated the adhesion, proliferation, and maturation of human osteoblasts in vitro.

Nickel-Iron Layered Double Hydroxides/Nickel Sulfide Heterostructured Electrocatalysts on Surface-Modified Ti Foam for the Oxygen Evolution Reaction.

Electrochemical approaches for generating hydrogen from water splitting can be more promising if the challenges in the anodic oxygen evolution reaction (OER) can be harnessed. The interface heterostructure materials offer strong electronic coupling and appropriate charge transport at the interface regions, promoting accessible active sites to prompt kinetics and optimize the adsorption-desorption of active species. Herein, we have designed an efficient multi-interface-engineered Ni3Fe1 LDH/Ni3S2/TW heterostructure on in situ generated titanate web layers from the titanium foam. The synergistic effects of the multi-interface heterostructure caused the exposure of rich interfacial electronic coupling, fast reaction kinetics, and enhanced accessible site activity and site populations. The as-prepared electrocatalyst demonstrates outstanding OER activity, demanding a low overpotential of 220 mV at a high current density of 100 mA cm-2. Similarly, the designed Ni3Fe1 LDH/Ni3S2/TW electrocatalyst exhibits a low Tafel slope of 43.2 mV dec-1 and excellent stability for 100 h of operation, suggesting rapid kinetics and good structural stability. Also, the electrocatalyst shows a low overpotential of 260 mV at 100 mA cm-2 for HER activity. Moreover, the integrated electrocatalyst exhibits an incredible OER activity in simulated seawater with an overpotential of 370 mV at 100 mA cm-2 and stability for 100 h of operation, indicating good OER selectivity. This work might benefit further fabricating effective and stable self-sustained electrocatalysts for water splitting in large-scale applications.

Water-Etched Porous Ti: Surface Manipulation of Ti Foam Fabricated by Liquid Metal Dealloying Technique.

The liquid metal dealloying (LMD) process enables the fabrication of porous metals with various chemical compositions. Despite its advantages, LMD still faces key challenges such as maintaining the high-temperature molten metal bath for a prolonged time, avoiding the use of toxic etchants, and so on. To overcome these challenges, the study develops a water-leachable and oxidation-resistant alloy melt (AM) in Ca-Mg binary system. Specifically, Ca72Mg28 eutectic AM is designed, which exhibits higher oxidation resistance and lower melting temperature compared to pure Mg, allowing LMD to be conducted in atmospheric conditions as well as temperatures >200K lower. The AM also enables an innovative process to fabricate Ti foams with a hexagonal faceted surface structure by carefully manipulating the etching rate during the water etching process. This approach allows for the creation of foam with a surface area over 13% larger than that of foams with smooth surfaces via normal acid etching, potentially enhancing efficiency in applications such as electrodes for electrochemical systems or biomedical materials where increased cell adhesion can be beneficial. This study paves the way for efficiently manipulating the LMD process to fabricate metal foams with customized compositions and enhanced surface properties.

FeNiCo@lyocell-based carbon cloth cathode for enhanced seawater electrolysis with bipolar membrane

The formation of inorganic precipitates at the cathode is the most persistent problem in direct seawater electrolysis (DSWE) for hydrogen production. To address this issue, we demonstrate the combination of lyocell-based carbon cloth (CC, as a conductive substrate) and bipolar membrane (BPM)-based DSWE. The entire process, from fabricating lyocell-based CC to coating FeNiCo catalysts, is conducted to ensure stable adhesion between the CC surface and electrocatalysts, thereby enhancing charge transfer. The hydrogen evolution reaction activity of FeNiCo@lyocell-based CC in 1.0 M NaOH shows the overpotential of 152 mV at 10 mA/cm2, which is much lower than that (342 mV) of bare lyocell-based CC. When the FeNiCo@lyocell-based CC is used as a cathode in the BPM-DSWE, the growth rate of inorganic precipitates formed at the cathode is significantly reduced. As a result, the rate of increase in cathodic potential over 100 h at 100 mA/cm2 is approximately 6 %, which is more than four times smaller than that of Pt-coated Ti foam. The woven structure of the lyocell-based CC provides small holes densely distributed at regular intervals and empty spaces between carbon fibers arranged in the same direction. The unique structure is expected to help the protons generated from the BPM escape directly into bulk seawater. In this process, free protons can play a role in reducing the high pH formed at the interfaces of each fiber, slowing down the growth rate of inorganic deposits. If the empty space ratio of the porous structure and the three-dimensional connectivity are optimized for BPM-DSWE, lyocell-based CC is expected to be a promising conductive substrate that can suppress the formation of inorganic deposits even at higher current densities.

Highly selective urea electrooxidation coupled with efficient hydrogen evolution

Electrochemical urea oxidation offers a sustainable avenue for H2 production and wastewater denitrification within the water-energy nexus; however, its wide application is limited by detrimental cyanate or nitrite production instead of innocuous N2. Herein we demonstrate that atomically isolated asymmetric Ni–O–Ti sites on Ti foam anode achieve a N2 selectivity of 99%, surpassing the connected symmetric Ni–O–Ni counterparts in documented Ni-based electrocatalysts with N2 selectivity below 55%, and also deliver a H2 evolution rate of 22.0 mL h–1 when coupled to a Pt counter cathode under 213 mA cm–2 at 1.40 VRHE. These asymmetric sites, featuring oxygenophilic Ti adjacent to Ni, favor interaction with the carbonyl over amino groups in urea, thus preventing premature resonant C⎓N bond breakage before intramolecular N–N coupling towards N2 evolution. A prototype device powered by a commercial Si photovoltaic cell is further developed for solar-powered on-site urine processing and decentralized H2 production.

Superior long service life of a porous Ti-foam/TiOxHy-NTs/SnO2-Sb anode for highly efficient degradation of the pretreatment polyacrylamide-containing fracturing flowback fluid

Doped-SnO2 electrodes have shown outstanding performances in electrochemical oxidation (EO), but limitations in long service life and high durability have necessitated further advances in electrode design. Herein, this study proposes a porous Ti-foam/TiOxHy-NTs/SnO2-Sb anode with superior long service life for efficient degradation of polyacrylamide (PAM) - containing fracturing flowback fluid. The Ti-foam/TiOxHy-NTs/SnO2-Sb anode was designed by preferably choosing reduced TiO2 nanotube arrays grown in situ on porous Ti foam (Ti-foam/TiOxHy-NTs) as substrate coated with SnO2-Sb coating through the sol-gel method. The superiority of the design concept is verified by achieving a superior long service life of 735.2 h (0.5 M H2SO4) and 53.2 h (0.5 M HCl) at a current density of 1.0 A cm−2 by the tests of accelerated service life. The superior long service life originates from multidimensional and hierarchical architecture for lowering electrical resistance by shorting the transport path of electrolyte ions and electrons, and loading more active material without aggregation. Furthermore, the Ti-foam/TiOxHy-NTs/SnO2-Sb electrode displays excellent ability in efficiently degrading the real and simulated PAM-containing fracturing flowback fluid, achieving a chemical oxygen demand decomposition of above 90.0 % after 120 min of EO process. Therefore, the synthesized Ti-foam/TiOxHy-NTs/SnO2-Sb electrode exhibits great potential industrial application for efficient decomposition of PAM-containing fracturing flowback fluid using in EO process.

Multi-sensor-based process monitoring and quality assessment during laser forming of novel titanium foam to prevent cellular structure damage

Titanium foam finds its application in different fields like battery electrodes, heat exchangers, biological prosthetics, and lightweight structures for aeronautical parts. However, the inherent property of the foam to fail during mechanical loading conditions poses a challenge in providing final shape to these materials for practical applications. The present work investigates forming of Titanium foam (Ti Foam) using inline process monitoring for achieving controlled foam deformation while maintaining its quality without failure. Infrared (IR) pyrometer and laser-based displacement sensor were used to monitor the foam deformation behavior and thermal signature. The monitoring data were used to understand the process mechanism of laser forming. The bending mechanism within the foam was analysed with respect to solid sheet bending process. The correlation of the achieved bending angles, was attempted with the process parameters for surface, microstructural, elemental, and phase transformation. A critical analysis of Ti foam behavior, like surface melting, in situ oxidation, phase transformation, and formation of nano-structures on foam surface was addressed based on process parameter combinations. Micro-computed tomography (μCT) was carried out to investigate the pore deformation mechanism. Metallurgical characterisations for foam surface and phase analysis were carried out using X-ray photoelectron spectroscopy (XPS) and tunneling electron microscopy (TEM) to determine the chemical and crystallographic states of the laser-formed surface.

Durable Nano-Flower Structured Foam Coupled with Electrically-Driven in Situ Aeration Enable High-Flux Oil/Water Emulsion Separation with Dynamic Antifouling Ability.

The conventional membranes used for separating oil/water emulsions are typically limited by the properties of the membrane materials and the impact of membrane fouling, making continuous long-term usage unachievable. In this study, a filtering electrode with synchronous self-cleaning functionality is devised, exhibiting notable antifouling ability and an extended operational lifespan, suitable for the continuous separation of oil/water emulsions. Compared with the original Ti foam, the in situ growth of NiTi-LDH (Layered double hydroxide) nano-flowers endows the modified Ti foam (NiTi-LDH/TF) with exceptional superhydrophilicity and underwater superoleophobicity. Driven by gravity, a rejection rate of over 99% is achieved for various emulsions containing oil content ranging from 1% to 50%, as well as oil/seawater emulsions. The flux recovery rate exceeds 90% after one hundred cycles and a 4-h filtration period. The enhanced separation performance is realized through the "gas bridge" effect during in situ aeration and electrochemical anodic oxidation. The internal aeration within the membrane pores contributes to the removal of oil foulants. This study underscores the potential of coupling foam metal filtration materials with electrochemical technology, providing a paradigm for the exploration of novel oil/water separation membranes.

Surface modification of titanium foams for modulated and targeted release of drug-loaded biocompatible hydrogel. Proof of concept

Bone-tissue replacement surgeries usually need medication to mitigate implant rejections or prevent local infections. In this study, a modulated and targeted tetracycline (TC) loaded gelatine type A hydrogel is release from Ti foams as a proof of concept for an innovative and intelligent drug release system. The drugs are released in a localized and controlled manner. The Ti foams fabricated by the space holder technique were surface modified by two different techniques of surface modification, i.e., thermal oxidation and acid etching, to assess their influence on TC release. The characterization carried out after the surface modification indicated that samples modified with acid etching have produced a rougher surface, increasing the diameter of pores (from 500 μm to 700 μm, approximately) due to coalescence of pores. The increase of pore roughness has demonstrated the delaying of the TC release due to the greater adhesion between the surface roughness and the hydrogel. In addition, the increase of pore size improves the possibility to infiltrate high amount of drug-loaded biocompatible hydrogel. Opposite, oxidized surface samples have generated a rutile type TiO2 layer that, because of its hydrophilic nature facilitate the degradation of the hydrogel, and consequently, the TC release from the Ti foams. Therefore, both methods show opposite behaviour, available to increase (acid etching) or decrease (thermal oxidation) the TC release thanks to the different kinetic degradation of hydrogel, as a potential way for drug-release from metallic implants. Thus, while acid-etched samples showed maximum TC release value of 35 wt%, after 120 min, the oxidized samples surpassed the 40 % of TC release after same 120 min of release time treatment.

Surface characterization and antibacterial efficiency of well-ordered TiO2 nanotube surfaces fabricated on titanium foams

Titanium (Ti)-based implants are not compatible enough due to their bio-inert character, insufficient antibacterial capabilities and stress-shielding problem for dental and orthopaedic implant applications. Thus, this work focused to fabricate, analyze and improve antibacterial properties titanium dioxide (TiO2) nanotube array surfaces on Ti foam by anodic oxidation (AO) process. The well-ordered nanotube arrays with approximately 75 nm were successfully fabricated at 40 V for 1 h on Ti foams. Ti and O were observed as major elements on AO-coated Ti foam surfaces. In addition, the existence of TiO2 structure was proved on AO-coated foam Ti surfaces. For potential dental and orthopedic implant application, in vitro antibacterial properties were investigated versus Staphylococcus aureus and Escherichia coli. For both bacteria, antibacterial properties of TiO2 nanotube surface were greater than bare Ti foam. The bacterial inhibition versus Staphylococcus aureus and Escherichia coli of TiO2 nanotube surfaces are improved as 53.3% and 69.4% compared to bare Ti foam.

Stabilizing non-iridium active sites by non-stoichiometric oxide for acidic water oxidation at high current density

Stabilizing active sites of non-iridium-based oxygen evolution reaction (OER) electrocatalysts is crucial, but remains a big challenge for hydrogen production by acidic water splitting. Here, we report that non-stoichiometric Ti oxides (TiOx) can safeguard the Ru sites through structural-confinement and charge-redistribution, thereby extending the catalyst lifetime in acid by 10 orders of magnitude longer compared to that of the stoichiometric one (Ru/TiO2). By exploiting the redox interaction-engaged strategy, the in situ growth of TiOx on Ti foam and the loading of Ru nanoparticles are realized in one step. The as-synthesized binder-free Ru/TiOx catalyst exhibits low OER overpotentials of 174 and 265 mV at 10 and 500 mA cm−2, respectively. Experimental characterizations and theoretical calculations confirm that TiOx stabilizes the Ru active center, enabling operation at 10 mA cm−2 for over 37 days. This work opens an avenue of using non-stoichiometric compounds as stable and active materials for energy technologies.

Synthesis and Characterization of a Titanium-Based Functionally Graded Material-Structured Biocomposite using Powder Metallurgy.

This investigation aims at synthesizing and characterizing a biocomposite of hydroxyapatite (HA) and titanium (Ti) as a functionally graded material (FGM) via an economical powder metallurgy route. Ti particles were produced through drilling and chipping, followed by compaction and sintering. Ti foams, so obtained, were then infused with varying volume fractions of HA. The pure Ti foam control sample and the FGM composite samples were then subjected to various characterizations to validate their biocompatibility, structural strength, and integrity. The interface development between the load-bearing Ti implant and living tissue was resolved through an FGM structure, where the base of the implant consisted of load-bearing Ti and the outer periphery changed to HA gradually. HA/Ti specimens of different volume fractions were tested for density measurements, microstructure, hardness, and bioactivity. The bioactive behavior was investigated using the potentiodynamic polarization technique to measure the corrosion rate of the pure Ti foam (0/100 HA/Ti) and the FGM composite (10/90 HA/Ti) samples in a simulated body fluid (SBF). The results showed that the hardness of FGM composites, despite being less than that of 0/100 HA/Ti, was still within safe limits. The corrosion rate, however, was found to be decreased by a significant value of almost 40% for the 10/90 HA/Ti FGM composite sample compared to the pure Ti foam control sample. It was concluded that the optimum composition 10/90 HA/Ti sample offers improved corrosion resistance while maintaining a sufficient allowable hardness level.

Investigation on the structure and antibacterial performance of Ni-doped Ti1-XNiXO2 nanotubes

Developing high-performance, low-cost, nontoxic antibacterial materials and equipment to prevent the spread of bacteria and viruses has become one of the most important research areas for scientists. Among all the developed antibacterial materials, TiO2 shows great potential and typically exhibits antibacterial properties through the ultraviolet light induced electron-hole pairs. Building upon this working principle, Ni-doped anatase Ti1-XNiXO2 nanotubes were designed. The doped Ni occupies the position of Ti4+ and forms a negative electron center. This negative electron center, along with the neighboring Ti4+ ions, plays a similar role to that of UV-light-induced electron-hole pairs. The nanotube structure was confirmed by using techniques such as X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Antibacterial performance tests showed that the Ni-doped Ti1-XNiXO2 nanotubes could inhibit the propagation of E. coli in culture media and a dark environment. Among all the designed materials, Ti0.95Ni0.05O2 showed the best antibacterial performance. Ti0.95Ni0.05O2 nanotubes were cold-sprayed on porous Ti foam tube and loaded on equipment, effectively preventing the spread of E. coli through gas flow. Ti1-XNiXO2 nanotubes show great potential as high-performance antibacterial materials and equipment through surface electron modulation. Surface electron modulation represents a novel strategy for designing high-performance antibacterial materials.

In-situ electrochemical synthesis of heteroatoms-doped reduced graphene oxide toward nonradical degradation of tetracycline

Nonradical-based advanced oxidation processes (AOPs) catalyzed by defective carbonaceous materials have exhibited great superiorities in trace antibiotics removal from natural water matrices. However, the complicated, extensive and highly-energy consumed synthesis methods are seriously hindering its development and application. Herein an in-situ electrochemical synthesis technology was developed and N/B/F-codoped RGO was assembled on the Ti foam effectively by using ionic liquid (IL) as the heteroatoms parents. Other benefits of the IL including anti-RGO agglomeration, suppressing hydrolysis side reaction and reducing internal resistance were also demonstrated. Based on the diverse substrates exploration and comprehensive characterizations, adsorption and desolvation of the water molecules around IL-GO was found the two critical procedures for GO reduction and heteroatoms-doping. Hydrophilicity and porosity are the two essential properties for substrate selection. The solvent substitute experiments indicated electrochemical reduction of GO is a proton-mediated electron transfer reaction and the protons come from the solvent. Remarkable heteroatoms content was obtained from −1.0 V ∼ -1.2 V within 30 min under normal temperature and pressure. The degradation performance of N/B/F-codoped RGO was examined in an electrochemical system without any chemical additive. 93.0 % of trace tetracycline (5 mg L-1) was removed at −0.6 V within 60 min and the corresponding TOC removal efficiency was 40 %. Electron transfer efficiency can be even improved in the natural water matrices. The degradation mechanism investigation suggested that N/B/F-codoped RGO is able to simultaneously catalyze two nonradical pathways including electron transfer and singlet-dominated AOP. This work provides a highly effective, green and low-cost nonradical-based AOP technology for controlling antibiotics pollution in the environmental water matrices.

Computational analysis of the graded porosity distribution on the elastic modulus of Ti foams

This work aims to do a computational analysis of the influence that graded porosity has on the elastic modulus of commercially pure Ti foams. This analysis is focused on Ti foams for biomedical uses. Two kinds of graded porosity were considered, longitudinal graded and latitudinal graded porosities. Each model was made considering three zones with different porosity levels. The elastic modulus simulations were made by the finite element analysis (FEA) using ANSYS software v19.3. The results were compared with experimental data reported in the literature. The longitudinal and latitudinal graded porosity distribution models were analyzed with equivalent porosity between 30% and 40% and 20–50%, respectively. The elastic modulus values decreased from 110 to 38 GPa for the longitudinal graded porosity, and from 110 to 36 GPa for the latitudinal graded porosity (0% and 40% porosity, respectively). Those results showed that longitudinal graded porosity was stiffer than latitudinal graded porosity models for all porosity levels.

Novel Method for the Production of Titanium Foams to Reduce Stress Shielding in Implants.

Titanium foams have potential applications in orthopedic and dental implants because of their low elastic modulus and good bone in-growth properties. In the present study, a novel method for the preparation of three-dimensional interconnected microporous titanium foams has been developed. This method is based on the insertion of a filler metal into the titanium metal by arc melting, followed by its removal by an electrochemical dealloying process for the development of foams. Complete removal of the filler metal by the electrochemical dealloying process was confirmed by an X-ray diffractometry (XRD) analysis, whereas scanning electron microscopy (SEM) analysis of the developed foams showed the development of interconnected porosity. Ti foams with different levels of porosities were successfully developed by varying the amount of the filler metal. Mechanical and thermal characterizations of the developed foams were carried out using compression testing and laser flash apparatus, respectively. The yield strength and elastic modulus of the developed foams were found to decrease by increasing the volume fraction of pores. The elastic modulus of the developed titanium foams (15.5-36 GPa) was found to be closer to that of human bones, whereas their yield strength (147-170 MPa) remained higher than that of human bones. It is therefore believed that the developed Ti foams can help in reducing the problem of stress shielding observed in orthopedic implants. The thermal diffusivity of the developed foams (4.3-0.69 mm2/s) was found to be very close to that of human dentine.

Energy-efficient electrochemical degradation of ciprofloxacin by a Ti-foam/PbO2-GN composite electrode: Electrode characteristics, parameter optimization, and reaction mechanism

Reducing energy comsuption is crucial to commercialize electrochemical oxidation technologies. In this study, a novel PbO2 composite electrode (Ti-foam/PbO2-GN) was successfully fabricated based on a porous titanium (Ti) foam substrate and a β-PbO2 active layer embedded with multiple graphene (GN) interlayers, and applied as an anode for energy-efficient pulse electrochemical oxidation of ciprofloxacin (CIP). In contrast to PbO2 and Ti-foam/PbO2 electrodes, the Ti-foam/PbO2-GN electrode surface exhibited a more compact structure, smaller crystal grain size, and greater electrochemical active surface area. CIP removal of 89.7% was obtained with a low energy consumption (EE/O) of 6.17 kWh m−3 under pulse electrolysis conditions with a current density of 25.00 mA cm−2, pulse frequency of 5000 Hz, and pulse duty cycle of 50.0%. Up to 70.7% of the energy was saved in the pulse current mode compared to the direct current mode. Narrowing the electrode spacing to 2 cm facilitated the mass transfer process and enhanced oxidation efficiency. According to the intermediates identified, the pulse electrolysis of CIP primarily involved hydroxylation of the quinolone ring, breaking of the piperazine ring, defluorination, and decarboxylation processes, and a possible degradation mechanism of CIP was proposed. The continuous oxidation performance of CIP and the relatively low leaching of Pb2+ suggested that the Ti-foam/PbO2-GN electrode exhibited excellent stability, repeatability, and safety. The degradation results of CIP in real water also exhibits the great potential of environmental application. As a result, pulse electrochemical oxidation using a Ti-foam/PbO2-GN electrode has proven to be an energy-efficient and promising alternative for antibiotic wastewater treatment.

Effect of Mg Powder's Particle Size on Structure and Mechanical Properties of Ti Foam Synthesized by Space Holder Technique.

Titanium foam has been the focus of special attention for its specific structure and potential applications in purification, catalyst substrate, heat exchanger, biomaterial, aerospace and naval industries. However, the liquid-state foaming techniques are difficult to use in fabricating Ti foam because of its high melting temperature and strong chemical reactivity with atmospheric gases. Here, the fabrication of Ti foams via the powder metallurgy route was carried out by utilizing both magnesium powders and magnesium particles as spacer holders, and Ti powders as matrix metal. The green compacts containing Ti powder, Mg powder and Mg particles were heated to a certain temperature to remove the magnesium and obtain the Ti foam. The results show that the porosities of the obtained Ti foam are about 35-65%, and Young's modulus and yield strength are found to be in the ranges of 22-126 MPa and 0.063-1.18 GPa, respectively. It is found that the magnesium powders play a more important role than the magnesium particles in the deformation and the densification of the green compact during the pressing, and the pore structure of Ti foam depends on the amount and the size of the magnesium spacer holders after sintering.

Liquid-diffusion electrode with core-shell structured mixed metal oxide catalyst for near-zero polarization in chlor-alkali electrolysis

Chlor-alkali electrolysis is a key industrial process for the production of chlorine gas, caustic soda, and hydrogen fuels. Here, we demonstrate that a Ti foam electrode, which has a diffusion layer of liquid reactant, deposited with a thin layer of core/shell-structured mixed metal oxide nanoparticles enables almost zero polarization in the range of hundreds of mA cm−2 towards the chlorine evolution reaction (CER), using noble-metals 20 times lower than commercial electrode. The fast charge-transfer kinetics induce near-zero overpotential at low current densities, while the high mass transport rates aided by porous channels lead to unprecedentedly high CER performance (LSV derived overpotentials of 9 and 44 mV at 10 and 500 mA cm−2 with Faradaic efficiency of 99.1% and 86.1% in 5.0 M NaCl). Under practical chlor-alkali process conditions, the RNTO/Ti foam exhibited remarkable performance as a bifunctional electrode for CER and hydrogen evolution reaction (HER) with overpotential of 11 mV for HER.