Titanium Nitride Research Articles

Ultrafast Metaphotonic PCR Chip with Near-Perfect Absorber.

Polymerase chain reaction (PCR) is the gold standard for nucleic acid amplification and quantification in diverse fields such as life sciences, global health, medicine, agricultural science, forensic science, and environmental science for global sustainability. However, implementing a cost-effective PCR remains challenging for rapid preventive medical action to the widespread pandemic diseases due to the absence of highly efficient and low-cost PCR chip-based POC molecular diagnostics. Here, this work reports an ultrafast metaphotonic PCR chip as a solution of a cost-effective and low-power-consumption POC device for the emerging global challenge of sustainable healthcare. This work designs a near-perfect photonic meta-absorber using ring-shaped titanium nitride to maximize the photothermal effect and realize rapid heating and cooling cycles during the PCR process. This work fabricates a large-area photonic meta-absorber on a 6-inch wafer cost-effectively using simple colloidal lithography. In addition, this work demonstrates 30 thermocycles from 65 (annealing temperature) to 95°C (denaturation temperature) within 3min 15s, achieving an average 16.66°Cs-1 heating rate and 7.77°Cs-1 cooling rate during thermocycling, succeeding rapid metaphotonic PCR. This work believes a metaphotonic PCR chip can be used to create a low-cost, ultrafast molecular diagnostic chip with a meta-absorber.

Enhancement of photocatalytic activity by thermal annealing of Au, Ag, and Cu implanted TiN thin films

The paper presents an investigation on the optoelectronic and photocatalytic properties of titanium-nitride (TiN) thin films, modified through the introduction of metal ions (Au, Ag, and Cu) during implantation, followed by thermal annealing. Employing high-resolution microscopic and spectroscopic techniques, we examined the microstructural and compositional features of the films in detail. The films exhibited a crystalline structure with distinct columnar patterns, attributed to defect release and recovery during annealing. Furthermore, metal nanoparticles were detected in samples implanted with gold and silver ions, indicating coalescence processes, while no such particles were observed in the case of Cu ions. Post-implantation annealing also led to surface oxidation and the formation of anatase TiO2, with a coexistence of TiO2, TiN, metallic Au and Ag, and CuO phases in subsurface regions. Comparative optical measurements revealed significant changes in photoluminescence efficiency and photocatalytic response of modified TiN. All implanted samples showed reduced photoluminescence intensity compared to pristine titanium-nitride, with the Au-implanted film exhibiting the most significant decrease, due to the presence of surface Au nanoparticles, thus resulting in the slower electron-hole recombination rates and enhanced photocatalytic activity.

Multipacting mitigation by atomic layer deposition: The case study of titanium nitride

Multipacting mitigation by atomic layer deposition: The case study of titanium nitride

Effects of Substrate and Annealing Conditions on the Ferroelectric Properties of Non-Doped HfO2 Deposited by RF Plasma Sputter.

In this study, the effect of annealing and substrate conditions on the ferroelectricity of undoped hafnium oxide (HfO2) was analyzed. Hafnium oxide was deposited on various substrates such as platinum, titanium nitride, and silicon (Pt, TiN, Si) through RF magnetron sputtering. Annealing was performed in a nitrogen atmosphere at temperatures ranging from 400 to 600 °C, and the process lasted anywhere from 1 to 30 min. As a result, it was confirmed that the orthorhombic phase, the main cause of ferroelectricity, was dominant after a post-anneal at 600 °C for 30 min. Additionally, it was observed that interface mixing between hafnium oxide and the substrate may degrade ferroelectricity. Accordingly, the highest remanent polarization, measured at 14.24 μC/cm2, was observed with the Pt electrode. This finding was further corroborated by piezo force microscopy and endurance tests, with the results being significant compared to previously reported values. This analysis demonstrates that optimizing substrate and annealing conditions, rather than doping, can enhance the ferroelectricity of hafnium oxide, laying the foundation for the future development of ferroelectric-based transistors.

Porous titanium nitride nanowire array on carbon fiber for the applications in fiber-shaped solar cell and lithium-ion battery

Porous titanium nitride nanowires were fabricated on carbon fibers (CFs) by growing a TiO2 nanowires array on CFs and subsequent ammonification (TiN-CF). This design combined the high electrical conductivity of CF with the superior electrocatalytic activity of TiN to construct a fast electron-transport passage and highly active sites along the electron pathway. Benefiting from both its construction advantages and high flexibility, TiN-CF could be effectively utilized in fiber-shaped dye-sensitized solar cells (FDSSCs) and fiber-shaped lithium-ion battery (FLIB). For the FDSSCs, TiN-CF had been demonstrated to function as low-cost and excellent counter electrodes (CEs) with a desirable photoelectric conversion efficiency of 6.48 %, comparable to or even surpassing that of a Pt wire CE at 6.36 %. When used as the anode for FLIB, TiN-CF exhibited favorable electrochemical properties including a good initial discharge capacity of 556.6 mAh g−1 at rates of 0.2C, a high rate capability of 493.5 and 272.2 mAh g−1 at 1C and 10C respectively, as well as superior cyclic stability with a capacity retention of 420.5 mAh g−1 after 300 cycles at 2C. This work also provides valuable insights for future development and rational design in fiber-shaped electronic devices.

Photocatalytic activity of TiO2:TiN nanocomposite films prepared by DC reactive sputtering technique for air purification

This study concerns the production of advanced materials and a novel technique for enhancing photocatalytic efficiency, focusing specifically on the purification of air contaminated with methane gas. Titanium dioxide:Titanium nitride (TiO2/TiN) nanocomposite films were prepared by dc reactive magnetron sputtering of highly-pure titanium sheet in presence of oxygen and nitrogen as reactive gases with optimized mixing ratios to produce the composite structures. The structural, morphological, and optical characteristics of the prepared nanocomposites were determined and analyzed. The primary goal of this study was to enhance the photocatalytic activity of such nanocomposites against methane gas pollution. It is observed that increasing the nitrogen content in the TiO2:TiN nanocomposite structure led to notable improvements in photocatalytic efficiency. Specifically, when these nanocomposites were subjected to a UV light, they exhibited enhanced photocatalytic activity in the removal of methane gas from the surrounding air, which demonstrates a direct correlation with increased nitrogen (N) content in the composite structure. These nanocomposites are reasonably promising in removing harmful gases and pollutants present in indoor and outdoor environments. This exploration not only sheds light on the remarkable potential of TiO2:TiN nanocomposites for air purification but also highlights the importance of innovative techniques, such as dc reactive magnetron sputtering in the field of materials science and engineering as well as in environmental remediation.

On mechanical and tribological behaviour of microwave sintered TiN – 5 wt% Al2O3–5 wt% Y2O3 nanocomposite

Titanium nitride has potential applications in wide range of mechanical parts, cutting tools etc., primarily due to its high wear resistance. In the present study, a novel TiN-based nanocomposite was developed with nano additives alumina (Al2O3) and (Y2O3), 5 wt% each; using microwave irradiation at 900 W in ambient atmosphere. In-situ microwave sintering was carried out at a temperature of 1500 °C and 5 min holding time. The sintered nanocomposites achieved a relative density of ∼93%. XRD analyses showed that the major TiN phase was retained without any significant change in its peak positions after sintering. Minor phases of Y2Ti2O7 and Y3Al5O12 were formed during sintering due to chemical realignment of the constituent phases, were detected which acted as crack inhibitors. Microstructural studies indicated homogeneous distribution of the additives throughout the TiN matrix. The average Vickers microhardness of the TiN nanocomposites was ∼14 GPa, while indentation crack resistance was estimated within 3.9–4.0 MPa·m1/2. Wear and friction studies (ball-on-disc) of the microwave sintered TiN nanocomposite carried out with bearing steel ball under dry (unlubricated) and under deionised water (lubricated) sliding exhibited promising tribological behaviour. The friction coefficient (COF) between the contact pair was monitored within 0.5–0.6 after 45 min of dry sliding. Wear volume of the nanocomposite was obtained between 0.013 and 0.058 mm3 after 45 min of sliding (dry). Presence of iron oxides on worn surfaces confirmed mass transfer from the steel counterbody to the nanocomposite surface. Analyses of the worn surfaces showed that the wear mechanisms were predominantly abrasive and adhesive.

Ultrafine IrNi nanoparticles supported onto titanium nitride as low-iridium and highly active OER electrocatalysts for proton exchange membrane water electrolysis

The development of cost-effective and highly efficient iridium-based catalysts for the anode of proton exchange membrane water electrolyzers (PEMWEs) is urgently required. This study utilized a straightforward wet-chemical method to produce IrNi nanoparticles that were supported on titanium nitride (TiN), where the ultra-small particle size of 1.9 nm for IrNi nanoparticles and the structural support provided by TiN ensure the full exposure of catalytic sites. The electronic interaction between Ir-Ni and Ir-TiN enhances the intrinsic activity of the catalytic sites. The developed catalyst exhibits excellent oxygen evolution reaction (OER) performance, with an overpotential of just 267 mV at a current density of 10 mA cm−2, and a mass activity of 1.07 A mgIr−1 at 1.55 V versus reversible hydrogen electrode, which is more than 14 times that of commercial IrO2. Furthermore, its catalytic performance is validated in a PEMWE single cell, along with stable operation for 100 h. The proposed design of the supported iridium-based alloy catalysts in this study presents a novel and referential method for developing anode catalysts in PEMWEs.

Adhesion and growth of titanium nitride coating deposited on AISI 316L using cylindrical magnetron sputtering

ABSTRACT This study explores the efficacy of plasma etching for AISI 316L stainless steel (SS), in improving the adhesion of titanium nitride (TiN) coatings. Due to the presence of an oxide layer on SS, as deposited TiN coatings typically exhibit poor adhesion. Here, varying duration of plasma etching was employed to assess TiN coating adherence to the SS. The TiN coatings were deposited onto the SS substrate via cylindrical magnetron sputtering technique. Surface roughness value of ~10 nm was obtained on SS post 60 minutes plasma etching compared to unetched SS sample ~4 nm which was evaluated using Atomic Force Microscopy. X ray Diffraction analysis of the TiN coating after plasma etching revealed a preferred growth of the TiN (111) phase. Adhesive strength of the TiN coating was assessed through scratch testing. Scanning electron Microscopy was employed to analyze the surface morphology of the TiN coating and its failure phenomena post scratch testing. A comparative analysis of TiN coatings on various plasma etched SS surfaces highlighted the direct influence of the surface condition on growth, surface morphology, and roughness. Notably, 60 minutes etching duration yielded the highest adhesion strength of 0.94 N for the TiN coating on SS, contributing to its enhanced corrosion resistance properties.

Four Birds with One Stone: A Bandgap-Regulated Multifunctional Schottky Heterojunction for Robust Synergistic Antitumor Therapy upon Endo-/Exogenous Stimuli.

Considering the profound impact of structure on heterojunction catalysts, the rational design of emerging catalysts with optimized energy band structures is required for antitumor efficiency. Herein, we select titanium nitride (TiN) and Pt to develop a multifunctional Schottky heterojunction named Pt/H-TiN&SRF (PHTS) nanoparticles (NPs) with a narrowed bandgap to accomplish "four birds with one stone" involving enzyo/sono/photo three modals and additional ferroptosis. The in situ-grown Pt NPs acted as electron traps that can cause the energy band to bend upward and form a Schottky barrier, thereby facilitating the separation of electron/hole pairs in exogenous stimulation catalytic therapy. In addition, endogenous catalytic reactions based on peroxidase (POD)- and catalase (CAT)-mimicking activities can also be amplified, triggering intense oxidative stress, in which CAT-like activity decomposes endogenous H2O2 into O2 alleviating hypoxia and provides reactants for sonodynamic therapy. Moreover, PHTS NPs can elicit mild photothermal therapy with boosted photothermal properties as well as ferroptosis with loaded ferroptosis inducer sorafenib for effective tumor ablation and apoptosis-ferroptosis synergistic tumor inhibitory effect. In summary, this paper proposes an attractive design for antitumor strategies and highlights findings for heterojunction catalytic therapy with potential in tumor theranostics.

Plasmonic Pt-PPCN/TiN Ohmic Junction for Photo-Thermo Catalytic Hydrogen Production.

The rational design of photocatalysts for improving the conversion of solar energy into hydrogen is a promising route for achieving carbon neutrality. Herein, we couple plasmonic titanium nitride (TiN) with highly crystalline potassium-doped polymeric carbon nitride (PPCN) to construct a PPCN/TiN ohmic junction. Such an ohmic junction not only broadens the absorption spectrum but also inhibits the recombination of electrons and holes. In addition, Pt nanoparticles are introduced into this ohmic junction to form plasmonic Pt-PPCN/TiN, improving the capture of hot electrons generated by TiN and thereby promoting the dissociation of the O-H bond in H2O. The energy barrier decreases from 0.7 to 0.2 eV. Enhanced separation of carrier, activation of water molecules, and capture of hot electrons are jointly promoting photo-thermo catalytic hydrogen production. Therefore, under full-spectrum irradiation, the hydrogen production rate of Pt-PPCN/TiN reaches 19 085 μmol g-1 h-1. This novel plasmonic photocatalyst is promising for full-spectrum photo-thermo catalytic hydrogen production.

Activation of the Radical‐Mediated Pathway and Facilitation of the Li2S Conversion by N‐Doped Carbon‐Embedded Ti1–xCoxN Nanowires as a Multifunctional Separator with a High Donor‐Number Solvent toward Advanced Lithium–Sulfur Batteries

Electrolyte modification with a high donor‐number solvent is necessary to increase sulfur utilization, but it also presents poor compatibility with lithium metal. The amount of the solvent should be optimized to maximize sulfur utilization at the cathode and minimize side reactions with Li metal at the anode. An electrolyte solution comprising 1 vol% N,N‐dimethylacetamide (DMA) in a 1,2‐dimethoxyethane (DME)/1,3‐dioxolane (DOL) co‐solvent demonstrated increased discharge capacity and reduced overpotential compared to DME/DOL and DMA/DOL. In addition to electrolyte, modification that creates radical‐mediated pathways from a high donor‐number solvent, long‐cycle performance is achieved by effectively mitigating the shuttling effect and enhancing reaction kinetics with an efficient electrocatalyst. Cobalt doping into TiN introduced an upshift of the d‐band center with ferromagnetic properties that suppressed the shuttling effect, activated radical‐mediated pathways, and facilitated the Li2S conversion. A multifunctional separator fabricated with N‐doped carbon‐embedded cobalt‐doped titanium nitride nanowires (NC‐Ti0.95Co0.05N NWs) under 1 vol% DMA electrolyte achieved a discharge capacity of 464.4 mA h g−1 even after 200 cycles at a decay rate of 0.093% per cycle through the synergistic effects of electrolyte and electrocatalyst modifications. This work highlights the importance of ferromagnetic catalysts with a high donor‐number solvent for lithium–sulfur (Li–S) batteries.

Computational approach to modeling electronic properties of titanium oxynitride systems

The study presents the use of a novel on-lattice sampling approach to generate titanium oxynitride (TiNxOy) structures with potential applications in photovoltaic and water splitting. This approach presents a simple route to overcome challenges with structure-generating tools like Cluster Approach to Statistical Mechanics (CASM), and Ab initio Random Structure Search (AIRSS), CASM faces difficulty in generating ternary structures with large unit cells. With AIRSS, there is an increase in probability of sampling amorphous sample spaces with increased number of atoms in the unit cell. Here an on-lattice sampling approach was used to model the electronic structure of TiNxOy as a function of composition. We present results for Ti2N2O, Ti5N4O4 and Ti7N4O8, with 33 %, 50 % and 67 % N replaced by O via substitution relative to titanium nitride (TiN), respectively. Koopmans theorem was used correct the Kohn-Sham Density Functional Theory (KS-DFT) bandgaps with corresponding values of 2.68 eV, 3.03 eV, and 3.65 eV for 33, 50 and 67 % O doping respectively. The projected density of states (PDOS) plot for TiN shows that the Fermi level is dominated by the 3d atomic orbitals of Ti, confirming pure TiN’s metallicity. The valence bands of TiNxOy structures were dominated by 2p orbitals of O at lower energy levels, but they were dominated by 2p orbitals of N at energies close to the valence band maximum (VBM). The conduction bands were dominated by the 3d atomic orbitals of Ti, with the bandgap increasing with O composition leading to creation of shallow trap states near the VBM, which negatively impacts carrier mobility. In conclusion, the on-lattice sampling approach is an effective tool to generate highly crystalline structures of large unit cells, also keeping O substitution for N below 33 % as seen in Ti2N2O is crucial for avoiding shallow traps in TiNxOy structures.

Morphology-Dependent Photocatalytic Activity of Nanostructured Titanium Dioxide Coatings with Silver Nanoparticles.

This study aims to improve the photocatalytic properties of titanium dioxide nanorods (TNRs) and other related nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) by modifying them with silver nanoparticles (AgNPs). This preparation is carried out using a two-step method: sol-gel dip-coating deposition combined with hydrothermal crystal growth. Further modification with AgNPs was achieved through the photoreduction of Ag+ ions under UV illumination. The investigation explores the impact of different growth factors on the morphological development of TiO2 nanostructures by modulating (i) the chemical composition, the water:acid ratio, (ii) the precursor concentration involved in the hydrothermal process, and (iii) the duration of the hydrothermal reaction. Morphological characteristics, including the length, diameter, and nanorod density of the nanostructures, were analyzed using scanning electron microscope (SEM). The chemical states were determined through use of the X-ray photoelectron spectroscopy (XPS) technique, while phase composition and crystalline structure analysis was performed using the Grazing Incidence X-ray Diffraction (GIXRD) method. The results indicate that various nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) can be obtained by modifying these parameters. The photocatalytic efficiency of these nanostructures and Ag-coated nanostructures was assessed by measuring the degradation of the organic dye rhodamine B (RhB) under both ultraviolet (UV) irradiation and visible light. The results clearly show that UV light causes the RhB solution to lose its color, whereas under visible light RhB changes into rhodamine 110, indicating a successful photocatalytic transformation. The nanoball-like structures' modification with the active metal silver (TNRs 4 Ag) exhibited high photocatalytic efficiency under both ultraviolet (UV) and visible light for different chemical composition parameters. The nanorod structure (TNRs 2 Ag) is more efficient under UV, but under visible-light photocatalyst, the TNRs 6 Ag (dense nanorods) sample is more effective.

Multifunctional conductive SA/ATO@TiO2 whisker aerogels for piezoresistive pressure sensor application

Ultralight and flexible aerogel sensors have garnered significant interest, yet challenges persist in developing their high elasticity and exceptional piezoresistive properties. In this work, laminated porous composite aerogels have been successfully prepared by a composite of sodium alginate (SA) and antimony-doped SnO2 coated titanium dioxide whiskers (ATO@TiO2) via directional freezing technique. The resulting SA and ATO@TiO2 (SAT) aerogels with laminated porous structure demonstrate lightweight with low-density (0.06 g·cm−3), good compressive properties, superplastic, and conductive properties. The incorporation of small amounts of rod-like ATO@TiO2 whiskers into SAT aerogels not only enhances its electrical conductivity and thermal insulation, but also imparts a light-colored appearance to the aerogel. The assembled SAT aerogel sensors exhibit high sensitivity within 1.0 kPa (225 kPa−1, 17.86 kPa−1) and maintains excellent fatigue resistance even over 1000 cycles. The temperature-responsive properties of SAT aerogel sensors presented superior thermal insulation properties, and it can operate properly even at a high temperature of 100 °C. More importantly, SAT piezoresistive sensors facilitated real-time monitoring and human-computer interactive activities related to human movement and health, showcasing significant potential in diverse fields.

Fabrication of silver-doped titanium vanadium nitride (TiVN) coatings for biomedical applications

The term "silver-doped vanadium titanium nitride" refers to a class of composite biomaterial that combines the characteristics of vanadium titanium nitride with silver's antibacterial and bioactive capabilities. Using the physical vapor deposition (PVD) technique, the coating was applied by first depositing a single layer of Titanium on a titanium substrate, followed by a layer of TiVN(Ag), with fixed power for the Titanium (450W) and vanadium (350W), and variable power for the silver (25–100W). Atomic force microscopy (AFM) was used to evaluate surface morphology, transmission electron microscopy (TEM) was used to evaluate cross-sectional microstructural analysis of coatings, X-ray diffraction (XRD) was used to evaluate the phase formation of the coating, X-ray photoemission spectroscopy (XPS) was used to evaluate composition and atomic bonding, and finally, the biocompatibility test was conducted individually to evaluate the viability of MG-63 cells. Our results showed that the fluctuation of the silver concentration in the system impacts the microstructural and biological characteristics of the coating. The best balance between cell viability and microstructure was obtained using a sample of TiVN(Ag) and 50W of electricity.

Boosting external quantum efficiency of a WSe2 photodetector across visible and NIR spectra through harnessing plasmonic hot electrons

The layered two-dimensional material tungsten diselenide ( WSe2 ) has triggered tremendous interests in the field of optoelectronic devices due to its exceptional carrier transport property. Nevertheless, the limited absorption of WSe2 in the near infrared (NIR) band poses a challenge for the application of WSe2 photodetectors in night vision, telecommunication, etc. Herein, the enhanced performance of the WSe2 photodetector is demonstrated through the incorporation of titanium nitride nanoparticles (TiN NPs), complemented by an atomically-thick Al2O3 layer that aids in suppressing the dark current. It is demonstrated that TiN NPs can dramatically enhance the absorption of light in the proposed WSe2 photodetector in the NIR regime. This enhancement boosts photocurrent responses through the generation of plasmonic hot electrons, leading to external quantum efficiency (EQE) enhancement factors of 379.66% at 850 nm and 178.47% at 1550 nm. This work presents, for the first time, to our knowledge, that the WSe2 photodetector is capable of detecting broadband light spanning from ultraviolet to the telecommunication range, all achieved without the reliance on additional semiconductor materials. This achievement opens avenues for the advancement of cost-effective NIR photodetectors.

Addressing safety and sustainability issues in the development of nano-enabled MULTI-FUNctional materials for metal additive manufacturing

This paper presents a comprehensive investigation into the sustainable development of nano-enabled multifunctional materials (NMMs) for metal additive manufacturing (MAM), based on the principles of the Safe and Sustainable-by-Design (SSbD) framework. The work focuses on both environmental impacts and health risks potentially associated with these materials, offering a groundwork for a more complete SSbD assessment that includes socio-economic considerations.The Life Cycle Assessment (LCA) identified significant environmental advantages of using Titanium Nitride (TiN) and Chromium Nitride (CrN) in wire coating processes over Titanium Carbide (TiC), with a 77% reduction in environmental impacts. However, despite the emphasis on environmental aspects during materials selection, the primary environmental hotspot is the heat treatment stage used during the process to shape NMMs into pellets. Eco-toxicity assessments performed on both nano- and microparticles from the studied NMMs for MAM, identified specific thresholds to ensure over 80% cell viability, labelling MoCu and CCuCr as particularly cytotoxic. Additionally, a task-based risk assessment in laboratory environments, evaluating the potential release of engineered nanoparticles (ENPs), identified minimal inhalation exposure risk for workers due to effective control measures implemented.Overall, by integrating findings on eco-toxicity, worker safety, and environmental hotspots in production processes, this study offers an approach for advancing sustainable practices during the production of NMMs for MAM in laboratory settings. These findings can be valuable for future research and development in the field, ensuring that sustainability and safety are integral to the advancement of nanotechnology.

Semiconducting Properties of Delaminated Titanium Nitride Ti4N3Tx MXene with Gate-Tunable Electrical Conductivity.

MXenes have garnered significant attention due to their atomically thin two-dimensional structure with metallic electronic properties. However, it has not yet been fully achieved to discover semiconducting MXenes to implement them into gate-tunable electronics such as field-effect transistors and phototransistors. Here, a semiconducting Ti4N3Tx MXene synthesized by using a modified oxygen-assisted molten salt etching method under ambient conditions, is reported. The oxygen-rich synthesis environment significantly enhances the etching reaction rate and selectivity of Al from a Ti4AlN3 MAX phase, resulting in well-delaminated and highly crystalline Ti4N3Tx MXene with minimal defects and high content of F and O, which led to its improved hydrophobicity and thermal stability. Notably, the synthesized Ti4N3Tx MXene exhibited p-type semiconducting characteristics, including gate-tunable electrical conductivity, with a current on-off ratio of 5 × 103 and a hole mobility of ∼0.008 cm2 V-1 s-1 at 243 K. The semiconducting property crucial for thin-film transistor applications is evidently associated with the surface terminations and the partial substitution of oxygen in the nitrogen lattice, as corroborated by density functional theory (DFT) calculations. Furthermore, the synthesized Ti4N3Tx exhibits strong light absorption characteristics and photocurrent generation. These findings highlight the delaminated Ti4N3Tx as an emerging two-dimensional semiconducting material for potential electronic and optoelectronic applications.

Coating Titanium Transport Layers for Enhanced Short and Long Term Performance in PEM Water Electrolysis Cells

The ageing of titanium porous transport layers (PTL) affects the longevity of polymer electrolyte membrane water electrolysis systems by the formation and thickening of a weakly conductive oxide layer. The evolving oxygen on the anode in combination with the high electrical potential provides a challenging environment in which a low electrical contact resistance to the catalyst layer (CL) needs to sustain over a long period. One previous approach is a precious metal coating of the PTL with platinum or iridium [1], which can prevent oxidation of the titanium. A cost-effective alternative is a hydrochloric acid treatment, which forms titanium hydride (TiH). [2] Titanium nitride (TiN) promises better electrical conductivity with similar corrosion resistance, but has not yet been tested as a coating. The same is true for niobium, which performed well as a coating for stainless steel bipolar plates. [3] In our studies, all these candidates face the same conditions aside an untreated PTL in one unique series of measurements. All types are repeated three times to ensure reproducibility. The mean polarization curves (figure 1 left) show that the two precious metals, iridium and platinum, significantly improve the cell voltage at a current density of 2A/cm² by 80mV and 95mV, respectively. Titanium hydride achieves an even higher reduction of 100mV without the use of precious metals. The high frequency resistance plots in figure 1 right determine that the improvement of up to 20% or 30mΩ∙cm² is attributable to a reduced contact resistance to the CL. This assumption is proven by the fact that a PTL that is only coated with iridium on the side facing the CL behaves identically to a PTL that is coated on both sides. The ohmic losses in contact with the BPP are therefore negligible in these experiments. Titanium nitride and niobium coated PTLs behave in the same way as the reference measurement. In addition to the measurements shown, long-term experiments (>1000 hours) are currently running for all types of coating, and corrosion measurements in sulphuric acid are being carried out in parallel. The joint results will determine the suitability of the various coatings for long-term use in electrolysers.[1] Liu, C., Shviro, M., Gago, A. S., Zaccarine, S. F., Bender, G., Gazdzicki, P., Morawietz, T., Biswas, I., Rasinski, M., Everwand, A., Schierholz, R., Pfeilsticker, J., Müller, M., Lopes, P. P., Eichel, R.-A., Pivovar, B., Pylypenko, S., Friedrich, K. A., Lehnert, W., Carmo, M., Exploring the Interface of Skin-Layered Titanium Fibers for Electrochemical Water Splitting. Adv. Energy Mater. 2021, 11, 2002926. https://doi.org/10.1002/aenm.202002926[2] Bystron, T., Vesely, M., Paidar, M. et al. Enhancing PEM water electrolysis efficiency by reducing the extent of Ti gas diffusion layer passivation. J Appl Electrochem 48, 713–723 (2018). https://doi.org/10.1007/s10800-018-1174-6[3] Stiber, S., Hehemann, M., Carmo, M., Müller, M., Ayers, K.E., Capuano, C., Danilovic, N., Morawietz, T., Biswas, I., Gazdzicki, P., Heger, J.-F., Gago, A.S. and Friedrich, K.A. (2022), Long-Term Operation of Nb-Coated Stainless Steel Bipolar Plates for Proton Exchange Membrane Water Electrolyzers. Adv. Energy Sustainability Res., 3: 2200024. https://doi.org/10.1002/aesr.202200024 Figure 1