Titanium Nitride Electrodes Research Articles

Effect of atomic layer deposition process parameters on TiN electrode for Hf0.5Zr0.5O2 ferroelectric capacitor

Abstract Hf0.5Zr0.5O2 (HZO), as a novel and outstanding ferroelectric material, exhibits an extremely high sensitivity, rendering it quite susceptible to electrode effect. Titanium nitride (TiN) is a commonly employed as electrode material in the complementary metal-oxide-semiconductor (CMOS) process. Adjusting the process parameters of preparing TiN film can alter matching degree with HZO, so as to find the optimal parameters of TiN process to improve ferroelectric property of HZO. In this study, the impact of key process parameters in atomic layer deposition (ALD) TiN, including cycle number, TiCl4 and NH3 pluse time, process temperature (Tp) on film thickness, crystalline phases of TiN, square resistivity (Rs), surface average roughness (Ra) and the root-mean-square roughness (Rq) of TiN film are comprehensively investigated. Through optimization, ~10nm ALD TiN film can achieve excellent uniformity of 0.43%, low Rs of 286.9Ω/sq, improved Ra and Rq of 1.82Å and 2.28Å. The results show that the maximum 2 times remnant polarization (2Pr) of the HZO ferroelectric capacitor with optimized TiN electrodes can reach 36.34µC/cm2, and the switching cycle endurance exceeds 1E7.

Reduced Graphene Oxide Decorated Titanium Nitride Nanorod Array Electrodes for Electrochemical Applications

This work describes the fabrication and characterization of a new high surface area nanocomposite electrode containing reduced graphene oxide (rGO) and titanium nitride (TiN) for electrochemical applications. This approach involves electrochemically depositing rGO on a high surface area TiN nanorod array electrode to form a new nanocomposite electrode. The TiN nanorod array was first formed by the glancing angle deposition technique in a DC (Direct Current) sputtering system. GO flakes of ~1.5 μm in diameter, as confirmed by Dynamic Light Scattering (DLS), were electrodeposited on the nanostructured TiN electrode via the application of a fixed potential for one hour. The surface morphology of the as-prepared rGO/TiN electrode was evaluated by scanning electron microscopy (SEM) and the presence of rGO on TiN was confirmed by Raman Microscopy. The CV shows an increase in the capacitive current at rGO/TiN as compared to TiN. The rGO decorated TiN electrode was then used for analyzing the electrocatalytic oxidation of ascorbic acid and dopamine, and the reduction of nitrate by CV and linear sweep voltammetry (LSV), respectively. CV or LSV show that the electrochemical kinetics of these three analytes are significantly faster on rGO/TiN than TiN itself. Overall, the rGO/TiN electrode showed better electrochemical behavior for biomolecules like ascorbic acid and dopamine as well as another target analyte, nitrate ions, compared to TiN by itself.

Effects of substrate bias voltage on conductivity and internal stress of TiN films

In order to make the service life of microelectronic devices longer, titanium nitride electrode films need to meet the requirements of high electrical conductivity and low internal stress. In this paper, the effect of substrate bias voltage on the properties of titanium nitride films prepared by direct current (DC) reactive magnetron sputtering was studied systematically. The changes of titanium nitride films properties were investigated in detail from the aspects of resistivity, growth rate, crystal orientation, roughness and internal stress. The results show that the introduction of substrate bias voltage is conducive to the formation of dense titanium nitride films. Considering that the resistivity and internal stress of titanium nitride film vary with substrate bias voltage, the film deposited at substrate bias voltage of -100 V is selected as the electrode film material with the best performance (resistivity of 47.5 μΩ·cm, roughness of 1.1 nm and internal stress of -5.6 GPa).

Long-lasting BDD/Si3N4–TiN electrodes for sustainable water remediation

Boron-doped diamond (BDD) thin films have the potential to revolutionize water remediation through electrochemical oxidation, converting persistent pollutants into CO2 and water. However, a significant challenge in implementing BDDs on a large scale is the choice of substrate material. Electrode failure typically occurs due to BDD delamination from the substrate. We propose using a ceramic composite of silicon nitride (Si3N4) and titanium nitride (TiN) as a substrate to address this issue. This electroconductive composite combines Si3N4's high wear resistance, chemical stability, and high affinity for diamond film growth with the TiN's metal-like conductivity. In this work, BDD films were grown by Hot Filament Chemical Vapor Deposition (HF-CVD) over Si3N4–TiN substrates containing 30%vol. TiN. The resulting BDD/Si3N4–TiN electrodes were analyzed concerning their microstructure, diamond quality, conductivity, adhesion strength, service life, and electrochemical properties. Phenol was used as a model to test the electrode's ability to oxidize pollutants. We found that the BDD/Si3N4–TiN electrode could eliminate phenol entirely and up to 98.8 % of the model solution's Chemical Oxygen Demand (COD) after 5 h of direct anodic oxidation, with an Average Current Efficiency (ACE) of 14 % and an energy consumption of 138 kW h kgCOD−1. Furthermore, the BDD/Si3N4–TiN electrode could withstand more than 2016 h of accelerated life test without film delamination. Overall, the results demonstrate that BDD/Si3N4–TiN electrodes are a potential long-lasting solution for large-scale water treatment by electrochemical advanced oxidation processes (EAOPs) in a sustainable manner, especially if combined with renewable energy sources.

Surface Functionalized Titanium Nitride Electrode for CMOS Compatible Bioelectronic Devices.

The development of bioelectronic devices is heading toward high throughput and high resolution. Yet, most electrode materials utilized in electrical biosensing are not compatible with the manufacturing techniques of semiconductor chips, which somehow hinders the integration and miniaturization of these devices. Titanium nitride (TiN) is a durable and economical material that is widely used in CMOS-based integrated circuits, bioelectronic systems, electrocatalytic systems, etc. Considering different application scenarios, new and efficient methods are required to functionalize TiN surface. In this study, a surface functionalization approach by covalent grafting of an organic thin film containing hydroxyl groups on TiN surface via electroreduction of diazonium salt 4-(2-hydroxyethyl)benzenediazonium was presented. Cyclic voltammetry (CV) procedures were carried out at the potential ranges of -0.8 V~0.5 V (vs Ag/AgCl) with varying numbers of potential cycles (i. e., 5, 25, and 50 cycles) in order to study the thickness of modification layer. Then, the electrochemical property, surface morphology, and chemical structures of the sample before and after modifications were investigated via multiple characterization techniques, such as CV, atomic force microscopy (AFM), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS), etc., thereby confirming the successful grafting of hydroxyl groups onto the TiN surface. The experiments on DNA synthesis aimed to explore the potential of modified TiN electrode as a novel platform for DNA data storage applications and the corresponding proof-of-principle was accomplished by the process of coupling Cy3-phosphoramidite. Finally, the experiments were successfully reproduced on the randomly selected sites of the modified TiN microarray chips demonstrating the potential of technical protocol to extend applications in future bioelectronic devices, such as bio-sensing, high-throughput DNA synthesis, and molecular manipulation.

Flexible a‐IGZO TFT‐Based Circuit for Active Addressing in Neural Stimulation Electrode Arrays

AbstractNeural interfaces have undergone significant advancements in recent decades, aiming for flexible, compact, and high‐density electrode arrays with a large number of channels. However, the scalability of these devices is often hindered by the number of wires needed to separately connect each electrode to external electronics. To address this limitation, thin‐film transistor (TFT)‐based electronic circuits offer a promising solution by enabling active addressing of stimulation electrodes and potentially increasing the channel count with fewer interconnections. This paper presents the integration of a circuit comprising two amorphous indium–gallium–zinc‐oxide (a‐IGZO) TFTs and a titanium nitride (TiN) electrode on a flexible polymer platform. This circuit precisely controls the electrode's On/Off states and the delivery of current for nerve stimulation. Characterization studies involving frequency and electrochemical analysis demonstrate the TFT‐based circuit's capability to operate at high frequencies, deliver biphasic stimulation pulses to the electrode, and store sufficient charge for effective neural stimulation. Moreover, the a‐IGZO TFTs exhibit remarkable stability during repeated gate voltage sweeps with minimal changes in electrical performance. This circuit has the potential to be extended to active‐matrix devices that enable electrode arrays with a high number of channels and enhanced spatial resolution, which is crucial for selective neural stimulation.

Microstructural and Electrical Resistivity of TiN Electrode Films Prepared by Direct Current (DC) Reactive Magnetron Sputtering

In this study, the crystal structure as well as electron transport of TiN thin films were evaluated. We used DC reactive magnetron sputtering to deposit a thin layer of polycrystalline titanium nitride (TiN) on a Si (100) substrate starting from elemental Ti in a nitrogen atmosphere. The influence of nitrogen flow rate on the crystal structure, surface morphology, and electron transport of TiN were investigated systematically. It was found that the preferred orientation and conductivity of TiN thin films exhibit strong nitrogen flow rate dependence. The preferred orientation changed from (111) to (200) initially and then changed back to (111) as the nitrogen flow rate increases. However, an increase in the (200) phase leads to higher conductivity and lower surface roughness. At the optimized deposition conditions, ultra-thin (around 30 nm) TiN thin films with a low resistivity of 101.8 μC·cm and a surface roughness of less than or equal to 0.51 nm were obtained. These superior performances, along with low running costs, suggest that TiN thin films have great potential for use as electrodes in microelectronic devices.

Interplay between Strain and Defects at the Interfaces of Ultra‐Thin Hf0.5Zr0.5O2‐Based Ferroelectric Capacitors

AbstractHafnium zirconium oxide (HZO) is an ideal candidate for the implementation of ferroelectric memristive devices, due to its compatibility with the complementary metal‐oxide‐semiconductor technology. Ferroelectricity in HZO films is significantly influenced by the properties of electrode/HZO interfaces. Here, the impact of the interfacial microstructure and chemistry on the ferroelectricity of 6 nm‐thick HZO‐based capacitors, realized by sputtering, with titanium nitride or tungsten electrode materials, is investigated. The results highlight a strong correlation between the structural properties of electrode/HZO interfaces and the HZO ferroelectric performance. Interface effects become significant at low HZO thickness, thus the precise control over the quality of electrode/HZO interfaces allows the remarkable improvement of HZO ferroelectric properties. A double remanent polarization of 40 µC cm−2 is achieved. This work is a new step towards high quality ultra‐thin HZO films with enhanced ferroelectricity for the implementation of ferroelectric tunnel junctions for brain‐inspired computing.

Effect of the bottom electrode on the digital and analog resistive switching behavior of SiNx-based RRAM

This Letter is about the role of the bottom electrode in the resistive switching of SiNx-based resistive random-access memory. Titanium nitride (TiN) and platinum (Pt) are used as bottom electrodes to fabricate devices whose I–V characteristics are compared. The devices with Pt as the bottom electrode have digital resistive switching behavior with a main memory window. However, the devices with TiN as the bottom electrode provide an analog resistive switching with the gradual operation. We propose that this switching difference is due to the different work functions of the top and bottom electrodes and the nitrogen-rich layer formed at the SiNx/TiN interface. The work function of the bottom electrode is larger than the top electrode in the device with Pt electrodes, which are considered non-reactive. However, the difference in the work functions between the bottom and top electrodes is not much for the device with a TiN electrode. As the nitrogen-rich layer formed at the SiNx/TiN interface has nitrogen accommodation ability, the nitrogen ions are more likely to drift to the bottom electrode, and resistive switching changes from digital to analog for the device with TiN electrodes.

Efficient electrochemical decomposition of sulfamethoxazole using a novel free-standing TiN anode

The utilization of electrochemical oxidation (EO) processes has become increasingly popular in the field of wastewater treatment, and the robust and sustainable electrode materials were highly desirable for such processes. Among these materials, titanium nitride (TiN) has emerged as a promising candidate due to its unique electronic configuration, which impart ideal electrical conductivity similar to metals, and good stability approaching that of ceramic electrode. This study aimed to develop a free-standing TiN electrode for the EO treatment of refractory antibiotics such as sulfamethoxazole (SMX), and to evaluate its efficacy for SMX removal. The results showed that the TiN electrode achieved a high SMX removal rate (100% removal at 60 min, kobs = 0.031 min−1). Density functional theory (DFT) calculations were utilized to explicate the underlying mechanism, revealing that water oxidation on the TiN surface generates ·OH rather than O2, making TiN an excellent material for the mineralization of recalcitrant SMX. Additionally, both the DFT and LC-MS/MS results demonstrated that the degradation pathway of SMX was induced by ·OH through H-abstraction and electron-transfer pathway, and the active sites responsible for the degradation intermediates were determined by DFT calculation. Overall, these findings provide valuable insights into the development of effective and environmental benign water purification method using novel, free-standing TiN anode material.

Physiological fluid based flexible NbN||TiN supercapacitor for biocompatible energy storage applications

For medical electronic devices, batteries and capacitors are crucial power sources. However, several challenges are associated with these power sources, such as their inflexibility, poor performance, and non-biocompatibility. In this work, a flexible and biocompatible supercapacitor device was fabricated with niobium nitride (NbN) and titanium nitride (TiN) electrodes. Magnetron sputtering was used to deposit NbN and TiN directly on stainless steel-304 (SS). The fabricated asymmetric supercapacitor device (NbN@SS||TiN@SS) demonstrated efficient electrochemical stability, with excellent electrode material adhesion on the substrate, high capacitive performance, and excellent cyclic stability (87.11 % capacitive retention after 10,000 cycles at 0.2 mAcm−2 current density) in physiological fluid (phosphate buffer saline). The device delivered a voltage window of 1.2 V, with superb electrochemical performance (areal energy and power density of 1.86 µWhcm−2 and 239.14 mWcm−2 respectively). Cell viability studies were performed to establish the in-vitro biocompatibility of the electrodes. There was significant cell growth (93 % for TiN@SS and 94 % for NbN@SS) and excellent protein adsorption after 72 h incubation of L929 fibroblasts. These astounding outcomes and the ideal bending electrochemical performance make it a potential candidate for powering medical and implantable electronic devices by directly utilizing physiological fluid.

TiN Electrode for High-Performance CsPbBr₃ Perovskite Nanocrystal-Based Photodetectors

Solution-processed all-inorganic lead halide perovskites are widely utilized to develop photodetectors (PDs) due to their excellent optoelectronic properties. The low-cost titanium nitride (TiN) electrode not only has better corrosion resistance than Ag electrode but also possesses good conductivity comparable to Au electrode, but the utilization of TiN electrode in perovskite PDs has been rarely reported. Here, based on all-inorganic CsPbBr3 perovskite nanocrystals (NCs) synthesized through the supersaturated recrystallization method, a high-performance metal–semiconductor–metal (MSM)-type PD with a photo-to-dark-current ratio (PDCR) above <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{4}$ </tex-math></inline-formula> and a dynamic range (DR) of 164 dB was demonstrated by employing the low-cost TiN electrode. It indicates that the PD with TiN electrode maintains a dark current as low as that of PD with Au electrode, while that with Ag electrode is hundreds of times inferior. It also reflects that the photocurrent of the PD with TiN electrode is quite close to that of the Au electrode counterpart, which exhibits a 161 times improvement with respect to the PD with Ag electrode. Moreover, the TiN electrode PD demonstrates a much better stability relative to the device with Ag electrode. Our work contributes to developing low-cost, high-performance PDs based on solution-processed semiconductors.

Nafion Modified Titanium Nitride pH Sensor for Future Biomedical Applications.

pH sensors are increasingly being utilized in the biomedical field and have been implicated in health applications that aim to improve the monitoring and treatment of patients. In this work, a previously developed Titanium Nitride (TiN) solid-state pH sensor is further enhanced, with the potential to be used for pH regulation inside the human body and for other biomedical, industrial, and environmental applications. One of the main limitations of existing solid-state pH sensors is their reduced performance in high redox mediums. The potential shift E0 value of the previously developed TiN pH electrode in the presence of oxidizing or reducing agents is 30 mV. To minimize this redox shift, a Nafion-modified TiN electrode was developed, tested, and evaluated in various mediums. The Nafion-modified electrode has been shown to shift the E0 value by only 2 mV, providing increased accuracy in highly redox samples while maintaining acceptable reaction times. Overcoming the redox interference for pH measurement enables several advantages of the Nafion-modified TiN electrode over the standard pH glass electrode, implicating its use in medical diagnosis, real-time health monitoring, and further development of miniaturized smart sensors.

Nanostructured Titanium Nitride and Its Composites as High-Performance Supercapacitor Electrode Material.

Electrochemical supercapacitors as an energy storage device have become trademark in current electronic, medical and industrial applications, as they are sources of impressive power output. Supercapacitors supply fast power output, suitable to cover the energy demand of future electronic devices. Electrode material design is a subject of intense research in the area of energy development and advancement, due to its essential role in the electrochemical process of charge storage and the cost of capacitors. The nano-dimensions allow for more electroactive sites, different pore size distributions, and a large specific surface area, making nanostructured electrode materials more promising. Electrode materials based on metal oxides, metal nitrides, and metal carbides are considered ideal for highly efficient electrochemical supercapacitors. Recently, much effort has been devoted to metal nitride-based electrodes and their diverse compositions as they possess higher electrical conductivity and better corrosion resistance, electrochemical stability, and chemical reactivity. Among these, titanium nitride (TiN), possesses high electrochemical stability, outstanding electrical conductivity, and a unique electronic structure. Nanocomposites based on titanium nitrides are known to deliver higher electrochemical performance than pristine nanostructured TiNs due to potential synergetic effects from both the materials. In this paper, recent advancements made in the field of nanostructural TiN electrode materials for SCs are reviewed along with their challenges and future opportunities. Additionally, some of the major techniques involved in the synthesis process are discussed, along with some basic concepts.

Filament Formation in TaOx Thin Films for Memristor Device Application: Modeling Electron Energy Loss Spectra and Electron Transport

AbstractAlthough understanding filament formation in oxide‐based memristive devices by theory has emerged, there are still fundamental unanswered questions. Importantly, for practical application of thin films the material in its amorphous state is to be considered, but mostly lacking so far, and details on sub‐stoichiometry are also scarce. To gain insight into the optical and electronic properties of sub‐stoichiometric amorphous tantalum oxide (TaOx), the electron energy loss spectrum (EELS) of model systems is characterized theoretically and electron transport characteristics are analyzed in detail. Calculated blue‐shifts by increasing sub‐stoichiometry explained the measurements, potentially suggesting estimation of oxygen vacancy concentrations through EEL spectra. Electron transport results based on TaOx material models validated by EELS measurements show that oxygen vacancy filamentary paths are initiated at low bias upon increasing sub‐stoichiometry yet noting an interplay with the local amorphous structure. Contact resistances at interfaces of the TaOx switching layer and a tantalum scavenging layer or titanium nitride electrode are quantified, indicating the possibility for either oxygen vacancy‐ or metal cluster‐based conduction mechanisms at the interface. The computational work, combined with experimental characterization for validation, provides a basis for investigating effects of sub‐stoichiometry on filament formation in TaOx thin film memristive devices.

Structure, Oxygen Content and Electric Properties of Titanium Nitride Electrodes in TiNx/La:HfO2/TiNx Stacks Grown by PEALD on SiO2/Si.

This work reports experimental results of the quantitative determination of oxygen and band gap measurement in the TiNx electrodes in planar TiNx top/La:HfO2/TiNx bottom MIM stacks obtained by plasma enhanced atomic layer deposition on SiO2. Methodological aspects of extracting structural and chemical information from (scanning) transmission electron microscopy imaging (bright field and high angular annular dark field), energy dispersive X-ray spectrometry and electron energy loss spectroscopy are thoroughly considered. The study shows that the oxygen concentration is higher in the TiNxOy bottom electrode (about 14.2 ± 0.1 at. %) compared to the TiNxOy top electrode (about 11.4 ± 0.5 at. %). The following average stoichiometric formulas are TiN0.52O0.20 top and TiN0.54O0.26 bottom for top and bottom electrodes, respectively. The amount of oxygen incorporated into TiNx during PEALD because of oxygen impurities in the plasma is minor compared to that because of diffusion from SiO2 and HfO2. This asymmetry, together with results on a sample grown on a Si substrate, shows that incorporating oxygen impurity from the plasma itself is a minor part compared to diffusion from the SiO2 substrate and HfO2 dielectric during the PEALD growth. We observe the presence of TiO2 at the interface between the Hf oxide layer and the Ti nitride electrodes as well as at the SiO2 interface. EELS analysis led to a band gap ranging from 2.2 to 2.5 eV for the bottom TiNxOy and 1.7–2.2 eV for the top TiNxOy, which is in fair agreement with results obtained on the top TiNx electrode (1.6 ± 01 eV) using optical absorption spectra. Measurement of sheet resistance, resistivity and temperature coefficient of resistance by a four-point probe on the top TiNxOy electrode from 20 to 100 °C corresponds to the typical values for semiconductors.

Machine Learning and High Throughput Synthesis Acceleration of the Discovery of Alkaline Electrolyte Oxygen Evolution Reaction Electrocatalysts

Accelerating the development and discovery of new catalysts is vital for advancing many electrochemical energy conversion technologies (EECT) required to achieve a sustainable future utilizing carbon-free fuel, a circular economy, and to meet the grand energy challenges of the 21st century. The oxygen evolution reaction (OER) is at the heart of many EECT such as water and carbon dioxide electrolyzers, fuel cells, and metal-oxygen batteries. The sluggish kinetics of oxygen electrocatalysis, resulting high overpotential necessary to attain practical current densities, and the high cost of the state-of-the-art OER platinum group metal (PGM) and precious metals catalysts (i.e., IrO2 and RuO2) limit the cost-effective implementation and development of several promising electrolysis technologies.1-3 The development of alternative PGM-free OER catalysts, with comparable or superior activity and durability to the PGM catalysts and derived from earth-abundant materials has thus been an active research area for decades.The application of perovskite oxides as PGM-free electrocatalysts for the OER in alkaline environments has seen significant research interest in the last decade, with tri-metallic and tetra-metallic compounds showing activities comparable to PGM-based catalysts.4,5 The chemical space of these compounds is exceptionally large, yet the development of new perovskite oxides with high OER performance (activity and durability) has been limited and often discovered through trial and error, a time and cost inefficient route that restricted the discovery of more advanced materials. Recent advances in high-performance computing, machine learning (ML), and high throughput material synthesis and screening technologies have enabled high-throughput catalyst design and discovery.4-10 This presentation will describe how the machine learning and high throughput synthesis technologies worked synergistically to accelerate the discovery of alkaline oxygen evolution reaction electrocatalysts. The role of ML in accelerating the materials synthesis and the role of high throughput synthesis in optimizing the ML model predictions will be discussed.AcknowledgmentsThis work was supported by the U.S. Department of Energy, Advanced Research Projects Agency-Energy (ARPA-E) under the DIFFERENTIATE program. This work was authored in part by Argonne National Laboratory, a U.S. Department of Energy (DOE) Office of Science laboratory operated for DOE by UChicago Argonne, LLC under contract no. DE-AC02-06CH11357.References Katsounaros, Ioannis, Serhiy Cherevko, Aleksandar R. Zeradjanin, and Karl JJ Mayrhofer. "Oxygen electrochemistry as a cornerstone for sustainable energy conversion." Angewandte Chemie International Edition53, no. 1 (2014): 102-121.Lee, Youngmin, Jin Suntivich, Kevin J. May, Erin E. Perry, and Yang Shao-Horn. "Synthesis and activities of rutile IrO2 and RuO2 nanoparticles for oxygen evolution in acid and alkaline solutions." The journal of physical chemistry letters3, no. 3 (2012): 399-404.Cherevko, S. et al. Oxygen and hydrogen evolution reactions on Ru, RuO2, Ir, and IrO2 thin film electrodes in acidic and alkaline electrolytes: A comparative study on activity and stability. Today 262, 170–180 (2016).Nahar, Lamia, Ahmed A. Farghaly, Richard J. Alan Esteves, and Indika U. Arachchige. "Shape controlled synthesis of Au/Ag/Pd nanoalloys and their oxidation-induced self-assembly into electrocatalytically active aerogel monoliths." Chemistry of Materials29, no. 18 (2017): 7704-7715.Farghaly, Ahmed A., Rezaul K. Khan, and Maryanne M. Collinson. "Biofouling-resistant platinum bimetallic alloys." ACS applied materials & interfaces10, no. 25 (2018): 21103-21112.Khan, Rezaul K., Ahmed A. Farghaly, Tiago A. Silva, Dexian Ye, and Maryanne M. Collinson. "Gold-Nanoparticle-Decorated Titanium Nitride Electrodes Prepared by Glancing-Angle Deposition for Sensing Applications." ACS Applied Nano Materials2, no. 3 (2019): 1562-1569.Farghaly, Ahmed A., Mai Lam, Christopher J. Freeman, Badharinadh Uppalapati, and Maryanne M. Collinson. "Potentiometric measurements in biofouling solutions: comparison of nanoporous gold to planar gold." Journal of The Electrochemical Society163, no. 4 (2015): H3083.Suntivich, Jin, Kevin J. May, Hubert A. Gasteiger, John B. Goodenough, and Yang Shao-Horn. "A perovskite oxide optimized for oxygen evolution catalysis from molecular orbital principles." Science334, no. 6061 (2011): 1383-1385.Hwang, Jonathan, Zhenxing Feng, Nenian Charles, Xiao Renshaw Wang, Dongkyu Lee, Kelsey A. Stoerzinger, Sokseiha Muy et al. "Tuning perovskite oxides by strain: electronic structure, properties, and functions in (electro) catalysis and ferroelectricity." Materials Today31 (2019): 100-118.Gómez-Bombarelli, Rafael, Jennifer N. Wei, David Duvenaud, José Miguel Hernández-Lobato, Benjamín Sánchez-Lengeling, Dennis Sheberla, Jorge Aguilera-Iparraguirre, Timothy D. Hirzel, Ryan P. Adams, and Alán Aspuru-Guzik. "Automatic chemical design using a data-driven continuous representation of molecules." ACS central science4, no. 2 (2018): 268-276.

High Throughput Synthesis of Perovskite Oxides for Alkaline Oxygen Evolution Reaction Electrocatalysis: Nature of the a and B Sites

Electrochemical energy conversion technologies based on the oxygen evolution reaction (OER) are at the heart of many efforts to achieve a sustainable future, carbon-free fuel, and a circular economy. The sluggish kinetics of oxygen electrocatalysis, as well as the high overpotential required to attain practical current densities, limit the efficiency of several promising electrochemical technologies, including water and carbon dioxide electrolyzers, metal–oxygen batteries, and fuel cells. The most efficient OER catalysts are precious metals such as iridium- and ruthenium-based materials (i.e., IrO2 and RuO2). This fact represents a challenge against the cost-effective implementation of these electrolysis technologies.1-3 As a result, there is a necessity for the development of cost effective PGM-free OER catalysts, with equivalent or superior activity and durability to the PGM catalysts.This presentation will discuss the development and implementation of high-throughput synthesis methodology for PGM-free OER catalysts exploiting the rich chemistry of nanoporous materials4-7 and Argonne National Laboratory's High-Throughput Research Facility. The developed high-throughput methodology will expedite the assessment of the effect of composition and synthesis parameters on the activity of perovskite oxide alkaline electrolyte OER catalysts.AcknowledgementsThis work was supported by the U.S. Department of Energy, Advanced Research Projects Agency Energy (ARPA-E) under the DIFFERENTIATE program. This work was authored in part by Argonne National Laboratory, a U.S. Department of Energy (DOE) Office of Science laboratory operated for DOE by UChicago Argonne, LLC under contract no. DE-AC02-06CH11357.References Katsounaros, Ioannis, Serhiy Cherevko, Aleksandar R. Zeradjanin, and Karl JJ Mayrhofer. "Oxygen electrochemistry as a cornerstone for sustainable energy conversion." Angewandte Chemie International Edition53, no. 1 (2014): 102-121.Lee, Youngmin, Jin Suntivich, Kevin J. May, Erin E. Perry, and Yang Shao-Horn. "Synthesis and activities of rutile IrO2 and RuO2 nanoparticles for oxygen evolution in acid and alkaline solutions." The journal of physical chemistry letters3, no. 3 (2012): 399-404.Cherevko, S. et al. Oxygen and hydrogen evolution reactions on Ru, RuO2, Ir, and IrO2 thin film electrodes in acidic and alkaline electrolytes: A comparative study on activity and stability. Today 262, 170–180 (2016).Nahar, Lamia, Ahmed A. Farghaly, Richard J. Alan Esteves, and Indika U. Arachchige. "Shape controlled synthesis of Au/Ag/Pd nanoalloys and their oxidation-induced self-assembly into electrocatalytically active aerogel monoliths." Chemistry of Materials29, no. 18 (2017): 7704-7715.Farghaly, Ahmed A., Rezaul K. Khan, and Maryanne M. Collinson. "Biofouling-resistant platinum bimetallic alloys." ACS applied materials & interfaces10, no. 25 (2018): 21103-21112.Khan, Rezaul K., Ahmed A. Farghaly, Tiago A. Silva, Dexian Ye, and Maryanne M. Collinson. "Gold-Nanoparticle-Decorated Titanium Nitride Electrodes Prepared by Glancing-Angle Deposition for Sensing Applications." ACS Applied Nano Materials2, no. 3 (2019): 1562-1569.Farghaly, Ahmed A., Mai Lam, Christopher J. Freeman, Badharinadh Uppalapati, and Maryanne M. Collinson. "Potentiometric measurements in biofouling solutions: comparison of nanoporous gold to planar gold." Journal of The Electrochemical Society 163, no. 4 (2015): H3083.

(Invited) Machine Learning Driven Discovery and Optimization of Perovskite Alkaline Electrolyte Oxygen Evolution Reaction Electrocatalysts

Electrochemical energy conversion technologies based on the oxygen evolution reaction (OER) are at the heart of many efforts to achieve a sustainable future, carbon-free fuel, and a circular economy. The sluggish kinetics of oxygen electrocatalysis, as well as the high overpotential required to attain practical current densities, limit the efficiency of several promising electrochemical technologies, including water and carbon dioxide electrolyzers, metal–oxygen batteries, and fuel cells. The most efficient OER catalysts are precious metals such as iridium- and ruthenium-based materials (i.e., IrO2 and RuO2). This fact represents a challenge against the cost-effective implementation of these electrolysis technologies.1-3 As a result, there is a necessity for the development of cost effective PGM-free OER catalysts, with equivalent or superior activity and durability to the PGM catalysts.This presentation will describe the application of machine learning (ML)-guided materials discovery and high-throughput synthesis to address these concerns, taking advantage of the intriguing properties and rich chemistry of nanoporous materials, the demonstrated capability of machine learning (ML)-guided materials discovery, and the high OER electrocatalytic activity of perovskites especially in alkaline media.4-10 Simulation of over 8,000 perovskites across a variety of cell sizes, space groups, and compositions using density functional theory (DFT) has been performed. Mining of the simulation data indicated that experimentally-known perovskites are characterized by low energy above the thermodynamic convex hull. Efficient search algorithms, deep learning-based models, and DFT calculations have been used to explore the space of perovskite oxides to produce novel compositions with tailored electronic descriptors. Promising compositions designed for high activity and stability are then selected for high throughput automated synthesis using the High-Throughput Research Facility at Argonne National Laboratory. A correlation between the phase purity, annealing temperature and OER activity has been identified.AcknowledgementsThis work was supported by the U.S. Department of Energy, Advanced Research Projects Agency-Energy (ARPA-E) under the DIFFERENTIATE program. This work was authored in part by Argonne National Laboratory, a U.S. Department of Energy (DOE) Office of Science laboratory operated for DOE by UChicago Argonne, LLC under contract no. DE-AC02-06CH11357.References Katsounaros, Ioannis, Serhiy Cherevko, Aleksandar R. Zeradjanin, and Karl JJ Mayrhofer. "Oxygen electrochemistry as a cornerstone for sustainable energy conversion." Angewandte Chemie International Edition53, no. 1 (2014): 102-121.Lee, Youngmin, Jin Suntivich, Kevin J. May, Erin E. Perry, and Yang Shao-Horn. "Synthesis and activities of rutile IrO2 and RuO2 nanoparticles for oxygen evolution in acid and alkaline solutions." The journal of physical chemistry letters3, no. 3 (2012): 399-404.Cherevko, S. et al. Oxygen and hydrogen evolution reactions on Ru, RuO2, Ir, and IrO2 thin film electrodes in acidic and alkaline electrolytes: A comparative study on activity and stability. Today 262, 170–180 (2016).Nahar, Lamia, Ahmed A. Farghaly, Richard J. Alan Esteves, and Indika U. Arachchige. "Shape controlled synthesis of Au/Ag/Pd nanoalloys and their oxidation-induced self-assembly into electrocatalytically active aerogel monoliths." Chemistry of Materials29, no. 18 (2017): 7704-7715.Farghaly, Ahmed A., Rezaul K. Khan, and Maryanne M. Collinson. "Biofouling-resistant platinum bimetallic alloys." ACS applied materials & interfaces10, no. 25 (2018): 21103-21112.Khan, Rezaul K., Ahmed A. Farghaly, Tiago A. Silva, Dexian Ye, and Maryanne M. Collinson. "Gold-Nanoparticle-Decorated Titanium Nitride Electrodes Prepared by Glancing-Angle Deposition for Sensing Applications." ACS Applied Nano Materials2, no. 3 (2019): 1562-1569.Farghaly, Ahmed A., Mai Lam, Christopher J. Freeman, Badharinadh Uppalapati, and Maryanne M. Collinson. "Potentiometric measurements in biofouling solutions: comparison of nanoporous gold to planar gold." Journal of The Electrochemical Society163, no. 4 (2015): H3083.Suntivich, Jin, Kevin J. May, Hubert A. Gasteiger, John B. Goodenough, and Yang Shao-Horn. "A perovskite oxide optimized for oxygen evolution catalysis from molecular orbital principles." Science334, no. 6061 (2011): 1383-1385.Hwang, Jonathan, Zhenxing Feng, Nenian Charles, Xiao Renshaw Wang, Dongkyu Lee, Kelsey A. Stoerzinger, Sokseiha Muy et al. "Tuning perovskite oxides by strain: electronic structure, properties, and functions in (electro) catalysis and ferroelectricity." Materials Today31 (2019): 100-118.Gómez-Bombarelli, Rafael, Jennifer N. Wei, David Duvenaud, José Miguel Hernández-Lobato, Benjamín Sánchez-Lengeling, Dennis Sheberla, Jorge Aguilera-Iparraguirre, Timothy D. Hirzel, Ryan P. Adams, and Alán Aspuru-Guzik. "Automatic chemical design using a data-driven continuous representation of molecules." ACS central science 4, no. 2 (2018): 268-276.

Metal Organic Framework-Based Alkaline Oxygen Evolution Reaction Electrocatalysts: Morphology, Metal Loading, and Durability

Electrochemical energy conversion technologies based on the oxygen evolution reaction (OER) are at the heart of many efforts to achieve a sustainable future, carbon-free fuel, and a circular economy. The sluggish kinetics of oxygen electrocatalysis, as well as the high overpotential required to attain practical current densities, limit the efficiency of several promising electrochemical technologies, including water and carbon dioxide electrolyzers, metal–oxygen batteries, and fuel cells. The most efficient OER catalysts are precious metals such as iridium- and ruthenium-based materials (i.e., IrO2 and RuO2). This fact represents a challenge against the cost-effective implementation of these electrolysis technologies.1-3 The rich chemistry of nanoporous materials provides an opportunity for the development of cost effective PGM-free OER catalysts, with equivalent or superior activity and durability to the PGM catalysts.4-7 Metal organic framework (MOF)-based OER catalysts with high activity and long-term stability in alkaline electrolytes will be discussed in this presentation. We will discuss the relationship between MOF morphology and metal-ion loading, and how their impact on OER activity.Acknowledgements: Argonne National Laboratory is managed for the U.S Department of Energy (DOE) by the University of Chicago Argonne, LLC, under contract DE-AC-02-06CH11357. This work was performed under the auspices of the Electrocatalysis Consortium (ElectroCat 2.0), a DOE Office of Energy Efficiency, Hydrogen and Fuel Cell Technologies (HFTO) consortium. Electron microscopy was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.References Katsounaros, Ioannis, Serhiy Cherevko, Aleksandar R. Zeradjanin, and Karl JJ Mayrhofer. "Oxygen electrochemistry as a cornerstone for sustainable energy conversion." Angewandte Chemie International Edition53, no. 1 (2014): 102-121.Lee, Youngmin, Jin Suntivich, Kevin J. May, Erin E. Perry, and Yang Shao-Horn. "Synthesis and activities of rutile IrO2 and RuO2 nanoparticles for oxygen evolution in acid and alkaline solutions." The journal of physical chemistry letters3, no. 3 (2012): 399-404.Cherevko, S. et al. Oxygen and hydrogen evolution reactions on Ru, RuO2, Ir, and IrO2 thin film electrodes in acidic and alkaline electrolytes: A comparative study on activity and stability. Today 262, 170–180 (2016).Nahar, Lamia, Ahmed A. Farghaly, Richard J. Alan Esteves, and Indika U. Arachchige. "Shape controlled synthesis of Au/Ag/Pd nanoalloys and their oxidation-induced self-assembly into electrocatalytically active aerogel monoliths." Chemistry of Materials29, no. 18 (2017): 7704-7715.Farghaly, Ahmed A., Rezaul K. Khan, and Maryanne M. Collinson. "Biofouling-resistant platinum bimetallic alloys." ACS applied materials & interfaces10, no. 25 (2018): 21103-21112.Khan, Rezaul K., Ahmed A. Farghaly, Tiago A. Silva, Dexian Ye, and Maryanne M. Collinson. "Gold-Nanoparticle-Decorated Titanium Nitride Electrodes Prepared by Glancing-Angle Deposition for Sensing Applications." ACS Applied Nano Materials2, no. 3 (2019): 1562-1569.Farghaly, Ahmed A., Mai Lam, Christopher J. Freeman, Badharinadh Uppalapati, and Maryanne M. Collinson. "Potentiometric measurements in biofouling solutions: comparison of nanoporous gold to planar gold." Journal of The Electrochemical Society 163, no. 4 (2015): H3083.