High-throughput Combinatorial Approach Research Articles

High-throughput design of complex oxides as isothermal, redox-activated CO2 sorbents for green hydrogen generation

A new family of Isothermal, redox-activated CO2 sorbents were successfully developed using a high-throughput combinatorial approach to facilitate the generation of green hydrogen from biogenic carbonaceous feedstocks.

Combinatorial experiments for discovering Al-C thin films with high strength and ductility

Aluminum (Al) is one of the most widely used structural material in various technologically relevant applications due to its light weight and formability. However, these advantages have been overshadowed by its relatively poor mechanical properties. In this paper, we report theexceptional mechanical properties of aluminum-carbon (Al-C) thin films deposited by multiple source co-sputtering. In the first set of experiments, a high-throughput combinatorial approach was taken to investigate mechanical and electrical properties of a blanket of Al-C thin film deposited with a compositional gradient. Hardness increased along with carbon addition, but at the cost of reduced electrical conductivity. These measurements allowed rapid screening of Al-C films and showed that regions with ∼ 6at% carbon possess a good balance of mechanical and electrical properties (2.8 GPa and 142 Ω·nm). Micro-tensile experiments of freestanding Al, Al-C 6.4at%, and Al-C 10.3at% films were conducted to acquire tensile properties and understand the strengthening mechanism. Al-C films with 6.4at% and 10.3at% carbon both exhibited significantly increased yield stress over 300 MPa while retaining ductility. Unexpectedly, an upper yield followed by a fall in the stress was observed, which resembles the mechanical behavior of low-carbon steel. The unusual mechanical behavior of Al-C is attributed to formation of the Cottrell atmosphere. We also demonstrated that C impurities suppress stress-induced grain growth, which leads to improved microstructural stability during deformation. This paper demonstrates that carbon addition by co-sputter deposition is a viable approach for improving the strength and microstructural stability of Al thin films without loss in ductility.

Rapid screening the mechanical properties of ZrNi-based metallic glasses by high-throughput combinatorial approach

Rapid and massive screening approaches of new materials with good mechanical properties are of great importance for fundamental research and practical applications of structural materials. Here, one experimental combinatorial approach based on high-throughput sample preparation combined with nanoindentation platform and EDS mapping is proposed to fast screen the mechanical properties of ZrNi-based metallic glasses. A composition gradient film for Zr–Ni–Cu–Al system were prepared by magnetron sputtering method and the compositions were mapped by EDS. Various mechanical properties including the elastic modulus, hardness, strength and plastic deformation ability were fast characterized by nanoindentation. The composition ranges with the optimal individual and comprehensive mechanical properties were separately identified. To verify the above fast-screen approach, the tensile tests and Vickers hardness measurement were conducted on the bulk samples with the same compositions of the screened optimal systems. Our approach will speed up the development of novel metallic glasses with good mechanical properties.

Elastic and plastic anisotropy in a refractory high entropy alloy utilizing combinatorial instrumented indentation and electron backscatter diffraction

A comprehensive study was carried out to predict the elastic and plastic anisotropy of the non-equiatomic Mo15Nb35Ta35V5W10 Refractory High Entropy alloy (RHEA) using a high throughput combinatorial approach employing instrumented micro-indentation with electron backscatter diffraction (EBSD). The Levenberg–Marquardt optimization algorithm was utilized to determine elastic stiffness constant (C11= 267, C12= 115 and C44= 52 GPa) for accessing elastic anisotropy. The anisotropy in plastic deformation of<001>,<011> and<111> orientated grains can be attributed to the activation of the different {112}<111> slip system along with cross slip and the conservative movement of jogs on the screw dislocation. The spatial distribution of misorientation on <001>, <011> and <111> orientated grains as well as slip plane trace analysis, indicates that symmetry in misorientation pattern results from the flow of material along <111> slip direction on the indented surface. The results of the present investigation clearly indicate that the anisotropy in the elastoplastic behavior of novel RHEA is distinct from its constituent elements and that simple rule of mixtures is not sufficient to determine elastic modulus and lattice friction stress of RHEAs. Thus, high throughput experimental techniques are necessary to establish the structure-property linkages in novel multicomponent multi-principal RHEA compositions.

Tuning the Sensitivity of CO2 Electroreduction on Copper Surfaces Via Electrolyte Engineering

With growing increase in energy demand and chemical production, electrochemical reduction (ER) of CO2 can potentially pave the route for generation of sustainable drop-in fuels using renewable wind and solar energy sources. Cu has been identified as a promising electrocatalyst for CO2 conversion to methane and ethylene, albeit the rates of the electrocatalytic reactions are strongly influenced by the reaction environment and the operating conditions [1,2]. Electrolytic ions are known to impact the rates of electrocatalytic reactions, though a molecular understanding of such impact is not comprehensively understood. Here, we employ a coupled quantum mechanics/molecular mechanics (QM/MM) scheme [3] to investigate the role played by the electrolytic ions under applied potential on the activity-selectivity relationships for CO2 ER. By varying the concentration and identity of electrolytic salts, we investigate their effect on the reaction energetics and binding strength of reaction intermediates in the CO2 ER pathway. Using a high throughput combinatorial approach that spans a wide range of electrolytes, we attempt to create design principles for electrolyte-based tuning of CO2 ER selectivity and compare with experimentally measured CO2 ER selectivities. The results of these studies provide a rationale for improved environment driven design and screening, and allow computation of reaction energetics using nuanced, dynamical models of the electrochemical double layer.* [1] Y. Hori, in Handbook of Fuel Cells: Fundamentals, Technology and Application (VHC Wiley, Chichester, 2003), Vol. 2, 720-733. [2] A. Murata & Y. Hori, Product selectivity affected by cationic species in electrochemical reduction of CO2 and CO at a Cu electrode. Bulletin of the Chemical Society of Japan (1991), 64(1), 123-127. [3] J. Haruyama, T. Ikeshoji and M. Otani, Electrode potential from density functional theory calculations combined with implicit solvation theory. Physical Review Materials (2018), 2(9), p.095801. *This work was performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

Catalyst discovery through megalibraries of nanomaterials

The nanomaterial landscape is so vast that a high-throughput combinatorial approach is required to understand structure-function relationships. To address this challenge, an approach for the synthesis and screening of megalibraries of unique nanoscale features (>10,000,000) with tailorable location, size, and composition has been developed. Polymer pen lithography, a parallel lithographic technique, is combined with an ink spray-coating method to create pen arrays, where each pen has a different but deliberately chosen quantity and composition of ink. With this technique, gradients of Au-Cu bimetallic nanoparticles have been synthesized and then screened for activity by in situ Raman spectroscopy with respect to single-walled carbon nanotube (SWNT) growth. Au3Cu, a composition not previously known to catalyze SWNT growth, has been identified as the most active composition.

Abstract 4860: A novel class of small-molecule inhibitors of galectin-1 for prostate cancer therapy

Abstract Galectin-1 (Gal-1) is a multifunctional carbohydrate-binding protein and plays a key role in cancer cell proliferation, apoptosis, cell cycle, tumor angiogenesis and evasion of immune responses. It is also directly involved in the process of angiogenesis and tumor immune escape. An elevated level of Gal-1 has been found in many cancers, including prostate cancer. We show by immunohistochemistry in human prostate tissue that Gal-1 expression level was very low in all non-tumor samples and highly expressed in prostate cancer tissues. In addition, Gal-1 was progressively upregulated from low- , intermediate- to high-grade prostate cancer. Taken together, Gal-1 is an excellent therapeutic target against cancer. Yet, no inhibitors against Gal-1 have been approved by the FDA for cancer treatment due to lack of potent, specific and in vivo effective molecules. We recently discovered a novel small-molecule inhibitor of Gal-1, named LLS2, through a high-throughput one-bead two-compound combinatorial library approach. LLS2 exhibits cytotoxic activity against prostate cancer and ovarian cancer cells. We synthesized a series of LLS2 analogs and performed structure-activity relationship studies, leading to a more potent inhibitor LLS30 that induced apoptosis in castration-resistant prostate cancer cells expressing high levels of Gal-1. Molecular modeling study showed LLS30 bound to the sugar-binding groove of Gal-1. In enzalutamide (ENZ)-resistant 22Rv1 prostate cancer cells expressing high levels of Gal-1 and androgen receptor (AR) splice variants, LLS30 could inhibit expression of AR splice variants and sensitize the cells to ENZ in a dose-dependent manner. Downregulation of Gal-1 by siRNA prevented the expression of alternatively spliced AR variants. More importantly, LLS30 showed potent in vivo antitumor efficacy and synergistic activities with docetaxel and ENZ against PC-3 and 22Rv1 prostate cancer models, respectively. Blood chemistry test from the treated animal showed minimum effect of LLS30 on the liver and kidney functions, implying low toxicity. LLS30 is an excellent drug candidate for preclinical development as a novel prostate cancer therapeutic. Citation Format: Ruiwu Liu, Tsung-Chieh Shih, Sophie Kiss, Xiaocen Li, Ting Wang, Jonathan S. Huynh, Chun-Te Wu, Yong Duan, Paramita M. Ghosh, Kit S. Lam. A novel class of small-molecule inhibitors of galectin-1 for prostate cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4860.

Evaluation of Solid-Solution Hardening in Several Binary Alloy Systems Using Diffusion Couples Combined with Nanoindentation

Analysis of solid-solution hardening (SSH) in alloys requires the synthesis of large composition libraries and the measurement of strength or hardness from these compositions. Conventional methods of synthesis and testing, however, are not efficient and high-throughput approaches have been developed in the past. In the present study, we use a high-throughput combinatorial approach to examine SSH at large concentrations in binary alloys of Fe-Ni, Fe-Co, Pt-Ni, Pt-Co, Ni-Co, Ni-Mo, and Co-Mo. The diffusion couple (DC) method is used to generate concentration (c) gradients and the nanoindentation (NI) technique to measure the hardness (H) along these gradients. The obtained H -c profiles are analyzed within the framework of the Labusch model of SSH, and the dependence of H predicted by the model is found to be generally applicable. The SSH behavior obtained using the combinatorial method is found to be largely consistent with that observed in the literature using conventional and DC-NI methods. This study evaluates SSH in Fe-, Ni-, Co-, and Pt-based binary alloys and confirms the applicability of the DC-NI approach for rapidly screening various solute elements for their SSH ability.

Thermoelectric properties of the LaCoO3-LaCrO3 system using a high-throughput combinatorial approach

A combinatorial film of the LaCo1-xCrxO3 system was fabricated using the LaCoO3 and LaCrO3 targets at the NIST Pulsed Laser Deposition (PLD) facility. As the ionic size of Cr3+ is greater than that of Co3+, the unit cell volume of the series increases with increasing x. Using a custom screening tool, the Seebeck coefficient of LaCo1-xCrxO3 approaches a measured maximum of 286 μV/K, near to the cobalt-rich end of the film library (with x ≈ 0.49). The resistivity value increases continuously with increasing x. The measured power factor, PF, of this series, which is related to the efficiency of energy conversion, also exhibits a maximum at the composition of x ≈ 0.49, which corresponds to the maximum value of the Seebeck coefficient. Our results illustrate the efficiency of applying the high-throughput combinatorial technique to study thermoelectric materials.

Design of Metastable Alloys for Energy Conversion

The design and discovery of new semiconductors with targeted multi-property functionalities for applications in solar energy conversion is a current challenge in developing new (photo-)electrode materials. Traditionally, theoretical predictions of ground state structures and their thermodynamic stability have facilitated the discovery of new materials and the optimization of known compounds. However, the field of materials design is experiencing a paradigm shift from near-equilibrium materials towards a much larger design space that includes materials far from equilibrium. In this work, we use theoretical and computational screening methods to identify and design metastable metal nitride and metal oxide alloys with desirable semiconducting properties for solar energy conversion applications. The materials design principles utilize both structure-property and composition-structure relationships to enable tunable multi-property functionalities. We leverage the possibility to overcome thermodynamic solubility limits by nonequilibrium thin-film growth to realize these novel semiconducting alloy electrode materials. Our theory guided synthesis employs a high-throughput combinatorial approach with reactive magnetron sputtering to rapidly screen composition and growth parameters to synthesize metastable spinel (Sn1-xTix)3N4 and polymorphic Mn1-xZnxO alloys. A proof of principle is provided by initial photo-electrocatalytic device measurements that corroborate the materials by design features of tunable band properties and transport mechanisms to improve solar hydrogen generation using the novel alloy electrodes. Our results demonstrate a broadly applicable approach for synthesis of metastable materials and establish the predictive design and discovery of far from equilibrium materials for energy conversion. Figure 1

On the influence of alloy composition on the oxidation performance and oxygen-induced phase transformations in Ti–(0–8) wt%Al alloys

Adopting a high-throughput combinatorial approach, a compositionally graded Ti–xAl (0 ≤ x ≤ 8 wt%) specimen was prepared to conduct a rapid systematic investigation of the influence of composition and exposure time on the oxidation performance of the titanium-rich section of the binary Ti–Al system. The compositionally graded specimen was solution heat treated and subjected to oxidation tests at 650 °C for different exposure times. The morphology, structure, and composition of the oxide scale as well as the microstructural changes in the base material were studied across the entire composition range, using a suite of characterization techniques. The observations revealed the presence of Al2O3 in the topmost layer of the oxide scale in addition to TiO2, indicating its early formation during oxidation. An increase in Al concentration improves the scaling rate of Ti; however, this is observed only for extended exposure times (i.e., 50 and 100 h), and a parabolic oxidation law is obeyed in the composition-time domain. The formation of the α2 phase (Ti3Al) also takes place for relatively higher Al contents (i.e., 8 wt%).

Material optimization via combinatorial deposition and analysis for thermoelectric thin films

This work presents a custom, high-throughput combinatorial approach for the optimization of thermoelectric thin films consisting of materials with complex chemistry and structures (e.g., the layered misfit cobaltite, Ca3FexCo4−xO9). Combinatorial thin films with graded compositions are produced on 100mm Si wafers from multiple target materials using pulsed laser deposition. Film thickness and composition are mapped as a function of wafer location. Crystal structures are determined using x–y mapping XRD analysis with specially designed algorithms for automated peak location and analysis. Thermoelectric properties, specifically the Seebeck coefficient and the electrical resistivity, are screened using a custom designed automated probe system. By combining the rapid synthesis of many compositions and structures simultaneously using combinatorial deposition and automated analytical tools capable of spatial mapping, trends in material performance are shown to be quickly obtained primarily due to the elimination of one-at-a-time synthesis and analysis. The possible approaches for such complex multivalent combinatorial optimization of thin films are identified and discussed.For the Ca3FexCo4−xO9 system presented, variations to the thermoelectric power factor are dominated by changes in the electrical resistivity. Enhancements to the Seebeck coefficient are observed due to the incorporation of Fe into the Ca3FexCo4−xO9 structure; however, this improvement is overshadowed by increases in the electrical resistivity due to variations in film thickness and the presence of secondary phases (Co3O4 and Ca2Fe2O5) which result from increasing Fe content and off-axis pulsed laser deposition.

Self-regulated growth and tunable properties of CuSbS2 solar absorbers

Polycrystalline thin film copper chalcogenide solar cells show remarkable efficiencies, and analogous but less-explored semiconducting materials may hold similar promise. With consideration of elemental abundance and process scalability, we explore the potential of the Cu–Sb–S material system for photovoltaic applications. Using a high-throughput combinatorial approach, Cu–Sb–S libraries were synthesized by magnetron co-sputtering of Cu2S and Sb2S3 targets and evaluated by a suite of spatially resolved characterization techniques. The resulting compounds include Cu1.8S (digenite), Cu12Sb4S13 (tetrahedrite), CuSbS2 (chalcostibite), and Sb2S3 (stibnite). Of the two ternary phases synthesized, CuSbS2 was found to have the most potential, however, when deposited at low temperatures its electrical conductivity varied by several orders of magnitude due to the presence of impurities. To address this issue, we developed a self-regulated approach to synthesize stoichiometric CuSbS2 films using excess Sb2S3 vapor at elevated substrate temperatures. Theoretical calculations explain that phase-pure CuSbS2 is expected to be formed over a relatively wide range of temperatures and pressures, bound by the sublimation of Sb2S3 and decomposition of CuSbS2. The carrier concentration of CuSbS2 films produced within this regime was tunable from 1016–1018cm−3 through appropriate control of Sb2S3 flux rate and substrate temperature. CuSbS2 displayed a sharp optical absorption onset indicative of a direct transition at 1.5eV and an absorption coefficient of 105cm−1 within 0.3eV of the onset. The results of this study suggest that CuSbS2 holds promise for solar energy conversion due to its tolerant processing window, tunable carrier concentration, solar-matched band gap, and high absorption coefficient.

Thin film synthesis and properties of copper nitride, a metastable semiconductor

Copper nitride (Cu3N) thin films were grown by reactive sputtering using a high-throughput combinatorial approach with orthogonal gradients of substrate temperature and target–substrate distance.

Evaluation of the Current Status of the Combinatorial Approach for the Study of Phase Diagrams.

This paper provides an evaluation of the effectiveness of using the high throughput combinatorial approach for preparing phase diagrams of thin film and bulk materials. Our evaluation is based primarily on examples of combinatorial phase diagrams that have been reported in the literature as well as based on our own laboratory experiments. Various factors that affect the construction of these phase diagrams are examined. Instrumentation and analytical approaches needed to improve data acquisition and data analysis are summarized.

Zn-Ni-Co-O wide-band-gap p-type conductive oxides with high work functions

Abstract

A combinatorial approach to metamaterials discovery

We report a high throughput combinatorial approach to photonic metamaterialoptimization. The new approach is based on parallel synthesis and subsequent opticalcharacterization of large numbers of spatially addressable nanofabricated metamaterialsamples (libraries) with quasi-continuous variation of design parameters under realmanufacturing conditions. We illustrate this method for Fano-resonance plasmonicnanostructures, arriving at explicit recipes for high quality factors needed for switching andsensing applications.

Composition dependence of ternary Pt–Ni–Cr catalyst activity for the methanol electro-oxidation reaction

Abstract Various compositions of binary and ternary Pt–Ni–Cr alloys were investigated as catalysts for the methanol electro-oxidation reaction (MOR). Among the binary (Pt 28 Ni 72 /C and Pt 28 Cr 72 /C) and ternary Pt–Ni–Cr catalysts (Pt 28 Ni 36 Cr 36 /C, Pt 22 Ni 39 Cr 39 /C, Pt 33 Ni 31 Cr 36 /C, and Pt 33 Ni 36 Cr 31 /C) examined, the Pt 28 Ni 36 Cr 36 /C composition exhibited the highest MOR mass activity (4.42 A g cat. −1 ) in the as-prepared version, which was higher than the 3.58 A g cat. −1 value of the PtRu/C catalyst after 60 min of chronoamperometry testing. The order of mass activity for the MOR was Pt 28 Ni 36 Cr 36 /C > Pt 33 Ni 36 Cr 31 /C > Pt 22 Ni 39 Cr 39 /C > Pt 33 Ni 31 Cr 36 /C > Pt 28 Cr 72 /C > Pt 28 Ni 72 /C, which was slightly changed to Pt 28 Ni 36 Cr 36 /C > Pt 22 Ni 39 Cr 39 /C > Pt 33 Ni 36 Cr 31 /C > Pt 33 Ni 31 Cr 36 /C > Pt 28 Cr 72 /C > Pt 28 Ni 72 /C after a conditioning process. The effect of anodic conditioning was also studied. A combination of X-ray diffraction, cyclic voltammetry, and chronoamperometry experiments revealed that the conditioning process caused dissolution and an oxidation state change of metallic Ni and Cr 2 O 3 in the binary catalysts. The higher MOR mass activities of the ternary catalysts compared to the binary ones is attributed to co-alloying of Ni and Cr, leading to exposure of more Pt on the catalyst surface without reducing specific activities of the catalysts. The results of this study also correlate well with a prior ranking of catalytic activity of the same compositions in the form of thin film catalysts that we processed and evaluated by a high-throughput combinatorial approach [J.S. Cooper, M.K. Jeon, P.J. McGinn, Electrochem. Commun. 10 (2008) 1545–1547].

New Combinatorial Approach for the Investigation of Kinetics and Temperature Dependence of Surface Reactions in Thin Organic Films

In this paper we present a new, simple, and reproducible method for the rapid determination of the temperature dependence of solution phase surface reactions of organic thin films on solid supports. Instead of estimating the extent of reaction for many separate samples for many different temperatures sequentially, we exploit in our new high throughput combinatorial approach surface reactions carried out under a thermal gradient followed by position-resolved contact angle (CA) measurements. The reaction kinetics, activation energies, and entropies are, thus, accessible on the basis of measurements on a very limited set of samples that differ in reaction times. The kinetics and temperature dependence of surface reactions of the previously studied alkaline hydrolysis of 11,11'-dithiobis(N-hydroxysuccinimidylundecanoate) (NHS-C10) self-assembled monolayers (SAMs) on gold, as well as the ester hydrolysis in SAMs of the novel disulfide 11,11-dithiobis(tert-butylundecanoate) (t-Bu-C10), were investigated in detail using the conventional sequential and the new combinatorial approach. The reaction kinetics, corresponding apparent rate constants k, and activation energies Ea, as well as activation entropies deltaS double dagger, determined according to both approaches agree well with each other to within the experimental error. Hence, these parameters can be quantitatively determined using the described combinatorial approach. A comparison of the reactions of the two model systems indicated that the transition state is tighter for the acid-catalyzed ester hydrolysis in SAMs of the novel disulfide t-Bu-C10 compared to the hydrolysis of the ester groups in SAMs of NHS-C10 on gold.

Combinatorial approach to the edge delamination test for thin film reliability—concept and simulation

A high-throughput combinatorial approach to edge delamination test is proposed to map the failure of adhesion as a function of both temperature and film thickness in a single step. In this approach, a single specimen of a thin film bonded to a substrate with orthogonal thickness and temperature gradients is subdivided into separate samples. This approach can be adopted to measure the adhesion reliability for films with thicknesses in the nano regime by the addition of an overlayer. In addition, it can increase the pace of material innovations in nanoscale science and technology. The experimental requirements for a valid combinatorial test are analyzed using three-dimensional computational fracture mechanics. A simulation result is presented to demonstrate the feasibility of the combinatorial approach and to design the experimental protocol.