In this talk, I will present an update on the current status of our ability to design and discover new materials, and discuss their relevance to understanding structure-property correlations in new functional materials and heading toward semiconductor device fabrication for potential materials. Specific examples will be chosen from our recent work including: (i) the strategy of utilizing a charge-transfer insulator with large photoluminescence responses into solar cells and (ii) the chemical and structural flexibility of new mixed-metal ruthenium chlorides and their influences on tuning magnetic properties.

Materials by Design: From conception to execution

Paramagnetic point defects in semiconductors and insulators are a promising qubit class with nitrogen-vacancy center in diamond as a prominent example. Identifying similar defects in other materials could lead to more flexibility in device design and greater functionality of the resulting devices. To create qubit systems by design, we studied the physical properties of the materials that host useful defect centers and came up with the hypothesis that wide band gap insulators with nuclear spin-free lattice can increase the spin-spin relaxation time, T2, which represents the maximum operation time of a qubit. To test this, we have grown oxygen deficient single crystals of Ba2CaWO6 where the oxygen vacancies create W(V) spin centers. We present x-ray diffraction, neutron diffraction, continuous wave and pulsed electron paramagnetic resonance spectroscopic measurements of this system`. Coherence studies show at 5 K, spin-lattice relaxation time T1, which is the upper limit to T2, in this material is 310(30) ms lending credence to the design hypothesis.

Oxygen vacancy induced defect spin centers by design in single crystals of Ba2CaWO6

A large solid-state entropy of reduction increases the thermodynamic efficiency of metal oxides for two-step thermochemical water splitting (TWS). We present a high-throughput density functional theory (HT-DFT) study of more than 11,000 oxide compounds to screen for thermodynamically favorable two-step TWS materials, and identify many materials as potential new candidates for TWS applications. In addition to the configurational entropy associated with oxygen off-stoichiometry, we also examine a different source of entropy, the on-site electronic configurational entropy arising from excitations of electrons distributed over a large number of multiplet states (as in f-electron cations). We find that this electronic entropy is sizable in all lanthanides, and reaches a maximum value of ~4.7 kB per oxygen vacancy for Ce+4 / Ce+3 reduction. The unique and large positive electronic entropy in ceria contributes to its excellent water-splitting properties.

Oxygen off-stoichiometry and defect entropies in solar thermochemical water splitting materials

Lithium-ion batteries are a common choice for portable electronic devices that require compact, efficient and long-life cycle secondary batteries. However, the dangers of liquid electrolytes used in lithium-ion batteries are well known and include leaks, erosion and toxicity. Improving the electrolytes in lithium-ion batteries entails fixing safety concerns, refining the electrical, mechanical and thermal properties, and creating cost-effective and environmentally friendly production methods. Solid polymer electrolytes (SPEs) act as physical separators while also allowing for the flow of ions and are liquid-free, thereby mitigating safety concerns. In this work, bio-based monomers derived from lignocellulosics were explored as monomers in the development of polymer electrolytes. Employing aromatic compounds, such as those derived from lignin, are known to increase the mechanical and thermal stability of resulting polymer networks. Additionally, photo-initiated thiol-ene polymerizations was explored as a green polymerization method as it is are fast, easy and relatively low-energy, making the process industrially desirable. The SPEs were formed by mixing solid lithium salt in a resin consisting of a bio-based functionalized monomer, ETTMP 1300, and a photo-initiator. The free radical-step growth thiol-ene polymerization was performed in a UV curing oven at 365 nm. The thermomechanical properties of the polymers were tested using TGA, DSC and DMA. The room temperature conductivities of the SPEs were determined to be on the order of 10-4 S cm-1. The relationship between Tg and conductivity was studied by changing the concentration of lithium salt in the resin. It was found that as concentration of lithium salt increased, the Tg of the SPEs increased. Conductivity also increased up to a certain point after which the segmental motion of the polymer chains was too limited and conductivity values subsequently dropped. In addition to conductivity, cationic flow was analyzed by determination of the lithium-ion transference numbers. The SPEs had lithium-ion transference values in the average range for such systems, with the highest at 0.38. The SPEs with the highest transference values had the lowest observed ion aggregations, as determined via FTIR, and the lowest host polymer polarities, as determined by dielectric constants. This study shows that there are many factors that affect current flow and ion transport in polymer electrolyte materials.

Conductivity and ion transport in lignin-derived solid polymer electrolytes

More sustainable Short Carbon Fiber Reinforced Polymers (SCFRPs) have been prepated via coupling highly bio-based epoxy matrices and recycled carbon fibers, reclaimed by the pyro-gasification of CFRPs. First, the thermo-mechanical properties of SCFRPs made of virgin (Vi), treated virgin (TVi), and recycled (Re) carbon fibers were assessed using a commercial BPA-petroleum based epoxy resin in a lab hot-press manufacturing process; then two single aromatic diglycidyl ethers from vanillyl alcohol (DGEVA) and gastrodigenin (DGEGD) were used for making SCFRPs either with virgin or recycled short carbon fibers with the same optimized processing conditions. Although all the recycled carbon fiber-based composites showed lower mechanical properties than the virgin fiber-based ones, it was determined that recycled carbon fibers reclaimed by the pyro-gasification are suitable to make SCRPS for non-structural applications, where lightweight and high-performance materials are still desired. Interestingly, the DGEVA- and DGEGD-based composites exhibited almost the same thermo-mechanical properties as the composites made of the commercial epoxy resin, highlighting the aptitude of these bio-based epoxy prepolymers to replace current BPA-, petroleum-based epoxy resins in composites manufacturing in the near future. This pioneering work paves the way for the development of more sustainable, high performance CFRPs and provides impetus toward the increase of polymers and composites derived from renewable resources.

Coupling bio-based epoxy resins and recycled carbon fibers: New advances in more sustainable CFRPs

Imines are precursors for synthesis of ligands, amines and heterocyclic compounds. Though various catalysts have been developed for carbonyl-primary amine condensation reactions. Solvents and catalysts often prolongs workup process. A concise and solvent-free procedure for synthesis of Schiff bases with aromatic aldehydes and primary amines has been developed. Conventional methods require azeotropic distillation and using drying agents. This is not only environmentally degrading but also time-consuming. In this poster we will present a concise method which will eliminate the need of solvent. The method is designed for energy efficiency by incorporating microwaves to supply heat and evaporate water.

Concise and green synthesis of imines using microwaves

The utilization of wood-derived building blocks (xylochemicals) to replace fossil-based precursors is an attractive research subject of modern polymer science [1, 2]. The continuing development of new bio-based feedstocks opens opportunities to increase the resource base from which chemical and materials engineers can draw to meet specific polymer property requirements. Recently, significant efforts have transpired to obtain bio-based polymers and copolymers with enhanced thermomechanical properties for a wide variety of applications [3, 4]. In continuing these efforts, we have prepared and examined novel linear aromatic, semiaromatic and aliphatic polyesters derived from varied xylochemicals. In order to prepare a series of polyesters with varied and well-defined thermomechanical properties, bio-based bisphenolic analogues, synthesized via electrophilic aromatic condensations of lignin-based building blocks, and naturally available triterpene diols were polymerized with multiple activated diacids through interfacial or melt polycondensations [5, 6]. These novel thermoplastics were characterized to assess their processing-structure-property relationships and compared to industrial, fossil-based “equivalents”. The results of our studies illustrate that these new polymers are valid alternatives to petroleum-based materials currently employed in the plastics industry and are able to withstand extremely elevated temperatures.

Towards sustainable high performance thermoplastics: Synthesis, characterization, and enzymatic hydrolysis of xylochemical based polyesters

Two-phase mixtures can evolve with time by the diffusion of mass from regions of high to low interfacial curvature, a process known as coarsening.  The coarsening process changes the size scale of the two-phase mixture, and thus has a major effect on the properties of many materials.  In the case of nearly spherical solid-particles in a liquid, an analog of precipitation hardened alloys used in structural materials, experiments on the International Space Station have been used to test the foundational classical theory of coarsening.  For dendritic solid-liquid mixtures, the lack of sedimentation has allowed us to examine the breakup of the dendritic structure found following solidification that plays a major role in setting the grain structure, and hence strength, of cast and additively manufactured metals. The results of the experiments and their implications to the design of new alloys will be discussed.

Microgravity materials science: The dynamics of coarsening processes

Environmental and health consciousness have propelled the advancement of biobased materials. Over the past few decades, polymers developed from sustainable resources have been deemed a viable alternative to their petrochemical analogs. For example, thermosets of isosorbide methacrylate, which is derived from glucose, displayed the highest ever glass transition temperature of a vinyl ester resin while containing a strikingly low viscosity as a polymerized resin. It is often the case that natural monomers contain unique substitution patterns which differ from there petrochemical analogs. Flavones are one such class of naturally abundant compounds whose aromatic substitution and core fused rings can offer structural integrity affording a stiff, highly crosslinked rigid polymeric material. Tri and di substituted methacrylates of flavone derivatives were synthesized, thermally and photocured in the presence of reactive diluent, acryloylmorpholine and styrene. Reactivity ratios were investigated in efforts to ascertain optimal cure conditions. Dynamic mechanical analysis was used to measure the glass transition temperatures and modulus of the cured resins.  Glass transition temperatures ranged from 170-200°C, depending on the formulation and moduli ranged from 3.1 GPa to 3.6 GPa.  Flory-Fox analysis was utilized to ascertain the glass transition temperature of the neat flavone resin, indicating a value of ~300°C.  Char content was high for these resins, at about 25%, which corresponds to carbonized structure of the bicyclic ring in the flavones used.

Novel bio-based methacrylate resins based on flavones

Photocure additive manufacturing, such as stereolithography, continuous liquid interface production, and digital light projection, have increased in popularity due to its excellent resolution, low porosity, and low defect concentration. Yet, photocure AM resins generally have low to moderate moduli and glass transition temperatures, making these poor choices for structural applications. We have thus developed improved (meth)acrylate resins for photocure additive manufacturing relative to commercial resins through formulation of commercial and new monomers. Prior to use in additive manufacturing equipment, we began identifying optimum formulations through examination of rheological properties of the resins, and thermal and mechanical properties of the polymers after photocure. Using this, we determined that use of approximately 25 wt% reactive diluent, isobornyl acrylate or acryloylmorpholine, is ideal. The use of reactive diluent in general is critical to maintaining low viscosities and increasing the extent of cure and strength of the resulting materials. Isosorbide methacrylate also reduced the resin viscosity while increasing the glass transition temperature significantly, but caused the materials to be more brittle when used as the sole crosslinker. Commercial urethane acrylate oligomeric crosslinkers, such as Allnex Radcure Ebecryl 4859, were ideal in increasing the strength of the resin. Ideal formulations comprised of isosorbide methacrylate, Ebecryl resins, and acryloylmorpholine were then cured on the Formlabs Form 1 Plus, steroelithography instrument. Additive manufacture of these resins produces similar properties relative to photocure and improved properties relative to commercial SLA resins.

Photocurable resins for additive manufacturing

This work focuses on novel acid-free dissolution recovery of high purity rare earth elements (REEs) from e-wastes. REEs are crucial for many applications including clean energy, transportation, high-tech devices, and advanced manufacturing. However economically viable REEs sources are limited. The current geographical distribution of REE production does not favor most countries. Considering the projected ~300% increase in REEs demand from 2010-2035,[1] supply disruptions can threaten national manufacturing and economic security. Any new technology with substantial critical REEs dependence can trigger supply disruptions and market instability that impact all users of these materials. The development of economical, efficient and safe recycling technologies can help to minimize the consequences of supply disruptions by reducing the burden on freshly-mined REOs. It is expected that recycling and recovery of REEs from sources such as electronic wastes could help to reduce the impact of any supply disruption from freshly mined materials. However, recycling rate is still low (less than 1%), mainly due to the low concentration of these REEs in products and the difficulty in developing profitable technologies. Typically, hydrometallurgical recycling processes rely on large amounts of strong mineral acids to dissolve and recover the REEs in their oxide forms. As result acid-contaminated wastes, which can harmfully impact the environment and limit technology adoption, are produced. Our new technology eliminates the use of acids whilst being efficient, fast and more environmentally friendly. As a result, REEs are recovered without the risks associated with acid-dissolution based technologies. To demonstrate the suitability of the recycled REE for remaking magnets, Nd-Pr metal ingot was made using the oxides recovered. The ingots were used to make permanent magnets with properties similar to the commercially available magnets.

Applying ‘green chemistry’ and ‘circular economy’ principles in recycling of rare earth elements from e-waste

As the search for green corrosion inhibitors for industrials metals intensifies, research focus is on polymers, particularly the natural polymers. Polymers are attractive due to their availability, cost effectiveness, compatibility with natural environment, inherent stability, and presence of multiple adsorption centers. However, their anticorrosive ability is challenged by their poor solubility property in aqueous medium and instability at elevated temperatures. Incorporation of silver nanoparticles (AgNPs) into polymer matrices has been found to enhance thermal stability property greatly. Chitosan/AgNPs, Gum Arabic/AgNPs, carboxymethyl cellulose/AgNPs, and Dextran/AgNPs composites have been successfully synthesized and tested as anticorrosive agent for low carbon steel in strong acid environments at different temperatures. They have been found to be effective in retarding steel corrosion. The corrosion protection performance of the natural polymer-AgNPs composites is found to be dependent on temperature, concentration and polymer molecular weight. The mechanism of corrosion protection by the polymer/AgNPs composites has been elucidated using advanced instruments including the X-ray Photoelectron Spectroscopy (XPS). Natural polymer/AgNPs composites are promising green anticorrosive agent for industrial processes like acid pickling, oil wells acidizing, descaling, etc.

Exploration of natural polymers/silver nanoparticles composites as inhibitors for corrosion protection of industrial metals

Particulate matter (PM) refers to the mixture of solids and liquids suspended in the air. PM can exist in many sizes, and is produced by different processes; thus size, chemical composition, and toxicity of PM depends on the source. Small PM (particularly PM2.5, referring to particles of diameter &lt; 2.5 µm) is known to have significant health impacts. This study focuses on the quantification of heterocyclic aromatic amines (HAAs) in environmental PM by High Performance Liquid Chromatography-Tandem Mass Spectrometry (HPLC-MS/MS). HAAs are produced by biomass combustion and in the cooking of meat, and are both mutagenic and carcinogenic. Relatively few published studies have reported concentrations of HAAs in environmental PM. The HAAs studied here include: 1-methyl-9H-pyrido[3,4-B]indole (Harman), 9H-pyrido[3,4-B]indole (Norharman), 2-amino-9H-pyrido(2,3-B)indole (AαC), 2-amino-3-methylimidazo[4,5-F]quinolone (IQ), 2-amino-3,4-dimethylimidazo(4,5-F)quinolone (MeIQ), 2-amino-3,8-dimethylimidazo[4,5-F]quinoxaline (MeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-B]pyridine (PhIP), and 2-amino-3,4,8-trimethylimidazo[4,5-F]quinoxaline (4,8-DiMeIQx). Samples analyzed include total suspended particulate samples from Ho Chi Minh City, Vietnam (HCMC). In addition, Standard Reference Material 1648a was used to assess method performance. HCMC and SRM samples were extracted ultrasonically in acetonitrile and analyzed (HPLC-MS/MS). Detection limits for the HAAs were in the range of 0.14-4.2 µg/g, based on laboratory method blanks and a nominal sample mass of 1 mg. Concentrations of harman, norharman, and AαC were found in ranges of 21-330 µg/g, while IQ, MeIQ, MeIQx, 4,8-DiMeIQx, and PhIP were not observed at concentrations above the detection limit.

Quantification of heterocyclic aromatic amines in particulate matter by high performance liquid chromatography-tandem mass spectrometry

With the support and training from cCWCS workshop, our research group has been actively investigating the antibacterial activities of various medicinal plant species. Our group has presented the previous work at national meetings. In this paper, we present the comparative study of the activities of various species of same basil family (Lamiaceae). Eight different basil plant samples were extracted and used for this study. Their antimicrobial activity results against Escherichia coli (E. coli) and comparison with tetracycline as a positive control are discussed.

In vitro antibacterial activities of basil species: Ocimum sanctum, Ocimum tenuiflorum, and Ocimum basilicum

After attending cCWCS workshop on medicinal plants chemistry, our research group has been actively exploring the chemical constituents of various medicinal plants. Basil, a popular culinary and medicinal herb is cultivated in several countries. A distinct flavor variation among Thai basil, Italian basil, and Indian basil prompted us to explore the variations in medicinal compounds in eight different species. Dried Basil species (Ocimum sanctum, Ocimum tenuiflorum, Ocimum basilicum) collected from various parts of the world were extracted using Soxhlet apparatus. Active ingredients, methyl eugenol and methyl chavecol, were identified using TLC/ HPLC and collected using column chromatography.

Comparison of chemical constituents of various species of basil

Medicinal Plants provide excellent learning opportunities that connect chemistry and biology. This paper describes the design and implementation of research project based on medicinal plants chemistry in undergraduate organic chemistry laboratory. The multidimensional approach for this research project was developed after attending the “cCWCS Medicinal Plants” curriculum and pedagogy workshop. Collaboration with Plant Biology faculty and the Library faculty helped students learn about various medicinal plants and the literature search. After selecting the medicinal plant for study, each group identified appropriate methods, instrumentation, and supplies applicable for this project. Students then integrated various laboratory techniques to isolate and identify medicinal compounds. This unique learning approach provided students real world experiences and developed students’ research skills. This early research experience resulted in development of senior research projects.

Design and implementation of medicinal plants research project in organic chemistry laboratory

Calculating a molecule’s vibronic spectrum is a hard problem in theoretical chemistry, as any ground-state vibrational mode can couple to any excited-state mode via the Duschinsky transformation. Though this problem scales combinatorially on a classical computer, researchers have previously proposed an O(N^3) scaling algorithm that solves the vibronic problem using a Boson Sampling Device. With a wholly different approach that uses the quantum phase estimation algorithm in the standard circuit model, we present a quantum algorithm that scales as O(N^2) in both classical and quantum operations, with linear circuit depth. Besides the scaling improvement, we also present methods that allow for substantial reductions of the number of samples collected. Additionally, because our measurement procedure does not destroy the vibronic state, the final state can be used in further computational analyses. Finally, we show how one would include finite temperature effects with a small cost. Our results are relevant to chemical/materials discovery and to the simulation of bosonic systems on a universal quantum computer.

Simulating vibronic molecular spectra on a universal quantum computer

The geometric, electronic and chemical properties of Au nanoparticles supported by TiO2 have been the subject of much work since the discovery by Haruta that Au is a low temperature oxidation catalyst. Despite this earlier work there is no definitive evidence for the binding site or the direction of charge transfer associated with gold atoms and nanoparticles on the model substrate TiO2(110). In this work we have used STM to examine the nucleation properties of Au nanoparticles dispersed over a reduced rutile TiO2(110) surface. From comparisons of the surface before and after Au deposition, and using atomic manipulation, the nucleation site of single Au atoms was directly observed to be at oxygen vacancies on the substrate (Ob-vacs), with dimers similarly anchored. Associated DFT calculations suggest electron transfer from bridging O vacancies to Au. In another attempt to gauge the degree of Au/TiO2 charge transfer, synchrotron based X-ray photoelectron emission microscopy (XPEEM) was used in conjunction with STM and low energy electron microscopy (LEEM) to probe the electronic character of Au nanoparticles as a function of particle size and coverage. Core-level binding energy measurements reveal a two stage shift in Au 4f binding energy as the nanoparticle size increased in line with electron transfer from bridging oxygen vacancies to Au for small nanoparticles (&lt;4 nm) on TiO2(110). To reduce experimental error, a method was developed to precisely pattern the substrate with discrete regions of varying Au coverage on the nanometer scale. Turning to the Au naoparticle size dependent behavior of photocatalysis, we show that H2 evolution from ethanol varies as the separation between nanoparticles. This appears to originate from a competition betweeen the nanoparticles to trap photogenerated electrons.

Gold nanoparticle interactions with rutile TiO2(110)

Small electron polarons associated with bridging oxygen vacancies have been shown to be present on TiO2(110). Above 17 K they hop around the vacancies. Here we look at the intercation between these polarons and water. Water-oxide surfaces are ubiquitous in nature and of widespread importance to phenomena like corrosion as well as contemporary industrial challenges such as energy production through water splitting. So far a reasonably robust understanding of the structure of such interfaces under certain conditions has been obtained. Considerably less is known about how overlayer water modifies the inherent reactivity of oxide surfaces. Here we address this issue experimentally for rutile TiO2(110) using scanning tunneling microscopy and photoemission, with complementary density functional theory calculations. Through detailed studies of adsorbed water nanoclusters and continuous water overlayers, we determine that excess electrons in TiO2 are attracted to the top surface layer by water molecules. Measurements on methanol show similar behavior. Our results suggest that adsorbate-induced surface segregation of polarons could be a general phenomenon for technologically relevant oxide materials, with consequences for surface chemistry and the associated catalytic activity.

Polarons on TiO2 and their affinity for water

Development of novel cathode materials having improved energy storage capabilities may lead to inflate the use of lithium ion batteries (LIBs) in electric vehicles (EV) and energy storage systems (ESS). The challenging requirement of high energy density can be achieved by developing cathode materials having either high gravimetric capacity and high operating voltage or a combination of both of aforementioned factors. This indicates that the synthesis of novel cathode materials demonstrating high gravimetric capacity and high operating voltage is really needed and a study devoted to this aim would be quite feasible. The proposed research work is focused on the synthesis and characterization of high voltage lithium-based cathode material with general formula Li4M3(PO4)2 (P2O7) [where M= Fe, Mn]. Among various possible transition metals (M), Fe and Mn are selected due to their promising electrochemical performance and cost effectiveness. All the materials were synthesized using sol-gel synthesis method. Furthermore, the graphene based composite cathodes were also synthesized to improve the electrical conductivity and thus energy storage performance of the above mentioned cathode materials. The structural (crystal structure, phase purity), morphological (particle size, shape, distribution), thermal and energy storage capability (CV, charge/discharge capacity, cyclability, rate capability) of the developed materials were studied using several characterization tools such as X-ray diffraction (XRD), scanning electron microscope (SEM), Thermal gravimetric analysis (TGA) and battery cycler.

Novel, high-potential cathode materials for next-generation lithium-ion batteries

Primary cell wall is a complex heterogeneous mixture of several polysaccharides including cellulose, hemicellulose and pectin. Within these cell walls, cellulose exists as microfibrils forming a crystalline structure that plays an important role in the biological processes of plant growth, conversion of cellulosic biomass into biofuels and in understanding the physical properties of cellulose derivatives. It also holds promise as a source of renewable energy and is an important raw material for paper, textile and construction materials. However, several aspects of crystalline structure of cellulose remain elusive. One such structural parameter is the orientation of cellulose crystallites within the fibrils. This parameter can be an important determinant of the mechanical properties of cell wall as well as cellulose-cellulose and cellulose-matrix interactions. We studied the structure of cellulose in primary cell walls of plants through grazing incidence wide angle X-ray scattering (GIWAXS). It is a morphological characterization tool that can probe the sample surface as well as beneath it. The grazing incidence geometry yields high signal-to-noise ratio and causes lesser radiation damage, making it ideal for plant cell wall samples which are fragile and weakly scattering. We found that the technique could decouple scattering from cellulose and wax crystals. X-ray scattering of different chemical treatments of the cell wall revealed strong texturing of cellulose. The degree of preferred orientation of the crystals was determined through pole figures constructed from the combination of GIWAXS and XRD rocking scans. It was found that the texturing depends on the developmental age of the tissue and also on its source.

Grazing incidence X-ray scattering reveals texturing in primary cell walls

Rational, data-driven materials discovery has the potential to make research and development efforts far faster and cheaper. In such a paradigm, computer models trained to find patterns in massive chemical datasets would rapidly scan compositions and systematically identify attractive candidates.  Here, we present several examples of our work on developing machine learning (ML) and deep learning methods capable of creating predictive models using a diverse range of materials data. As input training data, we demonstrate ML on both large computational datasets of DFT calculations, as implemented in the Open Quantum Materials Database (oqmd.org), and also experimental databases of materials properties.  We construct ML models using a large and chemically diverse list of attributes, which we demonstrate can be used as an effective tool to automatically learn intuitive design rules, predict diverse properties of crystalline and amorphous materials, such as formation energy, specific volume, band gap energy, and glass-forming ability, and accelerate combinatorial searches.

Using artificial intelligence to discover new materials

Pipelines move nearly 75% of the oil transported worldwide annually since they are efficient and environmentally friendly compared to other transportation means. Erosion and corrosion of the oil and gas pipelines are serious problems that lead to disastrous failure and damage to life and the environment. The global cost of such failure is in the billions of dollars annually. Therefore, there is an increased need for the development of strategies to combat such failure. Superior protective coatings, including electroless one, are the common method for protecting oil and gas pipeline steels for their unique combination of properties such as wear resistance, corrosion resistance, and higher hardness. In this talk, we will present the synthesis and characterization of novel electroless NiP-TiNi nanocomposite coatings on API X100 steel surfaces from an acidic electroless NiP plating solutions containing different concentrations of TiNi nanoparticles. The morphology, thickness and elemental composition for the nanocomposite coatings investigated by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy will be presented. The nanocomposite coatings were heat-treated at 400 oC for 1 hour. The phase structure, roughness and hydrophobicity of the as-plated and heat-treated coatings using X-ray diffraction, atomic force microscopy and contact angle measurements, respectively, were investigated. Effect of TiNi nanoparticles composition on the micro-hardness and corrosion resistance of the as-deposited and the heat-treated coatings will be also presented. The results indicated that the TiNi nanoparticles are distributed uniformly in the NiP matrix. The corrosion resistance and micro-hardness of the NiP-TiNi coatings were greatly enhanced after incorporation of the TiNi nanoparticles and even further improved by annealing at 400 oC for 1 hour, as shown in the enclosed Figure. The wear and anti-fouling characteristics of the coatings will be also discussed.

Novel NiP-TiNi nanocomposite coatings for harsh oil and gas environments made by the electroless technology

Photoelectrochemical (PEC) water splitting is one of the potential approaches for the generation of hydrogen which can fulfill the global energy requirement . In developing economical and efficient photo-catalysts for water oxidation, n-type monoclinic BiVO4 has been widely reported due to its favorable band gap. But the photo conversion efficiency of BiVO4 catalyst is relatively low due to poor charge transport, fast surface charge recombination and sluggish water oxidation kinetics . In current report, BiVO4 photocatalyst doped with ytterbium (Yb) was prepared by ultrasonic spray coating technique to overcome poor charge transport. Various percentage of Yb (1,2,3,4,5 wt %) is doped in pristine BiVO4 to optimize the PEC performance. The 3wt % Yb doped BiVO4 photo-anode has shown highest PEC photo current 2.8 mA/cm2 at 1.23 V RHE and 5.8 mA/cm2 at 2 V RHE under simulated one sunlight illumination at front surface in K2HPO4 electrolyte. However, the photocatalytic activity of the other Yb: BiVO4 photo anodes were suppressed as the Yb doping level decreased or increased, which could be attributed to the formation of photogenerated charge carrier recombination centers at the Yb substituting sites. Here, Yb3+ dopant replaces Bi3+ sites in BiVO4 lattice to provide expanded light absorption wavelength region from 400-600nm. Further, Yb: BIVO4 photoanode were investigated by XRD, XPS and SEM. It was observed from XRD that Yb-doping didn’t generate any impurity phases in pristine BiVO4. XPS analysis showed the Yb-peaks 4d3/2 and 4d5/2 at the binding energies 193eV and 184eV respectively, which confirm the oxidation state of Yb as +3. The electrochemical impedance and cyclic voltametry measurements showed that the Yb doping lowered the interfacial resistance, charge transfer resistance and increased the charge donor/surface state density. Further PEC performance was corroborated with changes in band gap, crystal lattice, surface grain morphology occurred due to Yb doping in BiVO4.

Light Absorption management by systematic ytterbium doping in monoclinic BiVO4 for enhancement in photoelectrochemical water oxidation

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.