Polymers derived from renewable resources are becoming considerably attractive as sustainable alternatives to their petroleum-derived counterparts. Lignin is a natural and abundant raw material made up of cross-linked aromatics that could potentially be broken down to yield renewable bio-based monomers for applications in high-performance thermosetting resins. Vanillin, a lignin-derived aromatic molecule, can be reduced to yield an aromatic diol, vanillyl alcohol. Vanillyl alcohol is a promising monomer for the synthesis of epoxy pre-polymers. In this work, diglycidyl ether of vanillyl alcohol (DGEVA) was synthesized and its chemical structure was confirmed by 1H-NMR, 13C-NMR, FT-IR, and GPC. Bimodal resin blends of diglycidyl ether of bisphenol A (DGEBA) with varying weight ratios of DGEVA as well as other single aromatic epoxies were prepared and cured with a diamine to investigate their structure-property relationships. Thermogravimetric and viscoelastic properties of the cured resins were characterized and compared using TGA and DMA, respectively. The vanillyl alcohol based epoxy-diamine system possesses a higher glass transition temperature Tg (106 °C) than the other single aromatic epoxy-diamine systems as well as a higher storage modulus E' at 25 °C (3 GPa) than the petroleum-based DGEBA-diamine resin.

Synthesis, characterization, and bimodal blend studies of renewable biobased epoxy resins from vanillyl alcohol

Photocatalysis by utilization of inexhaustive solar energy is a promising green technology that effectively degrades persistent environmental pollutants. However, current photocatalysts suffer from limited visible light adsorption, low reactivity, instability, and high cost. Recently, graphitic carbon nitride (g-C3N4) has emerged as a novel polymeric photocatalyst and attracts a great attention because it is capable of adsorbing visible light, because it is reactive for contaminant removal (e.g., NO, pathogens), because it is physically and chemically stable in oxidative reactions, and because it is made from inexpensive organic precursors. We synthesized g-C3N4 samples from four different precursors (urea, melamine, dicyandiamide, and thiourea), and applied them for phenol degradation under visible light irradiation (&gt; 400 nm). The preliminary results show that g-C3N4 synthesized from urea has the highest phenol removal efficiency, with a 1st order rate constant of 0.026 min-1. The reaction rate constant is 6-8.7 folds higher than those from the other precursors. The results indicate that the g-C3N4 has a promising future in removal of waterborne contaminants, and that performance is likely affected by physical and chemical properties of g-C3N4. To enhance the photocatalytic performance, we will increase the surface area of g-C3N4 by etching templates and creation of a porous structure, extend the absorption spectrum of g-C3N4 by carbon doping, and improve charge separation by loading metals or forming heterojunctions with other photocatalysts (e.g., TiO2, BiVO4). We will next apply the optimized g-C3N4 for persistent waterborne contaminant removal (e.g., carbamazepine, atrazine) in a complex water matrix to address challenges for contaminant removal in real water. This study explores the potential application of a new visible-light-responsive photocatalyst for water decontamination, and sheds light on achieving sustainable water treatment and water reuse.

Visible-light-responsive graphitic carbon nitride for photocatalytic degradation of persistent waterborne contaminants

Increasing the storage capacity is a crucial goal of battery research. Li-ion battery cathodes have severe capacity limitations; while Li-O2 batteries promise much higher theoretical capacity, they are plagued by several key challenges. Li-O2 batteries generally exhibit high overpotentials and form Li2O2 which may lead to electrolyte decomposition. In this talk, we explore hybrid materials that are a combination of the two – Li-transition metal-oxides that embody both Li-ion and Li-O2 reactions,1 with smaller-than-typical overpotentials and without forming Li2O2. The prototype hybrid Li-ion/Li-O2 material is Li5FeO4, which when used as an electrocatalyst in Li-O2 cells, reduces overpotentials and demonstrates a capacity of ~500 mAh/g unrelated to Li2O2 formation.2 Using first principles density functional theory (DFT) calculations, we performed a high-throughput search for similar hybrid materials with high capacities and suitable properties.3 While hybrid materials exhibit promising capacities of up to 1000 mAh/g, their reaction mechanisms remain unknown. We performed DFT investigations of the reaction mechanisms in several of these materials, including Li5FeO4, Li6MnO4, Li6CoO4, and Li8IrO6. DFT calculations are performed to investigate the thermodynamics of Li and Li-O removal from these materials, in order to establish the details of the charge reaction. Atomistic and electronic structural changes in the materials are tracked during the reactions. Results on the energetics indicate a cross-over between pure lithium removal and concomitant oxygen loss, which is electronically shown to be correlated with development of the peroxide-like character of oxygen. Acknowledgement This research was supported as part of the Center for Electrochemical Energy Science, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences (Award Number DE-AC02-750 06CH11357). Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. References (1) M. M. Thackeray, M. K. Y. Chan, L. Trahey, S. Kirklin, and C. Wolverton, JPCL, 2013, 4, 3607. (2) L. Trahey, C. S. Johnson, J. T. Vaughey, S.-H. Kang, L. J. Hardwick, S. A. Freunberger, P. G. Bruce, M. M. Thackeray, ESSL, 2011, 14, A64. (3) S. Kirklin, M. K. Y. Chan, L. Trahey, M. M. Thackeray, and C. Wolverton, PCCP, 2014, 16, 22073.

Li-ion and Li-O2: exploring hybrid electrode/electrocatalyst materials

Fundraising plays a major role in the ACS Student Affiliate Chapter of the NDSU Chemistry and Biochemistry Club. Fundraising allows us to be an increasingly active chapter and boost awareness of chemistry in the Fargo-Moorhead area. The fundraising is done both on and off campus. Some on-campus fundraising includes goggle sales for chemistry labs and selling practice chemistry tests in intro level courses. One of the valuable sources of off-campus fundraising opportunities includes networking with local companies. The majority of the funds raised go to the community outreach projects for the purchase of chemicals and supplies for demonstrations. The funding also supports inter-club activities and student attendance at the National ACS meeting. Fundraising enables the NDSU Chemistry and Biochemistry Club to get students more involved in research, community outreach, and networking opportunities.

Fundraising methods at North Dakota State University

The past fifty years has seen remarkable strides in chemists’ abilities to prepare materials, which has led to key advances from the silicon revolution to high performance turbines and battery technology. Recently, layered and two dimensional materials have come to prominence with a wide range of applications in batteries, sensors, photovoltaics, catalytic processes, and energy transport. Despite the existence of numerous preparative methods to concoct these materials, compared to other sub-fields of chemistry, existing synthetic methodologies and formal method development are in their infancy. In this talk, I will present some of our current efforts into understanding the reaction mechanisms and expanding the reaction scope of classic solid-state transformations in layered materials, with a particular emphasis on how control of the structure and electron count dictates the resulting chemical and physical properties. Examples will be drawn from our efforts in preparing higher performance superconductors useful in sensors and energy storage.

Preparation of new layered and 2D materials with basic science and energy applications

The superior light extinction properties of plasmonic nanostructures make these materials attractive candidates for enhancing the performance of photovoltaic devices. Such enhancement is predicted to be particularly prominent in the case of small-diameter metal nanoparticles, where radiation modes are strongly confined. Unfortunately, the energy of surface plasmon (SP) emission becomes difficult to collect if the nanostructure size falls below 20 nm, as it efficiently couples to lattice phonons, resulting in the generation of heat. Here, we explore the feasibility of converting such near-field radiation of 5-nm Au nanoparticles through resonant coupling to an array of PbS semiconductor nanocrystals. We demonstrate that the key to an efficient conversion of the SP emission into photovoltaic energy lies in the judiciously designed architecture of nanoparticle solar cells that reduces carrier scattering on Au dopants and simultaneously improves the stability of heat-prone plasmonic films. The contribution of the near-field emission in Au nanoparticles towards the charge carrier generation was manifested through the observation of an enhanced short circuit current and improved power conversion efficiency of prototype (Au, PbS) solar cells, as measured relative to PbS-only devices.

Plasmonic nanocrystal solar cells utilizing strongly confined radiation

The ability to control particle size and morphology through economically and environmentally sound techniques is highly desired in bulk-scale nanomaterial synthesis. Each of these facets is largely controlled by the solvent used for synthesis. Ionic liquids have recently been explored as novel solvents for chemical synthesis due to their unique solvation capabilities and low vapor pressures. However, these characteristics also make it difficult to recycle ionic liquids in chemical processes. We have developed a novel synthetic strategy using switchable ionic liquids (SWILs) for the synthesis of metal nanoparticles. SWILs are mixtures of an alcohol and an amine base with an acidic trigger gas (CO2, CS2, COS, SO2). The ionic character of the solvent can be turned on and off by addition or removal of the trigger gas from solution. This switch affords us the ability to dissolve high concentrations of precursors in a polar environment and then promote nucleation, growth, and isolation of nanoparticles in a non-polar environment. The applicability of these SWIL systems for nanoparticle synthesis and the characterization of these materials will be discussed.

Nanoparticle synthesis using switchable ionic liquids

This work studies the removal of Cd, Cr and Pb-ions in water using electric induction furnace slag (EIFS), which is an unused byproduct of the metallurgical industry in Mexico. The effects of initial ion concentration and adsorbent dose were investigated. X-ray Fluorescence, X-ray Diffraction and electrokinetic measurements of slag particles analyzed the EIFS. The results were correlated to the adsorption behavior of the slag for the respective heavy metals. Solutions of three different heavy metals ions were prepared in concentrations ranging from 1 to 10 mg/L, and adsorbent doses from 0.064 to 0.64 g/L were added following an experimental design for the removal of these pollutants by the EIFS. The maximum measured removal efficiencies were 74% for Cr6+, 64% for Cd2+ and 34% for Pb2+. The influence of ion concentration and adsorbent dose was statistically significant, showing that the lowest ion concentration and the highest adsorbent dose produced the best removal results. The efficiencies are similar to the ones reported for fly ash, natural oxides and other industrial waste materials, which demonstrates the possibility of using EIFS as a low-cost adsorbent for heavy metals. The most probable removal mechanism for Cd2+, Cr6+ and Pb2+ is chemical adsorption by silanol and aluminol groups present in EIFS.

Removal of heavy metals with steel furnace slag

249th National Meeting (2015)

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