bluuebunny/crossref_metadata_2025 huggingface dataset:
(Student Battery Slam Best Presentation Award Winner) “Water-in-Salt” Polymer Electrolyte for Li-Ion Batteries
Authors: Zhang Jiaxun , Yang Chongyin , Wang Chunsheng
Published: July 2021

Lithium ion batteries (LIBs) have been widely applied in multitudinous energy storage systems due to their high energy density, long cycle stability and high energy efficiency. While the public concern over the safety of LIBs increases rapidly with our reliance on this technology in our daily life, for which the nonaqueous and highly flammable electrolyte should bear most of the responsibility. Aqeuous rechargeable lithium ion batteries resolve several challenges of conventional LIBs. However, the electrochemical stability window of aqueous electrolytes is less than 2.0 V, beyond which the electrolysis of H2O with the hydrogen evolution reaction at anode (H2 generated) and oxygen evolution reaction at cathode (O2 generated). Recently, the ground-breaking of “water-in-salt” electrolyte (WiSE) successfully expanded the ESW of water to 3.0 V. To further enhance the energy density of WiSE based batteries, the cathodic limitation of 1.9 V needs to further reduced, and a high Coulombic efficiency (CE) of > 99.9% at a matched areal capacities of cathode/anode is required for a long-term cycling. Here, we designed a solid-state aqueous polymer electrolyte (SAPE) by incorporating WiSE with UV-curable methacrylic polymer. The abundant hydrophilic groups of the polymer stabilized water molecules due to the sluggish water mobility in SAPE and formed a water-less thin passivation interphase between anode and electrolyte. In addition, by pre-coating a strongly basic water-free solid polymer electrolyte on the surface of anode, an artificial passivation interphase was formed. A robust SEI was formed on the surface of anode and the water reduction reaction is suppressed in our electrolyte system. Also, an extended electrochemical stability window of 3.86 V is achieved at 12 mol kg-1 aqueous polymer electrolyte, enabling the 3 V full cells cycled with an unprecedented high initial CE of 90.5% and average CE of 99.97%. The SAPE exhibits intrinsic safety and tolerance of drastic mechanical abuse, the flexible full cell with supper robustness can be widely used for low-cost and high-safety flexible electronic devices. Moreover, the UV-cured polymerization process possesses the merit of facile and high efficiency, and the whole process have the potential to be practical used in a large scale. Overall, this newly developed reduced salt concentration WiSE not only reduces the cost of aqueous electrolyte, but also opens up another perspective on future directions and guidance for the design of aqueous electrolyte for high-energy-density Li-ion batteries in practical applications.
Understanding Chemical Crossover in Redox Flow Batteries Via Quantitative Structure-Property Relationship Modelling
Authors: Rhodes Zayn , Minteer Shelley D.
Published: July 2021

The understanding of anode and cathode chemical crossover in redox flow batteries (RFBs) is imperative to crossover mitigation and the development of high-performing RFBs for green energy storage. This may be accomplished through investigating the fundamental transport properties of chemical crossover in redox flow batteries (RFBs) through the discovery of quantitative structure-property relationships (QSPRs) by developing predictive multivariate linear regression (MLR) models. Through the isolation of steric and electronic molecular parameters that impede chemical crossover in RFBs, these parameters may be successfully tuned to rationally design electrolyte species that are crossover resistant. This approach effectively mitigates one of the predominate mechanisms of RFB degradation, thereby addressing a large hurdle to their successful commercialization. Herein, we demonstrate the process of model development and present our findings toward achieving crossover resistant electrolytes and tuning molecule-separator interactions to further enhance whole system crossover resistance.
Electrocatalytic Cross-Coupling Reactions Assisted By Redox-Active Mediators
Authors: Sevov Christo
Published: July 2021

The seminar will detail electrocatalytic C–C and C–N bond-forming methodologies enabled by redox-active mediators and shuttles. Here, we will demonstrate a symbiotic relationship between energy storage and metal-catalyzed organic synthesis. Two research initiatives will be discussed that highlight the use of a mediator to (i) protect a coupling catalyst from overreduction through a degenerate shuttling of electrons and (ii) assist in oxidation of complexes with slow ET kinetics under electrochemical conditions.

The concept of protecting catalyst from degradation using shuttles will be discussed in the context of cross-electrophile coupling (XEC). Couplings of alkyl and aryl halides promoted by electrochemistry represents an attractive alternative to conventional methods that require stoichiometric quantities of high-energy reductants. Most importantly, electroreduction can readily exceed the reducing potentials of chemical reductants to activate catalysts with improved reactivities and selectivities that are otherwise incompatible with conventional reductants. This work details the mechanistically-driven development of an electrochemical methodology for XEC that utilizes redox-active shuttles developed by the energy-storage community to protect reactive coupling catalysts from overreduction. The resulting electrocatalytic system is practical, scalable, and broadly applicable to the reductive coupling of a wide range of aryl, heteroaryl, or vinyl bromides with primary or secondary alkyl bromides. The impact of overcharge protection as a strategy for electrosynthetic methodologies is underscored by the dramatic differences in yields from coupling reactions with added redox shuttles (generally >80%) and those without (generally <20%). In addition to excellent yields for a wide range of substrates, reactions protected from overreduction can be performed at high currents and on multigram scales

The second half of the talk will demonstrate the use of mediators to protect ligandless complexes that are susceptible to electroplating on a cathode and to facilitate oxidation of the electrochemically-inactive catalysts to the active form. This strategy is applied to an electrochemically driven, scalable Chan-Lam-Evans reaction that utilizes simple copper salts to promote C-N bond formation under an inert atmosphere. This work represents a rare example of air-free CLE coupling. This oxidative reaction is performed in an undivided cell with a simple Cu salt that would otherwise rapidly plate out of solution. Mediator-assisted CLE coupling provides access to a broad range of amine products that are otherwise challenging to form even in air. The methodology seeks to eliminate the need for O2 on scale and provide an attractive alternative for process groups in industry.
Continuous Stirred Tank Electrochemical Reactor for High-Throughput Synthesis
Authors: Graaf Matthew
Published: July 2021

Flow electrolysis has been a crucial component for enabling large-scale applications of organic electrochemical transformations outperforming batch electrolysis. To-date, these applications have mainly focused on microchannel or parallel-plate style reactors1. Although having established numerous examples of successfully performing electrolyses on lab and commercials-scales2, the nature of these reactors often requires recirculating conditions rendering them as semi-batch and sometimes limiting through-put or product quality. This presentation with discuss a modular continuous stirred tank reactor capable of single-pass reactivity to provide multi-kilogram per day throughput and high-product quality with minimal reactor footprint.

References:

[1]: Pletcher, D., Green, R., Brown, R.; Chemical Reviews., 2018, 118, 4573

[2]: Cardoso, D., Sljukic, B., Santos, D., Sequeira, C.; OPRD, 2017, 21, 1213

Matthew Graaf is an employee of AbbVie and may own AbbVie stock. AbbVie sponsored and funded the study; contributed to the design; participated in the collection, analysis, and interpretation of data, and in writing, reviewing, and approval of the final publication.
Selective Aryl-Nitro Reduction of Pharmaceutical Intermediates
Authors: Graaf Matthew
Published: July 2021

Hydrogenation of nitro groups to produce anilines is a well-established transformation in organic chemistry and the pharmaceutical industry [1]. However, high pressure hydrogenations can be hazardous at multi-kilo scales and functional group compatibly is often problematic for pharmaceutical intermediates requiring a specialized catalyst [2]. In a continued effort to promote electrochemistry in pharma as a greener and safer alternative, an improved method of electrochemically producing anilines has been achieved. In this presentation, the development of a robust and efficient undivided Aryl-nitro reduction will be discussed.

References:

[1]: Jones, W.; Platinum Metals Rev., 1958, 2, 86

[2]: Blaser, H-U., Steiner, H., Studer, M.; ChemCatChem., 2009, 1, 210

Matthew Graaf is an employee of AbbVie and may own AbbVie stock. AbbVie sponsored and funded the study; contributed to the design; participated in the collection, analysis, and interpretation of data, and in writing, reviewing, and approval of the final publication.

Figure 1
Bioelectrocatalytic Conversion of N2: From Chemically Inert Gas to Chiral Chemicals
Authors: Chen Hui , Minteer Shelley D.
Published: July 2021

Dinitrogen molecule (N2) is the most abundant natural gas and also the ultimate source of nitrogen for nitrogenated industrial and natural compounds. So far, the fully hydrogenated product, ammonia (NH3), is the most common product of N2 fixation.1 However, NH3, the regular end-product of N2 fixation, is a bulk chemical with low added-value. The conversion of NH3 to nitrogenous compounds with high added-value and complicated structure still requires further tedious chemical synthesis with the use of precious metal catalysts.2 In our study, an upgraded N2 fixation system was firstly designed and constructed based on a bioelectrocatalytic N2 reduction architecture.3 The NH3 generated via N2 reduction catalyzed by nitrogenase was in situ utilized by L-alanine dehydrogenase to realize the reductive amination of pyruvate and the generation of alanine. The reduced equivalent to support the N2 reduction and reductive amination of pyruvate was regenerated by the electrochemical method. ω-TA transferred the amino group from alanine to ketone substrates and finally produced desired chiral amine intermediates.4 On this basis, an H2 fuel cell module was integrated into the upgraded N2 fixation system to construct a self-powered H2/α-keto acid fuel cell. In the new system, the upgraded N2 fixation was powered by the oxidation of H2 with high Faradaic efficiency and without the requirement of external electrical energy input.5 Finally, the end-product of N2 fixation in our study successfully went beyond NH3 and reached high-value-added chiral amine intermediates and chiral amino acids. The produced chiral amine intermediates and chiral amino acids have wild application in pharmaceuticals production and biotechnology research.

References

(1) Foster, S. L.; Bakovic, S. I. P.; Duda, R. D.; Maheshwari, S.; Milton, R. D.; Minteer, S. D.; Janik, M. J.; Renner, J. N.; Greenlee, L. F. Catalysts for nitrogen reduction to ammonia. Nat. Catal.
2018,
1, 490.

(2) Balaraman, E.; Srimani, D.; Diskin-Posner, Y.; Milstein, D. Direct synthesis of secondary amines from alcohols and ammonia catalyzed by a ruthenium pincer complex. Catal. Lett.
2015,
145, 139-144.

(3) Milton, R. D.; Cai, R.; Abdellaoui, S.; Leech, D.; De Lacey, A. L.; Pita, M.; Minteer, S. D. Bioelectrochemical Haber-Bosch Process: An Ammonia-Producing H2/N2 Fuel Cell. Angew. Chem. Int. Ed.
2017,
56, 2680-2683.

(4) Chen, H.; Cai, R.; Patel, J.; Dong, F.; Chen, H.; Minteer, S. D. Upgraded Bioelectrocatalytic N2 Fixation: From N2 to Chiral Amine Intermediates. J. Am. Chem. Soc.
2019,
141, 4963-4971.

(5) Chen, H.; Prater, M. B.; Cai, R.; Dong, F.; Chen, H.; Minteer, S. D., Bioelectrocatalytic Conversion from N2 to Chiral Amino Acids in a H2/α-Keto Acid Enzymatic Fuel Cell. J. Am. Chem. Soc.
2020,
142 (8), 4028-4036.
Electrochemical Cobalt-Catalyzed Selective Carboxylation of Benzyl Halides with CO2
Authors: Malapit Christian , Minteer Shelley D.
Published: July 2021

The direct, transition metal-catalyzed carboxylation of organohalides with carbon dioxide is a highly desirable transformation in organic synthesis as it utilizes feedstock chemicals and delivers carboxylic acids –among the most utilized class of organic molecules. This article reports the development of a sustainable and selective cobalt-catalyzed electrochemical carboxylation of benzyl halides with CO2 to generate phenyl acetic acids. The success of this transformation is enabled by the development of low-coordinate cobalt/pyrox complexes as electrocatalysts to convert various benzyl chlorides and bromides to their corresponding phenyl/heteroaryl acetic acids with high selectivity over undesired homocoupling of the benzyl chloride. The combination of electroanalytical methods, control reactions, and density-functional theory (DFT) calculations informed the mechanistic analysis of this reaction.
Electrochemical Triggering of Reflectin Protein Assembly
Authors: Liang Sheng-Ping , Levenson Robert , Malady Brandon , Gordon Michael , Morse Daniel , Sepunaru Lior
Published: July 2021

In this work, we demonstrate electrochemical triggering and assembly of reflectin, the protein that mediates neuronal fine-tuning of color reflected from skin cells used for camouflage and communication in squids. Electrochemical reduction of histidine residues in the protein acts as an in vitro surrogate for phosphorylation in vivo, driving the assembly previously shown to regulate its function. Using micro-drop voltammetry and in situ dynamic light scattering, we demonstrate selective reduction of the imidazolium sidechains of histidine in monomers, oligopeptides and reflectin in acidic solution. The formal reduction potential of imidazolium proves readily distinguishable from those of hydronium and primary amines, allowing unequivocal confirmation of the direct and energetically-selective deprotonation of histidine in reflectin. The resulting “electro-assembly” methodology provides a new approach to probe, understand, and control the mechanisms that dynamically tune protein structure and function.

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(Invited) Advanced Concepts for Ultra-High Conversion Efficiency of Solar Photons into Photovoltaics and Solar Fuels Based on Semiconductor Nanostructures and Molecular Singlet Fissionajn
Authors: Nozik Arthur J
Published: July 2021

In order to utilize solar power for the production of solar electricity and solar fuels on a global scale, it is necessary to develop solar photon conversion systems that have an appropriate combination of very high efficiency (delivered watts/m2) and low capital cost ($/m2). One potential promising approach to attain high conversion efficiencies well above the Shockley-Queisser limit of 33% is to utilize the unique properties of semiconductor nanostructures (viz., quantum dots/rods/films) and singlet fission chromophores to control the relaxation dynamics of photogenerated carriers and photochemical excited states, respectively. The former process creates enhanced photocurrent through efficient photogenerated electron-hole pair multiplication (electron-hole pairs exist as excitons in size-quantized nanostructures), or enhanced photopotential through hot carrier transport, transfer, and extraction processes. The latter process of singlet fission generates two triplets from an excited singlet state. These fundamental dynamics in various bulk and nanoscale semiconductors and in molecular chromophores have been studied using transient absorption, photoluminescence, photocurrent and THz spectroscopy with fs to ns time resolution. The predictions that the generation of more than one electron-hole pair or exciton per absorbed photon would be an efficient process in nanostructures, and via singlet fission, have been confirmed in different classes of materials, molecules, and their architectures in photon conversion devices. Selected aspects of this work will be summarized and recent advances will be discussed, including the very remarkable and beneficial theoretical effects of combining MEG or singlet fission with solar concentration and controlling the thicknesses of the photoactive layers in a two-photon photoelectrosynthesis cell structure for solar fuels.
(Invited) High-Quality Protonic Diodes and Their Transformation into Solar Cells and Conductors
Authors: Schulte Leanna , McClarin Geoffrey R. , White William , Renna Lawrence A. , Ardo Shane
Published: July 2021

Ionically conductive materials and diodes have been actively studied since the pioneering work of John Bockris in 1959. The subset of purely protonic diodes based on liquid water are far less common, yet are more analogous to electronic semiconductors in that generation, recombination, and transport each occur and junctions fully equilibrate.

In my presentation, I will explain how water is a protonic semiconductor and show that it can be doped through addition of salts of H+ and/or OH– that when fixed in place using polymeric bipolar membrane scaffolds enable purely protonic diodes. Electrochemical evaluation is achieved using membrane–electrode–assemblies that drive reversible H2 redox chemistry to transduce changes in electronic electrochemical potential into protonic electrochemical potential, and vice versa. Characterization of the semiconducting properties of these protonic diodes allowed for determination of flatband potentials using Mott–Schottky analysis, and mobilities via analysis of space-charge-limited conduction.

Further, via covalent modification of polymers with photoacid dye sensitizers we were able to demonstrate solar cell function, and modification with generation/recombination buffering groups we were able to demonstrate ohmic conduction. The latter is relevant for application of bipolar membranes in CO2 electrolyzers. Collectively, these efforts form the foundational framework for new devices and functions that benefit from purely protonic transport.
(Invited) Water Dissociation Catalysis in Bipolar Membranes and in Electrocatalysis
Authors: Boettcher Shannon W.
Published: July 2021

Water is arguably humanity’s most-important molecule due to its ubiquitous role in biological, industrial, and environmental processes. Reactions of water typically involve breaking H-O bonds. The simplest reaction is heterolytic water dissociation (WD), H2O -> H+ + OH-, the understanding of which has been one focus of experiment and theory for decades. WD is also a fundamental elementary step in many electrochemical processes. For example, the WD step is thought rate-limiting for the hydrogen-evolution reaction (HER) under alkaline conditions and modification of Pt surfaces with metal hydroxides, which presumably accelerate WD, increase HER activity. While measurements of dissociative water adsorption are often made using surface-science tools in vacuum, the WD reaction is remarkably poorly understood under electrochemical conditions.

We use a bipolar-membrane (BPM) electrolyzer, where WD is driven in the region between a hydroxide-exchange and proton-exchange membrane by an applied potential, to study WD kinetics across a range of materials.1 We find that the local pH is a critical, but previously unrecognized, variable affecting WD kinetics and propose a pH-dependent proton-transfer WD mechanism. Combining WD catalysts efficient in acidic and basic conditions nearly eliminates the WD overpotential in BPM electrolyzers operating at 20 mA cm-2 and enables BPM operation at 0.5 A cm-2 with a total applied electrolysis potential of ~ 2 V. These values are substantial improvements over the state of the art and enable new applications for BPMs. We further discovered that the WD kinetics measured in the BPM correlate with HER kinetics under conditions where WD is an important elementary step and illustrate the design of ‘bifunctional’ electrocatalysts based on insight into the underlying WD steps.

1Oener, S. Z.; Foster, M. J.; Boettcher, S. W., Accelerating water dissociation in bipolar membranes and for electrocatalysis. Science
2020, DOI: 10.1126/science.aaz1487

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(Invited) Potential Dependent Layering in the Electrochemical Double Layer of Highly Concentrated Electrolytes
Authors: Gewirth Andrew A. , Zhang Ruixian
Published: July 2021

Highly concentrated electrolytes are recently of great interest because of their possible relevance for batteries. The origin for their promising application has been ascribed to the formation of percolating nanodomains in the bulk. However, the interfacial structure of these concentrated electrolytes still remains to be understood. In this talk we characterize the potential dependent double layer of a LiTFSI-based electrolyte on a charged electrode surface. Ultramicroelectrode (UME) measurements reveal a surface-confinement effect for a ferricyanide redox species at the electrode/WiSE interface. Potential dependent atomic force microscopy (AFM) show the presence of layers, the structure of which changes with applied potential. Thicker layers (6.4 Å and 6.7 Å) are observed at positive potentials, associated with [Li(H2O)x]+([TFSI]-)y ion pairs, while thinner layers (2.8 Å and 3.3 Å) are found at negative potentials and associated with [Li(H2O)x]+ alone. Vibrational spectroscopy shows that the composition of the double layer also changes with potential, where [TFSI]- is enriched at positive and [Li(H2O)x]+ enriched at negative potentials, respectively. The talk will also discuss battery-related applications of these electrolytes.
Introducing the Virus Bioresistor: A New Electrochemical Biosensing Paradigm
Authors: Penner Reginald M.
Published: July 2021

Viruses are infamous for making us sick. That’s their dark side. But they don’t receive enough credit for the good they can do. Specifically, they can be convinced to collaborate with us to acquire information from bodily fluids about early stage diseases – and in particular, cancers. You already know that for many cancers, early detection means a cure is possible, even likely.

Together with a chemical biologist at UCI, Professor Greg Weiss and his team, our research group is designing a new type of biosensor that communicates electrically with viruses in order to diagnose bladder cancer, and to detect its recurrence in patients who have had it in the past. These biosensors are called Virus BioResistors or “VBRs”. A VBR will be capable of detecting early stage bladder cancer in a routine urinalysis test, in 5 min. or less, in a doctor’s office. This transformational capability has the potential to save lives. Bladder cancer is the “low hanging fruit” for this technology because it is the easiest cancer to detect in urine. But the possibility exists to develop VBRs capable of detecting several other cancers using urinalysis including cancers of the prostate, kidney, and possibly even pancreas.

How does it work? The VBR depends upon an electrodeposited bioaffinity layer, ≈100 nm in total thickness, that is a composite of PEDOT (poly(3,4-ethylenedioxythiophene)) and the M13 virus particles that serve as receptors. The impedance of this layer is measured using two gold electrodes. At low frequencies, this impedance increases when target protein molecules are bound within the PEDOT-virus layer. The high frequency impedance measures only the electrical conductivity of the solution, providing information on the hydration state of the patient undergoing testing. The orthogonality of the VBR response at low and high frequencies allows accurate measurement of target protein, without influence from the salt concentration of urine – an important capability for clinical applications of this technology. Other secrets of the VBR will be revealed in this presentation.

Figure 1
(Invited) Visualizing Carrier Transport and Recombination at Individual Defects within 2D Semiconductors
Authors: Hill Joshua W. , Hill Caleb M.
Published: July 2021

Two-dimensional (2D) semiconductors are attractive materials for a variety of electronic and photonic applications. This is due in large part to the ability to fabricate films of these materials with thicknesses approaching the monolayer limit and the emergent optical and electronic properties displayed at this extreme scale. Despite these fundamental advantages, active layers based on these materials exhibit a high density of edge/step terminations which are detrimental to carrier transport, limiting their utility in practical applications. Unambiguously evaluating the impact of different types of defects on carrier transport would help to guide the design of improved practical devices, but such information is impossible to generate using existing characterization techniques. Here, a novel mode of Scanning Electrochemical Cell Microscopy (SECCM) will be described which is capable of probing carrier transport across well-defined pathways within individual, well-defined 2D nanosheets. In this “Carrier Generation-Tip Collection” (CG-TC) mode, a focused light source is employed to locally generate carriers and an SECCM tip is used to collect carriers at another point within the same structure, allowing carrier transport within an individual nanosheet to be directly visualized. Analysis of CG-TC data obtained within pristine, defect-free regions of a material allows carrier diffusion lengths to be directly generated. CG-TC data obtained spanning step/edge defects then allows for recombination at individual, nanoscale defects to be rigorously evaluated. Quantitative studies applying CG-TC SECCM to visualize carrier transport within Transition Metal Dichalcogenide (TMD) materials will be presented to demonstrate the efficacy of this approach.
Electrochemical Surface Oxidation Enhanced Raman Scattering on Cu
Authors: Cheuquepan William , Perez-Estebañez Martin , Hernandez Sheila , Heras Maria Aranzazu , Colina Alvaro
Published: July 2021

One of the main characteristic of Analytical Chemistry is a constant searching for new methodologies to overcome analytical problems. Minimization of analysis time and sample volumes, replacement of extensive extraction protocols and improvement of selectivity are common tasks in analytical research all around the world. Spectroelectrochemistry is an instrumental technique that totally represents this spirit: The combination of electrochemical set-ups with spectroscopy techniques to study the surface processes has shown to be a powerful technique to resolve complex mixtures of molecules, where analytical signals can present severe interferences [1].

Spectroelectrochemistry has been demonstrated to be a powerful analytical technique to study adsorption processes and molecular reactivity on electrode surfaces. More specifically, Raman spectroelectrochemistry (Raman-SEC) combined with plasmonic structures has been demonstrated to be an excellent tool to study molecules at low concentration thanks to Surface Enhanced Raman Scattering (SERS) phenomenon. [2].

For almost half a century, Raman-SEC has broadly studied the properties of SERS substrates developed with nanoparticles of plasmonic metals, such as silver, gold and copper, focusing its efforts on the characterization of nanostructures morphology.

In 2018, our group discovered a novel methodology to enhance the Raman signal during the electrochemical oxidation of silver electrodes in acidic media [3]. We denoted this phenomenon as Electrochemical Surface Oxidation Enhanced Raman Scattering (EC-SOERS), and represents a phenomenon similar to SERS, because of the enhancement of the Raman signal, but contrary to SERS, since it suggests the loss of plasmonic properties (and thus, Raman enhancement) of metallic structures during the electrochemical oxidation of the plasmonic nanostructures.

In this communication, we demonstrate, for the first time, that EC-SOERS can be observed on copper electrodes. This metal, known for its SERS properties, can be also used to enhance selectively the Raman signal during its electrochemical oxidation, detecting different organic molecules with a wide variety of functional groups, opening new gates towards the development of new analytical tools based on EC-SOERS.
First-Principles Modeling of the Electrochemical Kinetics at Solid-Water Interface
Authors: Zhao Xunhua , Liu Yuanyue
Published: July 2021

Kinetic information, such as the activation energy and transition state, is critical to understanding the reaction. However, the kinetic information of electrochemistry at solid-water interface is challenging to obtain from conventional models of density functional theory (DFT), as they often neglect the presence and/or the dynamics of the surface charge [1] and the solvent configuration, which are further coupled. Here we present a new model that accounts for these effects, by combining hybrid solvation, constant-electron-potential, and slow-growth sampling techniques together. We then apply this model to elucidate the active site structure and the mechanism of electrochemical carbon dioxide reduction catalyzed by single-nickel-atom embedded in graphene, which shows high performance in experiments while is not well understood [2].

[1] D. Kim, J. Shi, Y. Liu, J. Am. Chem. Soc. 2018, DOI: 10.1021/jacs.8b03002

[2] X. Zhao, Y. Liu, J. Am. Chem. Soc. 2020, DOI: 10.1021/jacs.9b13872
A Soft On/Off Switch Based on the Electrochemically Reversible H-J Interconversion of a Porphyrin Membrane at an Electrified Liquid|Liquid Interface
Authors: Scanlon Micheal D. , Molina-Osorio Andrés F. , Yamamoto Sho , Nagatani Hirohisa
Published: July 2021

Soft molecular assemblies that respond reversibly to external stimuli are attractive materials as on/off switches, in optoelectronic, memory and sensor technologies. In this presentation, the reversible structural rearrangement of a soft porphyrin membrane under an electrical potential stimulus in the absence of solid-state architectures will be presented.

The free-floating porphyrin membrane lies at the interface between immiscible aqueous and organic electrolyte solutions and is formed through interfacial self-assembly of zinc(II) meso-tetrakis(4-carboxyphenyl)porphyrins (ZnPor). A potential difference between the two immiscible electrolyte solutions induces the intercalation of bis(triphenylphosphoranylidene)ammonium cations from the organic electrolyte that exchange with protons in the porphyrin membrane. In situ UV/vis absorbance spectroscopy shows that this ionic intercalation and exchange induces a structural interconversion of the individual porphyrin molecules in the membrane from an H- to a J-type molecular configuration. These structural rearrangements are reversible over 30 potential cycles. In situ polarisation-modulation fluorescence spectroscopy further provides clear evidence of structural interconversion of the porphyrin membrane, as intercalation of the organic electrolyte cations significantly affects the latter’s emissive properties. By adjusting the pH of the aqueous phase, additional control of the electrochemically reversible structural interconversion can be achieved, with total suppression at pH 3.

The work presented herein opens new opportunities to investigate the use of structurally dynamic soft supramolecular porphyrin assemblies at the interface between two immiscible electrolyte solution (ITIES) as switchable on/off responsive nanomaterials, with applications in optoelectronic, memory and sensor devices.

Figure 1
Ion Transfer at Liquid | Liquid Interface Modified with Silica Nanoparticles
Authors: Collins Martha , Hernando-Abad Eduardo , Hébrant Marc , Herzog Gregoire
Published: July 2021

The interface formed between two immiscible electrolyte solutions (ITIES) is a highly reproducible, defect-free surface that allows the assembly of nanometer-sized objects. Their adsorption at the liquid-liquid interface is governed by their dimensions, zeta potential, wettability and the interfacial tension. The interest for the use of silica nanomaterials at the ITIES is due to their favourable adsorption kinetics and to their rich surface chemistry that can provide selectivity.

At first, we followed the adsorption of silica nanoparticles (ø = 12 nm) at the ITIES by AC voltammetry and their interactions with methylene blue (MB+), selected as a model ion by cyclic voltammetry and UV-vis absorption spectroscopy. We determined the adsorption constant of the MB+ onto silica nanoparticles to be 1.66 × 105, which indicated a strong affinity between them. This is in contrast with two other ions tested (Eosin B and tetraethylammonium), which demonstrated low affinity for the silica nanoparticles.

In a second step, we synthesized silica nanoparticles with diclofenac molecular imprint with the aim of selective accumulation of diclofenac, a commonly used nonsteroidal anti-inflammatory drug. The presence of imprint cavities greatly improved the affinity for diclofenac for the silica nanoparticles, in contrast with diclofenac analogue such as aceclofenac. Electrochemistry experiments (including cyclic and AC voltammetries) revealed that diclofenac transfer is blocked by the presence of molecularly imprinted nanoparticles at the ITIES.

These two experimental examples show that target molecules can be accumulated at the ITIES by combining the ability of silica nanoparticles to adsorb onto the ITIES and their affinity for the targeted molecules. Such an accumulation localized at the interface could be of interest in sensing applications.

Figure 1
Earth-Abundant Electrocatalysts for the Oxygen Evolution Reaction of Water Splitting Using Nanostructured Layered Inorganic Materials
Authors: Colon Jorge L , Ramos-Garcés Mario V. , Sanchez Joel , Wu Yanyu , Barraza-Alvarez Isabel , La Luz-Rivera Kálery , Del Toro-Pedrosa Daniel E. , Villagran Dino , Jaramillo Thomas F
Published: July 2021

Nature uses solar energy and earth-abundant materials for splitting water into oxygen, in the oxygen evolution reaction (OER), and protons, which are then reduced into hydrogen in the hydrogen evolution reaction (HER). Hydrogen solar fuel produced in artificial photosynthesis schemes for water splitting could be used in fuel cells. Learning from nature, instead of using expensive catalysts such as platinum, cheaper alternatives (such as cobalt, iron, or nickel) would provide the opportunity to make solar energy even more competitive with fossil fuels. However, obtaining efficient catalysts based on earth-abundant materials is still a daunting task, particularly for the OER. Recent theory has shown that nanoscopic confinement of catalysts increases the stability and efficiency of catalysts for OER. We have designed and develop earth-abundant electrocatalysts for oxygen reduction and water splitting using nanostructured layered inorganic materials of zirconium phosphate (ZrP). We have demonstrated improved electrocatalytic activity of ZrP nanomaterials loaded with metal ions suitable for the OER of water splitting. Adsorbing Co or Ni catalysts on the ZrP nanoparticles surface proved to improved OER activity compared to intercalated catalysts. A comparison between adsorbed Co or Ni catalysts and those catalysts on exfoliated ZrP hexagonal nanoplatelets proved that those on exfoliated nanoplatelets were more active, with diminished overpotentials and reduced Tafel plot slopes as well as higher mass activities. More recently, comparison between Co and Ni catalyst on ZrP particles with different morphologies (hexagonal platelets, rods, cubes, and spheres) revealed that the more active Co catalysts are those on hexagonal ZrP platelets, whereas the best Ni catalysts are those on ZrP spheres. Finally, encouraging recent results with a cobalt porphyrin catalyst will be presented, as well as recent XAS operando results. These results demonstrate that ZrP nanoparticles are suitable supports for electrocatalysis of the OER and water splitting.

Sponsored by NSF Center for Chemical Innovation in Solar Fuels CHE-1305124 and NSF-PREM Center for Interfacial Electrochemistry for Energy Materials (CIE2M) grant DMR-1827622.
Simple Method for Preparing Customizable Pyrolyzed Photoresin Carbon Electrodes Using 3D Printing
Authors: Glasco Dalton Lee , Tamang Binny , Knust Kyle N.
Published: July 2021

We report an accessible fabrication procedure to prepare customizable pyrolyzed photoresin electrodes (PPE) for electroanalytical applications. A stereolithography 3D printer was used to pattern carbon containing photoresin on a quartz substrate before being pyrolyzed to yield a carbon electrode with X and Y dimensions ranging from mm to a minimum feature size of approximately 200 µm as determined by optical microscopy. Stylus profilometery was used to determine PPEs have an approximate step height of 600 nm. Atomic force microscopy was employed to examine the surface roughness of PPEs, which were found to have a rms roughness of approximately 25 nm. Cyclic voltammetry with hexaammineruthenium chloride was performed to examine the electrochemical behavior of the PPEs, which was consistent with the Randles-Sevcik equation and commercial glassy carbon electrodes.
Synthesis of FeCo-N-OLC Catalyst for Oxygen Reduction Reaction
Authors: Vargas Perez Brenda L , Gonzalez Sanchez Osvaldo , Serrano Rosario Yannelly Ann , Cunci Lisandro
Published: July 2021

The world's main source of energy is fossil fuels, but fossil fuels are finite resources and can also irreparably harm the environment. According to the United States Energy Information Administration, the burning of fossil fuels was responsible for 76 percent of the US greenhouse gas emissions. Fossil fuels not only pollute the environment, but also affect human health. My research focuses on making a catalyst that is economical, efficient and above all friendly to the environment. The oxygen reduction reaction (ORR) is an important reaction for energy conversion systems, such as fuel cells. The fuel cells generate electricity directly by electrochemically reducing oxygen and oxidizing fuel in water as the only by-product. Onion-like carbon (OLC) are used as a catalytic support for fuel cell applications due to their high conductivity and high surface-to-volume ratio. The combination of carbon compounds with conductive polymers results in new materials and devices with possible practical applications. In recent decades, several studies have been conducted on nitrogen doped structures in carbon materials for the ORR. In my research we use nanodiamonds (NDs) to dope them with the polymerization of the aniline monomer. Then, through a pyrolysis process, we convert the ND/PANI particles into N-OLC. These particles are then polymerized using the aniline and pyrrole monomers to dope the OLCs with nitrogen. These particles are characterized using the following techniques, Raman, Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and X-ray Diffraction (XRD). Then the synthesis is carried out with the non-precious metals. The non-precious metals that we use are iron and cobalt. ORR experiments were performed with the FeCo-N-OLC particles. In future work we will characterize these samples using synchrotron techniques.
High-Performance Fe-N-C Oxygen Reduction Catalysts Synthesized Via Chemical Vapor Deposition
Authors: Jiao Li , Mukerjee Sanjeev , Myers Deborah J. , Jaouen Frédéric , Jia Qingying
Published: July 2021

Abstract

Replacing scarce and expensive platinum (Pt) with metal-nitrogen-carbon (M-N-C) catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) has largely been impeded by the low activity of M-N-C. Herein, we implemented chemical vapor deposition (CVD) to synthesize Fe-N-C. The iron was deposited to N-C substrate at 750 ℃, has a record Fe-N4 site density of 2×1020 sites·gram-1. A combination of characterizations shows that the Fe-N4 sites formed via CVD are located exclusively on the outer-surface, with 100% site utilization. This catalyst delivers an unprecedented current density of 33 mA·cm-2 at 0.90 V
i

R-free (iR-corrected) in an H2-O2 PEMFC at 1.0 bar and 80 ℃.

Acknowledgements

This work was supported by the US Department of Energy under award number DE-EE0008416 and DE-EE0008075. The authors acknowledge the support from the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (DOE-EERE-HFTO) through the Electrocatalysis consortium (ElectroCat) and the DOE program and technology managers, Dimitrios Papageorgopoulos, David Peterson, and Nancy Garland. The ex situ XAS experiments at the Zn K-edge were performed at the Advanced Photon Source (APS), a DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The operation of MRCAT at the APS is supported by the Department of Energy and the MRCAT member institutions. The rest of the XAS data were collected at the beamlines 6-BM, 7-BM and 8-ID (ISS) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. AC-STEM was conducted at the Center for Nanophase Materials Sciences located at Oak Ridge National Laboratory, which is a DOE Office of Science User Facility.
Defective Metal-Organic Frameworks As Unpyrolyzed Electrocatalysts for Oxygen Reduction and Oxygen Evolution Reactions
Authors: Wang Hao
Published: July 2021

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) represent core electrocatalytic processes in unitized regenerative fuel cells and rechargeable metal-air batteries catalyzed by the costly platinum group metals (PGMs) materials. Finding highly efficient yet durable ORR/OER catalysts using earth-abundant, low-cost materials represents a critical path in lowering cost barrier for widespread commercialization of the devices. We herein report two approaches to construct defective metal-organic frameworks (MOFs) to remove PGM usage for oxygen electrocatalysis.

In approach 1, we prepared a coordinately unsaturated Co-MOF as a bifunctional ORR/OER electrocatalyst in an alkaline electrolyte. The Co-MOF possessed great π-π stacking and hydrogen bonding interactions, giving rise to excellent structural and catalytic stabilities. Structure characterizations demonstrated that the coordination of Co(II) was largely unsaturated. Modeling simulations further confirmed that the unsaturated coordination significantly promoted the interactions with molecular water and oxygen and improved the electronic conductivity, leading to enhanced mass and charge transfer properties.

In approach 2, we developed a partial ligand removal (or ligand-defect) approach to create mesopores and unsaturated coordination in a Cu-MOF. Since the micropores typically limit the mass-transfer properties (and the capability to store insoluble discharge product for aprotic metal-air battery), the mesopores of the as-prepared MOF showed less steric hindrance, and the unsaturated Cu coordination also boosted electronic conductivity and auxiliary reactant affinity, leading to high Li-air battery capacity.

The defective MOFs may open up a new venue for developing effective electrocatalysts with enhanced intrinsic activity towards oxygen electrocatalysis.
PEM Fuel Cell Performance of Cobalt Phthalocyanine Supported on CVD Graphene and Different Carbon Materials
Authors: Yazici Mehmet S , Dursun Sumeyye
Published: July 2021

Cobalt (II) phthalocyanine (CoPc) is investigated as an alternative catalyst to Pt to decrease the cost of polymer electrolyte membrane (PEM) fuel cell. Carbon nanotube (CNT), VulcanXC72 (V), graphene (G) and their hybridization (CNT/G, V/G, CNT/V) are used as catalyst support. Carbon supported CoPc is prepared by impregnation method using THF. Different support materials and back pressure effect are investigated for better catalytic activity and stability. Single fuel cell tests were carried out. Higher heat treatment temperatures and higher operational backpressure improves fuel cell performance. Hybridization of graphene with Vulcan gives lower performance. Hybridization of carbon nanotube and Vulcan XC72 as a catalyst support gives the best fuel cell performance. Operational parameters provided maximum power density of CNT-Vulcan 303 mW/cm2 with 0.3 mgCo/cm2 loading, 5-psi backpressure, 100% RH and 60 °C operational temperature.

Figure 1
Synthesizing a Novel Janus Carbon Nano-Onions Modified As a Catalyst Support for Oxygen Reduction Reaction
Authors: Del Valle-Perez Angelica , Nieves-Carrasquillo Armando Junior , Cunci Lisandro
Published: July 2021

Carbon materials have been awakening scientific interest for research because it allows chemical functionalization for multiple applications in the sciences, especially in energy applications. Carbon Nano-onions (CNO) are spherical structures composed of multilayers of fullerenes, these layers are connected in a way that shows a shape of an onion. Its development begins with the use of nano-diamonds, a carbon material of strong structure which it forms in a very violent environment. The nano-diamonds are taken to a furnace at a temperature of 1650°C to finally obtain the CNO. Janus particles are receiving increasing attention because of their dual properties, where each side can be functionalized to have distinctive characteristics. The modifications on the surface of these nanoparticles can provide different chemical and physical properties. The interesting properties of Janus nanoparticles are that they have different sizes and shapes which have now been able to be studied in more detail. The purpose of this project is to use asymmetrically modified CNO as a support for metal nanoparticles to avoid agglomeration and, thus, increase their surface area and efficiency. Janus nanoparticles will be designed by a wax-paraffin Pickering emulsion process using CNO on its surface. The deposition of Platinum (Pt) it was carried out by a chemical process using sodium borohydride. The removal process of the paraffin involves a treatment with chloroform and rinse with ethanol to finally obtain the amphiphilic nanoparticle. The differences on the surface of the particles before and after removing the paraffin were observed by Scanning Electron Microscopy. The Energy-Dispersive Spectroscopy was used to validate the elemental information of the particles and assure the deposition of Pt on the surface of the particles. Cyclic Voltammetry was used to characterize the CNO/Pt ink, providing information about the Pt deposition on the surface of the CNO. Oxygen Reduction Reaction experiments were conducted to test the efficiency of this catalyst using the Rotating Ring-Disk Electrode at rotations of 100, 400, 900, 1600, and 2500 rpm. The polarization curves of CNO/Pt and Pt/Vulcan were compared. Thermogravimetric Analysis were used as a characterization technique to corroborate the percent of Pt on the CNO/Pt particles. Characterization techniques as X-ray Diffraction and Raman Spectroscopy were used to validate the deposition of Pt and confirm the removal of paraffin.