bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Bias and Aerobic Conditions on Photocatalytic Nitrogen Fixation By Titania
Authors: Liu Yu-Hsuan (Carol) , Chen Sarah , Hatzell Marta C. 
Published: February 2020

Photo-catalytic nitrogen fixation on titania (TiO2) was discovered for decades ago by an Indian Soil Scientist (N Dhar) [1]. Dhar’s early work suggested that titania in soil produces fixed nitrogen (ammonia) from air. Despite these findings, a clear understanding regarding how nitrogen fixation occurs on titania remain unclear. Previous studies has demonstrated nitrogen photofixation in both gas and liquid phase and in various environmental conditions (temperature, pressure, relative humidity) [2]. Investigation have also centered on the use of various proton source (hydrogen, water) and hole scavengers. Under all conditions, the prevailing consensus is that ammonia is formed photo-catalytically. However, very few investigations have detailed the impact of oxygen, as a competing reactant. Most investigations used nitrogen that is separated from air. Separation nitrogen from air is energy intensive and expensive. If photocatalytic technologies are to be developed for ammonia production, omitting the air separation process and operating with air is necessary to drive down the cost. Therefore, it is important to understand the impact of oxygen plays in suppressing photo(electro)catalytic nitrogen fixation. Here we will present data from a series of photocatalytic experiments conducted in aerobic conditions (Air) and anerobic conditions (N2). We demonstrate the production rates and efficiencies as applied bias and light intensity varies. Results show that ammonia production in air flow nearly in all cases are 30% lower than nitrogen flow. Literature also indicated that oxygen will suppress the ammonia formation because oxygen will be easier to reduce in conductive band on titania than nitrogen due to more long pair ions on oxygen [3]. Therefore, we also investigate the potential for both nitrogen and oxygen reduction through a series of rotating ring disk experiments. Through biasing the ring potential, we evaluate the product of nitrogen reduction (ammonia) and oxygen reduction (hydrogen peroxide).
Reference
[1] N. Dhar, E. Seshacharyulu and N. Biswas, Proc. Natl. Acad. Sci., India, 1941,7, 115-131.
[2] G. Schrauzer and T. Guth, J, Am. Chem. Soc., 1977, 99, 7189-7193.
[3] H. Hirakawa, M. Hashimoto, Y. Shiraishi, T. Hirai, J, Am. Chem. Soc., 2017, 139(31), 10929-10936.
Radical Redox Mediator Free Photoelectrochemical Biomass Valorization
Authors: Lhermitte Charles Roger , Canjura Pamela , Plainpan Nukorn , Sivula Kevin 
Published: February 2020

Over the past decade, researchers have begun to re-explore the idea of replacing water oxidation with more kinetically facile oxidation reactions for photoelectrochemical solar H2 production.1–3 Alternate photo-oxidation reactions can be employed as a means of chemical valorization, in addition to providing electrons for H2 production from water while reducing the losses associated with water oxidation. In particular, the oxidation of 5-hydroxymethylfurfural (HMF)—which is a key intermediate derived from the acid catalyzed poly-dehydration of 6 carbon monosaccharides—has gained significant attention. This is because a number of its oxidation products, such as 2,5-Furandicarboxylic acid (FDCA), may be employed as monomers in the synthesis of renewable polyesters, and FDCA in particular, has also been identified by the US Department of Energy as one of 12 priority chemicals for establishing the green chemistry industry of the future.4

As a result, solar powered chemical transformations of HMF have recently gained attention. However, to date, the selective oxidation of HMF using either photo-, or electrochemical means, has been limited by the need to employ the radical redox mediator (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO). This additional redox-mediating reagent poses a problem by increasing system complexity, and by behaving as a competitive light absorber in photoelectrochemical (PEC) systems —which reduces the solar conversion efficiency.
Recently, our group has investigated TEMPO free, direct PEC oxidation of HMF using metal oxide photoelectrodes. In this presentation, we show that the direct oxidation of HMF can be carried out on sol-gel processed WO3 electrodes without the need to use an additional redox shuttle such as TEMPO. Figure 1 depicts a linear sweep voltammogram under 1 sun illumination of a sol-gel processed WO3 electrode in the presence and absence of HMF. We observe that the addition of HMF to an aqueous buffered solution improves photocurrent densities by 33%, and the onset potential is favorably shifted by -50 mV. These properties highlight this reaction’s promise as a replacement for water oxidation in an H2 producing PEC cell. In addition, we report the oxidation product distribution as well as efforts to control product selectivity via solution processed heterogeneous catalysts and the optimization of the electrolyte solution.
Figure 1: Linear sweep voltammograms of a WO3 electrode in a pH 4 0.1M KPi buffered solution with (red), and without (black), 5mM HMF in solution. The illumination intensity was 1 sun AM1.5G. Dotted lines represent the linear sweep voltammograms in the absence of illumination.
References:

C. R. Lhermitte and K. Sivula, ACS Catal., 9, 2007–2017 (2019).

H. G. Cha and K.-S. Choi, Nature Chemistry, 7, 328–333 (2015).

M. F. Kuehnel and E. Reisner, Angewandte Chemie International Edition, 57, 3290–3296 (2018).

J. J. Bozell and G. R. Petersen, Green Chem., 12, 539–554 (2010).

Figure 1
(Invited) Accelerated Materials Design and Discovery: Novel Approaches for Accelerating Synthesis, Characterization, and Screening of Materials
Authors: Suram Santosh K 
Published: February 2020

High-throughput computations have provided access to multiple properties of several inorganic materials. High-throughput experiments have enabled generation of materials properties under operating conditions. Both these approaches have accelerated discovery of materials. Further acceleration of materials discovery requires integration of these approaches that have different scopes and underlying assumptions.
In this talk, I will present novel approaches based on network theory to predict synthesizability and hence reduce the "synthesis gap" between theory and experiments. Another significant gap between theory and experiment is the "characterization gap" which is due to the need for laborious characterization methods to capture an experimentally synthesized material's fingerprint. In this talk, I will present the use of machine learning methods to address this gap to capture structural, chemical, and electronic fingerprints of materials.
High-throughput experiments have played a significant role in accessing high-dimensional chemical and screening space for materials discovery. However, practical implementations of high-throughput experimentation focuses on a specific region of the large chemical and screening space due to the exponential increase in number of experiments needed as dictated by the curse of dimensionality. I will present further acceleration of high-throughput experimentation by using machine learning approaches. Particularly, approaches that utilize information obtained from high-throughput computations will be discussed.
(Invited) HydroGEN PEC Supernode: Emergent Degradation Mechanisms with Integration and Scale up of PEC Devices
Authors: Danilovic Nemanja , Young James L. , Kistler Tobias , Steiner Myles A , Zeng Guosong , Weng Lien-Chun , Deutsch Todd G , Toma Francesca M. , Houle Frances A , Weber Adam Z. 
Published: February 2020

This talk will give an overview of the HydroGEN Photoelectrochemistry (PEC) Supernode and present recent progress. This Supernode project is a collaboration of nine PEC capability nodes that are part of the HydroGEN Advanced Water Splitting Materials (AWSM) consortium. These nodes are contributing to a common objective of developing an understanding of integration issues and emergent degradation mechanisms of PEC devices upon scale up above 1cm2 active areas. Larger devices are expected to introduce new component integration challenges and pathways for degradation that this PEC Supernode project will identify and propose pathways for future progress.
The objective of this Supernode includes: 1) Photoreactor chassis fabrication and baselining, 2) development, fabrication, and testing of larger area PEC devices, 3) development of in-situ morphology and corrosion analysis techniques and characterization, and 4) analysis of durability mechanisms and impacts using modeling LCA and TEA. A new photoreactor chassis will be presented that has been designed to facilitate indoor and on-sun efficiency and durability benchmarking measurements. The design will be validated in a preliminary set of multi-institution round robin measurements toward understanding and harmonizing measurement conditions and protocol. Furthermore, we will present initial STH, durability and degradation characterization results upon scale up to 8 cm2 active area of integrated vapor fed PEC cell.
(Invited) Hydrogen Storage Measurements; Protocols and Reproducibility
Authors: Hurst Katherine E. , Parilla Philip A. , Gennett Thomas 
Published: February 2020

The transport and storage of hydrogen remains one of the critical challenges for hydrogen-based technologies. Specifically, the U.S. Department of Energy (DOE) has set forth hydrogen storage system targets for gravimetric and volumetric capacities in order to make light-duty polymer electrolyte membrane fuel cell vehicles viable alternatives to the current vehicle driving ranges. Hydrogen storage sorbent materials have shown continuous improvement in the past decade and many DOE targets have been met singularly, however, further advancements in materials development are needed to meet all of the performance targets simultaneously.
The accuracy of hydrogen storage measurements is fundamental to identifying the potential of novel materials. Previous reports have called into question the reproducibility of hydrogen storage measurements. A round-robin report in 2009,[1] discovered large discrepancies among the different participating laboratories for H2 gravimetric capacity measurements on a standard material. This study brought attention to the challenges of H2 capacity measurements, provided recommendations, and discussed possible sources of errors. In a later study, we demonstrated an improved reproducibility amongst a smaller set of laboratories for the excess gravimetric capacity of standard sorption samples.[2] Both of these studies emphasized H2
gravimetric excess capacity. The volumetric capacity, however, is often not reported in the literature as determining volumetric capacities is not as straight-forward, especially for amorphous materials.
Research efforts at the National Renewable Energy Laboratory, as a part of HyMARC, include characterization of thermodynamic and kinetic energetics, and hydrogen adsorption capacity measurements. In this talk, we will discuss the recommended measurement protocols and show the results from a recent comparative study of reproducibility of both volumetric
and
gravimetric H2 capacities. Common analysis protocols and figure of merits for reporting data[3] allow the materials to be compared on an equal basis, and provide insight into the uncertainty of measurements amongst the research community. We will also discuss the issues of approximating absolute capacities and calculating isosteric heats of adsorption at super critical conditions.
[1] C. Zlotea, et.al. Int. J. Hydrog. Energy 34, 3044 (2009), [2] K.E. Hurst et.al. Appl. Phys. A2016, 122, 42.[3] P. Parilla, et.alAppl. Phys. A. 2016, 122, 201.
(Invited) On Dilemmas of Band Gap Engineering in Luminescence Thermometers
Authors: Sójka Małgorzata , Ramalho João Filipe Candeias Baptista , Brites Carlos Delgado Sousa , Fiaczyk Karolina , Carlos Luís D , Zych Eugeniusz 
Published: February 2020

Luminescence thermometry and 2D imaging by means of luminescence thermometric phosphors are of growing interest as these non-contact and almost non-invasive techniques may possibly offer important advantages in some areas of applications. The requirements such thermometers have to fulfill are quite dependent on considered application. It is obvious that bio and medical applications points on different parameters than measurements in cryo range and measuring high temperatures point on yet different needs. Nevertheless, high-sensitivity and low inaccuracy are always appreciated, as well as chemical stability in conditions the thermometers are used.
One of the limitations of luminescence thermometers proposed up to data is the limited range of temperatures they may measure. Clearly, some applications do not need a broad range of a thermometer usability. On the other hand, presenting a good performance over a wide range of temperatures luminescence thermometer could be considered a versatile “all-purpose” device. This might open a door for truly broad usage of such phosphors.
Trying to deliberately manage the performance of luminescence thermometers for broad-range temperature measuring we paid attention into the band gap engineering as a tool to achieve the goal. In this presentation we shall focus on Sr2(Ge,Si)O4:0.05%Pr powders with different Ge:Si ratio to adjust the host lattice band gap and consequently to manage the thermometer performance, see the figure attached. Basing on the lesson learned from Sr2(Ge,Si)O4:0.05%Pr we shell try to draw more general conclusions too.
This research was supported by Polish National Science Centre upon the grant #UMO-2017/25/B/ST5/00824 and by the Portuguese project CICECO-Aveiro Institute of Materials, FCT Ref. UID/CTM/50011/2019.

Figure 1
On-Line Monitoring of the Stability of Electrodes in Non-Aqueous Media
Authors: Ranninger Johanna , Wachs Susanne J. , Möller Jonas , Mayrhofer Karl J. J. , Berkes Balázs B. 
Published: February 2020

Stability of electrochemical systems is particularly important in applications. No matter if it is a fuel cell, a battery, a supercapacitor, a construction subject to corrosion or an electrode used for synthesis, economic considerations require a certain lifetime of these systems. Depending on the systems, instability can have several causes, like changes in the mechanical or crystal structure of electrodes, oxidation of materials, decomposition of electrolytes, loss of percolation and electrical conductivity, or material loss due dissolution. Many of these processes happen slowly, causing only minimal performance loss within laboratory timescales. Their studies involve therefore usually long-term measurements with ex situ analysis. In situ, real-time analysis requires very sophisticated and usually coupled analysis methods. In this work we show a powerful approach to study dissolution phenomena in non-aqueous electrochemical systems.
A scanning electrochemical flow cell (SFC) combined with on-line inductively coupled plasma mass spectrometric (ICP-MS) analysis has proven to be a very valuable tool for the study of stability of electrocatalysts in aqueous solutions. This coupled technique is mainly connected to the works of Dr. Mayrhofer and Dr. Cherevko. It was very appealing to develop this method further and make it useable in organic systems too. This task might seem for the first glance to be almost trivial, however, the harsh conditions caused by the organic electrolytes limit the usability of materials to contrive these systems to a huge extent. Furthermore, the ICP-MS is standardized mainly for aqueous media and a lot of experimental work has to be devoted for the optimization of the device for each individual organic solvent. Most of the chemicals used are sensitive to atmospheric components, like O2, H2O, CO2 or even N2. Therefore, the experiments have to be carried out in a glovebox that ensures a controlled and very clean atmosphere.
Platinum is often considered to be a model electrode and catalyst material. This metal is probably the most thoroughly studied one in electrochemistry, however, it still shows many interesting yet not well understood features. This is also true for the stability of the metal during potential cycling. The electrochemical stability window of organic electrolytes is usually much higher than that of water enabling the simultaneous cycling and downstream analysis of dissolution in a higher potential range. As a result, even the electrochemistry of platinum shows hitherto unveiled phenomena regarding its dissolution mechanism. In this work, we focus on the effect of water contamination, anions, cations and organic solvent molecules on the anodic and cathodic dissolution behavior of platinum. To demonstrate the benefits of this novel method on the field of non-aqueous electrochemistry the stability of other non-aqueous systems will be discussed shortly, too.
Modified Microelectrodes for the Detection of Reactive Oxygen Species in Biomedical Studies
Authors: Kranz Christine , Daboss Sven , Hellmann Andreas 
Published: February 2020

It has been long known that hydrogen peroxide (H2O2) as an endogenous reactive oxygen species (ROS) belongs to a group of destructive molecules that can lead to protein oxidation, lipid peroxidation, and DNA damage. Whereas elevated ROS production leads to oxidative stress, it was also recently shown that at lower physiological levels, H2O2 acts as an intracellular signalling molecule regulating kinase-driven pathways1. As the involvement and concentration levels of H2O2 at the cellular level are not fully understood, its localized detection at a cellular level is of particular importance. Fluorescent redox-sensitive dyes are frequently used for the detection of H2O2 at the cellular level. H2O2 can also be detected electrochemically, e.g. at anodic potentials (0.6 V vs. Ag/AgCl) at Platinum (Pt) electrodes. However, such high oxidation potential can be affected by co-oxidizable substances such as ascorbic acid, catecholamine etc., which may be present in biological samples2.
In this contribution, we present strategies of electrochemical H2O2 detection avoiding such interference problems based on electrocatalytically or enzyme-modified electrodes. Modification with Platinum black3 or Prussian Blue (PB)4 enables the detection at lower potential such as 0.3 V vs. Ag/AgCl at Pt-black modified electrodes and 0.0 V vs Ag/AgCl at PB modified electrodes, respectively. In particular, Prussian Blue (PB) modified electrodes show higher activity and significant higher electrochemical rate constants along with enhanced sensitivity. Hyperoxia treatment is controversial particularly in traumatic brain injury (TBI), due to increased radical and catecholamine production. To study increased release of ROS, measurements at porcine granulocytes and peripheral blood mononuclear cells will be presented using such modified microelectrodes. In addition, the co-detection of catecholamines such as epinephrine using dual sensors will be addressed. In order to study release at the single cell level, we recently introduced conductive colloidal AFM-SECM probes5, which serve as electrochemical transducers for the modification with Platinum black or Prussian Blue (PB) allowing the accurate provisioning of the biosensor at the cell surface.
References:
[1] D. R. Gough, T. G. Cotter, Cell Death and Disease 2, e213, (2011)
[2] Y. Zang, et al., Anal. Chem., 66, 1183-1188 (1994).
[3] S. Ben-Amor et al., Electrochim. Acta 126, 171–178 (2014)
[4] A. A. Karyakin, Electroanalysis, 13, 813−819 (2001)
[5] P. Knittel, H. Zhang, C. Kranz, G. G. Wallace and M. J. Higgins, Nanoscale,8, 4475–4481 (2016)
Advancing Battery Technology through Operando Neutron Scattering
Authors: Song Bohang 
Published: February 2020

Operando characterization techniques including diffraction, microscopy, spectroscopy, etc. are emerging in the last few decades for the study of lithium-ion batteries (LIBs).[1] One of the many advantages of those techniques is that it can help to firmly understand the dynamic behaviors of battery components during the real operations, from various perspectives such as the physical/electrochemical/mechanical properties.
Among all operando characterization methods, diffraction using X-rays, electrons, and neutrons undoubtedly plays a vital role as it manages to answer the fundamental questions on the structural changes of any battery components, particularly the electrode materials. Compared to X-ray/electron, neutron diffraction (ND) has irreplaceable advantages for the study of LIBs. For example, neutrons are sensitive to light elements such as Li, C and O, which are often difficult to detect with X-ray/electron diffraction. Neutrons also offer drastically different scattering lengths for neighboring elements in the periodic table or isotopes for the same element. This feature enables the distinction between 3d transition-metal elements (Mn, Fe, Co and Ni) those are frequently used in cathode materials for LIBs. Unlike diffraction, neutron radiography (NR) has often been overlooked to study LIBs, despite it can provide full-scaled imaging information of a battery thanks to the excellent penetration depth of neutrons and good contrast between elements.
In this presentation, the speaker will introduce the most-recent developments made in Spallation Neutron Source (SNS)/High Flux Isotope Reactor (HFIR) of Oak Ridge National Laboratory, dedicating to realize operando neutron scattering characterizations for the study of LIBs.[2] Operando ND and NR will be discussed individually based on the distinct scientific questions they could address.
[1] C. P. Grey; J. M. Tarascon, Sustainability and in situ monitoring in battery development, Nat. Mat., 2017, 16, 45–56.
[2] B. H. Song, et al. Metastable Li1+δMn2O4 (0 ≤ δ ≤ 1) Spinel Phases Revealed by in Operando Neutron Diffraction and First-Principles Calculations, Chem. Mater. 2019, 31, 124−134.
Investigation of Lithium-Silicon Alloy Phase Propagation Using High Resolution Operando X-Ray Microscopy
Authors: Choi Paul , Su Laisuo , Reeja-Jayan B. , Litster Shawn 
Published: February 2020

Silicon (Si) is a highly attractive anode material for next generation lithium-ion (Li-ion) batteries due to its exceptional specific capacity (up to 4200 mAh g-1), natural abundance, and low environmental impact. However, practical implementation of anodes with high Si loading is hindered by the dramatic volumetric change Si undergoes during lithium insertion and extraction (~300%); such change in the electrode structure causes rapid capacity fade, poor cycle life, and electrolyte degradation from repeated solid-electrolyte interphase (SEI) formation. As such, a better understanding of the alloying behavior of Si in Li-ion systems is necessary to alleviate the problems caused by the lithiation and delithiation volume changes.
In this work, we utilize a combination of operando x-ray transmission microscopy and in-situ x-ray computed tomography at high resolutions to directly observe the lithium-silicon alloy phase nucleation and propagation. Three-dimensional reconstructions of Si electrodes at varying stages of cycling are used to resolve the spatiotemporal changes of the lithium-silicon alloy phases, and the changes in x-ray absorption are used to determine the predominant alloy phase within the electrode.
This material is based upon work supported by the National Science Foundation under Grant No. CBET-1705321. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.