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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Enabling Space Biology Knowledge Discovery Through Biospecimen Sharing: The NASA Biological Institutional Scientific Collection

NASA and international partners have conducted experiments in space to understand the biological impacts and address hazards to health. The resulting basic and applied science is imperative to enabling humanity to venture back to the Moon and then to Mars and beyond. Sending organisms into space is a costly endeavor. All biospecimens not required by spaceflight-relevant Principal Investigators are harvested, preserved, and archived in the NASA Biological Institutional Scientific Collection (NBISC) to maximize the scientific return. The NASA Biological and Physical Sciences (BPS) Division has an ‘Open Science’ endeavor which includes NASA Genelab, the Space Biology Program’s Biospecimen Sharing Program, Physical Sciences Informatics, the Ames Life Sciences Data Archive, and NBISC. Its purpose is to integrate extensive data and biospecimen resources from spaceflight and/or ground-based analog experiments. NBISC biospecimens are collected and preserved according to well-established standard operating procedures to maintain scientific quality and are available on-request by the international scientific community. NBISC currently stores over 32,000 biospecimens from Shuttle, International Space Station, and ground-based space analog investigations. Tissue sharing has resulted in at least 33 publications since 2011 and 48 requests since 2016. Many requests for NBISC biospecimen come from first-time investigators who subsequently submit grants as the port-of-entry into the field of space biology. Some NBISC biospecimens have been awarded to NASA Genelab, who then generate various ‘Open Science’ -omics data sets on their platform for bioinformatics. Other NBISC biospecimen awards have led to multiple studies such as fecal microbiome analysis, DNA damage analysis using single-cell DNA sequencing, enzymatic-pathway identification involved in spaceflight muscle atrophy, and characterization of ocular morphological changes. Of note, NBISC has expanded to include a new Space Microbial Culture Collection (SMCC) for the collection, identification, documentation, long-term preservation, and distribution of space-related microbial isolates.

Ryan T. Scott↗
DOE OSTI2025

​​Updates to Anaerobic Digestion Pathways for Animal Manure in R&D GREET 2025​

Livestock and poultry manure management in the U.S. is a greenhouse gas (GHG) intensive process, emitting 81.7 MMT CO 2 e in 2022 (1.5% of net U.S. GHG emissions). The primary GHG is methane (CH 4 ), with 2,312 kt released in 2022 (9% of U.S. CH 4 emissions). Manure management methods are commonly categorized by whether they are anaerobic (“wet”) or aerobic (“dry”) techniques. Although dry methods manage the largest share of manure, the majority of GHG emissions are generated during storage of manure in anaerobic conditions – typically in water-filled tanks, pits, or lagoons. There has been a 65% increase in emissions from 1990, primarily due to an increasing cattle population. Also, this rise in population has been coupled with a rise in animal confinement and density, which typically adopt wet manure management methods. Within wet methods, anaerobic bacteria proliferate and decompose volatile solids (VS) within the manure in a process called anaerobic digestion to produce roughly equal mixtures of CH 4 and carbon dioxide (CO 2 ). These GHGs are fugitive, in that they are assumed to be released to the atmosphere and contribute to GHGs within U.S. GHG inventories. If the methane is captured and purified (i.e., “upgraded”) this simultaneously mitigates GHGs that would have otherwise been released and produces a valuable energy product known colloquially as Renewable Natural Gas (RNG). Such processes are acknowledged by U.S. policy through programs such as the U.S. Renewable Fuels Standard (RFS), the federal Clean Fuel Production Credit (45Z), and state clean fuel standards (CFS). In the 45Z and CFS schemes, the GHG emissions of the business-as-usual (BAU) manure management system is taken as a baseline, and credits are received based on GHG reductions relative to this baseline. Thus, estimating the GHG emissions of the BAU scenario (also known as the “counterfactual”) is necessary.

09 BIOMASS FUELS↗
DOE OSTI2016

Pentamidine blocks the interaction between mutant S100A5 and RAGE V domain and inhibits the RAGE signaling pathway

The human S100 protein family contains small, dimeric and acidic proteins that contain two EF-hand motifs and bind calcium. When S100A5 binds calcium, its conformation changes and promotes interaction with the target protein. The extracellular domain of RAGE (Receptor of Advanced Glycation End products) contain three domains: C1, C2 and V. The RAGE V domain is the target protein of S100A5 that promotes cell survival, growth and differentiation by activating several signaling pathways. Pentamidine is an apoptotic and antiparasitic drug that is used to treat or prevent pneumonia. Here, we found that pentamidine interacts with S100A5 using HSQC titration. We elucidated the interactions of S100A5 with RAGE V domain and pentamidine using fluorescence and NMR spectroscopy. We generated two binary models—the S100A5-RAGE V domain and S100A5-Pentamidine complex—and then observed that the pentamidine and RAGE V domain share a similar binding region in mS100A5. We also used the WST-1 assay to investigate the bioactivity of S100A5, RAGE V domain and pentamidine. These results indicated that pentamidine blocks the binding between S100A5 and RAGE V domain. This finding is useful for the development of new anti-proliferation drugs. - Highlights: • The interaction between mS100A5–RAGE V was investigated by fluorescence spectroscopy. • The interfacial residues on mS100A5–RAGE V and mS100A5–pentamidine contact surface were mapped by {sup 1}H-{sup 15}N HSQC experiments. • mS100A5–RAGE V and mS100A5–pentamidine complex models were generated from NMR restraints using HADDOCK program. • The bioactivity of the mS100A5–RAGE V and mS100A5–pentamidine complex was studied using WST-1 assay.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2026

Software Verification of VARPOW

The VARPOW program is a post-processing utility program for DIF3D, specifically DIF3DVARIANT, and it was developed to provide interface files for the thermal analysis program DASSH. The basic methodology of VARPOW is to take the neutron and gamma flux (moments) calculated by DIF3D (or GAMSOR) and combine them with the heating (coefficient) cross sections to calculate the spatial power distributions using the DIF3DVARIANT spatial basis. VARPOW can use the output from GAMSOR (both steady state neutron and gamma flux calculations) or standard DIF3D/REBUS calculations (neutron flux only). The correct approach for defining the power distribution is to use GAMSOR as its purpose was to properly compute the gamma heating throughout the modeled domain. The power desnities calculated by VARPOW are broken into fuel, cladding and coolant terms for which isotope-wise categorization is needed. VARPOW has built in options the user can select for the isotope categorization or VARPOW can import a file that details the isotope categorization. VARPOW can export the solution in the polynomial basis of DIF3D-VARIANT or the monomial basis of DIF3D-VARIANT. Recently the clad neutron damage calculation capability was introduced into VARPOW, and it now allows a pathway to get distributions of clad DPA. The purpose of this work is to verify the power distribution, fast neutron flux and clad DPA results calculated by VARPOW from both the GAMSOR and DIF3D input options and verify that the input and output options are consistent with the manual. Hand calculation and independent numerical calculation are used for this verification work.

Zhong, Zhaopeng [Argonne National Laboratory (ANL)↗
DOE OSTI2014

New Transposon Tools Tailored for Metabolic Engineering of Gram-Negative Microbial Cell Factories

Re-programming microorganisms to modify their existing functions and/or to bestow bacteria with entirely new-to-Nature tasks have largely relied so far on specialized molecular biology tools. Such endeavors are not only relevant in the burgeoning metabolic engineering arena but also instrumental to explore the functioning of complex regulatory networks from a fundamental point of view. À la carte modification of bacterial genomes thus calls for novel tools to make genetic manipulations easier. We propose the use of a series of new broad-host-range mini-Tn5-vectors, termed pBAMDs, for the delivery of gene(s) into the chromosome of Gram-negative bacteria and for generating saturated mutagenesis libraries in gene function studies. These delivery vectors endow the user with the possibility of easy cloning and subsequent insertion of functional cargoes with three different antibiotic-resistance markers (kanamycin, streptomycin, and gentamicin). After validating the pBAMD vectors in the environmental bacterium Pseudomonas putida KT2440, their use was also illustrated by inserting the entire poly(3-hydroxybutyrate) (PHB) synthesis pathway from Cupriavidus necator in the chromosome of a phosphotransacetylase mutant of Escherichia coli. PHB is a completely biodegradable polyester with a number of industrial applications that make it attractive as a potential replacement of oil-based plastics. The non-selective nature of chromosomal insertions of the biosynthetic genes was evidenced by a large landscape of PHB synthesis levels in independent clones. One clone was selected and further characterized as a microbial cell factory for PHB accumulation, and it achieved polymer accumulation levels comparable to those of a plasmid-bearing recombinant. Taken together, our results demonstrate that the new mini-Tn5-vectors can be used to confer interesting phenotypes in Gram-negative bacteria that would be very difficult to engineer through direct manipulation of the structural genes.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Measurement of thermal gap conductance using the laser flash method

Thermal gap conductance refers to overall heat conductance through a gas-filled gap as interface thermal resistance between the gas and surface has to be considered. The analysis of new ATR (Advanced Test Reactor) fuel experiments requires experimental data and models for the gap conductance of the cladding/fuel capsule gap, which typically varies from 5 μm to 50 μm and is filled with He at 1-3 atm. Although past research has studied the gap conductance between UO{sub 2} fuel and Zircaloy cladding, new experiments are needed to provide the gap conductance data between HT9 and stainless steel 316, and between advanced fuels and advanced cladding in the Accident Tolerant Fuels program. In this paper, the laser flash method is modified to measure the gap conductance. The gap is formed by welding two stainless steel 316 disks with three spacers. The temperature at the rear surface, after exposure to the laser pulse at the front surface, is modeled with 1D heat transfer through three layers. The analytic solution is then fitted with the measured temperature to determine gap conductance. The sensitivity analysis based on the 1D assumption and 3D numerical simulations were performed to assess the sensitivity and uncertainty of the measurement. It is concluded the heat capacity of the gas in the gap has minimal impact on the measurement, which indicates that the thermal property determined by this method is the thermal conductance, instead of the thermal diffusivity. Convective heat loss through sidewalls under the current experimental design has insignificant influences. Heat transfer through spacers may cause up to 10% overestimation of thermal gap conductance, but the effects can be mostly eliminated by the design of grooves on samples. The result established a pathway for gap conductance determination. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2016

Numerical simulations of depressurization-induced gas production from gas hydrates using 3-D heterogeneous models of L-Pad, Prudhoe Bay Unit, North Slope Alaska

Gas production potential is estimated using a three-dimensional reservoir model based on gas hydrate deposits located in the Prudhoe Bay region of the Alaska's North Slope. The model incorporates two hydrate-bearing sand units using detailed reservoir geological and structural information obtained from past and recent drilling programs. Geostatistical porosity models, conditioned to log data from 78 wells drilled in the vicinity of the Prudhoe Bay “L-Pad,” were developed, providing 3D heterogeneity in porosity, porosity-dependent hydrate saturation, and intrinsic permeability. The simulations utilize both vertical and inclined wellbores to induce depressurization of the reservoir at a constant bottom-hole pressure. The results show the superior performance of the inclined well design. Average gas production rates during the first five years were ~6.0 × 10 4 ST m 3 /day (~2.1 MMSCF/day) and ~2.7 × 10 4 ST m 3 /day (~1.0 MMSCF/day) for incline and vertical wells, respectively. After 30 years 5.3 × 10 8 - 5.7 × 10 8 ST m 3 (18.6–20.2 BSCF) and 6.2 × 10 8 - 6.4 × 10 8 ST m 3 (22.0–22.7 BSCF) gas were produced using the vertical and inclined well configurations, respectively. The analysis reveals that 2D reservoir models with homogeneous representations for porosity and hydrate saturation significantly underestimate production potential. The heterogeneity implemented in this work provides complex porous network and preferential pathways for mobile phase flow to a producing well. Consequently, no secondary hydrate formation around a wellbore is predicted in contrast to models that utilize uniform porosity and hydrate saturation distributions.

03 NATURAL GAS↗
DOE OSTI2022

Correlated nanoelectronics and the second quantum revolution

The growing field of correlated nanoelectronics exists at the intersection of two established fields: correlated oxide electronics and semiconductor nanoelectronics. The development of quantum technologies that exploit quantum coherence and entanglement for the purposes of computation, simulation, and sensing will require complex material properties to be controlled at nanoscale dimensions. Heterostructures and nanostructures formed at the interface between LaAlO 3 and SrTiO 3 exhibit striking behavior that arises from the ability to program the conductive behavior at extreme nanoscale dimensions. The active electronic layer, SrTiO 3 , exhibits a wide range of gate-tunable phenomena such as ferroelectricity, ferroelasticity, magnetism, superconductivity, and spin–orbit coupling, all of which can be controlled at the nanoscale using two reversible methods: conductive atomic force microscope lithography and ultra-low-voltage electron beam lithography. Mesoscopic devices such as single-electron transistors and quasi-one-dimensional electron waveguides can be “sketched” using these techniques, and the properties of these devices differ significantly from those created from traditional semiconductors, such as Si or GaAs. The strongly correlated nature of the SrTiO 3 system is evident from superconducting behavior as well as a state in which electrons are paired outside the superconducting state. A highly exotic phase was discovered in which a degenerate quantum liquid is formed from bound states of n = 2, 3, 4, … electrons. Further development of correlated nanoelectronics based on the LaAlO 3 /SrTiO 3 system can potentially lead to a general platform for quantum simulation as well as a pathway for the development of highly entangled states of multiple photons.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Summary of the Graduate Mentoring Assistance Program for PNNL PNNL.12.006 (April 2012 – May 31, 2013)

Summary of Students and Projects: Sarah Bender: The possible improvement of the Multi-Isotope Process (MIP) Monitor by the addition of Compton suppression is investigated for this study. The Compton continuum from the dominant 661.7 keV Cs-137 fission product peak obscures lower energy lines which could be used for spectral and multivariate analysis. A novel Compton suppression system which uses fast, room-temperature materials will be developed using simulation. As opposed to the standard high purity germanium (HPGe) detector suppressed using a thallium-doped sodium iodide (NaI(Tl)) guard detector array, cerium-doped lanthanum bromide (LaBr3) will be used as the primary spectroscopic detector. For Sarah’s Master’s degree, she constructed and validated the unsuppressed detector response of the Pennsylvania State University (PSU)-Compton suppression system. For Sarah’s PhD, she is completing that simulation by including the suppressed operation which will be validated with spent fuel samples. She is also going to use the validation of suppressed operation to predict the detector response of a LaBr3 based Compton suppression system. Richard Clark: Richard Clark completed his study this FY of a new technique known as Intrinsic Dosimetry. Intrinsic Dosimetry is the method of measuring total absorbed dose received by the walls of a container holding radioactive material. By considering the total absorbed dose received by a container in tandem with the physical characteristics of the radioactive material housed within that container, this method has the potential to provide enhanced pathway information regarding the history of the container and its radioactive contents. The latest in a series of experiments designed to validate and demonstrate this newly developed tool are reported. Kenneth Dayman: The MIP Monitor is an online, non-destructive approach to process monitoring in a nuclear fuel reprocessing facility using gamma spectra taken of process streams and multivariate data analysis to detect anomalies in operation. Last year, Mr. Dayman investigated methods to classify spent nuclear fuel according to both reactor type and burn up based on the constituent nuclide activities, which may be used to more accurately calibrate other models in an analysis scheme in order to improve the accuracy and precision of predictions. He is currently writing up his results for publication and has transitioned to another project with Dr. Derrick Haas at PNNL.

Schwantes, Jon M.↗
NASA NTRS1989

Feeding-associated alterations in striatal neurotransmitter release

Published evidence suggests a role for dopaminergic (DA) brain pathways in feeding-associated behaviors. Using the novel technique of brain microdialysis of striatal extracellular fluid (ECF) as an index of DA release, Church et al. described increases in levels of DA when animals had limited access to pellets, but not with free access. Dopamine release from the nucleus accumbens did increase with free access to pellets post starvation or after food reward. We used permanently implanted microdialysis probes to measure ECF levels of DA, DOPAC, HVA, and large neutral amino acids (LNAA) for up to 72 hours after implantation among rats experiencing different dietary regimens.

NASA Discipline Regulatory Physiology↗
DOE OSTI2023

Clean Hydrogen Production R&D

Comprehensive, concerted efforts supported by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy (EERE), Hydrogen and Fuel Cell Technologies Office (HFTO) are advancing research and development to demonstrate clean hydrogen production and industrial decarbonization pathways. These pathways enable an economically competitive and environmentally beneficial future energy system across sectors and can address specific applications that are difficult to decarbonize. NREL's research accelerates development, integration, and scale up of hydrogen and fuel cell technologies to enable widespread deployment across multiple energy sectors. Our work helps industry overcome technical challenges and supports DOE's H2@Scale vision for clean hydrogen across multiple applications and economic sectors. We also bridge technologies with other research areas across the lab and through multiple DOE and national lab research initiatives, consortia, and collaborations including: H2NEW: Hydrogen from Next-generation Electrolyzers of Water Consortium, HydroGEN: Advanced Water Splitting Materials Consortium, and BioH2. Within the plenary panel called: From the Classroom to the Lab to the Board Room, I will represent the Lab in this panel and will be talking about hydrogen technology at NREL, the lab's role in bridging university research with industry commercialization. I will also talk about my personal career path and what it's like to work at NREL, along with work force development and DEIA programs at NREL.

BIL↗
NASA NTRS2008

The Astronaut Glove Challenge: Big Innovation from a (Very) Small Team

Many measurements were taken by test engineers from Hamilton Sundstrand, the prime contractor for the current EVA suit. Because the raw measurements needed to be converted to torques and combined into a final score, it was impossible to keep track of who was ahead in this phase. The final comfort and dexterity test was performed in a depressurized glove box to simulate real on-orbit conditions. Each competitor was required to exercise the glove through a defined set of finger, thumb, and wrist motions without any sign of abrasion or bruising of the competitor's hand. I learned a lot about arm fatigue! This was a pass-fail event, and both of the remaining competitors came through intact. After taking what seemed like an eternity to tally the final scores, the judges announced that I had won the competition. My glove was the only one to have achieved lower finger-bending torques than the Phase VI glove. Looking back, I see three sources of the success of this project that I believe also operate in other programs where small teams have broken new ground in aerospace technologies. These are awareness, failure, and trust. By remaining aware of the big picture, continuously asking myself, "Am I converging on a solution?" and "Am I converging fast enough?" I was able to see that my original design was not going to succeed, leading to the decision to start over. I was also aware that, had I lingered over this choice or taken time to analyze it, I would not have been ready on the first day of competition. Failure forced me to look outside conventional thinking and opened the door to innovation. Choosing to make incremental failures enabled me to rapidly climb the learning curve. Trusting my "gut" feelings-which are really an internalized accumulation of experiences-and my newly acquired skills allowed me to devise new technologies rapidly and complete both gloves just in time. Awareness, failure, and trust are intertwined: failure provides experiences that inform awareness and provide decision-making opportunities that build trust among team members and managers while opening minds to new pathways for development. All three are necessary for teams-large or small-to achieve big innovation.

Homer, Peter↗
NASA NTRS1966

Progress in Development of Methods in Bone Densitometry

The effects of weightlessness and decreased activity on the astronaut's musculoskeletal system during prolonged space flight, missions are of concern to NASA. This problem was anticipated from the knowledge that human subjects lose significant quantities of calcium from the skeleton during periods of bedrest, immobilization, and water immersion. An accurate method of measurement of the changes in mineral content of the skeleton is required not only in the space program but also in the biological, medical, and dental fields for mineral metabolism studies and for studying various pathological conditions of the skeleton and teeth. This method is a difficult one requiring the coordinated efforts of physiologists, biophysicists, radiologists, and clinicians. The densitometry methods reported in this conference which have been used or are being developed include X-ray, beta excited X-rays, radioisotopes, sonic vibration, and neutron activation analysis Studies in the Gemini, Biosatellite, and Apollo flights use the X-ray bone densitometry method which requires making X-rays before and after the flights. An in-flight method of bone densitometry would be valuable, and use of radioisotope sources has been suggested. Many advances in bone densitometry have been made in the last five years, and the urgency of the requirement makes this working conference timely and valuable. In such a rapidly developing field with investigators working independently in a variety of scientific disciplines, a working conference is of great value in exchanging information and ideas, critically evaluating approaches and methods, and pointing out new research pathways.

DENSITOMETER↗
NASA NTRS2003

Synthetic Vision Enhances Situation Awareness and RNP Capabilities for Terrain-Challenged Approaches

The Synthetic Vision Systems (SVS) Project of Aviation Safety Program is striving to eliminate poor visibility as a causal factor in aircraft accidents as well as enhance operational capabilities of all aircraft through the display of computer generated imagery derived from an onboard database of terrain, obstacle, and airport information. To achieve these objectives, NASA 757 flight test research was conducted at the Eagle-Vail, Colorado airport to evaluate three SVS display types (Head-Up Display, Head-Down Size A, Head-Down Size X) and two terrain texture methods (photo-realistic, generic) in comparison to the simulated Baseline Boeing-757 Electronic Attitude Direction Indicator and Navigation / Terrain Awareness and Warning System displays. These independent variables were evaluated for situation awareness, path error, and workload while making approaches to Runway 25 and 07 and during simulated engine-out Cottonwood 2 and KREMM departures. The results of the experiment showed significantly improved situation awareness, performance, and workload for SVS concepts compared to the Baseline displays and confirmed the retrofit capability of the Head-Up Display and Size A SVS concepts. The research also demonstrated that the pathway and pursuit guidance used within the SVS concepts achieved required navigation performance (RNP) criteria.

Kramer, Lynda J.↗
DOE OSTI2020

Development and Characterization of Cementitious Waste Forms for Immobilization of Granular Activated Carbon, Silver Mordenite, and HEPA Filter Media Solid Secondary Waste

At the Department of Energy’s Hanford site, over 53 million gallons of chemically complex and radioactive wastes have been stored in 177 underground tanks. The Hanford Tank Waste Treatment and Immobilization Plant (WTP) is under construction and is designed to treat and immobilize these wastes. During operations of WTP, solid secondary wastes (SSWs) will be generated as a result of waste treatment, vitrification, off-gas management, and supporting process activities. SSW treatment processes and resulting disposal pathways for the final disposition form of the SSW are needed to support direct feed low activity waste (DFLAW) operations and facilitate continued operation of WTP. The SSWs produced through WTP operations are expected to include used process equipment, contaminated tools and instruments, decontamination wastes, high-efficiency particulate air (HEPA) filters, carbon absorption beds (granular activated carbon, GAC), silver mordenite (AgM) and spent ion-exchange resins. These waste streams are planned to be immobilized in a cementitious waste form and disposed of either as stabilized/blended (non-debris) or encapsulated (debris) in a cementitious waste form. Accordingly, cementitious waste forms from these streams were included in the 2017 Integrated Disposal Facility (IDF) Performance Assessment (PA). The input data used to represent these SSW forms in the 2017 IDF PA involved many assumptions and associated uncertainties. This data limitation was due to the lack of material- and site-specific data available for representative SSW materials in cementitious matrices. To verify the assumed values used in the IDF PA and fill this limitation in available data, Washington River Protection Solutions, LLC (WRPS), has initiated a program targeted toward gathering site specific data relevant to Hanford SSW disposal. The work within this report is a continuation of this ongoing program.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Divalent Ion Parameterization Strongly Affects Conformation and Interactions of an Anionic Biomimetic Polymer

The description of peptides and the use of molecular dynamics simulations to refine structures and investigate the dynamics on an atomistic scale are well developed. Through a consensus in this community over multiple decades, parameters were developed for molecular interactions that only require the sequence of amino-acids and an initial guess for the three-dimensional structure. The recent discovery of peptoids will require a retooling of the currently available interaction potentials in order to have the same level of confidence in the predicted structures and pathways as there is presently in the peptide counterparts. Here we present modeling of peptoids using a combination of ab initio molecular dynamics (AIMD) and atomistic resolution classical forcefield (FF) to span the relevant time and length scales. To properly account for the dominant forces that stabilize ordered structures of peptoids, namely steric-, electrostatic, and hydrophobic interactions mediated through sidechain-sidechain interactions in the FF model, those have to be first mapped out using high fidelity atomistic representations. A key feature here is not only to use gas phase quantum chemistry tools, but also account for solvation effects in the condensed phase through AIMD. One major challenge is to elucidate ion binding to charged or polar regions of the peptoid and its concomitant role in the creation of local order. Here, similar to proteins, a specific ion effect is observed suggesting that both the net charge and the precise chemical nature of the ion will need to be described. MDD was supported by MS3 (Materials Synthesis and Simulation Across Scales) Initiative at Pacific Northwest National Laboratory. Research was funded by the Laboratory Directed Research and Development program at Pacific Northwest National Laboratory. MDB acknowledges support from US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Material & Engineering. CJM acknowledges support from US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. PNNL is a multiprogram national laboratory operated by Battelle for the U.S. Department of Energy.

Daily, Michael D.↗
DOE OSTI2018

Kinetic Coupling of Water Splitting and Photoreforming on SrTiO 3 -Based Photocatalysts

Coupling the anodic half-reactions of overall water splitting and oxygenate photoreforming (i.e., proton reduction and oxygenate oxidations) on Al-doped SrTiO3 decorated with a co-catalyst enables efficient photocatalytic H2 generation along with oxygenate conversion without accumulating undesired intermediates such as formaldehyde. The net H2-evolution rates result from the interplay between water oxidation, oxygenate oxidation, and the back-reaction of H2 and O2 to water. When the latter pathway is quantitatively suppressed (e.g., on RhCrOx co-catalyst or in excess of oxygenated hydrocarbons), the initial H2-evolution rates are independent of the oxygenate nature and concentration. This is a consequence of the reduction equivalents for H2-evolution provided by water oxidation compensating changes in the rates of oxygenate conversion. Thus, under conditions of suppressed back-reaction, water and oxygenate oxidations have equal quantum efficiencies. The selectivities to water and oxygenate oxidation depend on oxygenate nature and concentration. Transformations mediated by indirect hole transfer dominate as a result of the water oxidation at the anode and the associated intermediates generated in O2-evolution catalysis (e.g. ·OH, ·O and ·OOH). On the undecorated semiconductor, the O2 produced during overall water splitting is reductively activated to participate in glycerol oxidation without consuming evolved H2. Acknowledgements The authors would like to thank ESRF in Grenoble, France, for providing beam time at the ID26 station for XAFS experiments. K.E.S. gratefully acknowledges financial support by the Fond der Chemischen Industrie (FCI). J.A.L. and O.Y.G. acknowledge support for his contribution by the Laboratory Directed Research and Development Program at Pacific Northwest National Laboratory, a multi-program national laboratory operated by Battelle for the U.S. Department of Energy. The authors thank Xaver Hecht for BET measurements, Martin Neukamm for SEM and AAS measurements and Dr. Udishnu Sanyal for TEM imaging. Christine Schwarz is acknowledged for technical assistance in NMR experiments.

Sanwald, Kai E.↗