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DOE OSTI2026

Thermodynamic Control of Interface Directs MnO 2 Nucleation Chemistry for Dense and Conformal Electrodeposition

Manganese dioxide (MnO 2 ) is widely recognized as a promising material for high-energy-density energy storage systems due to its broad applicability and facile electrodeposition. However, achieving uniform, thin, and high-mass-loading MnO 2 coatings on high-surface-area electrodes remains a significant challenge. Conventional electrodeposition methods typically yield nonuniform, thick layers with poor conductivity and limited material utilization, restricting their practical use. Here, we uncover a thermodynamically engineered vanadyl/pervanadyl (VO 2+ /VO 2 + ) interface that fundamentally reshapes MnO 2 electrodeposition chemistry, enabling highly uniform and dense coatings. Here, combining in situ AFM measurement, Classical Nucleation Theory, and Johnson–Mehl–Avrami–Kolmogorov modeling, we show that this interface reduces early-stage detectable MnO 2 island size by 35-fold and shifts the MnO 2 growth from diffusion-limited to reaction-limited progressive nucleation. This thermodynamically controlled interface yields highly dense and conformal MnO 2 films with record-high mass loading of 241 mg cm –2 (1607 mg cm –3 ) on 3D-printed graphene aerogels, without compromising porosity or inducing thickness gradient. As a prototype demonstration, the resulting MnO 2 electrodes deliver record-setting volumetric performance in both capacitors (106 F cm –3 ) and Zn//MnO 2 pouch cells (162 mAh cm –3 ). Beyond energy storage, our findings demonstrate the significance of thermodynamic interface control in MnO 2 nucleation chemistry for achieving dense and uniform coatings on various substrates, with implications for electrocatalysis, semiconductor processing, and advanced materials manufacturing.

Batteries↗

DOE OSTI2026

A Quantitative Examination of Catalyst Component Impacts on Hydrogen Adsorption and Spillover

Hydrogen spillover is a widely recognized but poorly understood surface phenomenon. We coupled volumetric chemisorption with Fourier transform infrared spectroscopy, thermogravimetric analysis, and acid–base titrations to quantify the roles of metal (Pt, Au) and support chemistry (anatase, rutile, P25 titania) on spillover. We show that metal identity has little to no impact on the amount of spillover hydrogen. Spillover pressure dependence is essentially the same on Au/TiO 2 and Pt/TiO 2 , indicating H 2 adsorption is equilibrated across both the metal and support. Conversely, spillover is highly sensitive to support surface chemistry, as rutile TiO 2 stabilizes ∼5× more surface hydrogen than anatase TiO 2 . This change is due to a combination of factors, including the rutile surface’s higher proton affinity, stabilized surface electronic states, and larger surface entropy. This work highlights the utility of Au/MO x catalysts as control materials for spillover, as they enable quantitative evaluation of H 2 adsorption on active metals and spillover onto the support.

Adsorption↗

DOE OSTI2019

Understanding and Design of Bidirectional and Reversible Catalysts of Multielectron, Multistep Reactions

The catalytic properties of the enzymes that transform H2 set very high standards for chemists who aim at designing synthetic electrocatalysts of H2 oxidation and production. Of particular relevance is the observation that some hydrogenases wired to electrodes function in either direction of the reaction depending on the driving force that is applied, and at a significant rate as a result of even a very small deviation from equilibrium. We call the former property "bidirectionality", and the latter "reversibility". Bidirectional and reversible catalysts of H2 oxidation and production have only recently been synthesized. Here we introduce the kinetic modelling of bidirectional two-electron redox reactions in the case of molecular catalysts and enzymes that are either attached to an electrode or diffusing in solution in the vicinity of an electrode. Our theoretical findings are illustrated by previous results obtained with hydrogenases and Nickel diphosphine molecular catalysts. We emphasize that trying to discuss bidirectionality and reversibility in relation to a single redox potential leads to an impasse: the catalyst undergoes two redox transitions, and two catalytic potentials must be defined, which may depart from the two potentials measured in the absence of catalysis. The difference between the two catalytic potentials defines the reversibility; the difference between their average value and the open circuit potential defines the directionality. We aim at giving rules that help discriminate between distinct mechanisms ("ECEC", "EECC" etc.) based on the voltammetric responses, and we discuss the design principles of bidirectionality and reversibility in terms of kinetics. In particular we conclude that neither bidirectionality nor reversibility requires that the catalytic energy landscape be flat. However, sinks and high energy intermediates may negatively impact the catalytic rates. The "efficiency" of a bidirectional catalyst appears to be defined by various figures of merit (rates, directionality, reversibility) that need to be recognized before they can be optimized simultaneously. E.S.W. was supported by the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy (USDOE), Office of Science, Office of Basic Energy Sciences (BES). The work discussed here was originally supported for WJS by the Office of Science Early Career Research Program through the USDOE, with current funding from the USDOE, BES, Chemical Sciences, Geosciences, and Biosciences program.

Fourmond, Vincent↗

DOE OSTI2021

macroMS: Image-Guided Analysis of Random Objects by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Mass spectrometry imaging is well-suited to characterizing sample surfaces for their chemical content in a spatially resolved manner. However, when the surface contains small objects with significant empty spaces between them, more efficient approaches to sample acquisition are possible. Image-guided mass spectrometry (MS) enables high-throughput analysis of a diverse range of sample types, such as microbial colonies, liquid microdroplets, and others, by recognizing and analyzing selected location targets in an image. Here, we describe an imaging protocol and macroMS, an online software suite that can be used to enhance MS measurements of macroscopic samples that are imaged by a camera or a flatbed scanner. Furthermore, the web-based tool enables users to find and filter targets from the optical images, correct optical distortion issues for improved spatial location of selected targets, input the custom geometry files into an MS device to acquire spectra at the selected locations, and finally, perform limited data analysis and use visualization tools to aid locating samples containing compounds of interest. Using the macroMS suite, an enzyme mutant library of Saccharomyces cerevisiae and nL droplet arrays of Escherichia coli and Pseudomonas fluorescens have been assayed at a rate of ~2 s/sample.

47 OTHER INSTRUMENTATION↗

DOE OSTI2015

Synthesis, radiolabeling, and biological evaluation of ( R )- and ( S )-2-amino-5-[ 18 F]fluoro-2-methylpentanoic acid (( R )-, ( S )-[ 18 F]FAMPe) as potential positron emission tomography tracers for brain tumors

In this paper, a novel 18 F-labeled α,α-disubstituted amino acid-based tracer, 2-amino-5-[ 18 F]fluoro-2-methylpentanoic acid ([ 18 F]FAMPe), has been developed for brain tumor imaging with a longer alkyl side chain than previously reported compounds to increase brain availability via system L amino acid transport. Both enantiomers of [ 18 F]FAMPe were obtained in good radiochemical yield (24–52% n = 8) and high radiochemical purity (>99%). In vitro uptake assays in mouse DBT gliomas cells revealed that ( S )-[ 18 F]FAMPe enters cells partly via sodium-independent system L transporters and also via other nonsystem A transport systems including transporters that recognize glutamine. Biodistribution and small animal PET/CT studies in the mouse DBT model of glioblastoma showed that both ( R )- and ( S )-[ 18 F]FAMPe have good tumor imaging properties with the ( S )-enantiomer providing higher tumor uptake and tumor to brain ratios. Finally, comparison of the SUVs showed that ( S )-[ 18 F]FAMPe had higher tumor to brain ratios compared to ( S )-[ 18 F]FET, a well-established system L substrate.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2012

New trends in chemistry and materials science in extremely tight space

Pressure plays a critical role in regulating the structures and properties of materials. Since Percy Bridgeman was recognized by the 1946 Nobel Prize in Physics for his contribution in high-pressure physics, high-pressure research has remained an interdisciplinary scientific frontier with many extraordinary breakthroughs. Over the past decade or so, in particular, high-pressure chemistry and materials research has undergone major advances with the discovery of numerous exotic structures and properties. Furthermore, brand new classes of inorganic materials of unusual stoichiometries and crystal structures, which have a wide range of optical, mechanical, electronic and magnetic properties, have been produced at high pressures.

36 MATERIALS SCIENCE↗

DOE OSTI2013

Evolution of Structure-Reactivity Correlations for the Hydrogen Abstraction Reaction by Chlorine Atom

Empirical structure-reactivity correlations are developed for log k298, the gas-phase rate constants for the reaction (Cl + HCR3 ClH + CR3 ). It has long been recognized that correlation with rH is weak. The poor performance of the linear Evans-Polanyi formulation s illustrated and was little improved by adding a quadratic term, e.g., by making its slope smoothly dependent on rH [ ( rH rHmin) / ( rHmax rHmin)]. The polar effect ( -Cl---H---CR3 +) has also been long discussed but there is no formalization of this dependence based on widely available independent variable(s). Using the sum of Hammett constants for the R substituents also gave at best modest correlations, either for para or for its dissection into F (field/inductive) and R (resonance) effects. Much greater success was achieved by combining these approaches with the preferred independent variable set being either [( rH)2, rH, F, and R] or [ , rH, F, and R]. For 64 rate constants which span 7 orders of magnitude, these correlation formulations give r2 > 0.87 and a mean unsigned deviation of <0.5 log k units, with even better performance if primary secondary, and tertiary reaction centers are treated separately.

chlorine atom↗

DOE OSTI2013

Isomorphism in Fluid Phase Diagrams: Kulinskii Transformations Related to the Acentric Factor

For a wide class of molecular fluids, the temperature-density phase diagrams exhibit two prominent generic properties: a nearly linear locus, termed the Zeno line, along which the compressibility factor, Z = P/rho RT = 1 (same as an ideal gas), and the widely arching border of the vapor-liquid coexistence region, termed the binodal curve, with gas and liquid branches meeting at the critical point. The Zeno and binodal loci have been known for more than a century, yet only during the past two decades were striking empirical correlations between them recognized. Recently, Kulinskii introduced a remarkably simple projective transformation, wherein the linearity of the Zeno line and its relation to the binodal curve are geometrical consequences of an approximate isomorphism of the fluid with a venerable theoretical model, the lattice gas (equivalent to the Ising spin model). Here we show the Kulinskii transformation is significantly improved in accuracy and scope by using as input, in place of the lattice gas, the original van der Waals equation or simulation results for the Lennard-Jones potential. Moreover, the key parameters in these transformations can be expressed in terms of the acentric factor, introduced by Pitzer to extend corresponding states.

Wei, Q↗

DOE OSTI2015

Mapping the Ultrafast Changes of Continuous Shape Measures in Photoexcited Spin Crossover Complexes without Long-Range Order

Establishing a tractable yet complete reaction coordinate for the spin-state interconversion in d(4)-d(7) transition metal complexes is an integral aspect of controlling the dynamics that govern their functionality. For spin crossover phenomena, the limitations of a single-mode approximation that solely accounts for an isotropic increase in the metal-ligand bond length have long been recognized for all but the simple octahedral monodentate FeII compounds. However, identifying the coupled deformations that also impact on the unimolecular rate constants remains experimentally and theoretically challenging, especially for samples that do not display long-range order or when crystallization profoundly alters the dynamics. Owing to the rapid progress in ultrafast X-ray absorption spectroscopy (XAS), it is now possible to obtain transient structural information in any physical phase with unprecedented details. Using picosecond XAS and DFT modeling, the structure adopted by the photoinduced high-spin state of solvated [Fe(terpy)(2)](2+) (terpy: 2,2':6',2 ''-terpyridine) has been recently established. Based on these results, the methodology of the continuous shape measure is applied to classify and quantify the short-lived distortion of the first coordination shell. The reaction coordinate of the spin-state interconversion is clearly identified as a double axial bending. This finding sets a benchmark for gauging the influence of first-sphere and second-sphere interactions in the family of FeII complexes that incorporate terpy derivatives. Some implications for the optimization of related photoactive FeII complexes are also outlined.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2015

Kinetics and Products of Vinyl + 1,3-Butadiene, a Potential Route to Benzene

The reaction between vinyl radical, C 2 H3, and 1,3-butadiene, 1,3-C 4 H 6 , has long been recognized as a potential route to benzene, particularly in 1,3-butadiene flames, but the lack of reliable rate coefficients has hindered assessments of its true contribution. Here, by using laser flash photolysis and visible laser absorbance (λ = 423.2 nm), we measured the overall rate coefficient for C 2 H 3 + 1,3-C 4 H 6 , k 1 , at 297 K ≤ T ≤ 494 K and 4 ≤ P ≤ 100 Torr. k 1 was in the high-pressure limit in this range and could be fit by the simple Arrhenius expression k1 = (1.1 ± 0.2) × 10 –12 cm 3 molecule –1 s –1 exp(–9.9 ± 0.6 kJ mol –1 /RT). Using photoionization time-of-flight mass spectrometry, we also investigated the products formed. At T ≤ 494 K and P = 25 Torr, we found only C 6 H 9 adduct species, while at 494 K ≤ T ≤ 700 K and P = 4 Torr, we observed ≤~10% branching to cyclohexadiene in addition to C 6 H 9 . Quantum chemistry master-equation calculations using the modified strong collision model indicate that n-C 6 H 9 is the dominant product at low temperature, consistent with our experimental results, and predict the rate coefficient and branching ratios at higher T where chemically activated channels become important. Predictions of k 1 are in close agreement with our experimental results, allowing us to recommend the following modified Arrhenius expression in the high-pressure limit from 300 to 2000 K: k 1 = 6.5 × 10 –20 cm 3 molecule –1 s –1 T 2.40 exp(–1.76 kJ mol –1 /RT).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2012

Critical Issues in Sensor Science To Aid Food and Water Safety

The stability of food and water supplies is widely recognized as a global issue of fundamental importance. Sensor development for food and water safety by nonconventional assays continues to overcome technological challenges. The delicate balance between attaining adequate limits of detection, chemical fingerprinting of the target species, dealing with the complex food matrix, and operating in difficult environments are still the focus of current efforts. While the traditional pursuit of robust recognition methods remains important, emerging engineered nanomaterials and nanotechnology promise better sensor performance but also bring about new challenges. Both advanced receptor-based sensors and emerging non-receptor-based physical sensors are evaluated for their critical challenges toward out-of-laboratory applications.

36 MATERIALS SCIENCE↗

DOE OSTI2012

Effect of Film Thickness and Domain Spacing on Defect Densities in Directed Self-Assembly of Cylindrical Morphology Block Copolymers

Directed assembly of block copolymer thin films is recognized as a high-throughput, low-cost complement to optical lithography with the ability to overcome the 32 nm natural resolution limit of conventional lithographic techniques. For bulk block copolymer systems, desired feature sizes ranging from 5 to 100 nm can be obtained by controlling the molecular weight and composition of a block copolymer, as long as the bulk order-disorder temperature (ODT) is such that the copolymer is well-segregated at the processing conditions. However, our studies on graphoepitaxially aligned cylindrical morphology block copolymer monolayer and bilayer films demonstrate that, as domain sizes are reduced, the block copolymer becomes increasingly susceptible to an unacceptably high density of thermally generated defects, resulting in a significant reduction of the ODT. Thus, in thin films, the minimum feature spacing accessible is limited by thermal defect generation and not by the bulk ODT. Our experimental studies on monolayer films of cylindrical morphology polystyrene-b-poly(2-vinyl pyridine) with microdomain spacings approaching 20 nm reveal that defect densities and the ODT are surprisingly sensitive to variations as small as 2 nm in the microdomain spacing. Additionally, the monolayer and bilayer ODT differ by nearly 100 C when the monolayer domain spacing is 20 nm, while the difference is only 20 C when the monolayer domain spacing is 22 nm. We explain this behavior using a quantitative estimation of the energetic cost of defect production in terms of the domain spacing, {chi}N, and block copolymer composition. These studies reveal unexpected consequences on the equilibrium defect densities of thin film block copolymers which must be accounted for when designing a block-copolymer-based directed-assembly process.

36 MATERIALS SCIENCE↗

DOE OSTI2012

Ecosystem carbon storage capacity as affected by disturbance regimes: A general theoretical model

Disturbances have been recognized as a key factor shaping terrestrial ecosystem states and dynamics. A general model that quantitatively describes the relationship between carbon storage and disturbance regime is critical for better understanding large scale terrestrial ecosystem carbon dynamics. We developed a model (REGIME) to quantify ecosystem carbon storage capacities (E[x]) under varying disturbance regimes with an analytical solution E[x] = U {center_dot} {tau}{sub E} {center_dot} {lambda}{lambda} + s {tau} 1, where U is ecosystem carbon influx, {tau}{sub E} is ecosystem carbon residence time, and {tau}{sub 1} is the residence time of the carbon pool affected by disturbances (biomass pool in this study). The disturbance regime is characterized by the mean disturbance interval ({lambda}) and the mean disturbance severity (s). It is a Michaelis-Menten-type equation illustrating the saturation of carbon content with mean disturbance interval. This model analytically integrates the deterministic ecosystem carbon processes with stochastic disturbance events to reveal a general pattern of terrestrial carbon dynamics at large scales. The model allows us to get a sense of the sensitivity of ecosystems to future environmental changes just by a few calculations. According to the REGIME model, for example, approximately 1.8 Pg C will be lost in the high-latitude regions of North America (>45{sup o} N) if fire disturbance intensity increases around 5.7 time the current intensity to the end of the twenty-first century, which will require around 12% increases in net primary productivity (NPP) to maintain stable carbon stocks. If the residence time decreased 10% at the same time additional 12.5% increases in NPP are required to keep current C stocks. The REGIME model also lays the foundation for analytically modeling the interactions between deterministic biogeochemical processes and stochastic disturbance events.

09 BIOMASS FUELS↗

DOE OSTI2017

A New Platform for Managing Soil Carbon and Soil Health

International Soil Carbon Network Workshop; Stanford, California, 27 February to 3 March 2017. Here, workshop participants recognized the need to identify vulnerabilities and opportunities for linking SOM-C science and the societal mandate to manage soils and ecosystems for productivity and carbon sequestration in future decades. Lastly, we outlined a path to gain support for the ISCN vision of a collective soil data platform from stakeholders and partners through engagement in coming years.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2019

Frequency-Bessel Transform Method for Effective Imaging of Higher-Mode Rayleigh Dispersion Curves From Ambient Seismic Noise Data

It has been widely recognized that the cross-correlation function of ambient seismic noise data recorded at two stations approximates to the part of Greens function between two stations. Therefore, the cross-correlation function should include higher modes, aside from the fundamental mode. However, the problem of measuring or extracting overtones from ambient seismic noise data remains. In this paper, we propose the frequency-Bessel transform method (F-J method) for extracting the dispersion curves of higher modes from ambient seismic noise data. We then assess the validity, accuracy, and applicability of the F-J method by conducting extensive numerical simulations and processing the observed ambient seismic noise data of the USArray. As demonstrated in this study, the F-J method is a convenient, practical, and accurate method for extracting the dispersion curves of multimodes from ambient seismic noise data and therefore has significant potentiality in the field of ambient seismic noise tomography.

58 GEOSCIENCES↗

DOE OSTI2019

Representing Nitrogen, Phosphorus, and Carbon Interactions in the E3SM Land Model: Development and Global Benchmarking

Over the past several decades, the land modeling community has recognized the importance of nutrient regulation on the global terrestrial carbon cycle. Implementations of nutrient limitation in land models are diverse, varying from applying simple empirical down–regulation of potential gross primary productivity under nutrient deficit conditions to more mechanistic treatments. In this study, we introduce a new approach to model multinutrient (nitrogen [N] and phosphorus [P]) limitations in the Energy Exascale Earth System Model (E3SM) Land Model version 1 (ELMv1–ECA). The development is grounded on (1) advances in representing multiple–consumer, multiple–nutrient competition; (2) a generic dynamic allocation scheme based on water, N, P, and light availability; (3) flexible plant CNP stoichiometry; (4) prognostic treatment of N and P constraints on several carbon cycle processes; and (5) global data sets of plant physiological traits. Through benchmarking the model against best knowledge of global plant and soil carbon pools and fluxes, we show that our implementation of nutrient constraints on the present–day carbon cycle is robust at the global scale. Compared with predecessor versions, ELMv1–ECA better predicts global–scale gross primary productivity, ecosystem respiration, leaf area index, vegetation biomass, soil carbon stocks, evapotranspiration, N2O emissions, and NO3– leaching. Factorial experiments imply that representing the phosphorus cycle improves modeled carbon fluxes, while considering dynamic allocation improves modeled carbon stock density. We also illustrate the value of using the International Land Model Benchmarking (ILAMB) package to evaluate and document performance during model development.

58 GEOSCIENCES↗

DOE OSTI2019

Rifting Processes at a Continent‐Ocean Transition Rift Revealed by Fault Analysis: Example of Dabbahu‐Manda‐Hararo Rift (Ethiopia)

Abstract Analyses of fault attributes have contributed to unraveling fault growth processes in diverse tectonic settings. By integrating such analysis at the scale of a fault population, we propose to investigate the characteristics of a rift that has evolved up to a stage typical of a continent‐ocean transition. We address this problem by considering Dabbahu‐Manda‐Hararo (DMH) rift segment (Central Afar, Ethiopia), recognized for being in a late rifting stage. We quantify fault azimuth, length, and throw attributes for 668 normal faults. Along DMH rift, the mean fault density is 0.87 ± 0.7 km/km 2 and the median tectonic strain ranges from 1.8% to 3.1% assuming a fault dip of 60° and 45°, respectively. Maximum tectonic strain (>10%) is found where the rift azimuth changes. Along‐rift variations in fault azimuth, length, and scaling relationships suggest a different stage of rifting in the northern part of the rift. We show that this difference can be attributed to the influence of the Dabbahu volcano located at the northern tip of the rift, which captured the propagating Manda‐Hararo rift in the last ~100 kyr. The morpho‐tectonic analysis reveals numerous common features with slow‐spreading ridge segments, such as the Lucky Strike segment located along the Mid‐Atlantic ridge (segment length, spreading rate, associated magmatic system) but also with intermediate and fast ones (axial valley, fault throws, and diking). This study reveals that a rift at the continent‐ocean transition may be characterized by a transient and evolutionary behavior that shares features with oceanic ridges from slow‐ to fast‐spreading rates.

Dumont, S.↗

DOE OSTI2019

Hillslope Hydrology in Global Change Research and Earth System Modeling

Earth System Models (ESMs) are essential tools for understanding and predicting global change, but they cannot explicitly resolve hillslope-scale terrain structures that have been long recognized by hydrologists as the fundamental organizers of water, energy, and biogeochemical stores and fluxes. Here, we bring together hydrologists, Critical Zone scientists and ESM developers, to explore how hillslope structures may modulate ESM grid-level water, energy and biogeochemical fluxes. In contrast to the traditional one-dimensional (1D), vertical, 2-3m deep, and free-draining soil hydrology in current ESM land models, we argue that 3D, lateral ridge-to-valley flow through shallow and deep paths, and insolation contrasts between sunny and shady slopes, are the top two basic, long-acknowledged, and readily quantifiable organizers of water and energy (and hence vegetation) within an ESM grid cell. We argue that these two processes will be most consequential where (and when) water and/or energy are limiting. We further hypothesize that if they are implemented in ESM land models, they will increase continental water storage and residence time, buffering land ecosystems against seasonal and interannual droughts. We explore efficient ways to capture these mechanisms in ESMs and identify critical knowledge gaps preventing us from scaling up hillslope to global processes. One such gap is our extremely limited view of the subsurface, where water is stored to support vegetation and released to stream baseflow and aquatic ecosystems. We conclude with a call for global syntheses activities and model experiments to assess the impact of hillslope hydrology on global change predictions.

Fan, Ying↗