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DOE OSTI2024

Mixed polyester recycling can enable a circular plastic economy with environmental benefits

The mixed and varied nature of fossil-based and bio-based plastic waste requires complex and costly separations to enable compatibility with recycling technologies. A circular plastic economy based on mixed polyesters through cleaving ester bonds to produce monomers, while re-utilizing bio-based monomers to produce high-quality sustainable plastics, charts an exciting solution. However, the feasibility of such a circular economy solution remains underexplored. Here, in this study, we conducted a techno-economic analysis and life-cycle assessment of three polyester depolymerization recycling processes-methanolysis, glycolysis, and acid hydrolysis-for a mixed feedstock (polyethylene terephthalate [PET], polylactic acid [PLA], and polybutylene adipate terephthalate [PBAT]). Methanolysis outperforms glycolysis and hydrolysis economically and environmentally due to more efficient downstream separations, generating products with a 31% decrease in selling price and 21%-46% reduction in acidification, carcinogenic toxicity, fossil-fuel depletion, global warming potential, particulate formation, and smog formation compared to conventional polyester manufacturing. This study highlights the viability of a circular plastic economy for mixed polyesters via a single chemical recycling process.

09 BIOMASS FUELS↗

DOE OSTI2026

Wave energy converter buoy for Arctic observations

Ocean observation buoys are currently powered-constrained by battery storage capacity or available solar power. Power constraints limit the number of measurements that can be made and the lifetime of the buoys. Ocean surface wave energy could be used for power production, but wave energy converters are not yet commercially available for ocean observation buoys. Here we present the design and testing of a drifting wave energy converter buoy using a pendulum transmission system (PTS). The wave energy converter buoy was designed to operate in Arctic temperatures and wave conditions, but it could be used in areas with warmer temperatures and larger waves. Field tests measured a maximum power production of 5 watts in waves with a significant wave height of 0.42 meters and a ten minute average power production of 37 milliwatts. Power production increased with the energy period and significant wave height. The energy harvesting capabilities of the PTS showed the utility of adding a wave energy conversion device to a drifting ocean observation buoy.

Arctic observations↗

DOE OSTI2025

Propagating synthetic populations with dynamic Bayesian networks: a framework for long-horizon demographic forecasting

This study presents a dynamic demographic microsimulator using dynamic Bayesian networks to forecast long–term changes in household and individual life events. Leveraging longitudinal Panel Study of Income Dynamics (PSID) data, two networks for individuals and households were modeled to simulate transitions in employment, income, education, marriage, childbirth, leaving the parental home, home ownership, mortality, and household formation or dissolution. Across 1,000 simulation runs spanning 24 years, household–level outcomes remain highly accurate and individual–level predictions reasonable. Although accuracy naturally declines with projection horizon, performance remains promising at both levels. This study addresses a key limitation of existing population synthesis models, which typically generate only a single static snapshot of the population. In conclusion, by introducing a framework that propagates cross-sectional outputs into the future, the microsimulator enables the tracking of demographic evolution over time, enhances realism in population-based simulations, and supplies credible inputs to agent-based travel demand models.

Demographic modeling↗

DOE OSTI2025

Poor reliability of public charging stations can impede the growth of the electric vehicle market

How does the reliability of public charging infrastructure affect electric vehicle (EV) adoption? Substantial public and private investments are expanding EV charging networks, but concerns are growing about the poor reliability of existing chargers and its potential impacts on EV adoption. Using data from a nationwide survey, we employ a choice model to quantify the effects of perceived charging reliability on Americans’ intentions to purchase new or used EVs. By randomly assigning participants to receive information characterizing public charging as either very reliable or very unreliable, we show a causal effect of reliability perceptions on EV purchase intentions. In conclusion, we find that differences in perceived reliability are equivalent to changing price by 32 % of purchasing budget or changing range by 366 miles, underscoring the importance of reliable public charging.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2025

Substrate matters: Coupled phonon modes of a spherical particle on a substrate probed with EELS

Using vibrational electron energy loss spectroscopy (vib-EELS) combined with numerical modeling, we investigate the physical mechanisms governing the phonon coupling between a spherical particle sustaining multipolar surface phonon modes and an underlying thin film. Depending upon their dielectric composition, a variety of hybrid phonon modes arise in the EEL spectrum due to the interaction between polarization charges in the particle and film. Mirror charge effects and phonon mode hybridization are the active mechanisms acting on dielectric and metallic-type films, respectively. Furthermore, processes beyond dipole-dipole interactions are required to describe the sphere-film coupling.

Localized surface phonon response↗

DOE OSTI2026

pH Regulates Ion Dynamics in Carboxylated Mixed Conductors

Coupled ionic and electronic transport underpins processes as diverse as electrochemical energy conversion, biological signaling, and soft adaptive electronics. Yet, how chemical environments such as pH modulate this coupling at the molecular scale remains poorly understood. Here, we show that the protonation state of carboxylated polythiophenes provides precise chemical control over ion dynamics, doping efficiency, solvent uptake, and mechanical response. Using a suite of multimodal operando techniques, supported by simulations, we reveal that pH dictates the balance of cation/anion uptake during electrochemical doping. Mapping across pH uncovers a quasi-nonswelling regime (≈pH 3–3.5) where charge compensation proceeds with minimal volumetric change yet pronounced stiffening. These findings establish molecular acidity as a general strategy to program ionic preference and mechanical stability, offering design principles for pH-responsive mixed conductors and soft electronic materials that couple ionic, electronic, and mechanical functionality.

PH↗

DOE OSTI2025

Single-Determinant Ground State in Ce 4+ Imidophosphorane Complexes

X-ray spectroscopy techniques are critical in the electronic structure analysis of high-valent lanthanides. The interpretation of multipeaked features at the lanthanide L 3 -edge has remained a challenging question, as it is observed across a range of material classes. A series of structurally related Ce 4+ complexes were prepared to probe the potential ligand field perturbation of the ground state within the series. The tuning of relative 4f and ligand orbital energies in homoleptic and heteroleptic tetravalent Ce imidophosphorane complexes is achieved through ligand derivatization and is clearly demonstrated by UV−vis spectroscopy and electrochemically measured redox potentials. However, Ce L 3 - edge high-energy resolution fluorescence-detected (HERFD) X-ray absorption near-edge structure (XANES) spectra present features at consistent numbers and energies across the range of complexes. Resonant inelastic X-ray scattering (RIXS) is employed to visualize the observed features in the HERFD-XANES spectra. Large complete active space configuration interaction singles and doubles (CASCISD) calculations demonstrate that the ground-state wave function of all complexes can be described employing a single determinant. As a result, the multielectron feature at the L 3 -edge observed in this study for the Ce 4+ imidophosphorane complexes is described as excited-state multiconfigurational behavior that is independent of ligand variation, in systems where the ground state is described using the simple single determinant wave function.

Lanthanides↗

DOE OSTI2025

Quantum Electrodynamics Coupled-Cluster at Scale: High-Performance Implementation for Complex Systems

Coupled-cluster theory (CC) is a highly accurate and versatile method for simulating complex interactions within quantum systems. The extension of CC theory to model mixed electron-photon processes with quantum electrodynamics (QED) has improved our capability to predict cavity-modified chemistry, a field where photons are used as cost-effective and eco-friendly alternatives to catalyze/inhibit chemical reactions. However, calculations with CC methods, even without incorporating QED effects, are often prohibitively expensive. Simulations of larger systems require scalable infrastructures that exist for traditional CC methods but not for QED-CC methods. As such, we present a GPU-enabled, high-performance, open-source implementation of the quantum electrodynamics coupled-cluster method with single and double excitations (QED-CCSD) within the ExaChem quantum chemistry software package. ExaChem relies on the Tensor Algebra for Many-body Methods (TAMM) infrastructure: a parallel heterogeneous tensor library designed to achieve scalable performance on modern heterogeneous supercomputing platforms. Furthermore, we discuss theoretical foundations, algorithmic details, and numerical benchmarks to showcase the larger systems that ExaChem can simulate and how the integration of photonic degrees-of-freedom alters their ground-state properties.

Basis sets↗

DOE OSTI2025

Characterization of Two Positional Isomers of the Cs + Gly Complex Using Two-Color, IR–IR Photobleaching of the Cryogenically Cooled Ions

Metal ion binding to amino acid residues is an important interaction motif that controls the tertiary structures of oligopeptides. Analyses of the vibrational band patterns displayed by the amino acid scaffolds are commonly used to characterize the local docking motifs. Here we carry out two-color, IR-IR photobleaching measurements to obtain isomer-selective vibrational spectra of the Cs + Gly ion-molecule complex isolated in a cryogenically cooled, radiofrequency ion trap. The distinct band patterns of two non-interconverting isomers are observed and traced to different bidentate binding motifs between Cs + and the glycine scaffold. In one isomer, the ion attaches to the oxygen atoms of the carboxyl group whereas in the other it docks to the amino nitrogen and the carbonyl oxygen. Attachment to the acid head group yields a very diffuse absorption associated the OH group engaged in a strong intramolecular H-bond that closes a 5 membered ring. Furthermore, the band assignments, rearrangement pathways and electrostatic distortion of the electron density distributions in the glycine scaffold by the proximal ion are explored with electronic structure calculations and anharmonic theory.

Infrared spectroscopy↗

DOE OSTI2024

Capturing Coupled Structural and Electronic Motions During Excited-State Intramolecular Proton Transfer via Computational Multiedge Resonant Inelastic X-ray Scattering

Proton-transfer processes build the foundation of many chemical processes. In Excited State Intramolecular Proton Transfer (ESIPT) processes the proton transfer process is impulsively started through light. Here, in this study, we explore the changes in coupled atomic and electronic motions during and following ESIPT through computational time-resolved Resonant Inelastic X-ray Scattering (trRIXS). Excited-state Ab Initio Molecular Dynamics (AIMD) simulations combined with Time-Dependent Density Functional Theory (TDDFT) calculations were performed for 10-hydroxybenzo[h]quinoline to obtain trRIXS signatures. RIXS at both the nitrogen and oxygen K-edges were computed to resolve the dynamics electronic structure from both the proton donor and acceptor perspective. The results show how RIXS can reveal the local electronic structure, the coupling between different electronic states and how electronic structure and coupling change during the proton transfer process. Additionally, we observe a strong correlation between spectral changes and structural changes during ESIPT.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Ion Transport in Self-Assembled Peptoid Membranes with Carbon Nanotube Porin Channels

Artificial membranes that combine high ionic selectivity with mechanical robustness remain a key challenge for next-generation separation technologies. Here, we report ion transport measurements in biomimetic membranes composed of crystalline peptoid nanosheets co-assembled with carbon nanotube porins (CNTPs). Pure peptoid sheets formed defect-free, ion-impermeable membranes, which were then suspended over small SiN x nanopore apertures for ion transport measurements. Incorporation of CNTPs into the peptoid sheet matrix made these membranes ion permeable, with ion conductance values consistent with ion transport through individual and multiple carbon nanotube channels. In conclusion, the modularity and molecular order of peptoid membranes, combined with the exceptional conductance properties of CNTPs, position this platform as a versatile framework for assembling programmable, selective, and robust nanofluidic membranes that can bridge the performance gap between biological and synthetic membrane materials.

Biotechnology↗

DOE OSTI2024

Aircraft Measurements from a U.S. Western Wildfire Demonstrating Day and Night Differences in the Chemical Composition and Optical Properties of Biomass Burning Aerosols and Their Atmospheric Evolution

The composition and transformations of biomass burning aerosols (BBA) have been measured onboard the NOAA Twin Otter research aircraft during the Fire Influence on Regional to Global Environments and Air Quality field study. Here, we analyze real-time aerosol mass spectrometry measurements across three flights during the afternoon, late afternoon, and night of August 28, 2019, for one midsized wildfire. Analysis of several metrics showed that the aerosol composition and optical properties varied depending on the burning conditions at the fire zone and the time of day the BBA was emitted, with substantial variations in the available sunlight. The total aerosol mass loadings were dominated by organic components with a much smaller contribution from inorganic species. A gradual buildup of organic material was observed during the afternoon as the plume aged, indicating the condensation of photochemically formed low-volatility oxidized organic compounds. Highly hygroscopic ammonium nitrate was the main inorganic component, suggesting potential water content in BBA particles and the likelihood of their aqueous-phase reactivity. Depletions of particle-phase NO 3 – and Cl – relative to carbon monoxide were observed in the late afternoon and nighttime plumes, respectively, aligning with known gas-particle partitioning thermodynamics and the heterogeneous chemistry of dissolved nitrate and chloride. The wavelength-dependent light absorption by aerosol species was higher for the plume sampled at night and showed no significant changes with plume age, despite observed trends in composition and mass downwind. These differences in particle composition and optical properties demonstrate that the processes involved in BBA aging are not uniform for the same wildfire over the course of the day and depend highly on when the BBA was emitted, as well as the burning phase at the emissions source.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2026

Polymorphism of Magnesium Chloride Decahydrate under High Pressures and Low Temperatures Found in Icy Moons

Magnesium chloride hydrates show a rich diversity of structural forms, with different hydration numbers ranging from 1 to 12. Here, we show that this structural versatility is also present within the same hydration numbers, with the formation of a new phase of magnesium chloride decahydrate (MgCl 2 ·10H 2 O-II) stable at the conditions of 0.03–0.40(14) GPa at 234(11) K and up to 2.11(3) GPa at 220(2) K, as determined by in situ single-crystal X-ray diffraction. The hydrogen bonding interactions of MgCl 2 ·10H 2 O-II are identified and the bulk modulus determined at B 0 = 18.9(12) GPa at 220(2) K. We discuss the implication of this high-pressure MgCl 2 hydrate for icy moon compositional investigations and showcase the structural and density changes between the various hydrates in MgCl 2 ·nH 2 O.

high pressure↗

DOE OSTI2025

Synchronized Breathing in Anion-Derived Interphases

Anion-derived interphases are crucial for extending the cycle life of lithium metal batteries. While their benefits are often attributed to crystalline inorganic species like LiF and Li 2 O, the role of amorphous inorganic species and the interplay between the anode-electrolyte interphase (SEI) and the cathode-electrolyte interphase (CEI) remain largely unexplored. Here, in this study, we examine two model electrolyte systems─one with solvent-derived interphases and the other with anion-derived interphases─using advanced X-ray scattering and spectroscopy techniques. Our findings reveal that anion-derived interphases contain substantial amounts of amorphous inorganic species, leading to a unique synchronization of "breathing" between SEI and CEI. During charging, the SEI grows while the CEI shrinks; during discharging, these roles reverse. This distinctive interfacial behavior originates from the competition of deposition and dissolution of amorphous inorganics during cycling. The study highlights the unique role of amorphous inorganics in anion-derived interphases, providing new insights into improving battery performance and durability.

25 ENERGY STORAGE↗

DOE OSTI2025

Advanced All-Fluorinated Electrolytes for Extended Cycle Life and Stability of Li||SPAN Batteries

Achieving long-term stability and consistent capacity in lithium (Li) metal batteries with sulfurized polyacrylonitrile (SPAN) cathodes requires precisely engineered electrolytes to optimize interphase formation and redox reversibility. Here, this study presents 1,1-difluoro-2-(2-methoxyethoxy)ethane (DFE)-based localized high-concentration electrolytes (LHCEs), incorporating fluorinated components such as salt, solvating solvent, and diluent for improved electrode stability. Molecular dynamics simulations and surface analyses reveal that the DFE-LHCE with 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane (BTFEE) diluent produces uniform and robust interphase layers on both cathode and anode, enriched with inorganic species like LiF and Li 2 O. These properties lead to prolonged redox reversibility of the SPAN cathode, suppressed side reactions, and extended cycle life for Li||SPAN cells. Remarkably, DFE-BTFEE-LHCE enables Li||SPAN coin cells with an areal capacity of ∼7 mAh cm -2 for SPAN to retain 81.3% capacity after 200 cycles and pouch cells of 0.12 Ah with 8 mAh cm -2 of SPAN and lean electrolyte to maintain 96.4% capacity over 80 cycles. These findings pave the way for advancing Li||SPAN battery technologies.

25 ENERGY STORAGE↗

DOE OSTI2025

Chemical Interface Damping Revealed by Single-Particle Absorption Spectroscopy

Plasmon-induced interfacial charge separation is a promising way to efficiently extract energetic carriers through direct plasmon decay. This mechanism of charge transfer has been investigated by single-particle scattering spectroscopy, which measures the homogeneous plasmon line width. The line width is broadened by charge transfer, generally known as chemical interface damping. However, conflicting reports exist regarding the effect of chemical interface damping on the corresponding single-particle absorption spectrum, which is needed to accurately determine absolute light conversion efficiencies. This work aims to resolve this question by directly correlating absorption and scattering spectra of individual gold nanorods in the presence and absence of a charge-accepting interface. We find that for TiO 2 coated nanorods, the absorption line width is indeed broadened due to chemical interface damping but is overall narrower than the scattering line width. Here, chemical interface damping is furthermore found to increase with larger resonance energies. The observed differences in line widths between absorption and scattering are elucidated within the context of an analytically tractable model describing the lowest energy optically bright and higher-order optically dark plasmon modes of the nanorod, including bulk, radiative, and chemical interface damping effects. Taken together, these results establish that single-particle absorption spectroscopy is capable of revealing interfacial charge injection by direct plasmon decay.

absorption↗

DOE OSTI2026

Leveraging Hydration Forces for Size-Specific Nanoparticle Enrichment with a Redox-Responsive Silica-Binding Elastin-Like Polypeptide

Elastin-like polypeptides (ELPs) are low-complexity proteins that coacervate above a characteristic lower critical solution temperature (LCST). While the thermoresponsiveness of ELPs has been widely exploited in the biomedical and biomaterials fields, their ability to mediate nanoparticle assembly below their transition temperature remains largely unexplored. Here, we show that unmodified ELPs induce the reversible flocculation of silica nanoparticles (SiNPs) by forming backbone hydrogen bonds with surface silanols. Interparticle bridging is modulated by ELP length and concentration and by the presence of N- and C-terminal anchoring groups such as a cysteine residue and a Car9 silica-binding peptide. Using a redox-responsive fusion protein consisting of disulfide-bonded ELP domains terminated by Car9 segments, we stabilize 20 nm SiNPs under oxidizing conditions while triggering particle flocculation upon addition of reductant. We find that SiNP sedimentation under reducing conditions exhibits a sharp dependency on particle size that arises from the curvature-dependent structure of surface silanols. While the isolated silanols of SiNPs smaller than 30 nm are efficiently engaged by the ELP domains of Car9-anchored proteins, repulsion forces associated with the presence of a layer of molecular water together with increased electrostatic repulsion preclude efficient engagement of H-bonded silanols displayed on the surface of SiNPs larger than 60 nm. We harness these findings to selectively enrich SiNPs based on size and expand the concept to titania (TiO2) by demonstrating that rutile nanoparticles can be stabilized or sedimented with solid-binding ELPs by adjusting the solution pH to promote or discourage the formation of a hydration layer. These strategies should prove broadly useful for the separation of other oxides and their polymorphs and provide a tunable strategy for nanoparticle assembly and bioinspired colloidal design.

ELP↗

DOE OSTI2025

Cell-Free-Based Thermophilic Biocatalyst for the Synthesis of Amino Acids from One-Carbon Feedstocks

Bioproduction from one-carbon compounds, such as formate, is an attractive prospect due to reduced energy requirements and the possibility for using CO 2 as a sustainable feedstock. Formate-fixing pathways engineered using Escherichia coli lysate-based cell-free expression (CFE) biocatalysts have the potential to route 100% of feedstock carbon toward chemical synthesis but are undermined by siphoning of in-pathway metabolites and cofactors by the CFE background metabolism. To address this limitation, we engineer a CFE-based thermophilic multienzyme biocatalyst for the synthesis of serine and glycine from formate, bicarbonate, and ammonia. After expression of the thermophilic formate-to-serine pathway in a one-pot reaction, the mesophilic E. coli CFE background machinery is removed by simple heat denaturation, eliminating the siphoning of cofactors, inpathway metabolites, and products. After bioprocess optimization, including pathway gene expression duration and chemical synthesis temperature, we achieve near stoichiometric conversion of formate and bicarbonate to serine and glycine, reaching 97% of stoichiometric yield. The use of a moderately thermophilic biocatalyst allowed chemical synthesis to take place at mesophilic temperatures, enabling the balance of optimal enzyme activity with minimal metabolite/cofactor thermal degradation. In a fed-batch experiment, the biocatalyst shows sustained chemical synthesis rates for 8 h, paving the way toward a continuous bioprocess. Finally, a sensitivity analysis of cofactor usage revealed that the most expensive cofactors, THF and NADPH, can be reduced by 5-fold without significantly lowering product yields. To the best of our knowledge, this is the first instance of expressing a thermophilic pathway in an E. coli lysate-based CFE system to generate a thermophilic biocatalyst for use at mesophilic temperatures. The CFEbased thermophilic formate-to-serine biocatalyst triples the combined serine and glycine yield previously obtained by a CFE-based mesophilic formate-to-serine biocatalyst (30%), and quadruple the yield obtained by a purified enzyme system (22%). Ultimately, this work opens the door to using E. coli lysate-based CFE for thermophilic biocatalyst generation to achieve high chemical synthesis yields.

bacteria↗