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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 181 records · Page 10
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DOE OSTI2026

Final Technical Report for U.S.-Japan Hadronic Physics Exchange Program for Studies of Hadron Structure and QCD

Nuclear physics explores the fundamental properties of matter -- how protons and neutrons emerge as quantum systems of elementary particles, how they form the atomic nuclei, and how they give rise to the wide variety of phenomena and applications at biological, technical, and astronomical scales. It is a global scientific effort centered around large-scale experimental user facilities (particle accelerators and detectors), advanced theoretical methods and concepts, and computational techniques and resources. Exchange of knowledge and ideas, scientific collaboration, and workforce development on a global scale are essential for the future of the field. The nuclear physics program envisaged in the 2023 DOE/NSF NSAC Long-Range Plan and pursued at the U.S. National Labs has strong synergies with programs at other facilities worldwide and will realize significant benefits from international collaboration. Nuclear physics is also recognized for promoting international cooperation in the broadest sense through joint construction and operation of experimental equipment, personal contacts between scientists, and education and training. The U.S.-Japan Hadronic Physics Exchange Program (USJPHE) supported collaborative scientific research in hadronic physics and quantum chromodynamics. USJHPE focused on subject areas related to the programs at current and future experimental facilities in the U.S.\ and Japan and supported both experimental and theoretical studies. USJHPE particularly aimed to realize synergies between the hadronic physics programs at Jefferson Lab 12 GeV and J-PARC resulting from the complementarity of electromagnetic and hadronic probes in the multi-GeV energy range. Subject areas of common interest included the quark-gluon structure of hadrons and nuclei, meson and baryon spectroscopy, strangeness and hypernuclear physics, and other related topics. USJHPE also supported research in hadronic physics and nuclear-physics-enabled tests of fundamental symmetries related to the programs at Brookhaven National Lab, Fermilab, KEK, Spring-8, and university-based facilities in the U.S. and Japan. USJHPE especially promoted collaboration between the U.S. and Japanese nuclear physics communities in developing the physics program and instrumentation for the future Electron-Ion Collider. USJHPE was intended to provide travel grants to U.S.-based scientists (primary institutional affiliation with a U.S.\ university, national laboratory, or other research center) to visit Japanese institutions and conduct collaborative research there. The program supported senior researchers, postdoctoral fellows, and students. Continuing the setup of the preceding grant period, J-PARC served as the Japanese “hub” for U.S. physicists for short- and long-term visits, and JLab served as the corresponding U.S. “hub”. The program was officially managed through the U. of Connecticut in Storrs, CT. Support for Japanese physicists visiting the U.S. was provided through funds from Japanese funding agencies. The USJHPE program promoted the scientific exchange and the collaborative spirit in hadronic physics between the two countries.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Bypassing Energy Barriers in Fiber-Polymer Torrefaction

The amount of waste generation has been increasing with a significant amount being landfilled. These non-recyclable wastes contain large number of fiber and plastic wastes which can be treated with thermal processes to turn them into energy sources since they have high calorific values, are abundant and usually tipping fees are paid to handle them. This paper studied the torrefaction of non-recyclable paper (fiber) wastes, mixed plastic wastes (MPW) and their blends at different ratios in the temperature range of 250–400°C through thermogravimetric analysis (TGA). The solid residues after the experiments were analyzed by nuclear magnetic resonance (NMR) spectroscopy. Significant synergy between fiber and MPW were observed at the range 250–300°C, showing both increase in the reaction rate as well as the overall mass loss. At 250°C, the maximum mass loss rate was more than two times higher and the mass loss at the end of the experiments were also much higher compared to the expected results. In addition, synergy was weakened with an increase of temperature, disappearing at 400°C. The existence of such interactions between fiber and plastic wastes indicates that the natural energy barriers during the individual torrefaction in paper waste or plastic waste could be bypassed, and the torrefaction of fiber and plastic blend can be achieved at lower temperatures and/or shorter residence times. The MPW and fiber wastes were also compounded by extrusion (to produce pellets) at 220°C with different blend ratios. The fiber-MPW pellets from extrusion were characterized by IR spectroscopy, rheology, thermal analysis and flexural properties and showed significant chemical changes from the non-extruded blends at the same ratios. From IR characterization, it was found that there was significant increase in hydroxyl (OH) group on account of the carbonyl (C = O) and etheric (C-O-C) groups. The interaction between paper and MPW can be attributed to the plastic polymers acting as a hydrogen donor during the reactive extrusion process. Synergistic effects were also found from mechanical and rheological properties.

09 BIOMASS FUELS↗
DOE OSTI2023

Synergistic effects of climate warming and atmospheric nutrient deposition on the alpine lake ecosystem in the south-eastern Tibetan Plateau during the Anthropocene

Alpine lakes on the Tibetan Plateau are highly sensitive to global change and have been recognized as the sentinel of climate warming. However, anthropogenic impacts in populated area are migrating to these remote areas via transporting particulate nutrients by atmospheric deposition. Whether warming and nutrient deposition would impose additive or synergistic effects on the lake ecosystem remains largely unknown. Here, we present multi-proxy (sediment pigment and geochemistry) records during the past two centuries at the Cuoqia Lake in the southeast Tibetan Plateau. We found that the lake exhibited rapid ecological changes since 1980 AD characterized by an increase in primary productivity due to algal proliferation, with more rapid growth of green algae and diatoms. These findings are in concert with many other lakes (e.g., Moon Lake and Shade Co) in the same area, suggesting a consistent pattern of ecosystem evolution at the region scale. Statistical analyses suggested that nutrient deposition and climate warming were strongly associated with the variations in primary productivity and algae composition, exerting both individual and interactive effects. In addition, scenario analyses with a well-established process-based ecosystem model further revealed that the two factors not only individually, but also synergistically promoted the algal proliferation and community succession. Such synergy is evident in that the effect of lake warming would be more pronounced under higher nutrient deposition scenario, which is potentially due to higher temperature-driven mineralization in warmer conditions, and higher efficiency of nutrient utilization under enhanced light availability attributing to declining ice thickness and duration in cold seasons. Overall, our study proposes the existence and quantifies the synergistic impacts of climate warming and anthropogenic activities in driving the ecological changes in remote alpine lakes on the Tibetan Plateau. The lake ecological consequences driven by individual factor would be worsen by such synergy, so that we cannot predict the lake ecosystem trajectory in the future based on each factor separately, and more efforts than previously expected would be needed for the lake restoration and management.

Zhang, Can↗
DOE OSTI2026

NASA’s Pandora SmallSat Mission: Simulated Modeling and Retrieval of Near-infrared Exoplanet Transmission Spectra

Pandora is a SmallSat mission dedicated to understanding exoplanets and their host stars by disentangling the impact of stellar heterogeneity on exoplanet transmission spectra. Selected as a NASA Astrophysics Pioneers mission in 2021, Pandora will provide simultaneous long-term visible photometric monitoring (0.4–0.7 μm) and low-resolution near-infrared (NIR) spectroscopy (0.9–1.6 μm) of transiting systems for the purposes of monitoring host star variability and characterizing exoplanetary atmospheres. Pandora’s year-long prime mission from 2026 to 2027 coincides with the middle of a decade defined by targeted efforts for atmospheric characterization of exoplanets, offering a key opportunity to leverage this new resource to maximize science with JWST and other observatories. Here we investigate Pandora’s anticipated performance for the general exoplanet population accessible to transit spectroscopy, from hot Jupiters to temperate sub-Neptunes. By modeling the atmospheres of five test cases broadly consistent with the bulk properties of HD 209458b, HD 189733b, WASP-80 b, HAT-P-18 b, and K2-18 b, we find that Pandora may provide abundance constraints as precise as ∼1.0 dex for main atmospheric absorbers such as H 2 O and CH 4 . Then, we explore the synergies between Pandora and JWST. Our results suggest that targets with JWST data in the NIR can benefit from the addition of Pandora observations and result in more reliable abundance estimates than with JWST data alone. Moreover, Pandora can serve the community by providing precursory observations of targets of interest for JWST atmospheric characterization. We conclude by outlining strategies for the use of Pandora as a standalone observatory and in synergy with JWST.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

In Situ MOF Pyrolysis Construction of Hierarchical Porous Co‐Nanoparticles/Carbon Cloth Composites for Enhanced Electromagnetic Wave Shielding and Absorption

The development of high-performance electromagnetic protection materials integrating broadband absorption and effective shielding capabilities is hindered by challenges in simultaneously optimizing multiple electromagnetic properties through conventional material designs. This study pioneers a hierarchical porous Co nanoparticle/carbon cloth (Co/CC) composite via controlled annealing of a Co-MOF precursor on carbon cloth. The Co-MOF served a dual role as both magnetic source and pore-forming agent, enabling in situ generation of uniformly dispersed Co nanoparticles and creation of abundant pores/interfaces on the CC fibers during pyrolysis. This unique architecture synergistically enhanced dielectric loss (via interfacial/dipolar polarization) and magnetic loss (via natural resonance, exchange interactions, and eddy currents), significantly improving impedance matching. The hierarchical pores further functioned as integrated “absorption–reflection” units for efficient electromagnetic energy attenuation. Consequently, the Co/CC composite annealed at 800°C (Co/CC-800) achieves minimum reflection loss (−40.69 dB) and 120% effective absorption bandwidth extension (6.16 GHz) as a filler, and exhibits superior electromagnetic interference shielding effectiveness (46.66 dB) as an integrated component. Significantly, Co/CC-800 demonstrated robust photothermal and electrothermal conversion capabilities, ensuring operational stability in ice-covered and humid harsh environments. This work pioneers a pore-structure-mediated strategy to harmonize dielectric–magnetic synergy, providing a new paradigm for designing advanced multifunctional electromagnetic protection materials.

dielectric‐magnetic synergy↗
DOE OSTI2022

An agent-based modeling tool supporting bioenergy and bio-product community communication regarding cellulosic bioeconomy development

The emergence of the cellulosic bioeconomy requires not only adequate technological, economic, and policy advances, but also effective communication and coordination among the multiple stakeholders in the bioeconomy community. Aiming to facilitate stakeholder communication and collaboration for cellulosic bioeconomy growth, an agent-based model is developed as a community communication tool in this study. The tool simulates the behaviors and interactions of key stakeholders, as well as the responses and interactions between the stakeholders and biophysical, socioeconomic, and environmental conditions. The agent behavior rules are developed and validated based on behavior and economic theories and information attained from a stakeholder focus group study and a land use survey. A pilot study in a Central Illinois watershed shows stakeholder synergies, i.e., positive feedback loops across multiple stakeholders. The modeling tool's role in facilitating community communication is demonstrated via the focus group study. A comparison of policy scenarios suggests that the cellulosic bioeconomy development is fastest under a portfolio of policies combining the views of the multiple stakeholders. Critically, subsidy for small-scale bio-facilities is essential as it rapidly initializes an early market for cellulosic feedstocks and the adoption of Miscanthus. As a result, the communication tool is applied to bringing stakeholders and researchers together to develop shared visions, assess barriers, and explore solution portfolios to initialize and speed up the regional cellulosic bioeconomy.

09 BIOMASS FUELS↗
DOE OSTI2023

Revealing Intermetallic Active Sites of PtNi Nanocatalysts for Reverse Water Gas Shift Reaction

Bimetallic nanoparticles have gained great interest due to their potential applications in catalysis. By combining Lattice Boltzmann Modeling (LBM), Density Functional Theory (DFT) calculations, and kinetic Monte Carlo (KMC) simulation, here we rationalize the superior performance of supported Pt-Ni alloy nanostructures over Pt and Ni alone during the reverse Water Gas Shift (rWGS) reaction, which was observed previously. The LBM simulation including the diffusion and flow of the reacting gas molecules within the supporting nanoporous channels in SBA-15 indicates that the simple combination of contributions from Ni and Pt alone is not enough to result in the observed promotion in rWGS activity and selectivity of the Pt-Ni alloy. Instead, the synergy between Pt and Ni via a unique intermetallic motif is responsible according to the DFT and KMC simulation. In conclusion, compared to the monometallic counterparts, the intermetallic-introduced ensemble effect at the low-coordinated Pt-Ni hybrid site of Pt-Ni alloy nanocatalysts enables the enhanced activation of CO 2 and promoted removal of CO/H 2 O as gas phase product.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Impact of Polymicrobial Infection on Fitness of Streptococcus gordonii In Vivo

Pathogenic microbial ecosystems are often polymicrobial, and interbacterial interactions drive emergent properties of these communities. In the oral cavity, Streptococcus gordonii is a foundational species in the development of plaque biofilms, which can contribute to periodontal disease and, after gaining access to the bloodstream, target remote sites such as heart valves. Here, we used a transposon sequencing (Tn-Seq) library of S. gordonii to identify genes that influence fitness in a murine abscess model, both as a monoinfection and as a coinfection with an oral partner species, Porphyromonas gingivalis. In the context of a monoinfection, conditionally essential genes were widely distributed among functional pathways. Coinfection with P. gingivalis almost completely changed the nature of in vivo gene essentiality. Community-dependent essential (CoDE) genes under the coinfection condition were primarily related to DNA replication, transcription, and translation, indicating that robust growth and replication are required to survive with P. gingivalis in vivo. Interestingly, a group of genes in an operon encoding streptococcal receptor polysaccharide (RPS) were associated with decreased fitness of S. gordonii in a coinfection with P. gingivalis. Individual deletion of two of these genes (SGO_2020 and SGO_2024) resulted in the loss of RPS production by S. gordonii and increased susceptibility to killing by neutrophils. P. gingivalis protected the RPS mutants by inhibiting neutrophil recruitment, degranulation, and neutrophil extracellular trap (NET) formation. These results provide insight into genes and functions that are important for S. gordonii survival in vivo and the nature of polymicrobial synergy with P. gingivalis. Furthermore, we show that RPS-mediated immune protection in S. gordonii is dispensable and detrimental in the presence of a synergistic partner species that can interfere with neutrophil killing mechanisms.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Circular Economy Contributions to Decarbonizing the US Steel Sector

The potential benefits of the circular economy (CE) for decarbonization have recently attracted much attention in the academic and grey literature. The department of energy (DOE) industrial decarbonization roadmap highlight that in addition to the four pillars (energy efficiency, electrification, low-carbon fuels, feedstocks, and energy sources, and carbon capture, utilization, and storage (CCUS)) identified in the roadmap, "scenarios [...] will need to be developed that incorporate materials efficiency and circular economy strategies". Moreover, the roadmap identifies hard-to-abate CO2 emissions across the five industrial subsectors included in the analysis (iron & steel, chemical, food & beverage, refining, and cement manufacturing). Thus, additional options to decarbonize the industrial sector, like the CE, could prove beneficial to address those hard-to-abate emissions. Moreover, they may be less costly, require less R&D or incentives, and be more readily adopted than other strategies such as energy efficiency and CCUS. While the Industrial Decarbonization Roadmap includes some CE strategies (e.g., the increasing market share of steel from electric arc furnaces - which incorporate steel scrap), a deeper dive into what role the CE could play in the United States (US) industrial decarbonization is needed. In this work, we present several industrial decarbonization scenarios that incorporate materials efficiency and circular economy strategies for the iron & steel subsector. The scenarios identify barriers (including technical limits and constraints), opportunities, and R&D needs.Moreover, we estimate the contribution of those scenarios to reducing the industrial sector's CO2 emissions and their potential synergies with the Industrial Decarbonization Roadmap's four pillars. Iron & steel manufacturing was responsible for 90 million tons of industrial CO2 emissions in 2020 - 7% of the industrial sector's total process- related emissions. Besides recycling - which presents technical limitations due to trace contaminants - CE strategies on the demand side could lower iron & steel manufacturing emissions (e.g., the development of lighter products or business models that encourage a more intensive use). This study reviews barriers, opportunities, and trade-offs for 5 material efficiency strategies. Many topics explored in the review call for further research.

barriers↗
DOE OSTI2020

Dual 3D Ceramic Textile Electrodes: Fast Kinetics for Carbon Oxidation Reaction and Oxygen Reduction Reaction in Direct Carbon Fuel Cells at Reduced Temperatures

Abstract Direct carbon fuel cells (DCFCs) are an efficient energy‐conversion technology capable of generating electricity with carbon‐dioxide‐capture chemistry with solid carbon as fuels. The efficiency and performance of DCFCs depend on the kinetics of the carbon oxidation reactions (COR) and the oxygen reduction reactions (ORR), each occurring at anode and cathode, respectively. The limited active sites paired with reduced temperatures greatly decrease the efficiency of the electrochemical reactions. Ultraporous dual‐3D ceramic textiles (dual‐3DCT) are integrated into electrolyte‐supported DCFCs to enhance charge and mass transfer at the electrodes. Improved COR at the anode is achieved by the synergy between the 3DCT NiO–Ce 0.8 Gd 0.2 O 1.95 (GDC) structure and optimal carbon fuel choice. In a comparative study, DCFCs using graphitic carbon (GC) as fuel show the best COR performance when compared to DCFCs utilizing alternative fuels such as carbon black (CB) and activated carbon (AC). The 3DCT Sm 0.5 Sr 0.5 CoO 3‐δ –GDC (SSC–GDC) composite cathode shows electrochemical performance superior to that of the conventional screen‐printed SSC–GDC. A peak power density of 392 mW cm −2 at 600 °C is obtained in a DCFC using the 3DCT‐anode/electrolyte/3DCT‐cathode configuration, an unprecedented value for any reported DCFC as of yet. This points toward promising applications of dual‐3DCT electrodes for reduced‐temperature DCFCs.

Bian, Wenjuan↗
DOE OSTI2020

Visible-Light-Activated Photocatalytic Films toward Self-Cleaning Membranes

Membranes are among the most promising means of delivering increased supplies of fit-for-purpose water, but membrane fouling remains a critical issue restricting their widespread application. Coupling photocatalysis with membrane separation has been proposed as a potentially effective approach to reduce membrane fouling. However, commonly used materials in photocatalysis limit use of low-cost sources such as sunlight due to their large band gaps. There are few examples of in situ photocatalytic self-cleaning of membranes, with removal from the filtration system and ex situ illumination being more common. In this study, a visible-light-activated photocatalytic film prepared by nitrogen doping into the lattice of TiO 2 was deposited on commercial ceramic membranes via atomic layer deposition (ALD). The synergy between membrane separation and redox reactions between organic pollutants and reactive oxygen species (ROS) produced by the visible-light-activated layer offers a possibility for stable and sustainable membrane operation under in situ solar irradiation.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Carbon Free and Noble Metal Free Ni 2 Mo 6 S 8 Electrocatalyst for Selective Electrosynthesis of H 2 O 2

Electrocatalytic two-electron reduction of oxygen is a promising method for producing sustainable H 2 O 2 but lacks low-cost and selective electrocatalysts. Here, the Chevrel phase chalcogenide Ni 2 Mo 6 S 8 is presented as a novel active motif for reducing oxygen to H 2 O 2 in an aqueous electrolyte. Although it has a low surface area, the Ni 2 Mo 6 S 8 catalyst exhibits exceptional activity for H 2 O 2 synthesis with >90% H 2 O 2 molar selectivity across a wide potential range. Chemical titration verified successful generation of H 2 O 2 and confirmed rates as high as 90 mmol H 2 O 2 g cat –1 h –1 . The outstanding activities are attributed to the ligand and ensemble effects of Ni that promote H 2 O dissociation and proton-coupled reduction of O 2 to HOO*, and the spatial effect of the Chevrel phase structure that isolates Ni active sites to inhibit O—O cleavage. The synergy of these effects delivers fast and selective production of H 2 O 2 with high turn-over frequencies of ≈30 s –1 . Additionally, the Ni 2 Mo 6 S 8 catalyst has a stable crystal structure that is resistive for oxidation and delivers good catalyst stability for continuous H 2 O 2 production. The described Ni-Mo6S8 active motif can unlock new opportunities for designing Earth-abundant electrocatalysts to tune oxygen reduction for practical H 2 O 2 production.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Design Principles of Diketopyrrolopyrrole‐Thienopyrrolodione Acceptor 1 –Acceptor 2 Copolymers

Abstract The design principles of acceptor 1 –acceptor 2 copolymers featuring alternating diketopyrrolopyrrole (DPP) and thienopyrrolodione (TPD) moieties are investigated. The investigated series of polymers is obtained by varying the aromatic linker between the two acceptor motifs between thiophene, thiazole, pyridine, and benzene. High electron affinities between 3.96 and 4.42 eV, facilitated by the synergy of the acceptor motifs are determined with optical gaps between 1.37 and 2.02 eV. Grazing incidence wide‐angle X‐ray scattering studies reveal a range of film morphologies after thermal annealing, including face‐on, end‐on and superstructure edge‐on‐like crystallites. Conversely, all materials form thin edge‐on layers on the polymer–air interface, as demonstrated by multi‐elemental near‐edge X‐ray absorption fine‐structure spectroscopy. The benefit of the electron‐deficient linkers thiazole and pyridine is evident: In organic field effect transistors, electron mobilities of up to 4.6 × 10 −2 cm 2 V −1 s −1 are obtained with outstanding on/off current ratios of 5 × 10 5 , facilitated by the absence of detectable hole transport in these materials. Viability for all‐polymer solar cells is assessed in active layer blends with the donor polymer PM6, yielding a maximum average power conversion efficiency of 4.8% and an open circuit voltage above 1 V.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Unconventional Anomalous Hall Effect in Hexagonal Polar Magnet Y 3 Co 8 Sn 4

A rare realization of unconventional anomalous Hall effect (UAHE) both below and above the magnetic transition temperature (T C ) in a hexagonal noncentrosymmetric magnet Y 3 Co 8 Sn 4 , using a combined experimental and ab initio calculations. Occurrence of such UAHE is mainly attributed to the reciprocal ($\mathscr{KS}$) topology (i.e., the presence of topological Weyl points at/near the Fermi level), along with some contribution from the topological magnetic texture (at low temperatures), as inferred from the measured field-dependent ac susceptibility. The effect of UAHE on the measured transport behavior however evolves differently with temperature above and below T C = 53 K, suggesting different physical mechanism responsible in the two phases. A unique planar ferrimagnetic ordering is found to be the most stable state with ab-plane as the easy plane below T C . The simulated net magnetization and the moment per Co atom agrees fairly well with the experimentally measured values. A reasonably large anomalous Hall conductivity (AHC) is also observed in both the phases (above and below T C ) of the present compound, which is again not so ubiquitous. In conclusion, the results underscore the family of R 3 Co 8 Sn 4 (R = rare earth) polar magnets as a compelling backdrop for exploring the synergy of magnetism and topological non-trivial electronic states, pivotal for spintronic applications.

Density functional theory calculations↗
DOE OSTI2026

MoS 2 Catalysts Selectively Achieve High Yield of Liquid Oxygenate from Direct Conversion of Methane via Hydroxyl Radicals

Directly converting methane (CH 4 ) into liquid oxygenates (e.g., methanol) can circumvent the cost and engineering limits of natural gas transportation and storage. However, oxygenate yields from CH 4 remain low, and sulfur present in natural gas hinders activity in most catalysts. Here, to overcome these barriers, we employ bulk molybdenum disulfide (MoS 2 ), a low-cost, robust catalyst which selectively produces large quantities of liquid oxygenates (>900 µmol/g cat ∙hr) from methane in the presence of hydroxyl (OH • ) radicals produced from dilute hydrogen peroxide (H 2 O 2 ) at 75°C. Under realistic reaction conditions, MoS 2 partially and reversibly adopts a metastable, more electrically conductive phase (1T’) that can only be observed through in situ structural probes. Herein, we elucidate that redox synergy between H 2 O 2 and MoS 2 produces active OH • radical species that selectively transform CH 4 to surface methoxy species at the gas-solid liquid interface, leading to the unitary production of liquid oxygenate at a rate competitive with more costly precious metal catalysts, without additional catalyst preparation steps.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Dendrite–Free Potassium Metal Anodes in a Carbonate Electrolyte

Potassium (K) metal anodes suffer from a challenging problem of dendrite growth. In this study, it is demonstrated that a tailored current collector will stabilize the metal plating–stripping behavior even with a conventional KPF 6 –carbonate electrolyte. A 3D copper current collector is functionalized with partially reduced graphene oxide to create a potassiophilic surface, the electrode being denoted as rGO@3D–Cu. Potassiophilic versus potassiophobic experiments demonstrate that molten K fully wets rGO@3D–Cu after 6 s, but does not wet unfunctionalized 3D–Cu. Electrochemically, a unique synergy is achieved that is driven by interfacial tension and geometry: the adherent rGO underlayer promotes 2D layer–by–layer (Frank–van der Merwe) metal film growth at early stages of plating, while the tortuous 3D–Cu electrode reduces the current density and geometrically frustrates dendrites. The rGO@3D–Cu symmetric cells and half–cells achieve state–of–the–art plating and stripping performance. Here, the symmetric rGO@3D–Cu cells exhibit stable cycling at 0.1–2 mA cm –2 , while baseline Cu prematurely fails when the current reaches 0.5 mA cm –2 . The half–cells cells of rGO@3D–Cu (no K reservoir) are stable at 0.5 mA cm –2 for 10 000 min (100 cycles), and at 1 mA cm –2 for 5000 min. The baseline 3D–Cu, planar rGO@Cu, and planar Cu foil fails after 5110, 3012, and 1410 min, respectively.

25 ENERGY STORAGE↗
DOE OSTI2020

Unraveling the Crystallization Kinetics of 2D Perovskites with Sandwich-Type Structure for High-Performance Photovoltaics

2D perovskite solar cells with high stability and high efficiency have attracted significant attention. A systematical static and dynamic structure investigation is carried out to show the details of 2D morphology evolution. A dual additive approach is used, where the synergy between an alkali metal cation and a polar solvent leads to high-quality 2D perovskite films with sandwich-type structures and vertical phase segregation. Such novel structure can induce high-quality 2D slab growth and reduce internal and surface defects, resulting in a high device efficiency of 16.48% with enhanced continuous illumination stability and improved moisture (55-60%) and thermal (85°C) tolerances. Transient absorption spectra reveal the carrier migration from low n to high n species with different kinetics. An [PbI 6 ] 4- octagon coalescence transformation mechanism coupled with metal and organic cations wrapped is proposed. By solvent vapor annealing, a recrystallization and reorientation of the 2D perovskite slabs occurs to form an ideal structure with improved device performance and stability.

36 MATERIALS SCIENCE↗