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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Impact of Residual Lithium on the Adoption of High-Nickel Layered Oxide Cathodes for Lithium-Ion Batteries

High-nickel layered oxide cathodes are becoming appealing for lithium-ion batteries employed in portable electronics and electric vehicles because of their higher energy density, low or no cobalt content, and ability to be manufactured with existing infrastructure. However, high-nickel layered oxides are plagued by the formation of residual lithium species, such as LiOH and Li 2 CO 3 , on the surface, which are detrimental to the manufacturing process and performance. Despite the problems residual lithium causes for the industry, academia mainly focuses on the safety risks and electrochemical impacts of residual lithium. In this Perspective, we examine the residual lithium problem through a lens of its impact on cathode slurry instability and large-scale manufacturing of high-nickel layered oxides. Additionally, methods of measuring residual lithium are discussed from the perspective of their accuracy as well as practicality in the manufacturing process. Furthermore, we hope that this Perspective would encourage the academic endeavor to consider the practical obstacles caused by residual lithium on the industrialization of high-nickel layered oxides and their mitigation, while attempting to improve their electrochemical performance and safety through doping, surface modifications, or other approaches.

25 ENERGY STORAGE↗
DOE OSTI2022

Computationally Accelerated Discovery of High Entropy Pyrochlore Oxides

High entropy ceramics provide enhanced flexibility for tailoring a wide range of physical properties, emerging from the diverse chemical and configurational degrees of freedom. Expanding upon the endeavors of recently synthesized high entropy ceramics in rock salt, fluorite, spinel, and perovskite structures, we explore the relative feasibility of formation of high entropy pyrochlore oxides, A 2 B 2 O 7 , with multication occupancy of the B-site, estimated from first-principles-based thermodynamic descriptors. Subsequently, we used Monte Carlo simulations to estimate the phase composition, oxygen vacancy concentration, and local ionic segregation as a function of temperature and oxygen partial pressure. In synergy with the theoretical calculations, we have investigated the synthesis of several multicomponent oxides with a pyrochlore composition, related to our computational investigations, resulting in four phase pure and one 97.4% pure high entropy pyrochlore oxides. Ultimately, our approach allows us to evaluate potential impurity phases, ionic disorder, and oxygen vacancy concentration in response to the experimental variables, thereby making realistic predictions that can direct and accelerate experimental synthesis of novel multicomponent ceramics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Role of Metal Selection in the Radiation Stability of Isostructural M-UiO-66 Metal–Organic Frameworks

Robust and versatile metal–organic frameworks (MOFs) have emerged as sophisticated scaffolds to meet the critical needs of the nuclear community, but their performance depends on their underexplored structural integrities in high- radiation fields. The contributions of selected metal nodes in the radiation stability of MOFs within the isostructural M-UiO-66 series (where M = Zr, Ce, Hf, Th, and Pu; Zr-UiO-66 experiments were executed in a previous work) have been determined. Ce-, Hf-, and Th-UiO-66 MOF samples were irradiated via gamma and He-ion methodologies to obtain doses up to 3 MGy and 85 MGy, respectively, the latter strikingly higher than that obtained in most other studies. Appreciable self-irradiation constituted the total absorbed doses, up to 31 MGy of the gamma-irradiated Pu-UiO-66 samples. Structural degradation was ascertained by powder X-ray diffraction, X-ray total scattering, vibrational spectroscopy, and, where possible, N 2 physisorption isotherms. Diffuse reflectance infrared Fourier transform spectroscopy provided atomic-level mechanistic insights to reveal that the node-linker connection was most susceptible to radiation damage. Density functional theory calculations were performed on cluster models to evaluate the binding energy of the linkers to each metal node. Here, while the isostructures disclosed the same breakdown signatures, distinct radiation sensitivity as a function of metal selection was evident and followed the trend Hf-UiO-66 ~ Zr-UiO-66 > Th-UiO-66 > Pu-UiO-66 > Ce-UiO-66. We anticipate that these endeavors will contribute to the rational design of radiation-resistant materials for targeted applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Low-Temperature Processing of Pyrolysis Bio-Oil for Sustainable Biographite Production

Catalytic graphitization of pyrolysis bio-oil with iron (Fe) can produce an anode material for lithium-ion batteries (LIBs) at a moderate temperature. The key challenge to scaling up the process is foaming, which occurs due to the oxidation of Fe by the organic acids present in bio-oil. This study explored five different pathways to control foaming in bio-oil upon Fe addition, including (i) defoamers use, (ii) use of iron oxide (Fe2O3) as graphitization catalyst, (iii) pH adjustment of bio-oil, (iv) bio-oil coking (300-500 degrees C), and (v) low-temperature pretreatment of bio-oil (150-200 degrees C). The low-temperature pretreatment successfully avoided foaming by removing the volatile acids in bio-oil. The bio-oil was solidified and powdered for even mixing with the Fe catalyst. The biographite catalytically prepared at 1500 degrees C following this pathway demonstrated nearly theoretical specific gravimetric capacity (~370 mAh/g), high initial Coulombic efficiency (90.03%), and minimal capacity fading after 50 cycles in LIB half-cells. The low-temperature pretreatment pathway also addressed the viscosity, swelling, and aging issues associated with bio-oil processing and will make scale-up endeavors more attainable.

09 BIOMASS FUELS↗
DOE OSTI2021

Safety moments in chemical safety education.

Chemical safety education is a critical aspect of an integrated culture of safety in academic research settings. Showcasing best practices and sharing practical solutions for recognizing hazards and minimizing risks represent one way of reinforcing a research community's actions, attitudes, and behavior toward safety. For goals of improving chemical safety education with nonformal endeavors, safety moments are similar to 1-2 slides that focus on raising awareness and knowledge for routine safety issues in research laboratories. Intended to catalyze brief discussions at the beginning of meetings and presentations, these materials provide a proactive way for students and faculty to engage in open communication on diverse research safety topics across science and engineering. This commentary provides an overview of designing effective safety moments and tailoring them to highlight practical safety needs and considerations. Key components of model safety moment slides are presented, alongside centralized resources assembled by student-led laboratory safety teams, which can also be extended to posters, social media platforms, online videos, and other forms of scientific communication. Combined with both top-down backing from institution leaders and bottom-up support from student researchers, safety moments remain a low-barrier risk reduction strategy that is easy to implement, encourages local dialogue on safety, combats complacency, and holds potential for facilitating long-term improvements to academic lab safety culture.

Communication/Writing↗
DOE OSTI2022

Accelerators for Classical Molecular Dynamics Simulations of Biomolecules

Atomistic Molecular Dynamics (MD) simulations provide researchers the ability to model biomolecular structures such as proteins and their interactions with drug-like small molecules with greater spatiotemporal resolution than is otherwise possible using experimental methods. MD simulations are notoriously expensive computational endeavors that have traditionally required massive investment in specialized hardware to access biologically relevant spatiotemporal scales. Our goal is to summarize the fundamental algorithms that are employed in the literature to then highlight the challenges that have affected accelerator implementations in practice. We consider three broad categories of accelerators: Graphics Processing Units (GPUs), Field-Programmable Gate Arrays (FPGAs), and Application Specific Integrated Circuits (ASICs). These categories are comparatively studied to facilitate discussion of their relative trade-offs and to gain context for the current state of the art. We conclude by providing insights into the potential of emerging hardware platforms and algorithms for MD.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Acceleration of Solvation Free Energy Calculation via Thermodynamic Integration Coupled with Gaussian Process Regression and Improved Gelman–Rubin Convergence Diagnostics

The determination of the solvation free energy of ions and molecules holds profound importance across a spectrum of applications spanning chemistry, biology, energy storage, and the environment. Molecular dynamics simulations are powerful tools for computing this critical parameter. Nevertheless, the accurate and efficient calculation of the solvation free energy becomes a formidable endeavor when dealing with complex systems characterized by potent Coulombic interactions and sluggish ion dynamics and, consequently, slow transition across various metastable states. Here, in the present study, we expose limitations stemming from the conventional calculation of the statistical inefficiency g in the thermodynamic integration method, a factor that can hinder the determination of convergence of the solvation free energy and its associated uncertainty. Instead, we propose a robust scheme based on Gelman–Rubin convergence diagnostics. We leverage this improved estimation of uncertainties to introduce an innovative accelerated thermodynamic integration method based on the Gaussian Process regression. This methodology is applied to the calculation of the solvation free energy of trivalent rare-earth elements immersed in ionic liquids, a scenario in which the aforementioned challenges render standard approaches ineffective. The proposed method proves to be effective in computing solvation free energy in situations where traditional thermodynamic integration methods fall short.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Homomolecular Triplet–Triplet Annihilation in Metalloporphyrin Photosensitizers

Metalloporphyrins are ubiquitous in their applications as triplet photosensitizers, particularly for promoting sensitized photochemical upconversion processes. In this study, bimolecular excited state triplet–triplet quenching kinetics, termed homomolecular triplet–triplet annihilation (HTTA), exhibited by the traditional triplet photosensitizers–zinc(II) tetraphenylporphyrin (ZnTPP), palladium(II) octaethylporphyrin (PdOEP), platinum(II) octaethylporphyrin (PtOEP), and platinum(II) tetraphenyltetrabenzoporphyrin (PtTPBP)–were revealed using conventional transient absorption spectroscopy. Nickel(II) tetraphenylporphyrin was used as a control sample as it is known to be rapidly quenched intramolecularly through ligand-field state deactivation and, therefore, cannot result in triplet–triplet annihilation (TTA). The single wavelength transients associated with the metalloporphyrin triplet excited state decay–measured as a function of incident laser pulse energy in toluene–were well modeled using parallel first- and second-order kinetics, consistent with HTTA being operable. The combined transient kinetic data enabled the determination of the first-order rate constants (k T ) for excited triplet decay in ZnTPP (4.0 × 10 3 s –1 ), PdOEP (3.6 × 10 3 s –1 ), PtOEP (1.2 × 10 4 s –1 ), and PtTPBP (2.1 × 10 4 s –1 ) as well as the second-order rate constant (k TT ) for HTTA in ZnTPP (5.5 × 10 9 M –1 s –1 ), PdOEP (1.1 × 10 10 M –1 s –1 ), PtOEP (7.1 × 10 9 M –1 s –1 ), and PtTPBP (1.6 × 10 10 M –1 s –1 ). In most instances, triplet excited state extinction coefficients are either reported for the first time or have been revised using ultrafast transient absorption spectroscopy and singlet depletion: ZnTPP (78,000 M –1 cm –1 ) at 470 nm, PdOEP (67,000 M –1 cm –1 ) at 430 nm, PtOEP (51,000 M –1 cm –1 ) at 418 nm, and PtTPBP (100,000 M –1 cm –1 ) at 460 nm. Furthermore, the combined experimental results establish competitive time scales for homo- and heteromolecular TTA rate constants, implying the significance of considering HTTA processes in future research endeavors harnessing TTA photochemistry using common metalloporphyrin photosensitizers.

14 SOLAR ENERGY↗
DOE OSTI2022

Role of Molecular Simulations in the Design of Metal–Organic Frameworks for Gas-Phase Thermocatalysis: A Perspective

Here, metal organic frameworks (MOFs) are highly tunable porous crystalline solids with spatially and electronically isolated catalytically active sites that have been demonstrated for a variety of thermo-, redox-, and photocatalytic reactions. Their tunable natures and relatively well-defined active sites make them advantageous for catalyst design, and molecular simulations have proven highly valuable in this endeavor. However, complexities in the MOF structure require advanced simulation strategies that accurately capture quantum chemistry at the strongly correlated transition metal cation active sites, compositional and structural changes caused by finite temperature and pressure reaction conditions, and transport effects in variously sized pore environments. Luckily, several groups have started using such simulation strategies, paving the way for rich opportunities to design MOF catalysts. Herein, we highlight such examples and provide a perspective on the needs for molecular simulations in the design of MOF catalysts moving forward.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Investigating Cu-Site Doped Cu–Sb–S Nanoparticles Using Photoelectron and Electron Paramagnetic Resonance Spectroscopy

Tetrahedrite (Cu 12 Sb 4 S 13 ) and famatinite (Cu 3 SbS 4 ) are good candidates for green energy applications because they possess promising thermoelectric and photovoltaic properties as well as contain earth-abundant and nontoxic constituents. Herein, X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and electron paramagnetic resonance spectroscopy (EPR) methods examined inherent electronic properties and interatomic magnetic interactions of Cu-site doped tetrahedrite and famatinite nanomaterials. An energy-efficient modified polyol method was utilized for the synthesis of tetrahedrite and famatinite nanoparticles doped on the Cu-site with Zn, Fe, Ni, Mn, and Co. This is the first parallel study of tetrahedrite and famatinite nanomaterials with XPS, UPS, and EPR methods alongside a systematic analysis of dopant-dependent effects on the electronic structure and magnetic interactions for each material. XPS showed that the Cu and Sb species in tetrahedrite and famatinite possess different oxidation states, while UPS characterization reveals larger dopant-dependent shifts in the work function for tetrahedrite nanoparticles (4.21 to 4.79 eV) than for famatinite nanoparticles (4.57 to 4.77 eV). Finally, all famatinite nanoparticles display an EPR signal, indicating trace amounts of paramagnetic Cu(II) present below the detection limit of XPS. For tetrahedrite, EPR signatures were observed only for the Zn-doped and Mn-doped nanoparticles, suggesting signal broadening from Cu–Cu spin exchange or spin–lattice relaxation. This study demonstrates the complementary nature of XPS and EPR techniques for studying the oxidation states of metals in solid-state nanomaterials. Comparing the electronic and magnetic properties of tetrahedrite and famatinite while studying the impact of dopant incorporation will guide future endeavors in designing sustainable, high-performance materials for renewable energy applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

The Ground State Electronic Energy of Benzene

We report here on the findings of a blind challenge devoted to determining the frozen-core, full configuration interaction (FCI) ground-state energy of the benzene molecule in a standard correlation-consistent basis set of double-ζ quality. As a broad international endeavor, our suite of wave function-based correlation methods collectively represents a diverse view of the high-accuracy repertoire offered by modern electronic structure theory. In our assessment, the evaluated high-level methods are all found to qualitatively agree on a final correlation energy, with most methods yielding an estimate of the FCI value around -863 mE H . However, we find the root-mean-square deviation of the energies from the studied methods to be considerable (1.3 mE H ), which in light of the acclaimed performance of each of the methods for smaller molecular systems clearly displays the challenges faced in extending reliable, near-exact correlation methods to larger systems. While the discrepancies exposed by our study thus emphasize the fact that the current state-of-the-art approaches leave room for improvement, we still expect the present assessment to provide a valuable community resource for benchmark and calibration purposes going forward.

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

Reassembly of Peptide Nanofibrils on Live Cell Surfaces Promotes Cell–Cell Interactions

Nature regulates cellular interactions through the cell-surface molecules and plasma membranes. Despite advances in cell-surface engineering with diverse ligands and reactive groups, modulating cell–cell interactions through scaffolds of the cell-binding cues remains a challenging endeavor. Here, we assembled peptide nanofibrils on live cell surfaces to present the ligands that bind to the target cells. Surprisingly, with the same ligands, reducing the thermal stability of the nanofibrils promoted cellular interactions. Characterizations of the system revealed a thermally induced fibril disassembly and reassembly pathway that facilitated the complexation of the fibrils with the cells. Using the nanofibrils of varied stabilities, the cell–cell interaction was promoted to different extents with free-to-bound cell conversion ratios achieved at low (31%), medium (54%), and high (93%) levels. Further, this study expands the toolbox to generate desired cell behaviors for applications in many areas and highlights the merits of thermally less stable nanoassemblies in designing functional materials.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Quantifying the Correlation between Coordination Chemistry, Interfacial Formation, and Electrochemical Performances for Mg Battery Electrolytes

Here, the rise of magnesium batteries as promising post-Li-ion energy storage technologies has sparked considerable attention toward understanding the fundamental aspects of coordination chemistry concerning Mg cations in multivalent electrolytes. This exploration includes investigating how coordination influences crucial electrolyte properties like solubility, electroreduction stability, and the formation of the interphase, all of which are pivotal for practical battery applications. Despite recent progress in developing a few functional electrolytes, a comprehensive understanding of the solvation structure that can facilitate efficient Mg deposition performance and the formulation of general design rules based on the solvation structure is still lacking. In our study, we endeavor to establish a connection between solvent and anion interactions with Mg 2+ , interface formation, and cycling performance through a series of organic ether solvents (tetrahydrofuran, glyme, diglyme, and triglyme) and amine solvents (dimethylamine, 3-methoxypropylamine, and dimethoxyethylamine). Our findings reveal a distinct coordination trend for solvent/Mg 2+ and (Mg-TFSI):solvent across various solvents, which dictates the extent of ion pairing for TFSI salts with increasing solvent molecule size and denticity. The solvated species in the bulk electrolyte across different solvents lead to diverse interfacial chemistries with varying decomposition components. We also explore the cycling efficiency as well as Mg deposition overpotentials for different solvents. A correlation analysis was conducted to assess the interplay between the structure and performance. Lastly, we apply the insights gained from these results to tailor the relative anion/Mg 2+ coordination structures using cosolvent systems, aiming for improved cell performance.

25 ENERGY STORAGE↗
DOE OSTI2022

Mechanically and Thermally Enhanced 3D-Printed Photocurable Polymer Nanocomposites Containing Functionalized Chitin Nanowhiskers by Stereolithography

Additive manufacturing, or simply 3D printing (3DP), where objects are built through layer-wise material deposition, has gained significant academic and industrial attention as a result of the development of advanced and functional materials requiring rapid, customized, and flexible solutions. In the context of green manufacturing, diversifying environmentally and economically sustainable material portfolios is an essential endeavor for the success of 3DP technology that uses widely available, highly valuable, and renewable materials. Here, we used stereolithography (SLA) for processing methacrylate-based photocurable resins containing crab shell-derived chitin nanowhiskers (CNWs), which are surface-functionalized by reactive acrylate groups. Results from full spectral, thermal, structural, and topological analyses corroborate not only the surface functionalization of CNWs but also indicate the presence of these photocurable CNW (pCNW) fillers in the 3D-printed nanocomposites. Owing to the strong interfacial bond induced by the physical and chemical crosslinking between the pCNW and methacrylate (MA) polymer matrix, the internally formulated nanocomposites displayed enhanced thermomechanical properties (e.g., storage modulus and glass transition temperature) compared to those of commercially available pure SLA resins. For instance, the inclusion of 0.5 wt % pCNW improved the tensile strength and stiffness to up to 78 and 71%, respectively, without compromising the toughness and ductility of the printed material. Accordingly, this result also evidences the compatibility between the filler and resin materials. Consequently, the formation of a crosslinked network in the nanocomposite structure results in a higher thermal stability and activation energy (i.e., up to ~79%) for all the hybrid materials than the pristine MA. Finally, the high-resolution SLA print features, dimensional accuracy, and enhanced mechanical performance of our microstructure-forming functionalized chitin-based nanocomposites make them promising materials for a wide range of robust and high-performance industrial applications.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Advances in Polymerizations Modulated by External Stimuli

Synthetic polymer chemistry endeavors to imitate the spatial and temporal control exhibited within biological systems to obtain well-defined polymeric materials with unique structures, properties, and applications. This is often approached through the development of dynamic catalyst (or initiator) systems that use external stimuli to elicit discrete, site specific transformations that impact the polymerization. In this work, we highlight developments in polymerizations that are modulated by external stimuli, with particular focus on those systems that enable notable changes in kinetics, monomer selectivity, polymer architecture, or tacticity. Examples of external stimuli include chemical oxidants or reductants, light, applied voltage, and mechanical force.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Nanocluster Active Sites Formed on Heterogeneous Thermal Catalysts and Electrocatalysts by Operando Reactive Environments

Here, in this Viewpoint, we summarize our recent studies in this endeavor, ending with a forward-looking perspective into the remaining challenges and open questions for consideration by the catalysis community. Through a computationally efficient framework of systematically investigating metal atom ejection from and migration onto metal surfaces, leading to the formation of metal atom clusters, we show that the surface of a metal catalyst is dynamic and much less rigid than previously thought. We suggest that the operando formed metal atom clusters are novel active sites, which can dominate the activity of steps or kinks (let aside terraces) from where their constituent atoms were ejected. Through more readily responding to reaction conditions by forming catalytically active clusters, solid metal catalysts approach not only homogeneous catalyst motifs, thus establishing a bridge between homogeneous and heterogeneous catalysis, but also liquid metals which have been suggested to be better than traditional heterogeneous catalysts.

adsorption↗
DOE OSTI2025

Machine Learning-Guided Identification of PET Hydrolases from Natural Diversity

The enzymatic depolymerization of poly(ethylene terephthalate) (PET) is emerging as a leading chemical recycling technology for waste polyester. As part of this endeavor, new candidate enzymes identified from natural diversity can serve as useful starting points for enzyme evolution and engineering. In this study, we improved upon HMM searches by applying an iterative machine learning strategy to identify 400 putative PET-degrading enzymes (PET hydrolases) from naturally occurring homologs. Using high-throughput (HTP) experimental techniques, we successfully expressed and purified >200 enzyme candidates and assayed them for PET hydrolysis activity as a function of pH, temperature, and substrate crystallinity. From this library, we discovered 91 previously unknown PET hydrolases, 35 of which retain activity at pH 4.5 on crystalline material, which are conditions relevant to developing more efficient commercial processes. Notably, four enzymes showed equal to or higher activity than LCC-ICCG, a benchmark PET hydrolase, at this challenging condition in our screening assay, and 11 of which have pH optima <7. Using these data, we identified regions of PETases statistically correlated to activity at lower pH. We additionally investigated the effect of condition-specific activity data on trained machine learning predictors and found a precision (putative hit rate) improvement of up to 30% compared to a Hidden Markov Model alone. Our findings show that by pointing enzyme discovery toward conditions of interest with multiple rounds of experimental and machine learning, we can discover large sets of active enzymes and explore factors associated with activity at those conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Elucidating the Competitive Hydrodeoxygenation of Lignin-Derived Oxygenates over Bulk MoO 3 Catalyst through Kinetic Analysis

Ambient pressure hydrodeoxygenation (HDO) of lignin-derived oxygenates over molybdenum oxide-based catalysts is an effective strategy to produce chemicals that can be directly integrated into our existing petrochemical infrastructure. Complexities pertaining to the simultaneous kinetic and mechanistic analysis of HDO have limited research endeavors to single-compound systems. Although valuable insight into the catalytic reaction has been gained through this approach, it provides limited understanding of the competitive adsorption behavior manifest in a realistic multioxygenate reaction environment. To address this shortcoming, simultaneous gas-phase acetone and anisole HDO was performed at 330 °C and ≤1 bar H 2 partial pressure over bulk MoO 3 . Propene, propane, and benzene were the HDO products formed, showing a similar product distribution to the single-compound system. Selectivity to propene and propane was ∼14 times higher than benzene, even at three times higher anisole partial pressure compared to acetone. A negative anisole HDO (−0.97 ± 0.22) rate order with varying acetone partial pressure suggested a strong inhibition effect on anisole HDO by acetone. Conversely, with increasing anisole partial pressure, a rate order of −0.07 ± 0.12 was observed for acetone HDO, implying a weak impact of anisole cofeed on acetone HDO. A kinetic-driven approach was taken to estimate the relative adsorption constants of the oxygenates. Acetone exhibited a 6.4 times higher adsorption propensity on the HDO active site than anisole. Relative adsorption constants for phenolics increased with increasing basicity of the oxygenate but decreased for aliphatic molecules, suggesting a volcano-shaped relationship. The results suggest the possibility of an optimal electron density around the molecule’s oxygen atom to maximize the molecule’s adsorption strength.

acid sites↗