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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 1,099 records · Page 61
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Significant slowdown of plasma-optimized surface energy deactivation by vacuum sealing for efficient adhesive bonding

This work proposes an approach to minimize surface energy deactivation of plasma-treated metal and carbon fiber-reinforced polymer (CFRP) surfaces by vacuum sealing. Plasma treatments enhance adhesive wettability on post-treated surfaces for adhesive joints, but the treated surfaces deactivate quickly in air. The surface energy of aluminum alloy AA6061 and carbon fiber-reinforced polymer-polyamide (CFRP-PA66) optimally treated by a blown air plasma instrument returns to the original surface energy within one hour. Vacuum sealing of AA6061 and CFRP-PA66 reduced the surface energy deactivation over 7 days by at least 230 times and 970 times compared to in air. Double Cantilever Beam (DCB) tests performed on adhesively-bonded AA6061/CFRP-PA66 joints showed that the total energy release and energy dissipation before failure of plasma-treated and vacuum-sealed materials was up to 60% more than plasma-treated materials without vacuum sealing and up to 125% more than non-plasma-treated materials.

42 ENGINEERING↗
DOE OSTI2020

A spatial-statistical investigation of surface expressions associated with cyclic steaming in the Midway-Sunset Oil Field, California

In the Midway Sunset Oil Field in Central California, operators inject steam into the shallow diatomite formation to enhance heavy oil recovery through imbibition, wettability alteration, and viscosity reduction, among other mechanisms. The injected steam, however, does not always remain in the reservoir or return through the wells. In two zones in the study area, the steam comes out at the surface, creating sinkholes, seeps, and steam outlets. These phenomena, called “surface expressions,” pose safety and environmental hazards. Even though these surface expressions are a widespread problem in Central California, they are not well documented and understood. Possible causes of the surface expressions include: high injection pressure, structurally controlled flow patterns, leakage of steam through old improperly abandoned wells, high injection volumes, or flow along naturally occurring faults, among other possible factors. This work examines attributes of the zones with surface expressions in order to determine factors that may contribute to their occurrence. Spatial statistical analysis using logistic regression, random forests, and classification trees is used to explore the relationship between the surface expressions and geological and production-related attributes. The results point to a significant spatial correlation between the surface expressions and two predictors: concentration of plugged wells and geologic seal thickness. The results guide follow-up studies to further investigate the role of well abandonment and seal thickness in the occurrence of surface expressions.

02 PETROLEUM↗
DOE OSTI2023

Topographic hydro-conditioning to resolve surface depression storage and ponding in a fully distributed hydrologic model

Land surface depressions play a central role in the transformation of rainfall to ponding, infiltration and runoff, yet digital elevation models (DEMs) used by spatially distributed hydrologic models that resolve land surface processes rarely capture land surface depressions at spatial scales relevant to this transformation. Methods to generate DEMs through processing of remote sensing data, such as optical and light detection and ranging (LiDAR) have favored surfaces without depressions to avoid adverse slopes that are problematic for many hydrologic routing methods. Here, in this study, we present a new topographic conditioning workflow, Depression-Preserved DEM Processing (D2P) algorithm, which is designed to preserve physically meaningful surface depressions for depression-integrated and efficient hydrologic modeling. D2P includes several features: (1) an adaptive screening interval for delineation of depressions, (2) the ability to filter out anthropogenic land surface features (e.g., bridges), (3) the ability to blend river smoothing (e.g., a general downslope profile) and depression resolving functionality. From a case study in the Goodwin Creek Experimental Watershed, D2P successfully resolved 86% of the ponds at a DEM resolution of 10 m. Topographic conditioning was achieved with minimum impact as D2P reduced the number of modified cells from the original DEM by 51% compared to a conventional algorithm. Furthermore, hydrologic simulation using a D2P processed DEM resulted in a more robust characterization on surface water dynamics based on higher surface water storage as well as an attenuated and delayed peak streamflow.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Surface evolution of synthetic bilgewater emulsion

Bilgewater is oil-in-water emulsion emitted from shipboard and it is a source of pollution to the ocean. Wastewater treatment needs fundamental knowledge of the bilgewater surface changes; however, limited information is available. We have reported the first surface characterization of synthetic bilgewater emulsion using time-of-flight secondary ion mass spectrometry (ToF-SIMS) coupled with optical microscopy. A NAVY synthetic bilgewater emulsion consisting of three oils and a detergent mixture is used as the synthetic bilgewater model. Both fresh and aged emulsion samples are analyzed to determine their droplet size distributions (DSDs) and surface chemical compositions. Our results show that fresh emulsions are largely mono-modal with hydrocarbon fragments as the main surface composition. Aged emulsions are also monomodal with slightly larger size. Both SIMS spectral comparison and Principal Component Analysis (PCA) show that some surfactant components appear on the fresh emulsion surface immediately while larger molecular weight components appear at the aged bilge droplet surface. Our results indicate that the oil-water interface evolves after emulsion droplet forms. More importantly, surface evolution not only changes the bilgewater DSD but also surface chemical composition and reactivity.

bilgewater, droplet size distribution, ToF-SIMS, s↗
DOE OSTI2024

Effect of CO 2 on the water slip flow at silica surfaces for nanometer slit pores of talc

In our previous study, Molecular Dynamics (MD) simulated water flow with no dissolved gas in nanometer slit pores of the hydrophobic talc surfaces revealed a slip length of about 0.5 nm, which is close to the size of “water exclusion zone” but much less than experimental slip length. Atomic Force Microscopy (AFM) imaging confirmed the presence of pancake shape nanobubbles at the hydrophobic talc (001) surface (size from tens to hundreds of nanometers). The effect of CO 2 on water slip flow in talc nanopores is reported to reveal the importance of dissolved gas for confined fluid flow. MD simulated 7 nm CO 2 nanobubbles were found to attach and spread at the talc (001) surface, consistent with the AFM observation. Simulated CO 2 saturated water flow in the slit pores of talc (001) surfaces predicted the generation of CO 2 nanobubbles at the end of the slit pore, due to the stabilization of a CO 2 film at the talc (001) surfaces and a water barrier at the edge surfaces of talc. A “critical thickness” of about 1.5 nm was found for CO 2 nanobubbles to be stabilized at the end of the talc (001) surface. With 1.5 nm CO 2 nanobubbles at the talc (001) surface of a 6 nm slit pore, a water slip length of 1.8 nm was determined. Furthermore, the nanometer slit pore simulations with dissolved CO 2 in water revealed an increased slip length. It is expected that an increased slip length value would be found with an increased CO 2 film thickness.

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

Experimental and numerical investigation of fracture conductivity between non-smooth rock surfaces with and without proppant

The enhancement of fracture conductivity is vital for the efficient recovery of subsurface resources, such as geothermal energy and petroleum hydrocarbons. Proppants, granular materials injected into hydraulic fractures to maintain their conductivity, have been studied primarily in the context of smooth fractures (i.e., fractures between smooth rock surfaces). However, non-smooth fractures (i.e., fractures between rough rock surfaces) are common in geoenergy reservoirs and thus require further investigations. In this study, we conducted laboratory measurements of fracture conductivity on shale slabs with non-smooth surfaces and carried out numerical simulation using the lattice Boltzmann (LB) method, which aimed to investigate the conductivity of non-smooth fractures with and without proppants placement. When ceramic proppant with an areal concentration of 2 lb/ft 2 was placed in the fracture, the conductivity was enhanced by roughly 3-8 times compared to fractures without proppant. In fractures with proppant, gas-measured conductivity was higher than that measured with water due to proppant embedment caused by water. The experiments demonstrate the advantages of using proppant in fractures, even if the rock surface roughness can provide certain fracture conductivity via the self-propping mechanism. For fractures without proppants, high rock surface roughness is not necessarily favorable for enhancing fracture conductivity because the self-propping mechanism requires shear slip along the fracture surface. If there is no shear slip, high rock surface roughness can cause a detrimental effect on the fracture conductivity due to the interlocking effect. Utilizing advanced experimental equipment and LB modeling, this research explores the interplays between proppant placement, fracture geometry, and stress conditions to develop a comprehensive understanding of the productivity in non-smooth fractures. Further, the outcomes of this investigation indicate the importance of creating fractures with surface roughness during hydraulic fracturing and will contribute to the development of more efficient stimulation techniques for subsurface energy extraction.

15 GEOTHERMAL ENERGY↗
DOE OSTI2020

Effects of micrometer-scale surface roughness on thermal infrared emittance spectra of silica glass

Surface roughness is known to decrease thermal infrared (TIR) absorption band intensity, but studies of the effect on geologically relevant samples are relatively limited. To determine the effect of surface roughness (with features smaller than ~2/3 of the wavelength) on TIR spectra, we investigated two glass compositions with prepared roughened surfaces: (1) high purity fused silica and (2) soda-lime glass (73 wt% SiO$_2$). We roughened the surfaces of the glasses by sandblasting and polishing with grit paper. The surfaces were characterized with scanning electron microscopy and stylus profilometry. We then analyzed the roughened glasses with TIR emittance spectroscopy. Micrometer-scale roughness causes a decrease in TIR absorption band intensity, relative to a specular surface. No significant changes in band shape or shifts in wavelength were detected. As roughness increases, empirical results show a logarithmic decrease in TIR absorption band intensity. The logarithmic trends of the two glass compositions are different; empirical roughness calibrations do not translate across different compositions. A linear, least-squares spectral deconvolution using two endmembers, specular and blackbody, predicts model spectra of roughened glass surfaces with relatively low error. This is of consequence to orbital TIR measurements of poorly constrained targets, such as the martian surface, because micrometer-scale roughness is adequately modeled by the addition of a blackbody spectrum to the deconvolution endmember matrix.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Application of community data to surface complexation modeling framework development: Iron oxide protolysis

This study presents a comprehensive community data-driven surface complexation modeling framework for simulating potentiometric titration of mineral surfaces. Compiled community data for ferrihydrite, goethite, hematite, and magnetite are fit to produce representative protolysis constants that can reproduce potentiometric titration data collected from multiple literature sources. Using this framework, the impact of surface complexation model type and surface site density (SSD) on the fit quality and protolysis constants can be readily evaluated. For example, the non-electrostatic model yielded a poor data fit compared to diffuse double layer model and constant capacitance models due to the absence of known surface charge effects. Regardless of the choice of iron oxide mineral, pK a1 decreased with increasing SSD while the opposite tendency was observed for pK a2 . This newly developed framework demonstrates a method to reconcile community data-wide potentiometric titration data using Findable, Accessible, Interoperable, Reusable data principles to produce mineral protolysis constants that improve robustness of surface complexation models for applications in metal sorption and reactive transport modeling. The framework is readily expandable (as community data increase) and extensible (as the number of minerals increase). The framework provides a path forward for developing self-consistent, comprehensive, and updateable surface complexation databases for surface complexation and reactive transport modeling.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Engineering surface segregation of perovskite oxide through wet exsolution for CO catalytic oxidation

Cation segregation occurring near the surface or interfaces of solid catalysts plays an important role in catalytic reactions. Unfortunately, the native surface of perovskite oxides is dominated by passivated A-site segregation, which severely hampers the catalytic activity and durability of the system. To address this issue, we present a wet exsolution method to reconstruct surface segregation in perovskite cobalt oxide. Here, under reduction etching treatment of glycol solution, inert surface Sr segregation was transformed into active Co 3 O 4 segregation. By varying the reaction time, we achieved differing coverage of the active Co 3 O 4 segregation on the La 0.5 Sr 0.5 CoO 3-δ (LSCO) perovskite oxide surface. This study reveals that CO oxidation activity exhibits a volcano-shaped dependence on the coverage of Co 3 O 4 segregation at the surface of a perovskite cobalt oxide. Furthermore, we find that a suitable coverage of Co 3 O 4 segregation can dramatically improve the catalytic activity of the perovskite catalyst by enhancing interface interactions. Co K-edge, Co L-edge, and O K-edge X-ray absorption spectra confirm that the synergistic effect optimizes the covalence of the metal-oxygen bond at the surface and interface. This work not only contributes to the design of perovskite-type catalysts, but also provides important insight into the relationship between surface segregation and catalytic activity.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Role of surface wetting on tribological behavior for laser nanotextured steel using ionic liquid lubricants

Here, this research evaluates the effect of surface wettability on the tribological performance through ball-on-flat tribology testing. The substrate material, M2 tool steel, is laser processed and then functionalized with fluorocarbon and nitrile chemistry to achieve distinct oleophobicity and oleophilicity, respectively, but with a similar nanoscale surface texture. The baseline lubricant is poly-alpha-olefin (PAO) oil, and ionic liquids (ILs) are used as additives for this study. The interaction between the nanoscale textured steel surface and ionic liquid-based oils is investigated. A set of reciprocating wear tests are performed to investigate the tribological behavior of the tribo-system consisting of the surface-engineered, flat M2 tool steel specimen and a standard, surface-polished steel ball. Results show that the oleophobic flat surface results in a lower friction, while the oleophilic surface modification leads to a better wear protection to the flat surface. Ammonium-based IL provides the highest friction reduction, while the phosphonium-based ILs provide an improved wear protection.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Surface smoothing for laser powder-bed Ti-6Al-4V by a transient liquid phase

Surface roughness is the primary driver of fatigue for additively manufactured metals. To address surface roughness, this work introduces a new method to smooth features beyond line-of-sight without material removal. The method applies a coating that triggers local surface remelting by activating a eutectic reaction during heat treatment. The associated liquid phase then wets and isothermally solidifies into a smoother surface. For Ti-6Al-4V fabricated with laser powder bed fusion, samples with and without TLP smoothing (using a Cu coating) were characterized with a suite of techniques, including mechanical testing, electron backscatter diffraction, synchrotron X-ray tomography, and fractography. TLP smoothing reduced surface roughness by 80% and amplified compressive residual stress at the surface by about 50%. With statistically equivalent virtual microstructures, crystal plasticity scrutinized the roles of phases, porosity, and surface roughness. Although the tensile strain-to-failure was reduced to 1% strain, the TLP smoothing process increased high-cycle fatigue strength by about 20% compared to control samples, pointing to future opportunities to optimize the new process through various coating compositions and heat treatment schedules. Overall, this work establishes a new paradigm for treating surfaces of materials for smoothness and compressive residual stress.

Additive manufacturing↗
DOE OSTI2021

The effects of free surfaces on deformation twinning in HCP metals

Deformation twinning is a predominant mode of plastic deformation for hexagonal close packed metals, like Mg and Ti. The heterogenous microstructure and the local stresses associated with twinning play a key role in their mechanical response and fracture. Surface analyses, like electron microscopy, are frequently employed to spatially map microstructure and micromechanical fields in order to study twinning behavior. However, these measurements are inherently influenced by the vicinity of the free surface. In this work, an elasto-visco-plastic fast-Fourier-transform (EVP-FFT) polycrystal modeling approach is employed to investigate the effects of free surfaces on twin development before and after loading. We compare calculated micromechanical fields on free surfaces with those calculated inside the bulk and, in some cases, experimental surface measurements. The results indicate that the creation of free surfaces can promote twin propagation and growth and can influence twin morphology by causing a twin lamella to become larger, more blunted and irregular. The structure along the twin boundaries are also affected, due to the higher driving stresses that extend prismatic-basal and basal-prismatic facets. Furthermore, free surfaces invoke different slip activities in the twin and the surrounding parent crystal by enhancing basal, prismatic and pyramidal slip in some localized regions, while reducing slip in others. We demonstrate that the simulated free-surface effects lead to better qualitative and quantitative agreement with experimental measurements from scanning electron microscopy and digital image correlation.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Directly resolving surface vs. lattice self-diffusion in iron at the nanoscale using in situ atom probe capabilities

Surface self-diffusion studies on metals under elevated reaction conditions are limited, as it is inherently challenging to unambiguously follow atomic transport across highly-reactive surfaces. Here, quantitative and mechanistic insight into thermally induced atomic transport processes in bcc α-iron at the sub-nanometer level was achieved using isotopic tracer techniques coupled with in situ atom probe tomography (APT) capabilities. Specifically, using a reactor directly connected to the APT, needle-shaped specimens fabricated from epitaxial thin films with an embedded 57 Fe tracer layer were annealed in Ar at 500 °C and 350 °C for 1 hour. Furthermore, the tracer was positioned at various depths in the APT specimen by field evaporation, enabling targeted and simultaneous analysis of lattice and surface diffusion. 57 Fe concentration profiles reveal lattice self-diffusion occurs at 500 °C on the order of ~7 – 9 monolayers, while lattice diffusion is not resolvable at 350 °C. Considerable surface transport was, however, observed at both conditions, where atomic transport over the specimen surface led to the formation of a thin (≤1 nm), isotopically-intermixed layer at the surface. Further, the observed isotopic redistributions at 500 °C were convoluted by additional processes occurring in the subsurface, such as atomic intermixing in correlation with lattice diffusion. However, surface diffusion was determined to be the primary transport process at 350 °C and was thereby quantified. Ultimately, these results demonstrate the significance of surface self-diffusion as a short circuit pathway. More broadly, this approach has the potential to provide detailed insight into (self-)diffusion mechanisms across various materials while targeting site-specific reactions under elevated reaction conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Surface roughness and dimensional evaluation of laser powder bed fusion additively manufactured shell and tube heat exchangers

The growing interest in additively manufactured (AM) heat exchangers drove the need to understand how this construction technique impacts heat exchanger performance. Two primary factors driven by AM that influence heat exchanger performance are surface roughness and geometry. To better understand these parameters, a range of shell and tube heat exchangers constructed using laser powder bed fusion were evaluated. Of those evaluated, the surface roughness throughout a fourteen-tube, zero-baffle heat exchanger was measured using computed tomography. Between the inner and outer tubes, the inner tube surfaces had a greater surface roughness than the outer by 8.07 μm, while the surfaces at the top of the build volume had higher surface roughness values than the bottom. Dimensionally, the inner tube diameters of this heat exchanger were 0.15% different from the design value, while the outer diameters were within a 0.84 % difference. Manual measurements across seven other heat exchangers yielded a maximum 1.15% difference between the design and measured diameters. Across the build volume for all heat exchangers studied, the tube diameters at the top were larger than at the bottom by a maximum of 1.24% difference. Inconsistent melting throughout the individual parts and the build volume, as well as particle splatter and thermal gradient variation were attributed to the surface roughness and dimensional changes seen. These results strengthen the knowledge of dimensional and surface roughness considerations when designing AM heat exchangers.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Planarizing Spalled GaAs(100) Surfaces by MOVPE Growth

III-V photovoltaic devices have demonstrated exceptional performance across various applications, with controlled crystal fracturing, known as controlled spalling, emerging as a promising method to reduce costs by enabling substrate reuse. Spalling GaAs(100) substrates, a commonly used substrate in III-V photovoltaics, results in faceted ridges that must be planarized to grow high-quality photovoltaic devices. Here, in this study, we demonstrate that a GaAs(100) wafer offcut toward [$0\bar{11}$] and spalled toward [$011$] can be efficiently planarized by growing C:GaAs by metal-organic vapor phase epitaxy (MOVPE) on the surface, with up to 95% of the nominally deposited material used to fill the valleys between ridges. We find that reducing the offcut to 2° enhances the planarizing capability of C:GaAs. A surface morphology model indicates that the density of surface dangling bonds significantly influences the growth evolution of undoped GaAs surfaces. In contrast, the model suggests that the effectiveness of C:GaAs as a smoothing layer stems from modifying the atomic surface structure and, consequently, the associated sticking coefficients of the facets, which can alter the evolution of surface morphology. Our findings provide guidelines for the epitaxial planarization of semiconductor surfaces and improve the understanding of MOVPE growth on nonplanar surfaces.

14 SOLAR ENERGY↗
DOE OSTI2020

Identifying and Tuning the In Situ Oxygen-Rich Surface of Molybdenum Nitride Electrocatalysts for Oxygen Reduction

Rigorous in situ studies of electrocatalysts are required to enable the design of higher performing materials. Nonplatinum group metals for oxygen reduction reaction (ORR) catalysis containing light elements such as O, N, and C are known to be susceptible to both ex situ and in situ oxidation, leading to challenges associated with ex situ characterization methods. We have previously shown that the bulk O content plays an important role in the activity and selectivity of Mo–N catalysts, but further understanding of the role of composition and morphological changes at the surface is needed. Here, we report the measurement of in situ surface changes to a molybdenum nitride (MoN) thin film under ORR conditions using grazing incidence X-ray absorption and reflectivity. We show that the half-wave potential of MoN can be improved by ~90 mV by potential conditioning up to 0.8 V versus RHE. Utilizing electrochemical analysis, dissolution monitoring, and surface-sensitive X-ray techniques, we show that under moderate polarization (0.3–0.7 V vs RHE) there is local ligand distortion, O incorporation, and amorphization of the MoN surface, without changes in roughness. Furthermore, with a controlled potential hold procedure, we show that the surface changes concurrent with potential conditioning are stable under ORR relevant potentials. Conversely, at higher potentials (≥0.8 V vs RHE), the film incorporates O, dissolves, and roughens, suggesting that in this higher potential regime, the performance enhancements are due to increased access to active sites. Density functional theory calculations and Pourbaix analysis provide insights into film stability and O incorporation as a function of potential. These findings coupled with in situ electrochemical surface-sensitive X-ray techniques demonstrate an approach to studying nontraditional surfaces in which we can leverage our understanding of surface dynamics to improve performance with the rational, in situ tuning of active sites.

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

Insights into the Electrochemical Oxidation and Reduction of Nickel Oxide Surfaces

Surface oxidation/reduction processes, driven by varying electrochemical potentials, can substantially impact catalyst effectiveness and, consequently, electrolyzer performance. Here, this study combines theoretical and experimental approaches to explore the surface redox behavior of nickel oxides, which are cost-effective and efficient catalysts for many electrochemical reactions. Surface Pourbaix diagrams for three different phases of nickel oxides, i.e., nickel hydroxide (Ni(OH) 2 ), nickel oxyhydroxide (NiOOH), and nickel dioxide (NiO 2 ), were constructed using density functional theory-based simulations. Various experimental methods, including cyclic voltammetry, in situ Raman spectroscopy, and electrochemical titration, were employed to probe the surface redox processes of nickel oxide thin films. Our findings indicate that the ABAB stacking sequence of Ni(OH) 2 lacks stability under oxidizing conditions to host the surface oxidation (deprotonation) events, while the AABBCC stacking sequence of NiOOH is energetically favorable due to the presence of interlayer hydrogen bonding. Rapid charge transfer facilitated by interlayer hydrogen bonding accounts for the higher reactivity of partially oxidized/reduced NiOOH (001) surfaces compared to Ni(OH) 2 (001) and NiO 2 (001) surfaces with the same stoichiometry, where interlayer hydrogen bonding is absent. Insights presented in this work can offer guidelines for optimizing operational conditions and tailoring the surface structures and oxidation states of nickel oxides to enhance performance in applications such as electrocatalysis and supercapacitors.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Off-Equilibrium Reactivity of Boron-Enriched Metal Diboride Surfaces in Electroreduction Conditions

Boron-based materials, featuring B-dependent reactivity and diverse phases, are emerging as promising catalyst systems. However, the catalytic mechanism on many borides remains poorly understood due to complex surface reconstructions under reaction conditions. Here, we investigate the MoB 2 surface in conditions of hydrogen evolution reaction in acidic media, using grand canonical global optimization, grand canonical density functional theory, ab initio molecular dynamics, free energy surface sampling, and an analytical model for electrochemical barrier evaluation. We propose a boron-enrichment strategy to tune the surface reactivity of the hexagonal face of MoB 2 . We reveal the dynamic nature of the B-enriched surface under H coverage and kinetic trapping of the system in the metastable regime with an extensive examination of the deactivation pathways. The metastable center B site on B-enriched surfaces, featuring buckled-up configuration and a usual relaxation effect, is found to be highly active toward HER via the Volmer–Heyrovsky mechanism. In conclusion, this work demonstrates how off-equilibrium behaviors can arise from the interplay between adsorbate coverage and surface reconstruction on a seemingly simple surface, and we present a theoretical framework and computational workflows to address these behaviors, along with other realistic complexities, in kinetics simulations.

Adsorption↗