Stable Chemisorption Research Articles

Effect of temperature and nanoparticle size on the interfacial layer thickness of TiO2–water nanofluids using molecular dynamics

Abstract In the design and optimization of nanofluids, it is crucial to investigate and characterize the thermal conductivity enhancement mechanisms and their influencing factors. Although the effect of the “liquid film” on the thermal conductivity of the solid–liquid interface in nanofluids has been extensively studied, most of the research in this area has examined metal–water nanofluids or Ar-based nanofluids. In this work, non-equilibrium molecular dynamics is utilized to explore the mechanism of thermal conductivity enhancement in TiO2–water nanofluids. It is noted that a distinct interfacial layer is formed within 5 Å from the nanoparticle surface. As the nanoparticle size increases, the number density also increases, resulting in a corresponding increase in the thermal conductivity. Moreover, adding 1% TiO2 nanoparticles to water leads to an increase in thermal conductivity of 1.5–3%. Notably, the interfacial layer thickness remains relatively constant with the change in temperature. The Materials Studio analysis results indicated that the water molecule will have stable chemisorption on the titanium dioxide surface with an adsorption energy of approximately −0.96 eV. The findings of this study offer new insights and useful information to support the selection of nanomaterials for the preparation of convective systems.

The influence of small molecule adsorption on the spectral characteristics of B12N12 superatoms

The luminescent spectra of boron–nitrogen (BN) superatoms under the influence of small molecule excitation remain unexplored, yet hold promising prospects for application in luminescent materials. This study employs density functional theory to investigate the absorption and fluorescence emission spectra of small molecules (pyrazine, pyridine, and benzene) adsorbed on B12N12 superatoms. The findings reveal the formation of stable chemisorption structures, namely pyrazine-B12N12 and pyridine-B12N12, while benzene forms a physisorption structure benzene-B12N12. Interestingly, the adsorbed benzene enhances the absorption spectrum intensity of B12N12, while pyrazine and pyridine adsorbed significantly amplify the emission spectrum intensity of B12N12. Moreover, this study discusses the impact of variation in the number of adsorbed small molecules on spectral characteristics. Results indicate that the absorption spectra intensity of 2pyrazine-B12N12, 2pyridine-B12N12, and 2benzene-B12N12 is relatively robust, with 2benzene-B12N12 exhibiting a stronger emission spectrum intensity compared to benzene-B12N12 and 4benzene-B12N12. These computational findings offer valuable insights for the exploration of luminescent materials and serve as theoretical reference for experimental investigations.

Effect of choline chloride/multiple diols deep eutectic solvents on the friction and vibration performance of Si3N4/GCr15 hybrid ceramic ball bearings

Six kinds of choline chloride (ChCl)/diols deep eutectic solvents (DESs) with different alkyl chain lengths and hydroxyl positions were prepared, which are easily synthesized and biodegradable. Tribological and bearing tests show that ChCl/ethylene glycol (EG) has the best performance on the surface of Si3N4/GCr15 tribo-pairs. Compared with PAO10, friction coefficient, wear scar diameter, bearing vibration, and friction torque decreased by 71 %, 28 %, 34.8 %, and 24.6 %, respectively. ChCl/EG, which has the shortest alkyl chain length and hydroxyl distance, has the highest molecular polarity. Such a dense and stable chemisorption film is formed and the lubrication performance is improved, which is confirmed by the inconspicuous tribochemical films. Consequently, ChCl/EG serves as a potentially superior lubricant for Si3N4 hybrid ceramic ball bearings.

Probing the Interaction Mechanism of Sodium Oleate and Dodecyl Amine with Quartz Surfaces in the Presence of Ca2+ Ions by AFM Force Measurement.

Quartz is a key raw material in high-tech fields (such as photovoltaics and semiconductor microelectronics), and the most efficient extraction method of quartz is mineral flotation. Quartz activation plays a crucial role in mineral flotation. However, the mechanism underlying the process remains unclear, and the role of additional metal ions is controversial. In this study, the interaction forces between the quartz surface, the dodecylamine (DDA) cation/sodium oleate (NaOL) anion mixed collectors, and Ca2+ were analyzed using atomic force microscopy in order to systematically explore the activation process of quartz flotation. The results confirmed that the activation process was initialized from NaOL, which was adsorbed on the surface of a calcium-covered quartz surface. The existence of DDA inhibited the binding of Ca2+ to NaOL so that more Ca2+ was adsorbed on the quartz surface to provide the adsorption site for NaOL. Moreover, the best adsorption condition of Ca2+ + NaOL + DDA mixed solution was analyzed by quartz crystal microbalance with dissipation, and it demonstrated that the most stable chemisorption environment on the quartz surface was at pH 11.0. In these circumstances, Ca2+ could first adsorb in a point-like manner on the quartz surface, which was then adsorbed with a mixture of NaOL and DDA. This result showed that, at a specific pH, Ca2+ could encourage the coadsorption of cationic/anionic mixed collectors on quartz. This work provides an important new understanding of the intermolecular interactions that take place during complex mineral flotation processes between chemical additives and mineral surfaces. The methodology used in this study can be easily adapted to different interfacial processes, including water treatment, membrane technology, bioengineering, and oil production.

Adsorption behavior and corrosion inhibition performance of tetrazolium derivatives on electrolytic copper foil surface

The development of chromate-based post-treatment methods has been limited mainly due to their toxicity, thus it is essential to explore environmentally friendly corrosion inhibitors for electrolytic copper foil. Herein, we evaluated three tetrazolium compounds (tetrazolium, 5-methyl-tetrazolium, and 5-amino-tetrazolium) as potential corrosion inhibitors for electrolytic copper foil, and explored their adsorption behavior onto the copper foil surface and their efficiency in inhibiting corrosion when exposed to a 3.5 wt% NaCl solution. Density functional theory calculations provide insights into the relationship between the molecular structure of the inhibitors and their corrosion inhibition efficiency. Furthermore, molecular dynamics simulations elucidate the adsorption behavior of these inhibitors on copper surfaces under solvation conditions. Notably, the 5-amino-tetrazolium molecule exhibits the most stable chemisorption on the Cu(111) surface. Finally, both electrochemical tests and antioxidation experiments confirm that ATZ is the most effective corrosion inhibitor with a corrosion inhibition efficiency (η) of 93.09%, consistent with theoretical predictions. This study highlights the potential application of the tetrazolium derivative 5-amino-tetrazolium in environmentally friendly and chromium-free post-treatment of electrolytic copper foil surfaces.

Preventing lead leakage in perovskite solar cells and modules with a low-cost and stable chemisorption coating.

Despite the promising commercial prospects of perovskite solar cells, the issue of lead toxicity continues to hinder their future industrial applications. Here, we report a low-cost and rapidly degraded sulfosuccinic acid-modified polyvinyl alcohol (SMP) coating that prevents lead leakage and enhances device stability without compromising device performance. Even under different strict conditions (simulated heavy rain, acid rain, high temperatures, and competing ions), the coatings effectively prevent lead leakage by over 99%. After 75 days of outdoor exposure, the coating still demonstrates similar lead sequestration efficiency (SQE). In addition, it can be applied to different device structures (n-i-p and p-i-n) and modules, with over 99% SQE, making it a general method for preventing lead leakage.

Plasma-induced reversible surface modification and its impact on oxygen heterogeneous recombination

A novel model is developed for atomic oxygen surface kinetics in silica-like walls, introducing a plasma-induced surface modification, which may impact intermediate pressure plasma reactors. The model is the first to reproduce experimental measurements in an oxygen glow discharge operating in the pressure range between 0.27 mbar (0.2 Torr) and 4 mbar (3 Torr), showing a decrease with pressure of the O recombination probability on Pyrex between 0.27 mbar and 1 mbar. The numerical simulations suggest that a modification is induced by the production and destruction of metastable chemisorption sites at the surface. As such, the Langmuir–Hinshelwood (L-H) and Eley-Rideal (E-R) recombination mechanisms take place involving not only physisorption and stable chemisorption sites, but also metastable chemisorption sites, produced by the impact of fast O2 ions and neutrals. The presence of metastable sites can be reversed by increasing the plasma pressure.

Electron regulation and gas-sensitivity analysis of hBN-Graphene lateral heterojunctions——First principle study

In this paper, the first-principle calculations of the lateral heterojunction model synthesized by hBN-Graphene were carried out, and it was found that the bandgap of graphene varied with the change in the proportion of hBN, and the bandgap was best regulated with a bandgap of 1.177 eV when the proportion of hBN was 66.67 %. At this time, the adsorption structures of HCN, CO, NH3, and Cl2 were established and energy band calculations were performed on the hBN and Graphene portions of the hBN-Graphene lateral heterojunctions, respectively, and it was found that the adsorption of Cl2 resulted in a significant change in the band gap, which showed a very high electrical sensitivity. To further investigate the adsorption mechanism of Cl2 on the surface of hBN-Graphene lateral heterojunction, the energy band structure, PDOS, charge transfer, adsorption energy, and recovery time of each stabilized adsorption site of Cl2 on the surface of hBN-Graphene lateral heterojunction were calculated. The results show that the adsorption of Cl2 on the surface of hBN-Graphene lateral heterojunction is a stable chemisorption, and the band gap of C-Top1 increases to 1.274 eV, and the band gaps of C-Top3, N-Top1, and N-Top2 decrease to 0.684 eV, 0.376 eV, and 0.398 eV, respectively, and the changes of band gaps are significant and easy to be electrically detection. The recovery time of Cl2 on the surface of hBN-Graphene lateral heterojunction was 7.36 s–2.59 s in visible light and in the temperature interval of 273 K–283 K. The recovery time of Cl2 on the surface of hBN-Graphene lateral heterojunction was 7.36 s–2.59 s in visible light and in the temperature interval of 273 K–283 K. These findings have implications for the research and application of graphene-based Cl2 gas sensors.

Edge-Functionalized Graphene/Polydimethylsiloxane Composite Films for Flexible Neural Cuff Electrodes.

The design of neural electrodes has changed in the past decade, driven mainly by the development of new materials that open the possibility of manufacturing electrodes with adaptable mechanical properties and promising electrical properties. In this paper, we report on the mechanical and electrochemical properties of a polydimethylsiloxane (PDMS) composite with edge-functionalized graphene (EFG) and demonstrate its potential for use in neural implants with the fabrication of a novel neural cuff electrode. We have shown that a 200 μm thick 1:1 EFG/PDMS composite film has a stretchability of up to 20%, a Young's modulus of 2.52 MPa, and a lifetime of more than 10000 mechanical cycles, making it highly suitable for interfacing with soft tissue. Electrochemical characterization of the EFG/PDMS composite film showed that the capacitance of the composite increased up to 35 times after electrochemical reduction, widening the electrochemical water window and remaining stable after soaking for 5 weeks in phosphate buffered saline. The electrochemically activated EFG/PDMS electrode had a 3 times increase in the charge injection capacity, which is more than double that of a commercial platinum-based neural cuff. Electrochemical and spectrochemical investigations supported the conclusion that this effect originated from the stable chemisorption of hydrogen on the graphene surface. The biocompatibility of the composite was confirmed with an in vitro cell culture study using mouse spinal cord cells. Finally, the potential of the EFG/PDMS composite was demonstrated with the fabrication of a novel neural cuff electrode, whose double-layered and open structured design increased the cuff stretchability up to 140%, well beyond that required for an operational neural cuff. In addition, the cuff design offers better integration with neural tissue and simpler nerve fiber installation and locking.

DFT study of coadsorption of fatty acid and kerosene on fluorapatite (001) surface

The adsorption of fatty acid, kerosene and fatty acid-kerosene on fluorapatite (001) surface were investigated by density functional theory (DFT) calculations. The results showed that the single fatty acid could form stable chemisorption on fluorapatite (001) surface by the O of fatty acids bonding with Ca1 site. The single kerosene could not be stably adsorbed on fluorapatite (001) surface because the H of kerosene did not form hydrogen bond with the O of PO<sub>4</sub><sup>3-</sup> on (001) surface (O<sub>surf</sub>). For the coadsorption conformation, the chemisorption of fatty acid-kerosene on fluorapatite (001) surface was contributed by the interaction between O of fatty acids and Ca1, the H of kerosene did not bond with the O<sub>surf</sub>, but the carbon chain length of kerosene has a large influence on the coadsorption. Compared with the coadsorption of fatty acid-decane, the adsorption of butyric acid-tetradecane and octanoic acid-tetradecane on fluorapatite (001) surface have greater adsorption energies and overlapping region of DOS between O 2p and Ca 4d, indicating that there is a synergistic effect between fatty acid and tetradecane. Meanwhile, the collaborative effects exist between the molecules of fatty acids. The interpenetrating adsorption of fatty acid and kerosene on the fluorapatite surface could improve the adsorption strength and density. The flotation test further confirmed that the single kerosene could not collect fluorapatite, but it could be collected by the single fatty acid. Besides, the synergistic effect between fatty acid and kerosene could increase the flotation recovery of fluorapatite.

Spectral properties of B40 enhanced by small molecule adsorption.

The luminescence characteristics of small molecule excited B40 have not been studied yet, and it may have a potential application value in quantum dot luminescence. Herein, the adsorption and fluorescence emission spectra of small molecules (pyridine, pyrazine and benzene) adsorbed on B40 are studied using first-principles. The results show that the absorption of pyridine and pyrazine on B40 can form stable chemisorption structures pyridine-B40 and pyrazine-B40, while benzene adsorption can form physisorption structure benzene-B40. Moreover, the adsorbed pyridine can enhance the intensity of emission spectra of B40. And the pyrazine adsorbed can obviously enhance the intensity of absorption and emission spectra of B40 and cause the spectra to redshift to the visible light range. And the adsorption of benzene has almost no enhancement effect on absorption and emission spectra of B40. In addition, the influence of different computational basis sets on spectra characteristics has also been discussed and the results show that the main peaks of absorption and emission spectra calculated by the diffuse function augmented basis sets are redshifted relatively. This finding provides a strategy for quantum dot luminescence and a theoretical reference for experimental research.

Molecular insights into migration of heavy metal ion in calcium silicate hydrate (CSH) surface and intra-CSH (Ca/Si = 1.3)

In order to enhance the efficiency of heavy metal solidification/stabilization (s/s), unexplored atomic-scale interaction mechanisms between cement hydration products and metal ion are important. The atomic underlying mechanism of migration of heavy metals in the main cement hydration products, hydrated calcium silicate (CSH), is investigated under multifactor via molecular dynamics simulation. The multifactor combines: The adsorption at CSH surface determining the ratio of free ions to adsorbed ions; Heavy metals at CSH interlayer causes CSH particles swelling/shrinkage. The pore consisting of CSH will be wider/narrower, in turn acting on the migration of free heavy metal ion. Simulation shows that CSH bonding heavy metal (Cu/Zn/Pb) capacity depends on the ability of Ca exchanging with them as determined by hydration shell stability of heavy metals. Within interphase zone, part heavy metals form a stable chemisorption with silicon chains via metal-OCSH-Si connection and others form fragile physical adsorption near the outside interphase. Moreover, Pb ion swells the particles but Cu and Zn shrink them, making the multilevel pore structures denser/sparser. Different amounts of free ions due to different interaction with CSH migrates in sparser/denser pores, ultimately determining the solidification/stabilization efficiency.

DFTB investigation of strain affecting the combination of C60 and graphene having single-vacancy on electronic-scale

Density functional tight-binding calculations have been employed to study the effect of applying strain on the combination of C 60 and defective graphene with different coverage. Charge density difference indicate that in the more stable configurations, the active 6:6 bond atoms in C 60 combine with carbon atoms with dangling bonds in graphene by forming two typical C C covalent bonds for chemisorption, where more charge are transferred from the s or p orbitals of bonded C atoms in graphene to C atoms in C 60 whereas the charge transfer occurs only on the atoms near the defect in graphene for the physisorption case. For the comparison of different coverages of C 60 on graphene, strain engineering under smaller coverage was more likely to achieve a stable chemisorption configuration via the newly formed two C C bonds. The magnitudes and directions of the applied strain, and whether it is uniaxial or biaxial, significantly affect the combination of C 60 /graphene nanohybrid systems. • The active 6:6 bond atoms in C 60 combine with carbon atoms with dangling bonds in graphene by forming two typical C C covalent bonds for chemisorption. • Strain engineering under smaller coverage was more likely to achieve a stable chemisorption configuration via the newly formed C C bonds. • The magnitudes and directions of the applied strain, and whether it is uniaxial or biaxial, significantly affect the combination of C 60 /graphene nanohybrid system.

Ni-doped boron nitride nanotubes as promising gas sensing material for dissolved gases in transformer oil

This paper reports that the transition metals (TM), including Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, are substituted in a perfect zigzag (8, 0) boron nitride nanotubes (BNNTs) at B-site and N-site to improve the adsorption performance of intrinsic BNNTs towards oil-dissolved gases (H 2 , CH 4 , and C 2 H 2 ), particularly C 2 H 2 . In this regard, the quantum chemical calculations are performed based on the density functional theory (DFT). The results show that the C 2 H 2 gas adsorption characteristic of BNNTs is selectively enhanced due to the intervention of the TM atom. The Co B , Ni B, Cu B, Zn B, and Zn N are preliminarily selected as potential gas sensors for C 2 H 2 gas based on their suitable range of adsorption energy. The sensitivity, selectivity, and recovery time of the above five structures are compared. It is found that Ni B is a superior sensing material with exceptionally high sensitivity and selectivity. Moreover, the Ni B presented preferable desorption properties for C 2 H 2 gas at room temperature, making it promising for a chemical resistance-type gas sensing device. The analysis of charge transfer and density of states illustrates that the Ni B donates electrons to C 2 H 2 , proving its superiority over the adsorption properties for C 2 H 2 gas over H 2 and CH 4 . The suitable recovery time (2.3 s), extremely high gas response value (494383%), and stable chemisorption demonstrate that the Ni-doped BNNTs at B-site can be a superior chemical gas sensor for C 2 H 2 gas at room temperature.

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N 5 Site for Enhanced Electrocatalytic Reaction

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N ₅ Site for Enhanced Electrocatalytic Reaction

Ultraviolet-assisted construction of low-Pt-loaded MXene catalysts for high-performance Li−O2 batteries

Achieving high electrocatalytic activity with low amount of noble metals is critical for improving the performance and reducing the cost of Li‒O 2 batteries. Herein we describe an ultraviolet-assisted synthesis method of preparing highly active and superb stable MXene-based electrocatalysts containing low Pt content. The obtained electrocatalysts feature homogenous Pt nanocrystals embedded within multilayer Ti 3 C 2 MXene (Pt‒Ti 3 C 2 ). Because of the improvement on electrical and catalytic properties and structural stability, this catalyst design enables promising electrochemical performance. Notably, at an ultralow Pt loading of 0.01 mg cm −2 cathode, the catalyst exhibits a high discharge capacity of 14,769 mAh/g Pt‒Ti3C2 , a low charge overpotential of 0.32 V, and excellent cycle performance over 100 cycles. Systematic studies reveal the relevancy between electrocatalytic performance and chemical microstructure, whereas the stable Pt‒Ti chemisorption facilitates the synergistic catalysis between Pt nanocrystals over multilayer Ti 3 C 2 substrates. Density functional theory reveals mechanistic insights into electrocatalytic effect on the reduction of charge overpotential, whereas the mild interaction between Pt‒Ti 3 C 2 and Li 2 O 2 monomer enables low charge overpotential.

Long-term performance of granular activated carbon electrode system for the removal of amoxicillin

Three-dimensional electrode reactor, packed with conductive particles, is more cost-effective than traditional two-dimensional electrode reactor. In this study, granular activated carbon (GAC) was applied as particle electrode, then the long-term performance on amoxicillin (AMX) removal and activated carbon regeneration of the GAC particle electrode oxidation process (GAC EOP) was investigated, and the GAC adsorption process (GAC ADS) was carried out for comparison. Both of them ran continuously to remove AMX. Because of the regeneration effect of electrochemical action, the GAC EOP showed a more stable physisorption capacity than GAC ADS, with less change in micropore volume, pore size distribution and surface morphology of GAC. The result of XPS revealed the AMX chemisorption mechanism: the carbonyl (CO) and phenolic hydroxyl (OH) on activated carbon combined with carboxyl (COOH) and ammonium group (NH3+) on AMX, respectively. Correspondingly, the content of CO and OH on GAC fell significantly during the GAC ADS. However, due to the chemical bond regeneration effect of electrolysis, noticeable declines were not observed in GAC EOP, which ensured the stable chemisorption capacity of this system. It was shown that during the 50 consecutive runs, the AMX removal in GAC EOP was always higher than 60%. Even the removal efficiency showed an upward tendency, with the average value reached 86.1% and 99.1% in the 31–40 and 41–50 run times respectively. It was because of the rising specific surface area of GAC and the effect of electro-polarization, which made it more meaningful to explore the long-term performance of three-dimensional electrode reactor.

As2O3 adsorption enhancement over Ni-modified γ-Al2O3 in complex flue gas constituents

Arsenic adsorption capacities of γ-Al2O3 are easily affected by some flue gas constituents (e.g. SO2, NOx) based on previous studies. Therefore, promotion of arsenic adsorption performances under effects of different flue gas constituents is necessary. In this study, γ-Al2O3 plays a role of the raw adsorbent and nickel nitrate acts as the modifying agent for γ-Al2O3. Then, Ni-modified γ-Al2O3 is used as the adsorbent for arsenic adsorption experiments. Besides experiments, molecular dynamics (MD) simulations and density functional theory (DFT) calculations are performed to reveal mesoscopic and microscopic adsorption mechanisms, respectively. As to DFT calculations, the average arsenic adsorption energies are promoted by 77.5 kJ/mol, which means that nearly all adsorption structures belong to stable chemisorption. For MD simulations, the adverse molecular collision and aggregation are weakened to make the total arsenic adsorption efficiencies increase by 15.8 % averagely. As far as experiments are concerned, the arsenic adsorption amounts of Ni-modified γ-Al2O3 are averagely 0.033 mg/g bigger than those of pure γ-Al2O3 (i.e. 16.5 % in adsorption efficiencies) under some conditions, consistently corresponding to results of DFT and MD calculations. The whole understanding of this study from above three aspects can provide valuable information for applying Ni-modified γ-Al2O3 to removing arsenic in real industries.

Electrochemical Storage of Atomic Hydrogen on Single Layer Graphene.

If hydrogen can be stored and carried safely at a high density, hydrogen-fuel cells offer effective solutions for vehicles. The stable chemisorption of atomic hydrogen on single layer graphene (SLG) seems a perfect solution in this regard, with a theoretical maximum storage capacity of 7.7 wt %. However, generating hydrogenated graphene from H2 requires extreme temperatures and pressures. Alternatively, hydrogen adatoms can easily be produced under mild conditions by the electroreduction of protons in solid/liquid systems. Graphene is electrochemically inert for this reaction, but H-chemisorption on SLG can be carried out under mild conditions via a novel Pt-electrocatalyzed "spillover-surface diffusion-chemisorption" mechanism, as we demonstrate using dynamic electrochemistry and isotopic Raman spectroscopy. The apparent surface diffusion coefficient (∼10-5 cm2 s-1), capacity (∼6.6 wt %, ∼85.7% surface coverage), and stability of hydrogen adatoms on SLG at room temperature and atmospheric pressure are significant, and they are perfectly suited for applications involving stored hydrogen atoms on graphene.

Interaction of H and Li with epitaxial graphene on SiC: A comparative analysis by first principles study

Ever-growing energy consumption in the world fosters the development of innovative energy technologies for sustainable energy production and storage. In this view, monolayer epitaxial graphene grown on 4H-SiC (MLEG/SiC) may be considered as a potential component of energy-related systems. The current paper deals with modelling of adsorption, diffusion and intercalation of hydrogen and lithium using MLEG/SiC model encompassing 2 × 2 graphene on √3 × √3R30° surface reconstructed nine-bilayer 4H-SiC. The obtained results demonstrate a strong and stable chemisorption of hydrogen on top site of epitaxial graphene with limited surface mobility, while lithiation process occurs via formation of LiC6 phase. The stages of hydrogen and lithium intercalation beneath graphene are studied in detail by performing potential energy scan. Energetic preferences for MLEG/SiC with intercalated hydrogen and lithium atoms versus MLEG/SiC with top-adsorbed H and Li are revealed. Li intercalant-induced complete decoupling of the buffer layer from the SiC substrate followed by the formation of bilayer graphene with inequivalent doping per layer is proposed as an explanation of experimentally observed Raman G peak splitting in electrochemically lithiated epitaxial graphene on 4H-SiC. This work provides deep insights into the nature of atomic-scale processes at epitaxial graphene, which is essential for improving performance of energy-related devices.