Adsorption Energy Research Articles

Resolution of Selectivity Steps of CO Reduction Reaction on Copper by Quantum Monte Carlo.

Electrochemical reduction of carbon monoxide to valuable fuels and chemicals on copper surfaces remains a challenging area in catalysis due to a limited understanding of adsorption mechanisms and reaction pathways. Although density functional theory (DFT)-based studies have investigated these processes, their accuracy varies across different functionals. Here, we present the application of fixed-node diffusion Monte Carlo (FNDMC) to benchmark the adsorption energies of CO*, H*, and key CO reduction reaction (CORR) intermediates, COH* and CHO* on the Cu(111) surface. Our results for CO* and H* adsorption energies closely align with experimentally measured chemisorption reactions, highlighting the limitations of DFT and providing site-specific energy comparisons that are often not available experimentally. Additionally, we explore the effect of explicit solvation, demonstrating how water stabilizes the COH* over CHO*, thus suggesting a critical role of COH* in CORR. Finally, we release our high-accuracy FNDMC benchmarks for testing and developing new DFT functionals for electrocatalysis. Overall, this study underscores the potential of FNDMC for detailed surface chemistry studies and offers new insights into catalytic processes.

Amorphous PdRuOx as High-Activity Sensitizers for Ultrafast Low-Humidity Sensors.

Amorphous noble metals often display excellent sensitization due to their unsaturated atomic coordination and abundant active sites on the surface. In this work, amorphous palladium-ruthenium bimetallic nanoparticles were successfully prepared by lithium doping and incorporated into MOF-303 by using a confinement strategy. Compared with crystalline c-PdRuOx@MOF-303, the low-humidity sensor constructed with amorphous a-PdRuOx@MOF-303 exhibits higher response values (3600 Hz to 3.39% RH), shorter response/recovery time (9/7 s), low-humidity hysteresis (0.16% RH) and excellent stability. Meanwhile, the a-PdRuOx@MOF-303 sensor has been further explored to achieve continuous monitoring of human breathing, cough, and finger humidity, providing broad application prospects for amorphous materials in wearable medical devices and noncontact human-machine interactions. Additionally, the sensitive mechanism was explored by GCMC methods. The simulation results demonstrate that introducing a-PdRuOx into the pores of MOF-303 leads to significant enhancement in adsorption properties. This improvement is not only due tothe increase of active sites provided by a-PdRuOx but also the substantial rise in adsorption energy for the hydrophilic pocket of MOF-303. The adsorption energy increases from -25.70 to -31.56 kJ/mol, highlighting that the abundant active sites of the a-PdRuOx work in synergy with the hydrophilic pocket of MOF-303. This synergy enables the adsorption and activation of more water molecules, effectively enhancing the overall adsorption capacity and performance of the MOF-303.

Predicting electrocatalytic urea synthesis using a two-dimensional descriptor

Electrochemical synthesis routes powered by renewable electricity can provide sustainable chemical commodities by replacing conventional fossil-based processes. Increasing research focuses on value-added chemicals like the indispensable fertilizer urea, which also constitutes a study case for electrochemical CN-coupling. To guide the identification of highly selective catalysts, we aim to provide new insight by analysing existing experimental data on the selectivity of transition metal catalysts towards electrochemically synthesized urea. Firstly, we project high dimensional experimental data using principal component analysis (PCA) to lower dimensions, and thereby confirm that urea selectivity is correlated with the selectivity towards CO and NH3. Furthermore, we identified the most suitable two-dimensional descriptors for selectivity prediction out of various adsorption energies calculated using density functional theory (DFT). We suggest that the adsorption energies of *H and *O on transition metal slabs predict the selectivity towards urea in the co-reduction of CO2 and nitrite (NO2−).

Breaking linear scaling relationships in oxygen evolution via dynamic structural regulation of active sites

The universal linear scaling relationships between the adsorption energies of reactive intermediates limit the performance of catalysts in multi-step catalytic reactions. Here, we show how these scaling relationships can be circumvented in electrochemical oxygen evolution reaction by dynamic structural regulation of active sites. We construct a model Ni-Fe2 molecular catalyst via in situ electrochemical activation, which is able to deliver a notable intrinsic oxygen evolution reaction activity. Theoretical calculations and electrokinetic studies reveal that the dynamic evolution of Ni-adsorbate coordination driven by intramolecular proton transfer can effectively alter the electronic structure of the adjacent Fe active centre during the catalytic cycle. This dynamic dual-site cooperation simultaneously lowers the free energy change associated with O–H bond cleavage and O–O bond formation, thereby disrupting the inherent scaling relationship in oxygen evolution reaction. The present study not only advances the development of molecular water oxidation catalysts, but also provides an unconventional paradigm for breaking the linear scaling relationships in multi-intermediates involved catalysis.

Theoretical investigation of adsorptive nitrate ion removal by pure graphene, Mo-decorated graphene and reduced graphene oxide based adsorbents: a DFT study

Density functional theory (DFT) calculations were used to investigate the efficacy of pure graphene (G), Mo-decorated graphene and Mo-decorated reduced graphene oxide (rGO) in removing nitrate anion (NO3 −) pollutants. Initially, the adsorption mechanism was analyzed to identify the most probable position of nitrate adsorption through optimized geometries, adsorption energy, bond length and electronic structures. Subsequently, a comprehensive analysis was executed to examine the adsorption properties of the NO3 − anion. Analyses of the adsorption energy, charge density difference and density of states indicated that defect sites, functional groups and Mo-atom decorations in graphene could significantly enhance the nitrate adsorption energy. The results indicated that the adsorption mechanisms of the NO3 − anion on pure G, Mo-decorated G and Mo-decorated rGO were different. NO3–Mo-decorated rGO demonstrated the highest adsorption energy. Conversely, NO3–pure G exhibited the lowest adsorption energy, while the NO3–Mo-decorated G showed the highest Fermi energy. Bader and projected density of states analyses suggest that the orbitals in the NO3–Mo-decorated G structure occupy the largest share in the valence band compared with the NO3–Mo-decorated rGO structure, which led to high electron accumulation. Consequently, the NO3–Mo-decorated rGO structure allows the complete absorption of nitrate, resulting in the breaking of chemical bonds. These results indicate that the NO3–Mo-decorated rGO structure has the highest nitrate absorption energy among the studied structures.

MoS[formula omitted] containing (Si, Se, P+Cl) structure doping and (Au and Ag) surface decorating as a sensor of Methanethiol biomarker: A first-principles study

MoS2 monolayer is a highly promising material for gas and biosensors due to its exceptional physical and chemical properties. Recent research suggests that modified MoS2 monolayers demonstrate improved properties compared to unmodified ones. In this study, we employed density functional theory to investigate MoS2 doped and decorated with transition metallic atoms such as Ag and Au, as well as non-metallic atoms like Se, Si, P, and Cl, for the detection of the Methanethiol biomarker. In this regard, the adsorption energy, charge transfer, adsorption distance, I-V, TDOS, PDOS, and sensitivity are calculated for each structure. The results reveal that the adsorption energy and charge transfer of the Methanethiol biomarker on MoS2 modified with Ag, Au, and Si atoms are higher than that of unmodified MoS2. The most significant changes in I-V curves and chemical adsorption occurr in these structures. The highest sensitivity is achieved when the MoS2 monolayer is decorated with Ag atoms, Au decorated, and doped with two Si atoms, respectively. Also, doping with Se, P, and Cl atoms results in the lowest adsorption energy, charge transfer, and sensitivity. This study provides valuable insights into the potential applications of both unmodified and modified MoS2 as Methanethiol biomarker sensor materials.

Magnetically recyclable CoFe2O4 nanocatalysts for efficient glycolysis of polyethylene terephthalate

Efficient and sustainable recycling of polyethylene terephthalate (PET) is essential in mitigating its environmental impacts on climate, human health, and global ecosystems. Glycolysis, a closed-loop recycling method that converts PET into bis(2-hydroxyethyl) terephthalate (BHET), stands out as one of the most promising methods due to its mild operating conditions and environmentally friendly nature. However, the complete convert PET into BHET with a high stability are still challenging. In this study, magnetically recyclable CoFe2O4 nanocatalysts were synthesized by the solvothermal method and surface-modulated with Na3Cit·2H2O as a modifier. When utilizing an optimized CoFe2O4 catalyst, conversion of PET achieved 100 %, with a BHET yield of 91.7 % at 210 °C for 1 h. The excellent catalytic performance of CoFe2O4 is attributed to its smaller particle size, improved dispersion, higher surface Co/Fe ratio, and increased oxygen vacancies, all of which can be achieved through straightforward surface modulation. DFT calculations of M−O distance (M = Co or Fe), adsorption energy, and Bader charges confirm that a higher surface Co/Fe ratio enhanced PET glycolysis, consistent with experimental results. Additionally, a modified energy economy coefficient (εm) was proposed to characterize the catalytic efficiency. The εm value of CoFe2O4-60 % was 0.624, indicating promising applications in efficient PET glycolysis. This work presents a versatile approach for easily manipulating the surface properties of magnetic catalysts and identifies key factors for achieving high performance in PET-to-BHET conversion. It offers valuable guidelines for the future design of nanoparticle catalysts with magnetic properties for chemocatalytic reactions.

Edge-substituents and center metal optimization boosting oxygen electrocatalysis in porphyrin-based covalent organic polymers.

The promising non-noble electrocatalyst with well-defined structure is significant for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for the renewable energy devices like zinc-air batteries (ZABs). Herein, the four phenyl-linked cobaltporphyrin-based covalent organic polymers (COPs-1-4) with the different edge substituents (1=-tBu, 2=-Me, 3=-F, and 4=-CF3) are firstly designed and synthesized via a simple, efficient one-pot method. With the increase of electron donating capacity of the substituents, the highest occupied molecular orbital energy (EHOMO) gradually increases in the order of COP-4<COP-3<COP-2<COP-1. Consequently, the optimal COP-1 with -tBu edge groups exhibits the highest half-wave potential (E1/2) of 0.84V (vs. RHE) among the four COPs, which is comparable with commercial Pt/C in alkaline media. The DFT calculations further reveal that with strong electron donating capacity, the Gibbs free energy decreases in the order of COP-4>COP-3>COP-2>COP-1 by modulating the adsorption energy of OOH* at rate-determining step (RDS) to promote ORR activity. Furthermore, introducing Ni (II) and Co (II) into porphyrin centers afford the bimetallic CoNi-COP-1 with both Co-N4, Ni-N4 active sites and edge substituted -tBu. The synergistic effect of Co, Ni bimetallic active sites and strong electron-donating -tBu substituents renders the CoNi-COP-1 the highest HOMO and smallest energy gap between the ELUMO and EF among the as-prepared five COPs, which leads to more filling electrons of its LUMO level, and thus exhibits the excellent ORR and OER bifunctional catalytic activities with an E1/2 as high as 0.85V and an overpotential (η) of 0.34V at 10mA cm-2 in alkaline media, superior to monometallic Co-containing COPs-1-4. In particular, the assembled ZABs with bifunctional catalyst CoNi-COP-1 possesses high power density (94.10 mW cm-2), high specific capacity (841.71 mAh gZn-1) and long durability of over 160,000s. This work exemplifies the rational design of pyrolysis-free non-noble metal COP-based electrocatalyst through optimizing the intrinsic metal center and its secondary coordination environment.

Prediction of oxygen adsorption energy on TiZrNbMoAl high-entropy alloys: DFT and machine learning

Prediction of oxygen adsorption energy on TiZrNbMoAl high-entropy alloys: DFT and machine learning

A coral-like Co/Ni foam cathode with superior intermediates adsorption energy for efficient electrocatalytic nitrate removal

A coral-like Co/Ni foam cathode with superior intermediates adsorption energy for efficient electrocatalytic nitrate removal

Computational Investigation of Pristine, Al-, and Ga-Doped Zn12O12 nanoclusters as Detection Platforms for Methadone in gas and solvent phases

Electrochemical sensors are emerging as promising tools for point-of-care diagnostic medical devices, benefiting from advancements in nanomaterials. These nanomaterials enable the development of smaller, more sensitive, and selective sensors while reducing fabrication and maintenance costs. This work presents a comprehensive theoretical investigation of the potential application of pristine, Ga- and Al-doped Zn12O12 nanoclusters for detecting methadone, a critical analyte in various medical and law enforcement applications. Employing density functional theory (DFT) calculations at the B3LYP-D level with the 6-311G (d, p) basis set, we have elucidated the interactions between these nanoclusters and methadone. The results reveal that methadone exhibits intense adsorption energies of -41.02, -39.79, and -59.77 kcal/mol on the pristine Zn12O12, GaZn11O12, and AlZn11O12 nanoclusters, respectively, in their most stable configurations. The doped nanoclusters, GaZn11O12 and AlZn11O12, displayed significant gap energies (Eg) changes upon methadone adsorption, indicating enhanced sensitivity towards this analyte. The UV-Vis spectroscopic analysis showed that methadone adsorption on the GaZn11O12 and AlZn11O12 nanoclusters led to distinct spectral shifts and oscillator strength variations compared to the Zn12O12 nanocluster. The transition theory calculations highlighted the GaZn11O12 nanocluster's short recovery time of 0.44 seconds, a crucial attribute for practical applications. Solvent effect studies demonstrated the stability of the methadone/GaZn11O12 complex in water and revealed its heightened polarization, as evidenced by the increased dipole moment. These findings suggest that the GaZn11O12 nanocluster is a promising candidate for detecting methadone in gas and liquid phases, with favorable attributes such as high sensitivity, rapid reversibility, and stability in gas and aqueous environments. Thus, this nanocluster can be used in sensor devices.

Effects of van der Waals interactions on the dipole moment and adsorption energy of H2O on Au(100) and Cu(100) surfaces: Density functional theory study

Effects of van der Waals interactions on the dipole moment and adsorption energy of H2O on Au(100) and Cu(100) surfaces: Density functional theory study

Tailoring the interaction between metal atoms and two-dimensional materials through surface functionalization

In this study, we employed density functional theory (DFT) to assess the potential of H, F, and O decoration on two-dimensional (2D) materials for modulating the interaction between metal atoms and the 2D substrates. The 2D substrate materials investigated include graphene, black phosphorus, MoS2, and InSe, while the metal atoms considered are Li, Ca, Ti, and Au. The results show that the adsorption energy of 2D materials with metals increases significantly after being functionalized with H, F and O. Furthermore, we observed an enhanced rate of charge transfer and the ability to adjust the diffusion barrier. The decoration with H, F, and O facilitates the stable anchoring of metal atoms on the substrates. This study proposes a practical approach to solving the problem of metal atoms clustering on the surface of 2D materials in the fields of single atom catalysis and hydrogen storage, where the dispersion of metal atoms on the substrate surface is essential.

On the potential of Zn@B38 superatom as a drug delivery vehicle for several anticancer drugs: A DFT study

The interaction between a boron-based Zn@B38 superatom and five drugs, including cisplatin (DDP), 5-fluorouracil (FU), mercaptopurine (MP), hydroxyurea (HU) and nitrogen mustard (CM) have been investigated. The adsorption of these anticancer drugs onto Zn@B38 reduces the energy gap of this superatom. Except for DDP, these drugs exhibit strong covalent interaction with the vertex of Zn@B38 because the lone pair of N/O atom of FU, MP, HU, and CM can fill into the empty atomic orbital of the electron-deficient boron atom of Zn@B38 to form polar covalent bonds, resulting in the charge transfer from drugs to Zn@B38. Hence, the adsorption energies of drug@[Zn@B38] (drug = FU, MP, HU, and CM) are −37.67 ∼ −57.21 kcal/mol, but can be significantly decreased to −8.63 ∼ 5.48 kcal/mol upon protonation, suggesting that these drugs can be efficiently adsorbed by the Zn@B38 carrier in neutral aqueous solution but are easily released in the acidic tumor microenvironment.

DFT Study of the ORR Catalytic Activity of As-Doped and As-N Co-Doped Graphene Substrates.

This study employs first-principles methods to investigate the ORR catalytic activity of As-doped and AsN co-doped graphene. As atoms, as catalytic active sites, exhibit excellent catalytic activity. Due to the strong interaction between As and N, the stability of the As-N co-doped substrate is enhanced. In particular, As-N4 co-doped graphene not only demonstrates the best thermodynamic and kinetic stability, but also has an ORR overpotential of only 0.53 V. We also propose a method to predict the Gibbs free energy change of the system by calculating the adsorption energies of the adsorbates. This approach can streamline the process by eliminating the need to calculate the Gibbs free energy of the ORR system, making it highly advantageous for future studies on the ORR catalytic activity of multi-impurity co-doped graphene.

The Negative Role of Proton Insertion on the Lifetime of Vanadium-Based Aqueous Zinc Batteries.

Vanadium oxides are attracted cathodes for aqueous zinc batteries owing to their high capacity. However, the limited cyclability of vanadium-based oxide cathodes, especially at low current densities, impedes their practical application. Here, it is revealed that proton insertion is responsible for the limited lifetime of vanadium oxides. Proton insertion promotes the dissolution of vanadium oxides, deteriorating electrochemical performance. Propylene carbonate (PC) is introduced into Zn(CF3SO3)2 electrolyte to regulate the coordination environment of water, forming PC-coordinated Zn2+ solvation structure and [H2O-CF3SO3 --PC] complex. The optimized coordination environment of water weakens the adsorption energy between water molecules and vanadium oxides, inhibiting proton insertion. As a result, vanadium-based oxides cathode without proton insertion can maintain the stability of crystal structure and avoid the dissolution of V. Taking CaV8O20·nH2O as cathode, Zn||CaV8O20·nH2O battery without proton insertion performs enhanced cycling performance. This work not only reveals the negative effect of proton insertion on the lifetime of vanadium-based oxides cathode but also provides an effective strategy to modulate proton insertion.

Anti-icing properties of polar bear fur.

The polar bear (Ursus maritimus) is the only Arctic land mammal that dives into water to hunt. Despite thermal insulation provided by blubber and fur layers and low Arctic temperatures, their fur is typically observed to be free of ice. This study investigates the anti-icing properties of polar bear fur. Here, we show that polar bear fur exhibits low ice adhesion strengths comparable to fluorocarbon-coated fibers, with the low ice adhesion a consequence of the fur sebum (hair grease). Lipid analyses reveal the presence of cholesterol, diacylglycerols, anteisomethyl-branched fatty acids, and the unexpected absence of squalene. Quantum chemical calculations predict low ice adsorption energies for identified lipids and high adsorption for squalene, suggesting that sebum composition is responsible for the observed anti-icing properties. Our work enhances understanding of polar bears and their interactions with their environment and builds on Inuit knowledge of natural anti-icing materials.

Synergistic Catalysis in Fe─In Diatomic Sites Anchored on Nitrogen-Doped Carbon for Enhanced CO2 Electroreduction.

Diatomic catalysts are promising for the electrochemical CO2 reduction reaction (CO2RR) due to their maximum atom utilization and the presence of multiple active sites. However, the atomic-scale design of diatomic catalysts and the elucidation of synergistic catalytic mechanisms between multiple active centers remain challenging. In this study, heteronuclear Fe─In diatomic sites anchored on nitrogen-doped carbon (FeIn DA/NC) are constructed. The FeIn DA/NC electrocatalyst achieves a CO Faradaic efficiency exceeding 90% across a wide range of applied potentials from -0.4 to -0.7V, with a peak efficiency of 99.1% at -0.5V versus the reversible hydrogen electrode. In situ, attenuated total reflection surface-enhanced infrared absorption spectroscopy and density functional theory calculations reveal that the synergistic interaction between Fe and In diatomic sites induce an asymmetric charge distribution, which promote the adsorption of CO2 at the Fe site and lowered the energy barrier for the formation of *COOH. Moreover, the unique Fe─In diatomic site structure increase the adsorption energy of *OH through a bridging interaction, which decrease the energy barrier for water dissociation and further promoted CO2RR activity.

Highly Reversible Aqueous Zinc-Ion Batteries via Multifunctional Hydrogen-Bond-Rich Dulcitol at Lower Temperature.

Aqueous zinc-ion batteries (AZIBs) are consideredoneofthemost promising next-generation energy storage devices due tocost-effectiveness and high safety. However, the uncontrolled dendrite growthandthe intolerance against low temperatures hinder the application of AZIBs. Herein, hydrogen-bonding-rich dulcitol (DOL) is introduced into the ZnSO4, which reshaped the hydrogen-bond network in the electrolyte and optimized the solvation sheath structure, effectively reducing the amount of active water molecules and inhibiting hydrogen evolution and the parasitic reaction at the zinc anode. In addition, higher adsorption energy DOL preferentially adsorbs on the surface of the zinc anode, guiding the uniform deposition of Zn2+ and inhibiting the formation of dendrites. DOL also enhances the interaction between free and free water and improves the resistance to freeze of the electrolyte. Consequently, the Zn//Zn symmetric cells assembled with DOL are extremely stable cycled for 2000h at 2mA cm-2. The NH4V4O10 (NVO)//Zn full cell showed more excellent specific capacity of 183.07 mAh g-1 after 800 cycles. Even at the low temperature of -10 °C, the cell still maintains 155.95 mAh g-1 capacity after 600 cycles. This work provides a new strategy for the subsequent study of AZIBs with high stability at low temperatures.

Theoretical Study on Adsorption of Halogenated Benzenes on Montmorillonites Modified With M(I)/M(II) Cations.

Halogenated benzenes (HBs) are hydrophobic organic chemicals belonging to persistent organic pollutants. Owing to their persistence, they represent a serious problem in environmental contamination, specifically of soils and sediments. One of the most important physical processes determining the fate of HBs in soils is adsorption to main soil components such as soil organic matter and soil minerals. Smectites, layered clay minerals of the 2:1 type, are common minerals in clay-rich soils, of which montmorillonite (Mt) is a typical representative. This work focuses on a systematic modeling study of the adsorption mechanism of selected HBs interacting with the basal (001) surface, which is the dominant surface of Mt particles. The HB···Mt interactions were studied by means of a quantum chemical approach based on the density functional theory method. HBs were represented by five molecules, particularly C6F6, C6Cl3F3, C6Cl6, C6Br3Cl3, and C6Br6. In mixed HBs (C6Cl3F3 and C6Br3Cl3) Cl atoms are in 1,3,5 or rather 2,4,6 positions. The effect of a different cation type on adsorption was investigated for M+/M2+-Mt models with cations from alkali group (M+: Li, K, Na, Rb, Cs) and alkaline earth metal group (M2+: Mg, Ca, Sr., Ba). The calculations were also performed on the gas phase HB···M+/M2+ complexes for comparison. Adsorption energies and distances of the main HB molecular plane from the Mt surface were calculated as a measure of the adsorption strength. The results showed that the strongest HB adsorption is for the Na+-Mt and Ca2+-Mt surfaces. The strongest affinity was observed for hexabromobenzene, while the weakest adsorption was found for hexafluorobenzene. The decomposition of the adsorption energy showed that its dominant component is dispersion energy and less important is the cation-π interaction. The calculated adsorption energies showed a good correlation with experimentally determined log Kd values.