Enabling Multi-Chemisorption Sites on Carbon Nanofibers Cathodes by an In-situ Exfoliation Strategy for High-Performance Zn–Ion Hybrid Capacitors

Carbon nanofibers films are typical flexible electrode in the field of energy storage,but their application in Zinc-ion hybrid capacitors(ZIHCs)is limited by the low energy density due to the lack of active adsorption sites.In this work,an in-situ exfoliation strategy is reported to modulate the chemisorption sites of carbon nanofibers by high pyridine/pyrrole nitrogen doping and carbonyl functionalization.The experimental results and theoretical calculations indicate that the highly electronegative pyridine/pyrrole nitrogen dopants can not only greatly reduce the binding energy between carbonyl group and Z n2+by inducing charge delocalization of the carbonyl group,but also promote the adsorption of Zn2+by bonding with the carbonyl group to form N–Zn–O bond.Benefit from the multiple highly active chemisorption sites generated by the synergy between carbonyl groups and pyridine/pyrrole nitrogen atoms,the resulting carbon nanofibers film cathode displays a high energy density,an ultralong-term lifespan,and excellent capacity reservation under commercial mass loading(14.45 mg cm-2).Particularly,the cathodes can also operate stably in flexible or quasi-solid devices,indicating its application potential in flexible electronic products.This work established a universal method to solve the bottleneck problem of insufficient active adsorption sites of carbon-based ZIHCs.Imoproved should be changed into Improved.

Study on Chemisorption and Desorption of Hydrogen and Nitrogen on Ru-based Ammonia Synthesis Catalyst

The effects of promoters K, Ba, Sm on the chemisorption and desorption of hydrogen and nitrogen, dispersion of metallic Ru. and catalytic activity of active carbon (AC) supported ruthenium catalyst for ammonia synthesis have been studied by means of pulse chromatography, temperature-programmed desorption, and activity test. Promoters K, Ba and Sm increased the activity of Ru/AC catalysts for ammonia synthesis significantly, and particularly, potassium exhibited the best promotion on the activity because of the strong electronic donation to metallic Ru. Much higher activity can be obtained for Ru/AC catalyst with binary or triple promoters. The activity of Ru/AC catalyst is dependent on the adsorption of hydrogen and nitrogen. The high activity of catalyst could be ascribed to strong dissociation of nitrogen on the catalyst surface. Strong adsorption of hydrogen would inhibit the adsorption of nitrogen, resulted in decrease of the catalytic activity. Ru/AC catalyst promoted by Sm2O3 shows the best dispersion of metallic Ru, since the partly reduced SmOx on the surface modifies the morphology of active sites and favors the dispersion of metallic Ru. The activity of Ru/AC catalysts is in accordance to the corresponding amount of nitrogen chemisorption and the desorption activation energy of nitrogen. The desorption activation energy for nitrogen decreases in the order of Ru>Ru-Ba>Ru-Sm>Ru-Ba-Sm>Ru-K>Ru-K-Sm>Ru-K-Ba>Ru-K-Ba-Sm, just opposite to the order of catalytic activity, suggesting that the ammonia synthesis over Ru-based catalyst is controlled by the step of dissociation of nitrogen.

Research of the behaviour of O chemisorption on the （110） surface of Rhx-Pt1-x alloy

An atomic group model of the disordered binary alloy Rhx-Pt1-x has been constructed to investigate surface segregation. According to the model, we have calculated the electronic structure of the Rhx-Pt1-x alloy surface by using the recursion method when O atoms are adsorbed on the Rhx-Pt1-x （110） surface under the condition of coverage 0.5. The calculation results indicate that the chemical adsorption of O changes greatly the density of states near the Fermi level, and the surface segregation exhibits a reversal behaviour. In addition, when x 〈 0.3, the surface on which O is adsorbed displays the property of Pt; whereas when x 〉 0.3 it displays the property of Rh.

Decorating ketjen black with ultra-small Mo_(2)C nanoparticles to enhance polysulfides chemisorption and redox kinetics for lithium-sulfur batteries

The low sulfur utilization and fast capacity fading resulting from the sluggish redox reaction and abominable polysulfides shuttle greatly hinder the practical applications of lithium-sulfur(Li-S) batteries.Herein, we develop a facile "in-situ growth" method to decorate ultra-small Mo2 C nanoparticles(USMo2 C) on the surface of Ketjen Black(KB) to functionalize the commercial polypropylene(PP) separators,which can accelerate the redox kinetics of lithium polysulfides conversion and effectively increase the utilization of sulfur for Li-S batteries. Importantly, the US-Mo2 C nanoparticles have abundant sites for chemical adsorption towards polysulfides and the conductive carbon networks of KB have cross-linked pore channels, which can promote electron transport and provide physical barrier and volume expansion space for polysulfides. Due to the combined effects of the US-Mo2 C and KB, Li-S cells employing the multifunctional PP separators modified with KB/US-Mo2 C composite(KB/US-Mo2 C@PP) exhibit a high specific capacity(1212.8 mAh g^(-1) at 0.2 C), and maintain a reversible capacity of 1053.3 m Ah g^(-1) after 100 cycles.More importantly, the KB/US-Mo2 C@PP cells with higher sulfur mass loading of 4.9 mg cm^(-2) have superb areal capacity of 2.3 mAh cm^(-2). This work offers a novel and promising perspective for high-performance Li-S batteries from both the shuttle effect and the complex polysulfides conversion.

Tuning the reversible chemisorption of hydroxyl ions to promote the electrocatalysis on ultrathin metal-organic framework nanosheets

Interfacial engineering to alter the configuration of active sites in heterogeneous catalysts is a potential strategy for activity enhancement,but it remains unelucidated for metal-organic frameworks(MOFs).Here,we demonstrate that the surface of two-dimensional Co-based MOF is modified by decorating Ag quantum dots(QDs)simply through in-situ reduction of Ag+ions.Toward oxygen evolution reaction(OER),it reveals that the catalysis is mediated by the reversible redox of Co sites between Co^(3+) and Co^(4+) states coupling with transfer of OHions.The decoration of Ag QDs decreases the redox potential of Co sites,and thus effectively decreases the overpotential of OER.The TOFs of Co sites are increased by 77 times to reach 5.4 s^(-1) at an overpotential of 0.35 V.We attribute the activity enhancement to the tuning of the coupling process between Co sites and OHions during the redox of Co sites by Ag QDs decoration based on Pourbaix analysis.

O2, CO2, and H2O Chemisorption on UN（001） Surface： Density Functional Theory Study

We performed density functional theory calculations of O2, CO2, and H2O chemisorption on the UN（001） surface using the generalized gradient approximation and PW91 exchangecorrelation functional at non-spin polarized level with the periodic slab model. Chemisorption energies vs. molecular distance from UN（001） surface were optimized for four symmetrical chemisorption sites. The results showed that the bridge parallel, hollow parallel and bridge hydrogen-up adsorption sites were the most stable site for O2, CO2, and H2O molecular with chemisorption energies of 14.48, 4.492, and 5.85 kJ/mol, respectively. From the point of adsorbent （the UN（001） surface）, interaction of O2 with the UN（001） surface was of the maximum magnitude, then CO2 and H2O, indicating that these interactions were associated with structures of the adsorbate. O2 chemisorption caused N atoms on the surface to migrate into the bulk, however CO2 and H2O had a moderate and negligible effect on the surface, respectively. Calculated electronic density of states demonstrated the electronic charge transfer between s, p orbital in chemisorption molecular and U6d, U5f orbital.

A Density Functional Theory Study of Methoxy and Atomic Hydrogen Chemisorption on Au(100) Surface

The adsorption of CH3O and H on the (100) facet of gold was studied using self-consistent periodic density functional theory (DFT-GGA) calculations. The best binding site, energy, and structural parameter, as well as the local density of states, of each species were determined. CH3O is predicted to strongly adsorb on the bridge and hollow sites, with the bridge site as preferred one, with one of the hydrogen atoms pointing toward a fourfold vacancy (bridge-H hollow). The top site was found to be unstable, the CH3O radical moving to the bridge –H top site during geometry optimization. Adsorption of H is unstable on the hollow site, the atom moving to the bridge site during geometry optimization. The 4-layer slab is predicted to be endothermic with respect to gaseous H2 and a clean Au surface.

Effects of Vibrational and Rotational Excitations on Dissociative Chemisorption Dynamics of N_(2) on Fe(111)

The dissociative chemisorption of N_(2) is the rate-limiting step for ammonia synthesis in industry.Here,we investigated the role of initially vibrational excitation and ro-tational excitation of N_(2) for its reactivity on the Fe(111)surface,based on a recently developed six-dimensional potential energy surface.Six-dimensional quantum dynamics study was carried out to investi-gate the effect of vibrational excitation for incidence energy below 1.6 eV,due to sig-nificant quantum effects for this reaction.The effects of vibrational and rotational excitations at high incidence energies were revealed by quasiclassical trajectory calculations.We found that raising the translational energy can enhance the dissociation probability to some extent,however,the vibrational excitation or rotational excitation can promote disso-ciation more efficiently than the same amount of translational energy.This study provides valuable insight into the mode-specific dynamics of this heavy diatom-surface reaction.

Chemisorption and Physical Adsorption Roles in Cadmium Biosorption by Chlamydomonas Reinhardtii

The aim of this study was to investigate the mechanism of cadmium (Cd) adsorbed by microalgae Chlamydomonas reinhardtii (C.reinhardtii). The kinetic and adsorption isotherm of the process could be well described by mathematical models. Chemical modification experiments and Fourier transform infrared spectra indicated that carboxyl and amine groups were the important functional groups for adsorption of Cd. The maximum contribution of physical adsorption in the overall adsorption process was evaluated as 5.5%. These results indicated that chemisorption was the dominating mechanism of Cd biosorption by C.reinhardtii.

THEORETICAL STUDY OF MOLYBDENUM CHEMISORPTION ON Si(111) AND Si(100 ) SURFACES

The chemisorptions of Mo on both Si(111)and Si(100)surfaces are inves tiga ted by the DV-Xct-SCF met hod.The resul ts show that after overcoming a certain energy barrier the adsorbate Mo can penetrate the surface to form adamantine structure.The electronic states of chemisorption are calculated and compared with experimental results.

A MOLECULAR BEAM INVESTIGATION ON ACTIVATED CHEMISORPTION OF N_2 ON Ni SURFACE AND La FILM

The activated chemisorption of N2 on Ni （poly） and La film was performed on a molecular beam—surface scattering apparatus. Experimental results indicate that the initial sticking probability so increases linearly from 0 to 0.03 as normal component of translational energy of the molecuar beam En increases from 11.00 to 19.91 kcal/mol for N2/Ni system and S0 from 0 to 0. 10 as En from 10. 40 to 19.91 kcal/mol for N2/La system. The apparent activation energy △E are 6.16 kcal/mol and 5.30 kcal/mol for N2/Ni and N2/La systems respectively.

A QUANTUM CHEMISTRY STUDY ON THE SIZE-DEPENDENCE OF THE CHEMISORPTION OF AMMONIA AND CARBON MONOXIDE ON ALUMINUM CLUSTERS

The chemisorption intensities of NH_3 and CO on aluminum clusters A1_n(n=l-13) have been theoretically predicted by using CNDO/2 method and properly selecting the clusters' geometries.The results show that the chemisorptions of NH_3 and GO on Al_2,Al_6 and Al_12 are magically stable and thus are in good agreement with the experimental results.In addition,an electronic structure analysis is made to expound the nature of such a size effect.

Elucidating the Chemisorption Phenomena in SERS Studies via Computational Modeling

Colloidal gold solutions with nanostars and nanospheres as well as KlariteTM gold and gold-copper bimetallic substrates were used for SERS analysis of aniline and nitroaniline isomers to investigate their chemisorption phenomena. Computational modeling based on Density Functional Theory (DFT) was used in conjunction with the SERS analysis to study the adsorption behaviors of the analytes on metal surfaces. Gold nanospheres and KlariteTM samples produced about a 10-fold increase in signal enhancement compared to gold nanostars for the SERS analysis of aniline, nitroaniline isomers, and nitrobenzene. Signal enhancement is significantly greater for aniline compared to nitrobenzene and it is dependent on the proximity of the NH2 to the NO2 group for the nitroaniline isomers. Charge-transfer in chemisorbed analytes is an important contributing factor for SERS signal. The relative strengths of enhancement can be predicted by the DFT calculation of the HOMO-LUMO energy gaps of the analyte-metal cluster. Aniline and the three nitroaniline isomers showed stronger preference for the copper substrates if both the gold and copper substrates are present. The NO2 group in 2-nitroaniline has a very strong preference and affinity for the copper in the Au-Cu bimetallic cluster.

The Ab Initio Studies of NO Chemisorption on TiO_2(110) Surface

The studies of NO chemisorption on TiO2(110) surface are the base of research to NO decomposed to N2O on TiO2 surface. In this paper, 12 kinds of possible models of NO adsorbed on TiO2 perfect and defect surface were calculated by use of ab initio cluster method. We carried out optimization of the geometry, calculation of the chemisorption energy and analysis of the Mulliken population to those adsorption models. According to the calculation results, it can be got that the adsorbed decomposition of NO on defect surface is more advantageous and M6 and M12 are the important models to NO chemisorption and decomposition on TiO2 surface.

Lead chemisorption:Paving the last step for industrial perovskite solar cells

Perovskite solar cells(PSCs)have exhibited impressive performance,achieving a power conversion efficiency(PCE)of 26.1%.However,the water-soluble and toxic nature of lead(Pb)in PSCs hinders their industrialization.Pb chemisorption has emerged as a promising approach to address this issue to prevent Pb leakage and ensure long-term stability.This perspective provides a comprehensive overview of recent advancements in Pb chemisorption in PSCs and discusses the prospects for future developments and challenges in this field.

Challenges in hydrogen adsorptions： from physisorption to chemisorption

In this short review, we will briefly discuss the story of hydrogen storage, its impact on clean energy application, especially the challenges of using hydrogen adsorption for onboard application. After a short comparison of the main methods of hydrogen storage （high pressure tank, metal hydride and adsorption）, we will focus our discussion on adsorption of hydrogen in graphitie carbon based large surface area adsorbents including carbon nanotubes, graphene and metal organic frameworks. The mechanisms, advantages, disadvantages and recent progresses will be discussed and reviewed for physisorption, metal-assisted storage and chemisorption. In the last section, we will discuss hydrogen spillover chemisorption in detail for the mechanism, status, challenges and perspectives. We hope to present a clear picture of the present technologies, challenges and the perspectives of hydrogen storage for the future studies.

Chemisorption solid materials for hydrogen storage near ambient temperature:A review

Solid chemisorption technologies for hydrogen storage,especially high-efficiency hydrogen storage of fuel cells in near ambient temperature zone defined from−20 to 100℃,have a great application potential for realizing the global goal of carbon dioxide emission reduction and vision of carbon neutrality.However,there are several challenges to be solved at near ambient temperature,i.e.,unclear hydrogen storage mechanism,low sorption capacity,poor sorption kinetics,and complicated synthetic procedures.In this review,the characteristics and modification methods of chemisorption hydrogen storage materials at near ambient temperature are discussed.The interaction between hydrogen and materials is analyzed,including the microscopic,thermodynamic,and mechanical properties.Based on the classification of hydrogen storage metals,the operation temperature zone and temperature shifting methods are discussed.A series of modification and reprocessing methods are summarized,including preparation,synthesis,simulation,and experimental analysis.Finally,perspectives on advanced solid chemisorption materials promising for efficient and scalable hydrogen storage systems are provided.

Water on silicene： A hydrogen bond-autocatalyzed physisorption-chemisorption-dissociation transition

A single water molecule is nothing special. However, macroscopic water displays many anomalous properties at interfaces, such as hydrophobicity and hydrophilicity. Although the underlying mechanisms remain elusive, hydrogen bonds between water molecules are expected to play a major role in these interesting phenomena. An important question concerns whether water clusters containing few molecules are qualitatively different from a single molecule. Using the water adsorption behavior as an example and by carefully choosing two-dimensional silicene as the substrate material, we demonstrate that water monomers, dimers, and trimers show distinct adsorption properties at the substrate surface. On silicene, the additional water molecules in dimers and trimers induce a transition from physisorption to chemisorption and then to dissociation, arising from the enhancement of charge transfer and proton transfer processes induced by hydrogen bonding. Such a hydrogen bond autocatalytic effect is expected to have broad applications in metal-free catalysis for the oxygen reduction reaction and water dissociation.

Dissociative chemisorption dynamics of small molecules on metal surfaces

Much progress has been achieved for both experimental and theoretical studies on the dissociative chemisorption of molecules on surfaces.Quantum state-resolved experimental data has provided unprecedented details for these fundamental steps in heterogeneous catalysis,while the quantitative dynamics is still not fully understood in theory.An in-depth understanding of experimental observations relies on accurate dynamical calculations,in which the potential energy surface and adequate quantum mechanical implementation are desired.This article summarizes the current methodologies on the construction of potential energy surfaces and the quantum mechanical treatments,some of which are promising for future applications.The challenges in this field are also addressed.

Electronic structure factors and the importance of adsorbate effects in chemisorption on surface alloys

The chemisorption energy is an integral aspect of surface chemistry,central to numerous fields such as catalysis,corrosion,and nanotechnology.Electronic-structure-based methods such as the Newns-Anderson model are therefore of great importance in guiding the engineering of material surfaces with optimal properties.However,existing methods are inadequate for interpreting complex,multi-metallic systems.Herein,we introduce a physics-based chemisorption model for alloyed transition metal surfaces employing primarily metal d-band properties that accounts for perturbations in both the substrate and adsorbate electronic states upon interaction.Importantly,we show that adsorbate-induced changes in the adsorption site interact with its chemical environment leading to a second-order response in chemisorption energy with the d-filling of the neighboring atoms.We demonstrate the robustness of the model on a wide range of transition metal alloys with O,N,CH,and Li adsorbates yielding a mean absolute error of 0.13 eV versus density functional theory reference chemisorption energies.