Revealing the correlation between adsorption energy and activation energy to predict the catalytic activity of metal oxides for HMX using DFT

Traditional selection of combustion catalysis is time-consuming and labor-intensive.Theoretical calculation is expected to resolve this problem.The adsorption energy of HMX and O atoms on 13 metal oxides was calculated using DMol3,since HMX and O are key substances in decomposition process.And the relationship between the adsorption energy of HMX,O on metal oxides(TiO_(2),Al_(2)O_(3),PbO,CuO,Fe_(2)O_(3),Co_(3)O_(4),Bi_(2)O_(3),NiO)and experimental T30 values(time required for the decomposition depth of HMX to reach 30%)was depicted as volcano plot.Thus,the T30 values of other metal oxides was predicted based on their adsorption energy on volcano plot and validated by previous experimental data.Further,the adsorption energy of HMX on ZrO_(2)and MnO_(2)was predicted based on the linear relationship between surface energy and adsorption energy,and T30 values were estimated based on volcano plot.The apparent activation energy data of HMX/MgO,HMX/SnO_(2),HMX/ZrO_(2),and HMX/MnO_(2)obtained from DSC experiments are basically consistent with our predicted T30 values,indicating that it is feasible to predict the catalytic activity based on the adsorption calculation,and it is expected that these simple structural properties can predict adsorption energy to reduce the large quantities of computation and experiment cost.

Oxygen‑Defect Enhanced Anion Adsorption Energy Toward Super‑Rate and Durable Cathode for Ni–Zn Batteries

The alkaline zinc-based batteries with high energy density are becoming a research hotspot.However,the poor cycle stability and low-rate performance limit their wide application.Herein,ultra-thin CoNiO2 nanosheet with rich oxygen defects anchored on the vertically arranged Ni nanotube arrays(Od-CNO@Ni NTs)is used as a positive material for rechargeable alkaline Ni–Zn batteries.As the highly uniform Ni nanotube arrays provide a fast electron/ion transport path and abundant active sites,the Od-CNO@Ni NTs electrode delivers excellent capacity(432.7 mAh g^(−1))and rate capability(218.3 mAh g^(−1) at 60 A g^(−1)).Moreover,our Od-CNO@Ni NTs//Zn battery is capable of an ultra-long lifespan(93.0%of initial capacity after 5000 cycles),extremely high energy density of 547.5 Wh kg^(−1) and power density of 92.9 kW kg^(−1)(based on the mass of cathode active substance).Meanwhile,the theoretical calculations reveal that the oxygen defects can enhance the interaction between electrode surface and electrolyte ions,contributing to higher capacity.This work opens a reasonable idea for the development of ultra-durable,ultra-fast,and high-energy Ni–Zn battery.

Regulated adsorption-diffusion and enhanced charge transfer in expanded graphite cohered with N,B bridge-doping carbon patches to boost K-ion storage

The great challenges are remained in constructing graphite-based anode with well built-in structures to accelerate kinetics and enhance stability in the advanced K-ion batteries(KIBs).Here,we firstly report the design of expanded graphite cohered by N,B bridge-doping carbon patches(NBEG)for efficient K-ion adsorption/diffusion and long-term durability.It is the B co-doping that plays a crucial role in maximizing doping-site utilization of N atoms,balancing the adsorption-diffusion kinetics,and promoting the charge transfer between NBEG and K ions.Especially,the robust lamellar structure,suitable interlayer distance,and rich active sites of the designed NBEG favor the rapid ion/electron transfer pathways and high K-ion storage capacity.Consequently,even at a low N,B doping concentration(4.36 at%,2.07 at%),NBEG anode shows prominent electrochemical performance for KIBs,surpassing most of the advanced carbon-based anodes.Kinetic studies,density functional theory simulations,and in-situ Raman spectroscopy are further performed to reveal the K-ion storage mechanism and confirm the critical actions of co-doping B.This work offers the new methods for graphite-electrode design and the deeper insights into their energy storage mechanisms in KIBs.

Water adsorption on the Be(0001) surface:from monomer to trimer adsorption

In this paper, the density functional theory has been used to perform a comparative theoretical study of water monomer, dimer, trimer, and bilayer adsorptions on the Be（0001） surface. In our calculations, the adsorbed water molecules are energetically favoured adsorbed on the atop sites, and the dimer adsorption is found to be the most stable with a peak adsorption energy of - 437 meV. Further analyses have revealed that the essential bonding interaction between the water monomer and the metal substrate is the hybridization of the water 3al-like molecular orbital with the （s, P2） orbitals of the surface beryllium atoms. While in the case of the water dimer adsorption, the lbz-like orbital of the H2O molecule plays a dominant role.

Density Functional Theory Study of Oxygen Atom Adsorption on Different Surfaces of Pyrite

We discussed the oxidation differential and mechanisms on different planes of pyrite. The experimental results show that the oxidation priority is：（222） plane〉（200） plane〉（200） plane, and there is no direct correlation between the crystal plane index, the atom numbers, and the oxidation priority. However, with more exchanged charge among atoms, the oxidation could be conducted more easily, and the distribution rule of the electric charge conforms with the variation trend of adsorption energy, which will provide more overall cognition on the oxidation mechanism of pyrite from the atomic scale.

First-principles study of co-adsorption behavior of O_(2)and CO_(2)molecules onδ-Pu(100)surface

First principles calculation is performed to study the co-adsorption behaviors of O_(2)and CO_(2)onδ-Pu(100)surface by using a slab model within the framework of density functional theory(DFT).The results demonstrate that the most favorable co-adsorption configurations are T_(v)-C_(4)O_(7)and T_(p1)-C_(2)O_(8),with adsorption energy of-17.296 e V and-23.131 e V for CO_(2)-based and O_(2)-based system,respectively.The C and O atoms mainly interact with the Pu surface atoms.Furthermore,the chemical bonding between C/O and Pu atom is mainly of ionic state,and the reaction mechanism is that C 2 s,C 2 p,O 2s,and O 2p orbitals overlap and hybridize with Pu 6 p,Pu 6 d,and Pu 5 f orbital,resulting in the occurrence of new band structure.The adsorption and dissociation of CO_(2)molecule are obviously promoted by preferentially occupying adsorbed O atoms,therefore,a potential CO_(2)protection mechanism for plutonium-based materials is that in CO_(2)molecule there occurs complete dissociation of CO_(2)→C+O+O,then the dissociated C atom combines with O atom from O_(2)dissociation and produces CO,which will inhibit the O_(2)from further oxidizing Pu surface,and slow down the corrosion rate of plutoniumbased materials.

Comparative study of adsorption characteristics of Cs on the GaN(0001) and GaN(000) surfaces

The adsorption characteristics of Cs on GaN （0001） and GaN （0001） surfaces with a coverage from 1/4 to 1 monolayer have been investigated using the density functional theory with a plane-wave uttrasoft pseudopotential method based on first-principles calculations. The results show that the most stable position of the Cs adatom on the GaN （0001） surface is at the N-bridge site for 1/4 monolayer coverage. As the coverage of Cs atoms at the N-bridge site is increased, the adsorption energy reduces. As the Cs atoms achieve saturation, the adsorption is no longer stable when the coverage is 3/4 monolayer. The work function achieves its minimum value when the Cs adatom coverage is 2/4 monolayer, and then rises with Cs atomic coverage. The most stable position of Cs adatoms on the GaN （000i） surface is at H3 site for 1/4 monolayer coverage. As the Cs atomic coverage at H3 site is increased, the adsorption energy reduces, and the adsorption is still stable when the Cs adatom coverage is 1 monolayer. The work function reduces persistently, and does not rise with the increase of Cs coverage.

Adsorption of Synthesized Pyridinyl-pyrazolecarbox Amide Derivatives as Anti-fungal on the Surface of Ge-nanotube(6,6)

The anti-fungal activities of synthesized pyridinyl-pyrazole-carbox amide derivatives 1a^1c were investigated via theoretical parameters. The obtained results in present paper were compared with the reported experimental results. Experimental results show that derivative 1a has the highest and derivative 1c the lowest anti-fungal activity. The interactions of derivatives 1a^1c with Ge-nanotube（6, 6） were investigated, and also quantum molecular descriptors of derivatives 1a^1c were calculated. Results show that, derivatives 1a^1c can interact with Ge-nanotube（6, 6） effectively, and their adsorptions were exothermic and possible from the theoretical viewpoint. The absolute ΔEad and ΔGad values of derivative 1a on Ge-nanotube（6, 6） were higher than the absolute ΔEad and ΔGad values of 1 b and 1c. Derivative 1a has the highest absolute μ, ω and ΔN values. The theoretical and experimental trends of anti-fungal activity of derivatives 1a^1c were similar, successfully.

Density Functional Theory Study of C_2H_x(x=4～6) Adsorption on the Fe(110) Surface

The density functional theory（DFT） and self-consistent periodic calculation were used to investigate the C2Hx（x = 4～6） species adsorption on the Fe（110） surface. The adsorption energy and equilibrium geometry of the species C2Hx（x = 4～6） on four possible sites（top,hcp,SB and LB） on the Fe（110） surface were predicted and compared. Mulliken charges and density of states analysis of the most stable site have been discussed. It is found that the species of C2H6 and C2H5 are adsorbed strongly on the Fe（110） surface with calculated adsorption energy of -80.24 and -178.89 kJ·mol^-1 at the Fe-LB（long-bridge） ,respectively. However,the C2H4 is adsorbed strongly on the Fe（110） surface with calculated adsorption energies of -114.96 kJ·mol^-1 at the top. The results indicate that the charge transferring process can be completed by chemisorption between Fe（110） surface and the species. Moreover,the chemical bands can be formed by chemisorptions between the Fe（110） surface and the species,too.

Dual-conductive metal-organic framework@MXene heterogeneity stabilizes lithium-ion storage

Although a few pristine metal-organic frameworks(MOFs) of graphene analogue topology exhibit high intrinsic electrical conductivity, their use in lithium-ion batteries(LIBs) is still hampered by unfavorable Li+adsorption energy(ΔEa). In this paper, an electroconductive ferrocene-based MOF@MXene heterostructure is built to provide stable anodes for Li+storage. Charge density difference and planar average potential charge density show substantial redistribution of charges at the interfaces, transferring from MXene to MOF layers. Moreover, density functional theory(DFT) calculations reveal that the interaction between MXene and MOF significantly increases the ΔEa. As a result, the heterostructure anode exhibits high capacities and outstanding cycling stability with a capacity retention of 80% after 5000 cycles at 5 A g^(-1), outperforming mono-component MXene and MOF. Furthermore, the heterostructure anode is built into a full cell with a commercial NCM 532 cathode, delivering a high energy density of 611 Wh kg^(-1)and power density of 7600 W kg^(-1). The developed conductive MOF@MXene heterogeneity for improved LIB offers valuable insights into the design of advanced electrode materials for energy storage.

Density-functional study of CO adsorbed on Rh_N (N=2-19) clusters

We investigate the structural, electronic and adsorption properties of one single CO molecule adsorbed on RhN （N = 2-19） clusters, using the density-functional theory in the spin-polarized generalized gradient approximation. It is found that the structural growth model of the RhN clusters transforms from double layers （N = 12-16） to three layers （N ： 17-19）. Three different adsorption types are the atop site adsorption for N = 6, 8, 9, 11, 12, the bridge site adsorption for N ： 2-5, 7, 10, 13-15, 17 and the face adsorption for N = 16, 18, 19. The adsorption abilities of RhN clusters are related to C-O bond length, vibrational frequency, adsorption energy and the charge transfer between CO and Rh clusters as well as the electronic density of state. With the increase of Rh cluster size, the adsorption energy of CO adsorbed on RhN clusters tends to be 2.2 eV-2.3 eV, which is 0.2 eV-0.3 eV larger than the theoretical value （about 2.0 eV） of CO molecule adsorption on clean Rh （111） surface.

Density functional theory calculations of tetracene on low index surfaces of copper crystal

This paper carries out the density functional theory calculations to study the adsorbate-substrate interaction between tetracene and Cu substrates （Cu （110） and Cu （100） surface）. On each of the surfaces, two kinds of geometry are calculated, namely ＇flat-lying＇ mode and ＇upright standing＇ mode. For ＇flat-lying＇ geometry, the molecule is found to be aligned with its longer molecular axis along close-packed direction of the substrate surfaces. For ＇upright standing＇ geometry, the long axis of tetracene is found to be parallel to the surface normal of the substrate on Cu （110） surface. However, tetracene appears as ＇tilted＇ mode on Cu （100） surface. Structures with ＇flat-lying＇ mode have much larger adsorption energy and charge transfer upon adsorption than that with ＇upright standing＇ mode, indicating the preference of ＇flat-lying＇ geometry on both Cu （110） and Cu （100） surface.

DFT Investigations About Pyrazine Molecules on Si(100)-2×1 Surface

It is important to understand the interface of aromatic molecules on semiconductor surfaces because of the rich functionality of such molecules on semiconductor surfaces. The chemisorption of pyrazine molecules on the Si （100）- 2×1 surface has been investigated using the B3LYP density functional theory with Si9H12 one-dimer and Si15Hl6 two-dimer cluster models. The calculated results predict that N-dative bonded-state, C2=C5 [E4＋2] and the tight- bridgel,2,5,6 products may coexist on the Si（100）-2 × 1 surface.

Long-cycling lithium-oxygen batteries enabled by tailoring Li nucleation and deposition via lithiophilic oxygen vacancy in Vo-TiO_(2)/Ti_(3)C_(2)Tx composite anodes

Uncontrollable Li dendrite growth and infinite volume fluctuation during durative plating and stripping process gravely hinder the application of metallic Li electrode in lithium-oxygen batteries.Herein,oxygen vacancy-rich TiO_(2)(Vo-TiO_(2))nanoparticles(NPs)uniformly dispersing on Ti_(3)C_(2)T_(x)(Vo-TiO_(2)/Ti_(3)C_(2) T_(x))with excellent lithiophilicity feature are presented as effective composite anodes,on which a dense and uniform Li growth behavior is observed.Based on electrochemical studies,mutiphysics simulation and theoretical calculation,it is found that Vo-TiO_(2) coupling with three dimensional(3 D)conductive Ti_(3)C_(2) T_(x) MXene forms highly ordered lithiophilic sites which succeed in guiding Li ions flux and adsorption,thus modulating the uniform Li nucleation and growth.As a result,this composite electrode is capable of preserving Li with high areal capacity of~10 mAh cm^(-2) without the presence of dendrites and large volume expansion.Consequently,the as-prepared Vo-TiO_(2)/Ti_(3)C_(2) T_(x)@Li anode shows outstanding performance including low voltage hysteresis(~19 mV)and superior durability(over 750 h).When assembling with the Vo-TiO_(2)/Ti_(3)C_(2) T_(x)@Li anodes,lithium-oxygen batteries also deliver enhanced cycling stability and improved rate performance.This work demonstrates the effectiveness of oxygen vacancies in guiding Li nucleating and plating behavior at initial stage and brings a promising strategy for promoting the development of advanced Li metal-based batteries.

Na decorated B_6 cluster and its hydrogen storage properties

The structures and hydrogen storage properties of sodium atoms decorated B6 clusters are investigated by the B3LYP method with a 6-311＋G （d, p） basis set. For NamB6 （m = 1-3） clusters, Na atoms are always inclined to separate far enough from each other and not cluster together on a B6 cluster surface so that each Na atom has sufficient space to bind hydrogen molecules. The hydrogen storage gravimetric density of a two Na atoms decorated B6 cluster is 17.91 wt% with an adsorption energy per H2 molecule （AAE/H2） of 0.6851 kcal.mo1^-1. The appropriate AAE/H2 and preferable gravimetric density of the two Na atoms decorated B6 cluster complex indicate that it is feasible for hydrogen storage application in ambient conditions.

Beryllium carbide as diffusion barrier against Cu:First-principles study

Beryllium carbide is used in inertial confinement fusion(ICF)capsule ablation material due to its low atomic number,low opacity,and high melting point properties.We used the method of climbing image nudged elastic band(CINEB)to calculate the diffusion barrier of copper atom in the crystal of beryllium and beryllium carbide.The diffusion barrier of copper atom in crystal beryllium is only 0.79 eV,and the barrier in beryllium carbide is larger than 2.85 eV.The three structures of beryllium carbide:anti-fluorite Be2C,Be2C-Ⅰ,and Be2C-Ⅲhave a good blocking effect to the diffusion of copper atom.Among them,the Be2C-Ⅲstructure has the highest diffusion barrier of 6.09 eV.Our research can provide useful help for studying Cu diffusion barrier materials.

Studies on the Ability of Carbon Nanotube(5,5) as Drug Carrier and Anticancer Properties of Benzylthio-indolyl-triazol-amine Derivatives

The anticancer activities of synthesized benzylthio-indolyl-triazol-amine derivatives 1a^1c were investigated via theoretical scales. The experimental results show that derivative 1a has the highest anticancer activity, and 1c has the lowest one. The interactions of 1a^1c with C-nanotube（5,5） were investigated. Also the quantum molecular descriptors of derivatives 1a^1c were calculated and the results show that they can interact with C-nanotube（5,5） effectively. The adsorptions of 1a^1c on C-nanotube（5,5） surface were exothermic and experimentally possible from the energetic viewpoint. The results indicated that ΔEad and ΔGad values of derivative 1a on C-nanotube（5,5） were higher than those of the corresponding derivatives 1b and 1c, so 1a has the highest ｜μ｜, ω and ｜？N｜ values and the lowest value, and the trends of theoretical anticancer activities of 1a^1c are similar to the experimental values successfully.

Study on Lubricant Materials Transfer between Head and Disk

With the increase of hard disk storage density,the flying height of magnetic head sliders has become lower in recent years,which makes it easier for lubricant materials to transfer between the magnetic head and disk.The ability for lubricant materials to transfer is not only related to the operating conditions of disk but also related to the types of lubricant materials(Perfluoropolyether,PFPE)and diamond⁃like carbon(DLC)coating applied to the disk.Based on the principle of molecular dynamics,this study established the adsorption models on disks with different carbon content and the diffusion models of several common PFPE molecules in air.Besides,the adsorption energy and the diffusion coefficients of different models were calculated.Furthermore,the molecular weight,the molecular structure,the lubricant material􀆳s end functional groups,and the disk􀆳s carbon content were found to have influence on the transfer ability of lubricant materials.In particular,the latter two factors have further influence.

Hierarchical polypyrrole@cobalt sulfide-based flexible on-chip microsupercapacitors with ultrahigh energy density for selfcharging system

Herein,we prepare the unique hierarchical polypyrrole@cobalt sulfide(PPy-hs@CoS)hollow sphere-based nanofilms as interdigitated electrodes for flexible on-chip micro-supercapacitors(MSC).Benefiting from the excellent flexibility and high electrical conductivity of PPy-hs combined with the great electrochemical activity of CoS,such PPy-hs@CoS composite material can not only inhibit the volume expansion of PPy but also promote the diffusion of the electrolyte ions.The PPy-hs@CoS filmbased electrode delivers a greatly improved specific capacitance and small resistance.Density functional theory calculations infer that OH−prefers to bind to PPy on CoS@PPy and confirms the synergistic effect of each component for enhanced reaction kinetics.A quasi-solid-state on-chip flexible asymmetric MSC based on PPy-hs@CoS and activated carbon(AC)microelectrodes exhibits large areal-specific capacitance(131.9 mF/cm2 at 0.3 mA/cm2),ultrahigh energy density(0.041 mWh/cm2@0.224 mW/cm2 and 25.6 mWh/cm3@140.6 mW/cm3),and long cycle lifespan.We demonstrate the possibility to scale up the PPy-hs@CoS nanofilm microelectrode by arranging two of our asymmetric MSC in series and parallel connections,which respectively increase the output voltage and current.A self-charging system by connecting our asymmetric MSCs with a piece of commercial solar cells is developed as a potential possible mode for future highly durable and high-voltage integrated electronics.

Lifting surface reconstruction of Au(100)by tellurium adsorption

The Au(100)surface has been a subject of intense studies due to excellent catalytic activities and its model character for surface science.However,the spontaneous surface reconstruction buries active Au(100)plane and limits practical applications,how to controllably eliminate the surface reconstruction over large scale remains challenging.Here,we experimentally and theoretically demonstrate that simple decoration of the Au(100)surface by tellurium(Te)atoms can uniquely lift its reconstruction over large scale.Scanning tunneling microscopy imaging reveals that the lifting of surface reconstruction preferentially starts from the boundaries of distinct domains and then extends progressively into the domains with the reconstruction rows perpendicular to the boundaries,leaving a Au(100)-(1×1)surface behind.The Au(100)-(1×1)is saturated at~84%±2%with respect to the whole surface at a Te coverage of 0.16 monolayer.With further increasing the Te coverage to 0.25 monolayer,the Au(100)-(1×1)surface becomes reduced and overlapped by a well-ordered(2×2)-Te superstructure.No similar behavior is found for Te-decorated Au(111),Cu(111),Cu(100)surfaces,nor for the decorated Au(100)with other elements.This result may pave the way to design Au-based catalysts and,as an intermediate step,even potentially open a new route to constructing complex transition metal dichalcogenides.