In cluster scientific research, determining the ground state structure is a fundamental aspect of investigating the properties and applications of clusters. However, the determi-nation of the lowest-energy structure of clusters is not only a complex global optimization problem but also a crucial challenge in current cluster research. In the work the geometric structure and electronic properties of LaHn/+ (n = 2-20) nanoclusters with potential for hydrogen storage are investigated using Crystal structure AnaLYsis by Particle Swarm Optimization (CALYPSO) method and Density Functional Theory (DFT). By calculating the average adsorption energy and hydrogen storage mass fraction, it is predicted that neutral LaH13 and cationic LaH14+ clusters exhibit high hydrogen storage densities of 8.6 wt% and 9.2 wt%, respectively. Furthermore, the molecular orbital composition and internal chemical bond binding mode were analyzed using adaptive natural density partition (AdNDP) and natural bond orbital (NBO). The results indicate that the strong hybridization between La 5d orbitals and H 1s orbitals is the primary factor contributing to the high stability of both neutral LaH13 and cationic LaH14+ clusters. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

As a potential candidate for lithium-ion batterys (LIBs) electrode materials, V2C, a type of MXene, demonstrates exceptional electrical conductivity, a large specific surface area and easy lithium diffusion. However, the preparation process inevitably leads to the formation of various functional groups on the material's surface, which can significantly influence its electrochemical properties. Four stable symmetrical models V2CO2, V2CO4/S-3(2/3), V2CO2/3S4/3 and V2CS2 with excellent electronic conductivity and thermodynamic stability are selected to investigate the electrochemical performance using first-principles calculations. The results demonstrate that the order of diffusion barriers for Li ion on functionalized V2C MXene is as follows: V2C2O2 (0.15 eV) < V2C2S2 (0.22 eV) < V2CO4/3S2/3 (0.28 eV) < V2CO2/3S4/3 (0.33 eV). The maximum adsorption concentrations of Li ions are observed in V2CO2Li2, V(2)CO(4/3)S(2/3)li(4), V2CO2/3S4/3Li6 and V2CS2Li4 with corresponding theoretical storage capacities 367 mA center dot h/g, 538 mA center dot h/g, 729 mA center dot h/g and 602 mA center dot h/g, respectively. The excellent energy storage capacity of V2CO2/3S4/3, with a low average voltage of 0.29 V, surpasses that of several previously predicted anode materials. This work further elucidates the regulatory mechanism of functional groups on the properties of MXenes and provides a novel strategy for modifying MXenes.

Due to the rapid evolution of the global electronic product industry, the limited availability of lithium resources has prompted extensive research into alternative metal ion batteries that can substitute for lithium batteries. The exceptional potentiality for MXenes as electrode materials in energy storage batteries is demonstrated by excellent conductivity, expansive surface area, and mechanical strength. The performance of Na and Mg on Mo2C and Mo2CO2 monolayers have been investigated employing first-principles calculations, including geometry configurations, electronic structures, ion diffusion properties, open-circuit voltages, and theoretical specific capacities. The conductivity of stable anodes is superior both before and after ion adsorption. Additionally, the formation energies of Na/Mg on the monolayer are negative, indicating a strong binding between metal atoms and the substrate. The migration energy barriers of Na and Mg on Mo2C are estimated to be 0.017 eV and 0.070 eV, respectively, suggesting a significant level of mobility and reversibility for Mo2C. The predicted range of average open-circuit voltages for Na/Mg-ion battery anodes is approximately 0.05–1.00 V in the case of Mo2C and Mo2CO2. The highest concentrations of Na and Mg atoms on Mo2C and Mo2CO2 are achieved through multilayer adsorption up to Mo2CNa3.3, Mo2CMg2, Mo2CO2Na3.3, and Mo2CO2Mg1.8, resulting in corresponding theoretical capacities of 438, 526, 379 and 411 mA·h/g, respectively. In conclusion, the outstanding electrochemical performance of Mo2C and Mo2CO2 anode materials in sodium-ion batteries (SIBs) and magnesium-ion batteries (MIBs) has prompted the exploration of other MXenes electrodes with advantageous characteristics for ion battery applications, contributing to the advancement of renewable energy technology.

Due to the rapid evolution of the global electronic product industry, the limited availability of lithium resources has prompted extensive research into alternative metal ion batteries that can substitute for lithium batteries. The exceptional potentiality for MXenes as electrode materials in energy storage batteries is demonstrated by excellent conductivity, expansive surface area, and mechanical strength. The performance of Na and Mg on Mo 2 C and Mo 2 CO 2 monolayers have been investigated employing first-principles calculations, including geometry configurations, electronic structures, ion diffusion properties, open-circuit voltages, and theoretical specific capacities. The conductivity of stable anodes is superior both before and after ion adsorption. Additionally, the formation energies of Na/Mg on the monolayer are negative, indicating a strong binding between metal atoms and the substrate. The migration energy barriers of Na and Mg on Mo 2 C are estimated to be 0.017 eV and 0.070 eV, respectively, suggesting a significant level of mobility and reversibility for Mo 2 C. The predicted range of average open-circuit voltages for Na/Mg-ion battery anodes is approximately 0.05 - 1.00 V in the case of Mo 2 C and Mo 2 CO 2 . The highest concentrations of Na and Mg atoms on Mo 2 C and Mo 2 CO 2 are achieved through multilayer adsorption up to Mo 2 CNa 3.3 , Mo 2 CMg 2 , Mo 2 CO 2 Na 3.3 , and Mo 2 CO 2 Mg 1.8 , resulting in corresponding theoretical capacities of 438, 526, 379 and 411 mA & sdot; h/g, respectively. In conclusion, the outstanding electrochemical performance of Mo 2 C and Mo 2 CO 2 anode materials in sodium-ion batteries (SIBs) and magnesium-ion batteries (MIBs) has prompted the exploration of other MXenes electrodes with advantageous characteristics for ion battery applications, contributing to the advancement of renewable energy technology.

The unique 4f orbitals and abundant electronic energy levels of rare earth elements enable effective doping and modification to enhance hydrogen storage performance, making it an increasingly prominent focus of research. The structures of neutral and cationic CeHn0/+ (n = 2-20) clusters have been determined using the Crystal Structure AnaLYsis by Particle Swarm Optimization (CALYPSO) method in conjunction with density functional theory (DFT). Interestingly, the CeH13 and CeH14+ exhibit remarkable stability in the doublet state with Cs and C2v symmetry, respectively. The adsorption energy of CeHn0/+ (n = 2-20) suggests a preference for H atoms to chemically adsorb on Ce atoms. The analysis of molecular orbital composition reveals that the stability of both CeH13 and CeH14+ is attributed to the significant hybridization between the H 1s and Ce 4f orbitals. Both CeH13 and CeH14+ demonstrate significant hydrogen storage capacities, with values reaching 8.5 wt% and 9.1 wt%, respectively.

The utilization of MBenes as electrode materials for lithium/sodium-ion batteries (LIBs/NIBs) has emerged as a prominent research area. The potential application of two-dimensional niobium boride (NbB) in LIBs/NIBs was explored through first-principles calculations. The results indicate that the monolayer of NbB exhibits exceptional dynamic stability, thermodynamic stability and electrical conductivity. The migration path of Li/Na on the NbB surface was determined, revealing diffusion barriers as low as 0.034 and 0.017 eV respectively, indicating the exceptional mobility and reversibility exhibited by NbB. The theoretical capacities of Li and Na on NbB are 258 and 323 mAh g-1, respectively. The open circuit voltage (OCV) varies within the range of 0.58 to 0.71 V and 0.05 to 0.81 V for Li/Na concentrations. Meanwhile, the investigation into the influence of various functional groups of NbB on the adsorption properties of Li/Na atoms reveals that both NbBO and NbBS surfaces retain their maximum capacity for Li/Na adsorption, whereas the NbBSe surface fails to achieve complete layer adsorption of Li/Na atoms. The introduction of the S functional groups not only maintains the ultra-low diffusion barrier (0.09 eV) of Na ions but also results in a significant decrease in the average OCV of Li/Na adsorption, which is approximately 0.37 and 0.14 V, respectively. The electrochemical properties of NbB in LIBs/NIBs are exceptional, positioning it as a promising electrode material within the MBenes family.

MXenes exhibit outstanding potential as electrode materials for lithium-ion batteries (LIBs) due to their extensive specific surface area, superior electrical conductivity and abundant surface-active terminations. The electrochemical properties of Mo2CT2 (T = bare, -O, -S) as anodes for LIBs have been studied by adopting the firstprinciples calculations and experiments. The results reveal that Mo2CO2 has a negative impact on Li storage, leading to a slight decrease in theoretical capacity and a significant increase in average voltage. The low migration energy barriers of Mo2C, Mo2CO2 and Mo2CS2 are estimated as 0.037 eV, 0.145 eV and 0.244 eV. Moreover, the predicted average voltages of Mo2C and Mo2CS2 are 0.79 V and 0.11 V, rendering them highly desirable for low charging voltage applications. It is striking that the storage capacity of Mo2C is improved remarkably from 263 mA & BULL;h/g to 400 mA & BULL;h/g by introducing S functional group. Herein, experimental batteries are fabricated with Mo2CSx and Mo2C as anodes to investigate their electrochemical properties, which exhibit both stability and reversibility. Interestingly, the exceptional discharge capacity and cycling stability of Mo2CSx can be attributed to its unique structure, which is consistent with the calculated results. Therefore, S-decorated Mo2C is a more suitable anode for LIBs with excellent performance, which also provides guidance for introducing appropriate functional groups to enhance the electrode performance of other MXenes.

With the development of the energy industry, electrochemical energy storage technology is increasingly involved in developing innovations in the field. The materials of the electrode have a significant influence on the per-formance of energy storage devices. For this purpose, two-dimensional MXene with excellent electrical con-ductivity, mechanical strength, and a variety of possible surface-active terminations are attracting much attention. In the present work, S-decorated d-Mo2CTx (d-Mo2CTx--S) is designed. The first-principles calculations reveal that it may possess good energy storage characteristics. Due to the decoration with S, unique morphology and structure are obtained, conferring stability, optimized Li+ storage, improved charge transport, and lithium -ion adsorption capabilities. Compared with d-Mo2CTx, d-Mo2CTx--S exhibits higher discharge capacity (623 mAh g+1 at 1 A g+1) as lithium-ion electrode material and higher specific capacitance (561 F g+1 at 1 A g+1). As a supercapacitor, the material also shows excellent cyclic stability (20,000 charge-discharge cycles). This work may inspire the exploration of other MXene and new surface functionalization methods to improve the perfor-mance of MXene as electrode materials for new energy devices.

MBenes, a class of two-dimensional metal borides, have emerged as a cutting-edge research frontier and a hotspot for electrode materials in ion batteries. This work presents a systematic investigation of the performance of two-dimensional iron boride (FeB) as an electrode material for lithium-ion batteries (LIBs), utilizing first-principles calculations. The results indicate that FeB exhibits remarkable structural stability and excellent conductivity, making it an extremely promising electrode material for LIBs. FeB has the capability to adsorb a monolayer of Li atoms, and exhibits a maximum theoretical capacity of 364 mA h g-1, a high average open circuit voltage (OCV) of 1.08 V, and a low diffusion barrier energy of 0.24 eV. Through the investigation of electrochemical properties of functionalized FeB, it has been discovered that surface functionalization exerts a positive impact on lithium storage. Theoretical lithium storage capacities of FeBT (T = F, O and S) are 538 mA h g-1, 555 mA h g-1 and 476 mA h g-1, respectively. However, the introduction of F and O functional groups significantly reduces diffusion barriers to 0.081 eV and 0.036 eV, respectively, while the introduction of the S functional group markedly decreases the average OCV to approximately 0.25 V. These interesting findings suggest that FeB has great potential in the future development of LIBs.