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Finding advanced hydrogen storage materials with high capacity and high efficiency is a key issue for hydrogen transportation and application. In this study, the first-principles calculation method is used to examine the potential of 2D pentagonal BN 2 (Penta-BN 2) as an excellent hydrogen storage material. The results indicate that Penta-BN 2 has superior metallic and structural stable properties. The pristine Penta-BN 2 is found to have weak adsorption energy for H 2 molecules, which cannot meet the requirements of hydrogen storage. However, the Li-functionalized Penta-BN 2 substrate is found to be relatively excellent to adsorb H 2 molecules. A Li atom is bound closely to Penta-BN 2 with large adsorption energy reaching more than 3.79 eV, and the 2 × 2 × 1 Penta-BN 2 supercell can be suitably accommodated 4 Li atoms. 4Li-functionalized Penta-BN 2 stores up to 16H 2 molecules with a hydrogen gravimetric density of 8.70 wt%. The adsorption and desorption capacity of the system for H 2 molecules under practical temperature and pressure conditions are investigated with semi-empirical calculations. The maximum reversible hydrogen storage capacity is up to 7.92 wt% between the practical condition of 30 atm/233 K for adsorption to 3 atm/358 K for desorption, which is better than other 2D pentagonal materials and boron-nitrogen compounds. The proposed investigations of this work illustrate that Li-functionalized Penta-BN 2 is a promising hydrogen storage material with high efficiency, reversibility, and high-capacity characteristics. • Li-functionalized Penta-BN 2 is a good potential hydrogen storage material. • The functionalization of the Li atoms enhances the hydrogen storage capacity. • The hydrogen storage capacity of Li-functionalized Penta-BN 2 can reach 8.70 wt%. • The reversible hydrogen storage capacity is up to 7.92 wt% in real situations. [ABSTRACT FROM AUTHOR]

The promise of using 2D materials for hydrogen storage has broad prospects, ascribe to their significant specific surface area and lightweight properties. In this work, the hydrogen storage capability and reversible storage mechanism of 2D penta-SiCN material are investigated based on the first-principles computational method. Thermal stability of penta-SiCN is calculated by the ab-initio molecular dynamics (AIMD) simulation and root-mean-square displacement (RMSD) algorithm. It has been found that penta-SiCN is thermodynamically stable even after adsorbing hydrogen molecules. Taking into account the benchmarks of average and continuous adsorption energies of the adsorption systems, a pristine 2 × 2 × 1 penta-SiCN substrate has the ability to adsorb up to 26H 2 molecules, which results in a maximum hydrogen storage capacity of 10.80 wt%. According to the semi-empirical calculation method that based on the thermodynamic analysis, the penta-SiCN adsorption system has a high reversible hydrogen storage capacity of 9.57 wt% within the adsorption and desorption application working conditions. The results proposed in this study demonstrates that penta-SiCN exhibits considerable promise for hydrogen storage with its substantial hydrogen storage capacity, exceptional reversibility, and eco-friendly characteristics. [Display omitted] • Pristine penta-SiCN is a promising material for hydrogen storage. • Theoretical predictions by combining DFT and a semi-empirical calculation method. • The gravimetric densities of penta-SiCN can reach 10.80 wt%. • The penta-SiCN has a high reversible hydrogen storage capacity of 9.57 wt% within the adsorption and desorption working environment. [ABSTRACT FROM AUTHOR]

Defects can significantly alter the properties of 2D material surfaces, thereby affecting the application results. In this work, the adsorption behaviors of H 2 S, SO 2 , NH 3 , and NO 2 gas molecules on rationally defective diboron dinitride (n -BN) monolayers in the presence and absence of an external electric field and moisture condition are studied by the first-principles calculation approach. The results demonstrate that the boron and nitrogen defects are more likely to be generated and both defective monolayers have strong absorption effects on SO 2 and NO 2 gas molecules with absolute values of adsorption energy above 2.5 eV. And the conductivity change after adsorption of NO 2 molecule is particularly pronounced in nitrogen defect monolayer, thus greatly increasing the sensitivity to the gas molecule. Based on the high sensitivity, the defective monolayer could be an ideal one-time scavenger for SO 2 and NO 2 gas molecules. While the H 2 S and NH 3 molecules could obtain the appropriate adsorption energy and the adjustable recovery time on the defective monolayer under the dry or existent external electric field environment. These results make it possible to design a useable gas device with good gas sensing and capturing characteristics on the defective n -BN monolayer. [Display omitted] • The gas sensing and capturing properties on defective n -BN are studied by DFT method. • Defects can improve the sensitivity of the n -BN monolayer to H 2 S, NH 3 , SO 2 and NO 2 gas molecules. • Electrical conductivity, recovery time, electrical field and humidity are all considered. • Defective n -BN monolayer can be expect to be an ideal scavenger for SO 2 and NO 2 gas molecules. [ABSTRACT FROM AUTHOR]