Based on first-principles plane wave calculations, we showed that Ca adsorbed on graphene can serve as a high-capacity hydrogen storage medium, which can be recycled by operations at room temperature. Ca is chemisorbed by donating part of its $4s$ charge to the empty ${\ensuremath{\pi}}^{\ensuremath{\ast}}$ band of graphene. At the end the adsorbed Ca atom becomes positively charged and the semimetallic graphene changes into a metallic state. While each of the adsorbed Ca atoms forming the $(4\ifmmode\times\else\texttimes\fi{}4)$ pattern on the graphene can absorb up to five ${\text{H}}_{2}$ molecules, hydrogen storage capacity can be increased to $8.4\text{ }\text{wt}\text{ }%$ by adsorbing Ca to both sides of graphene and by increasing the coverage to form the $(2\ifmmode\times\else\texttimes\fi{}2)$ pattern. Clustering of Ca atoms is hindered by the repulsive Coulomb interaction between charged Ca atoms.

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Hydrogen storage of calcium atoms adsorbed on graphene: First-principles plane wave calculations

Using first-principles theory, we investigated the most stable configuration for the Rh dopant on a MoSe2 monolayer, and the interaction of the Rh-doped MoSe2 (Rh-MoSe2) monolayer with four toxic gases (CO, NO, NO2 and SO2) to exploit the potential application of the Rh-MoS2 monolayer as a gas sensor or adsorbent. Based on adsorption behavior comparison with other 2D adsorbents and desorption behavior analysis, we assume that the Rh-MoSe2 monolayer is a desirable adsorbent for CO, NO and NO2 storage or removal given the larger adsorption energy (Ead) of −2.00, −2.56 and −1.88 eV, respectively, compared with other materials. In the meanwhile, the Rh-MoSe2 monolayer is a good sensing material for SO2 detection according to its desirable adsorption and desorption behaviors towards the target molecule. Our theoretical calculation would provide a first insight into the TM-doping effect on the structural and electronic properties of the MoSe2 monolayer, and shed light on the application of Rh-MoSe2 for the sensing or disposal of common toxic gases.

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Hao Cui

Papers

Rh-doped MoSe2 as a toxic gas scavenger: a first-principles study

First-principles insight into Ni-doped InN monolayer as a noxious gases scavenger

Pd-doped MoS2 monolayer: A promising candidate for DGA in transformer oil based on DFT method

Adsorption of SO2 and NO2 molecule on intrinsic and Pd-doped HfSe2 monolayer: A first-principles study

Adsorption and sensing behaviors of SF6 decomposed species on Ni-doped C3N monolayer: A first-principles study