The effect of functional groups (O,F, or OH) on reversible hydrogen storage properties of Ti2X (X=C or N) monolayer |
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| Affiliation: | 1. School of Science, Hubei University of Technology, Wuhan, 430068, China;2. Hubei Engineering Technology Research Centre of Energy Photoelectric Device and System Hubei University of Technology, Wuhan, 430068, China |
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| Abstract: | The effect of functional groups (O, F, or OH) on the hydrogen storage properties of Ti2X (X = C or N) monolayer was systematically investigated by first-principles calculations. The results show that the reversible hydrogen storage capacity of Ti2X(OH)2 monolayer is approximately 2.7 wt%, which is larger than that of Ti2XO2 and Ti2XF2 monolayers. The binding energy of the OH group at the F site is stronger than H atom. Thus, H2 molecules will not be dissociated on Ti2X(OH)2 monolayer. At this time, the loss of 1.8 wt% hydrogen storage capacity is not produced in Ti2X(OH)2 monolayer. Furthermore, the PDOS, the population analysis, and the electron density difference explore that electron transfer appears between Ti and the second layer H2 molecules on Ti2X(OH)2 monolayer, and a Dewar-Kubas interaction lies between second layer H2 molecules and Ti2X(OH)2 monolayer. For Ti2X(OH)2 monolayer, the molecular dynamic simulation indicates that the H2 molecules by Dewar-Kubas interaction sable adsorption at 300 K, and desorption at 400 K. Therefore, Ti2X(OH)2 is appropriate for reversible hydrogen sorbent storage materials under ambient conditions. |
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| Keywords: | MXenes Hydrogen storage Functional groups Dewar-Kubas interaction First-principles |
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