DFT simulation of hydrogen storage on manganese phosphorous trisulphide (MnPS3)

Manganese phosphorous trisulphide, MnPS3, is a solid layered material. The hydrogen gravimetric storage capacities of MnPS3 powder at 80.15, 173.15 and 298.15 K and at moderate pressures has been recently measured in experiments. The origin of the storage capacities of this material is not well understood. The main hypothesis is that hydrogen is stored in the pores of MnPS3 powder. The pores are modelled as two parallel MnPS3 layers separated a certain distance. Density Functional Theory simulations of the interaction of H2 with the surface of a MnPS3 layer have been carried out, in order to test that hypothesis. The simulations indicate that the adsorption of hydrogen on the surface of a MnPS3 layer is energetically favourable, but only through the physisorption mechanism. Calculations of the gravimetric capacities of the pores of MnPS3 powder have also been carried out, obtaining a reasonable agreement with the experimental results. The comparison of the calculated and experimental gravimetric capacities show that the hydrogen storage on MnPS3 powder is mainly due to compression in the pores and that the contribution of the physisorption process to the storage is very small.