Ni/P, Pt/P and Pd/P-modified graphitic carbon nitride nanosheets for hydrogen storage application using a DFT investigation

Abstract

Hydrogen storage has become a challenge for many researchers in recent years because it is a clean, cheap, and non-pollutant molecule existing in nature. Hence, in this paper, we report the hydrogen storage capability of P, Ni/P, Pt/P and Pd/P-embedded heptazine graphitic carbon nitride (hgCN) systems utilising the first-principle simulations. The structures of transition metal-modified hgCN were relaxed and found the stable position of the metal elements over the hgCN. The results of simulations revealed that the H2 molecules interacted feebly with the P-doped hgCN but were strongly adsorbed on the introduced active site of the metal atoms in the embedded hgCN with improved adsorption. The adsorption energy (Eads ) of H2 molecules on the Pt/P-codoped hgCN (Eads = −2.749 eV) was much higher than many adsorbents such as graphene, graphane, graphyne, MoS2, B4N, boron carbide nanocage, etc. With adsorption of H2 molecules over the modified hgCN, the optimised structures, charge density and conductivity of systems significantly modulated. Based on these results, it is concluded that these modified hgCN (especially Pt/P-codoped) are promising candidates in the field of hydrogen storage in comparison to all other considered adsorbents.