The Mechanism of Enhanced Hydrogen Storage by Ca Decorated g-C₃N₄

The Ca atom decorated g-C₃N₄ (Ca-C₃N₄) is demonstrated to exhibit a high capacity to store hydrogen, by using the first-principles calculations. The enhanced adsorption energy of H to Ca-C₃N₄ is mainly attributed to the strong chemical adsorption between H-1s and Ca-1s orbitals and the hybridization of H-1s and Ca-3d orbitals. The polarization between Ca and C₃N₄ exhibits good modulation under the external electric field, which plays an important role in H adsorption and release. Our theoretical results may provide a practical route to improving the hydrogen storage of g-C₃N₄ by suitable metal atoms decorating.