Multifunctional Porous Silicon Carbide p-SiC x (p-SiC3 and p-SiC) Nanosheets for Photocatalytic Hydrogen Production and Storage

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Abstract Hydrogen energy has emerged as one of the most promising solutions to meet the growing global energy demand. In this work, we employ density functional theory-based simulations to predict two distinct two-dimensional (2D) porous nanosheets of silicon carbide, p-SiCx (p-SiC3 and p-SiC). Both materials exhibit excellent mechanical and thermodynamic stability at room temperature. The larger surface area and incorporation of Si atoms along with the carbon framework in holey graphyne-like p-SiC3 enhance its potential for a wide variety of real-world applications. In contrast, p-SiC exhibits a distinct structural morphology from holey graphyne. Electronic structure analysis reveals that p-SiC3 and p-SiC are indirect bandgap semiconductors with bandgaps of 2.19 and 2.79 eV, respectively. While most of the 2D porous materials exhibit limited hydrogen storage capacity, both p-SiC3 and p-SiC show remarkable storage capacity of 24 H2 molecules per unit cell, corresponding to 11.17 and 9.14 wt %, with binding energies of 73.64 and 78.21 meV, respectively, indicating their suitability for efficient hydrogen storage via physisorption. Furthermore, the calculated desorption temperatures of 94 K for p-SiC3 and 100 K for p-SiC at 1 bar pressure confirm that the cryo-compression method is an optimal approach for effective hydrogen storage in these materials.

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