Surface functionalization of penta-siligraphene monolayer for nanoelectronic, optoelectronic and photocatalytic water-splitting: A first-principles study

Herein, we have investigated theoretically using density functional theory the effect of surface functionalization with hydrogen, fluorine and chlorine atoms on electronic and optic properties of the penta-siligraphene monolayer (p-Si2C4). By assessing the stability, we have found that the hydrogenated p-Si2C4 monolayer (p-Si2C4-4H) is energetically (negative formation energy), dynamically (absence of soft modes) and thermally (small drift in the total energy at standard temperature) stable. The electronic-property analysis revealed that the p-Si2C4-4H monolayer is a semiconductor with indirect bandgap varying from 2.06 to 3.41 eV depending on the used functional. Moreover, the p-Si2C4-4H monolayer exhibits a considerable absorption in the ultra-violet (UV) region and a negligible amount of absorption in the visible region. Interestingly, the band edge positions of the p-Si2C4-4H monolayer could perfectly satisfy the redox potentials of photocatalytic water splitting. Furthermore, we have found that bandgap of p-Si2C4-4H monolayer can be tuned using biaxial strain. While, according to HSE06 functional, the bandgap decreases from 3.01 (0%) to 2.38 eV (at 5% biaxial strain) corresponding to a good fitting of band edge with redox potentials and an enhancement in the optical absorption in visible-UV region. This Leads to an improvement the photocatalytic performance of p-Si2C4-4H. Our findings suggest the p-Si2C4-4H monolayer as a promising candidate for applications in new generation of nano- and opto-electronics, especially in UV light shielding (for absorbing the harmful-UV radiations), solar cells (as an anti-reflection layers) and photocatalytic water splitting (for hydrogen and oxygen production).

Automated summary

In this study, the effect of surface functionalization with hydrogen, fluorine, and chlorine atoms on the electronic and optic properties of the penta-siligraphene monolayer was theoretically investigated using density functional theory. It was found that the hydrogenated p-Si2C4 monolayer is stable and exhibits semiconductor behavior, with its bandgap depending on the functional used.