Engineering electronic structures and optical properties of a MoSiN monolayer modulating surface hydrogen chemisorption.

Recently, a MoSiN monolayer has been successfully synthesized by a delicately designed chemical vapor deposition (CVD) method. It exhibits promising (opto)electronic properties due to a relatively narrow bandgap (∼1.94 eV), high electron/hole mobility, and excellent thermal/chemical stability. Currently, much effort is being devoted to further improving its properties through engineering defects or constructing nanocomposites (, van der Waals heterostructures). Herein, we report a theoretical investigation on hydrogenation as an alternative surface functionalization approach to effectively manipulate its electronic structures and optical properties. The calculation results suggested that chemisorption of H atoms on the top of N atoms on MoSiN was energetically most favored. Upon H chemisorption, the band gap values gradually decreased from 1.89 eV (for intrinsic MoSiN) to 0 eV (for MoSiN-16H) and 0.25 eV (for MoSiN-32H), respectively. The results of optical properties studies revealed that a noticeable enhancement in light absorption intensity could be realized in the visible light range after the surface hydrogenation process. Specifically, full-hydrogenated MoSiN (MoSiN-32H) manifested a higher absorption coefficient than that of semi-hydrogenated MoSiN (MoSiN-16H) in the visible light range. This work can provide theoretical guidance for rational engineering of optical and optoelectronic properties of MoSiN monolayer materials surface hydrogenation towards emerging applications in electronics, optoelectronics, photocatalysis,