Abstract
Single-layer MoSi2N4, a high-quality two-dimensional material, has recently been fabricated by chemical vapor deposition. Motivated by this latest experimental work, herein, we apply first-principles calculations to investigate the electronic, optical, and photocatalytic properties of alkali-metals(Li, Na, and K)-adsorbed MoSi2N4 monolayer. The electronic structure analysis show that the pristine MoSi2N4 monolayer exhibits an indirect band gap (Eg=1.89 eV). By contrast, the band gaps of one Li-, Na- and K-adsorbed MoSi2N4 monolayers are 1.73, 1.61, and 1.75 eV, respectively. Moreover, the work function of the MoSi2N4 monolayer (4.80eV) is significantly reduced after the adsorption of alkali metal atoms. The work function of one Li-, Na- and K-adsorbed MoSi2N4 monolayers are 1.50, 1.43, and 2.03 eV, respectively. Then, the optical investigations indicate that alkali metal adsorption processes substantially increase the visible light absorption range and coefficient of the MoSi2N4 monolayer. Furthermore, based on redox potential variations after alkali-metals adsorbed, the Li-, and Na-adsorbed MoSi2N4 monolayer are more suitable for water splitting photocatalytic process, and the Li-adsorbed case shows the highest potential application for CO2 reduction. In conclusion, the alkali-metals-adsorbed MoSi2N4 monolayer exhibits promising applications as novel optoelectronic devices and photocatalytic materials due to the unique physical and chemical properties.