  Group IV and V monolayers are the promising state-of-the-art 2D materials
owing to their high carrier mobility, tunable bandgaps, and optical linear
dichroism along with outstanding electronic and thermoelectric properties.
Furthermore, recent studies reveal the stability of free-standing 2D monolayers
by hydrogenation. Inspired by this, we systematically predict and investigate
the structure and properties of various hydrogen saturated silicon phosphide
(H-Si-P) monolayers, based on first-principles calculations. According to the
results, H-Si-P monolayers belong to indirect bandgap semiconductors with a
highly stable structure. Their bandgaps and band edge positions assessed using
accurate hybrid functional are shown to be effectively adjusted by applying a
biaxial strain. Furthermore, the absorption spectra of these monolayers,
simulated in the context of time-dependent density functional theory, exhibit
their excellent potential for solar energy conversion and visible-light-driven
photocatalytic water splitting. In this respect, this work provides valuable
guidance for finding more 2D semiconductors and nanostructures for
nanoelectronic and optoelectronic applications, as well as for photocatalytic
water splitting.
