  Highly efficient and sustainable resources of energy are of great demand
today to combat with environmental pollution and the energy crisis. In this
work, we have examined the novel 2D Janus AsTeX (X = Cl, Br and I) monolayers
using first-principles calculations and explore their potential energy
conversion applications. We have demonstrated the thermal, energetic, dynamic
and mechanical stability of AsTeX (X = Cl, Br, and I) monolayers. Janus AsTeX
(X = Cl, Br and I) monolayers are indirect bandgap semiconductors with high
carrier mobilities and excellent visible light optical absorption. Our findings
demonstrate that the Janus AsTeCl and AsTeBr monolayers exhibits low lattice
thermal conductivity and excellent electronic transport properties obtained
using semi-classical Boltzmann transport theory including various scattering
mechanism. Additionally, the redox potential of water is adequately engulfed by
the band alignments of the AsTeCl and AsTeBr monolayers. The water splitting
process under illumination can proceeds spontaneously on Janus AsTeBr
monolayer, while a minimal low external potential (0.26-0.29 eV) is required to
trigger water splitting process on Janus AsTeCl monolayer. A more than 10% STH
efficiency of these monolayers indicate their potential practical applications
in the commercial production of hydrogen. Thus, our study demonstrates that
these monolayers can show potential applications in energy conversion fields.
