Enhanced photocatalytic water splitting with two-dimensional van der Waals heterostructures of BAs/WTeSe

The photocatalytic efficiency of monolayer materials can be significantly enhanced by constructing two-dimensional van der Waals heterostructures. This study presents first principles calculations based on density functional theory to investigate the electronic properties and photocatalytic mechanism of van der Waals heterostructures of boron arsenide (BAs) with the Janus MXY (M = W; X/Y = Se, Te) monolayers, with and without Se vacancies. Results from binding energies, phonon spectra, and ab initio molecular dynamics simulations indicate that the heterostructures are thermodynamically stable. The deformation potential theory was then used to investigate carrier mobility mu in 2D materials. All the heterostructures exhibit direct bandgaps with valence band maxima and conduction band minima suitable for water splitting. Additionally, these heterostructures possess high optical absorption coefficients in the visible and ultraviolet regions. In particular, our calculations predict BAs/WTeSe, with and without Se vacancies, as promising candidates for photocatalytic water splitting applications. DFT predicts stable boron arsenide-Janus monolayer heterostructures with tunable bandgaps, high light absorption, and good carrier mobility, making them ideal for photocatalytic water splitting.