Two-dimensional h-BAs/MoXTe (X = S, Se) heterojunctions with high photocatalytic performance and high photoelectric conversion efficiency†

In this paper, the geometric structures and electronic and optical properties of h-BAs/MoXTe (X = S, Se) heterojunctions are systematically investigated based on first-principles calculations. It is demonstrated that the h-BAs/TeMoS, h-BAs/SMoTe, h-BAs/TeMoSe, and h-BAs/SeMoTe heterojunctions are highly stable at room temperature. The four heterojunctions have extremely high carrier mobility in the order of 10⁵ cm² V⁻¹ s⁻¹ and excellent visible light absorption. Among them, the h-BAs/TeMoS, h-BAs/SMoTe, and h-BAs/SeMoTe heterojunctions have type-II band alignment. Specifically, the h-BAs/TeMoS heterojunction has a solar-to-hydrogen (STH) efficiency of up to 33.7%. The h-BAs/SeMoTe heterojunction is expected to be a direct Z-scheme photocatalyst for overall water splitting. Moreover, we also find that the h-BAs/SMoTe heterojunction has both preeminent photocatalytic performance and a high photoelectric conversion efficiency (PCE) of 22.96%. Our study shows that the h-BAs/MoXTe (X = S, Se) van der Waals heterojunctions are promising candidate materials for applications in photocatalytic water splitting, optoelectronic devices, and photovoltaic cells.