Two-dimensional BxS materials with biphenylene network structure: A first-principles study

Two-dimensional (2D) boron-sulfur (BxSy) materials have garnered significant attention due to their potential applications in optoelectronic devices, catalysis, and energy conversion. In this study, we have innovatively designed a series of 2D-BxS materials (x = 2, 3, 5) with biphenylene (BP) network structures, denoted as BP-like BxS. Density functional theory calculations reveal that, with the exception of B5S, the metallic B2S and B3S exhibit exceptional thermal and mechanical stability, showcasing anisotropic mechanical and optical properties. Furthermore, B2S and B3S demonstrate a broad spectrum of light absorption capabilities, spanning from infrared to ultraviolet and visible light. Remarkably, these materials exhibit promising photocatalytic activity for the hydrogen evolution reaction (HER), with limiting potentials (UL) of 0.55 eV for B2S and 0.94 eV for B3S, respectively. The catalytic behavior is pH-dependent, with B2S favoring acidic conditions and B3S favoring alkaline conditions, where UL for B3S can reach 0.28 eV at pH = 12.58. This work reports BP-like BxS materials for the first time, thereby enriching the BxSy material family and extending their properties and potential applications in the fields of optoelectronics and catalysis.