context: Recently, the atomic-level thickness and large surface area of 2D materials are beneficial to the generation of carriers on the surface and separation of photogenerated carriers. Typically, in comparison to their 3D counterparts, 2D materials present extremely numerous active sites, high carrier mobility, and controllable interface, which offer a large number of advantages for catalysts, electronics, optoelectronics, etc. Among them, penta-type materials have been developed as a series of novel 2D materials. For instance, Yang et al. reported a novel 2D material, penta-Pt2N4, with a large direct band gap, high carrier mobility and high Young's modulus, suggesting numerous potential applications in nanoelectronics. Xiao et al. found that penta-graphene shows desirable electrochemical performance and it may be a potential candidate for Li/Na-ion battery anodes. However, bulk pyrite-SiAs2 has been synthesized under high pressure and validated as a semiconductor decades ago. Meanwhile, this type of pyrite structure can form a 2D penta structure after cleaving the plane, but 2D penta-SiAs2 has not yet been explored.