Severe carbon accumulation on black phosphorous flakes induced by synchrotron x-ray radiation.

[Display omitted] • Severe carbon accumulation was observed on black phosphorus flake under synchrotron radiation. • The carbon accumulation was hardly observed on MoS 2 flake due to its lower surface reactivity. • Our statistical approach revealed beam-induced surface modification quantitatively. • Studying reactive surface must require careful examination of beam-induced surface modification. • Careful selection of synchrotron beam power density would prevent reported carbon accumulation. Two-dimensional (2D) materials, such as black phosphorus (BP) and transition metal dichalcogenide, recently gained much interest due to their unique electronic, photonic, and mechanical properties. Synchrotron-based scanning photoelectron microscopy (s -SPEM) with a spatial resolution (down to 70 nm) has actively applied for exploring the relationship between chemical information and electronic structure of 2D materials on concerned local surface area. Here, we compare carbon accumulation on the surface of BP and MoS 2 during synchrotron beam irradiation. During the BP characterization, carbon was rapidly accumulated on BP surface as irradiation progress, while MoS 2 demonstrated better resistance to carbon accumulation in comparison to BP. Our work suggests that the higher surface reactivity of BP results in the formation of even BP-carbide structure upon the irradiation, while MoS 2 with relatively low reactivity is rather stable against carbon accumulation. This photon-induced carbon accumulation causes the misleading result of surface chemical information and electronic structure in highly reactive 2D materials or nanostructures. [ABSTRACT FROM AUTHOR]