Photoelectrochemical Imaging of Charge Separation between MoS<sub>2</sub> Triangles and Insulating SiO<sub>2</sub> Support
Ziyuan Wang, Qing Huang, Chenwei Ni, Tianyu Bo, Fengtao Fan, Michael V. Mirkin
Abstract
High Resolution Image Download MS PowerPoint Slide The role of the insulating support in photocatalysis is poorly understood. Using high-resolution photo-scanning electrochemical microscopy (photo-SECM), we observed significant spatial charge separation in few-layer-thick molybdenum disulfide (MoS 2 ) triangles attached to a SiO 2 substrate. Spatially resolved surface photovoltage (SPV) measurements revealed that photogenerated holes migrate from MoS 2 to the SiO 2 surface and travel laterally over distances exceeding 2 μm, driven by the built-in electric field of ∼1.7 kV/cm. In thicker and less uniform flakes, the charge separation is dominated by internal driving forces within MoS 2, without significant contribution from SiO 2 . These findings underscore the importance of insulator–semiconductor interactions for effective charge separation, suggesting a new strategy for optimizing photocatalytic systems.