Nanoscale redox mapping at the MoS2-liquid interface

• Published in: Nature communications Vol. 12; no. 1; p. 1321
• Main Authors: Du, He-Yun, Huang, Yi-Fan, Wong, Deniz, Tseng, Mao-Feng, Lee, Yi-Hsin, Wang, Chen-Hao, Lin, Cheng-Lan, Hoffmann, Germar, Chen, Kuei-Hsien, Chen, Li-Chyong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 26.02.2021; Nature Portfolio
• Subjects: 140/133; 147/138; 147/3; 639/301; 639/4077; 639/925; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-21660-z

Layered MoS 2 is considered as one of the most promising two-dimensional photocatalytic materials for hydrogen evolution and water splitting; however, the electronic structure at the MoS 2 -liquid interface is so far insufficiently resolved. Measuring and understanding the band offset at the surfaces of MoS 2 are crucial for understanding catalytic reactions and to achieve further improvements in performance. Herein, the heterogeneous charge transfer behavior of MoS 2 flakes of various layer numbers and sizes is addressed with high spatial resolution in organic solutions using the ferrocene/ferrocenium (Fc/Fc + ) redox pair as a probe in near-field scanning electrochemical microscopy, i.e. in close nm probe-sample proximity. Redox mapping reveals an area and layer dependent reactivity for MoS 2 with a detailed insight into the local processes as band offset and confinement of the faradaic current obtained. In combination with additional characterization methods, we deduce a band alignment occurring at the liquid-solid interface. Here, high-resolution atomic force microscopy and scanning electrochemical microscopy are used to investigate the electron transfer behaviour of layered MoS 2 flakes in organic solutions, offering insights on the electronic band alignment at the solid-liquid interface.