Lu Yang-Sheng1,Yu Chun-Hung2,Cheng Yu-Chieh3,Chen Chun-Wei2,Li Shao-Sian1
Institute of Materials Science and Engineering, National Taipei University of Technology, Taiwan1,Department of Materials Science and Engineering, National Taiwan University, Taiwan2,Department of Electro-Optical Engineering, Taipei Tech3
Lu Yang-Sheng1,Yu Chun-Hung2,Cheng Yu-Chieh3,Chen Chun-Wei2,Li Shao-Sian1
Institute of Materials Science and Engineering, National Taipei University of Technology, Taiwan1,Department of Materials Science and Engineering, National Taiwan University, Taiwan2,Department of Electro-Optical Engineering, Taipei Tech3
In recent years scientists have used microelectrode technology to probe the electrochemical properties of a surface of interest through position feedback, allowing direct topographic and electrochemical imaging. It is especially important to determine the topological information correlated to the electrochemical activity of atomically thin 2D materials. Many researches have revealed that two-dimensional materials possess a promising potential for electrochemical catalytic reactions, such as Hydrogen Evolution Reaction (HER), Oxygen Evolution Reaction (OER), Carbon Dioxide Reduction (CO<sub>2</sub>RR), Nitrogen Reduction Reaction (NRR),Iodide oxidation reaction (IOR).However, the topological correlation with electrochemical reactivity is relatively less reported due to a lack of high spatial resolution electrochemical measurement techniques. In this work, an advanced scanning electrochemical cell microscope (SECCM) is used to probe the microscale electrochemical reactivity of 2D materials for HER. With minuscule electrolyte droplets and surface feedback signals to adjust the surface-to-probe height, a highly spatial resolved topological correlation with electrochemical reactivity for 2D materials is revealed.<br/>We have previously used SECCM to evaluate the activity of MoS<sub>2</sub>, identifying the HER activity differences between edge areas and basal areas. Besides the defect related active sites, some processes were also applied to manipulate the surface properties of 2D materials for enhanced reactivity, such as light modulation, strain, or surface polarization. The morphological and topological properties that correlated to the water splitting performance of 2D materials were visually revealed through the measurements of Kelvin probe (KPFM), piezo response force microscopy (PFM), and SECCM. This work fills the gap between electrocatalytic HER and topological properties of 2D materials, and provides a microscopic understanding to further improve water splitting performance for clean energy.