Development of in-situ flow electrochemical Scanning Transmission X-ray Microscopy

Abstract

Understanding electrically activated processes at electrode-electrolyte interfaces is needed to improve many technologies, including energy conversion, semiconductor devices, bio-sensors, corrosion protection, etc. In-situ spectro-electrochemical studies based on a wide range of spectroscopies are particularly useful. Scanning Transmission X-ray microscopy (STXM) is a synchrotron-based technique which measures near-edge X-ray absorption fine structure (NEXAFS) with high spatial resolution. In addition to information on morphology, STXM also provides chemical state analysis using the X-ray absorption data, which makes in-situ STXM studies of electrochemical process of special interest. This thesis reports ex-situ and in-situ STXM based qualitative and quantitative studies on copper (Cu) electrodeposition and electrostripping. The influence of electrolyte pH on the distribution of Cu(I) and Cu(0) species electrodeposited from aqueous CuSO4 solutions was studied. An instrument capable of performing in-situ flow electrochemical STXM studies was designed and fabricated. The performance of this device was evaluated for in-situ Cu electrodeposition studies. Findings based on ex-situ and in-situ STXM studies are discussed. Suggestions are made for further instrumentation improvements.