LAUSR

Highlights • Pulse-plating of Mn-oxide/polypyrrole nanocomposite studied in situ by ptychography. • Electrocrystallization followed in operando by dynamic coherent diffractive imaging. • Morphology and chemical state evolutions monitored in situ during electrodeposition. • Spectroscopic ptychography reveals valence distribution with nanometric resolution. • Local magnitude and phase spectra extracted from recostructued ptychographic images. Abstract Crucial for the advancement of electrochemical materials science is understanding the lateral variations in the elemental and chemical state of constituents induced by electrochemical reactions at nanoscales. This requires in situ studies to provide observables that contribute to both modeling beyond the phenomenological level and transducing exactly the functionally relevant quantities A range of X-ray coherent diffraction imaging (CDI) approaches has recently been proposed for imaging beyond the diffraction limit with potentially dramatic improvements of time resolution with chemical sensitivity. In this paper we report a selection of ptychography results obtained in situ after successive steps of electrochemically driven growth, complemented with absorption and phase spectroscopy at high lateral resolution. We demonstrate the onset of morphological instability feature formation and correlate the chemical state of Mn with local growth rate controlled by the current density distribution resulting from morphological evolution.