Fig. 3: Operando Raman imaging and gas bubble imaging.
From: Concurrent oxygen evolution reaction pathways revealed by high-speed compressive Raman imaging
a Raman intensity images of 640 cm-1 mode at selected potentials during the first, second and fourth electrochemical cycles of α-Li2IrO3 using KOH as the electrolyte. Cycling is performed at 4 mV/s (see Supplementary Videos 1–2 for other cycles and Supplementary Videos 3–4 and Supplementary Note 13 for repeats over more particles). The scale bar is 5 μm. b Rate of evolution of O2 molecules from three different individual agglomerates, obtained using bright-field imaging of gas bubble evolution. c Histogram of a number of O2 molecules generated from individual agglomerates on reaching 1.7 V vs RHE. 30 agglomerates are imaged. d Pseudo ‘velocity’ of phase front, which is dominated by Li+ deintercalation during the initial anodic scan and K+ deintercalation in scans 2 to 4. All values are extracted from the anodic scan (see Supplementary Note 15 for the method). Error bars represent both measurement and fitting uncertainties.
