Fig. 2: Time-resolved X-ray scattering during the catalyst activation and initial CO2 reduction reaction stage. | Nature Communications

Fig. 2: Time-resolved X-ray scattering during the catalyst activation and initial CO2 reduction reaction stage.

From: Multiscale X-ray scattering elucidates activation and deactivation of oxide-derived copper electrocatalysts for CO2 reduction

Fig. 2

An iR-corrected electrode potential of –1.0 VRHE is applied at time t = 0. a Wide-angle X-ray scattering (WAXS) patterns measured at t = 0 s and t = 60 s, patterns are shifted for clarity. Inset shows a zoom of the Cu2O (111) and Cu (111) reflections. b Calculated X-ray powder diffractogram for Cu (red) and Cu2O (blue)69,70. c Differential WAXS patterns, relative to the mean of the initial 10 diffractograms (recorded over the first 3.4 s). Blue region: negative features. Red regions: positive features. d Normalized differential WAXS signal of Cu (111) and Cu2O (111) peaks in red and blue, respectively, during the first minute. e Six representative small-angle X-ray scattering (SAXS) patterns (dots) and corresponding fits (solid lines) taken during the first 60 s (0, 5, 10, 20, 40, 60 s) of the reaction (vertically shifted for clarity). The purple and green dashed lines indicate the position of the second minimum for the first and last pattern, respectively. The model is fitted to the q-value range highlighted in grey. f Mean edge length as a function of the reaction time, as determined by fitting the SAXS patterns. The light blue shaded area shows the ±σ polydispersity of the particles. g Cartoon showing the shrinkage effect of electrochemical reduction on the unit cell of Cu2O and Cu. h Focused ion beam scanning electron microscopy (FIB-SEM) imaging of a singular spent octahedron reveals a porous interior within the particle. i Scattering invariant of octahedral catalyst particles as function of time for cathodic biases of –1.0 VRHE. The data is normalised with respect to the first measurement of each experiment (scattering invariant of 1.0). The expected increase in the scattering invariant for full conversion of Cu2O to Cu with retention of all Cu atoms in the final particles is indicated by the grey dashed line (see Supplementary Fig. SI16). j In situ Raman spectra collected during the first minute of the reaction (15 s per spectrum). Source data are provided as a Source Data file.

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