Fig. 3: In situ spectroscopic interrogation.
From: In situ copper faceting enables efficient CO2/CO electrolysis
a–c In situ Raman spectra of Cu precatalyst evolution with (solid) and without (dot) phosphate collected in CO2-flowed 0.1 M KHCO3 electrolyte at −1.1 V vs RHE; the shade areas represent the vibrations of the PO43- group32. Time-dependent Cu K-edge XANES (b) and Fourier-transformed EXAFS (c) of Cu precatalyst with phosphate addition, the test was performed in CO2-flowed 0.1 M KHCO3 electrolyte at −1.1 V vs. RHE over the course of 30-min reduction time; ocp stands for open-circuit potential. d The corresponding XANES fitting spectra in b, solid lines represent the experiment data and circles represent the linear combination fit spectra. e The percentage of metallic Cu at different reduction times. Values are extracted from linear combination fit using the XANES spectra of Cu precatalyst at ocp and metallic Cu as standards with the weighting factors as fit parameters. Coordination numbers (CN) of Cu-Cu (f) and Cu-O (g) at different reduction times extracted from the Cu K-edge EXAFS fittings (see Supplementary Table 10).
