Fig. 3: In situ electrochemical SERS characterizations.

a Schematic illustration of the in situ electrochemical SERS setup (WE refers to the working electrode, RE refers to the reference electrode, CE refers to the counter electrode). b In situ electrochemical SERS spectra of the O-H stretching vibrational mode of Pt/C in 0.1 M KOH (HB refers to H-bonds, OCP refers to open circuit potential, cps refers to counts per second). c In situ electrochemical SERS spectra of the O-H stretching vibrational mode of Pt/cage in 0.1 M KOH. d Potential-dependence of the Raman shifts of the three deconvoluted peaks of interfacial water on Pt/C and Pt/cage, respectively. e Potential-dependence of the ratio of the three deconvoluted peaks of interfacial water on Pt/C and Pt/cage, respectively. f Comparison of the ratios of the three deconvoluted peaks of interfacial water on Pt/C and Pt/cage at an applied potential of −0.3 V. Strong HB (blue), weak HB (red), and free water (yellow). Error bars in (d, e, f) represent standard deviation for each data point with three independent experiments.