Fig. 1: In situ electrochemical spectrum by home-built spectroelectrochemical cell.

a The LSV curve of the py-B12 b Nyquist plots of ORR on py-B12 with concurrent XAS measurement. c The EIS fitting spectra of ORR recorded with concurrent XAS measurement. All the signals were collected on a home-built spectroelectrochemical cell with a catalyst loading of 100 mg cm−2 and under O2-saturated 0.1-M HClO4 solution.