Fig. 5: The identification of the participation of CO₃* in CO₂RR.

a EPR trapping of carbon radicals and hydrogen radicals. b In situ Raman spectroscopy for BOC-2 at a series of working potentials. c, d, e In situ Raman spectroscopy with ¹²CO₂ and ¹³CO₂ as carbon source for BOC-2, BOC-3 and BOC-C, respectively.