Fig. 4: Alcohol catalysis by surface-immobilized nitroxide (STEMPO) monitored with operando FE-EPR.
a, CV scan from the FE-EPR cell placed inside the EPR cavity, recorded at 5 mV s−1 with 20 mM MBA in 8 ml of buffer solution, pH 8.0, in air and under flow conditions. b, EPR spectra at the potentials highlighted on the CV scan in a during forward (green) and reverse (yellow) CV scans (Extended Data Fig. 6 provides a complete set of EPR spectra). c, Double integrals of the EPR spectra (normalised to the maximum data point) plotted against potential and fitted with the Nernst equation (apparent number of electrons transferred, napp = 0.3) during the forward (green, Eforward (catalytic, FE-EPR) = +859 mV) and reverse (yellow, Ereverse(catalytic, FE-EPR) = +902 mV) CV scans. Grey open circles are from all EPR spectra collected (Extended Data Fig. 6), and the coloured circles correspond to the EPR data shown in b. d, Catalytic CV scans from operando FECV-EPR experiments with different concentrations of MBA. e, Double integrals of the EPR spectra from c, plotted against potential and fitted with the Nernst equation during the forward CV scan (Supplementary Section 5).
