The Faradaic efficiency of a solution-phase product s was calculated according to the equation: For formic acid, acetic acid, ethanol and 1-propanol, Ns equals 2, 8, 12 and 18, respectively. ns is the total amount of s generated in one chronoamperometry test (unit: mol). Q is the integrated charge of one test (unit: C). cDMSO is the concentration of DMSO in standard solution (6.17 mmol/L) and VDMSO is the volume of standard solution (40 μL). As,H is the relative area of the peak in 1 H-NMR spectrum used for quantification of s with respect to the peak of 6 H atoms of DMSO. For ethanol and 1propanol, the peaks of methyl groups were used for quantification. Ns,H is the number of H atoms in one s molecule used for quantification. For formic acid, acetic acid, ethanol and 1-propanol, Ns,H equals 1, 3, 3 and 3, respectively. Vele is the volume of electrolyte for working electrode and VNMR is the volume of electrolyte used for NMR test.