Figure 3.

a) pH dependent CV scans for mesoITO|STEMPO, in the presence of 30 mm MBA. b) TON and FE metrics compiled from CPE experiments under a range of pH values. Conditions: pH 7.3: CO₂ saturated aq. HCO₃ ⁻/CO₃ ²⁻ (0.5 m); pH 8–10: aq. HCO₃ ⁻/CO₃ ²⁻ (0.5 m) titrated under ambient conditions to the correct pH; for CV: ν=20 mV s⁻¹, r.t.; for CPE: E _app=1.0 V vs. NHE, t _CPE=3 h, r.t., MBA (30 mm). Product quantification by HPLC was used for TON and FE calculation (Supporting Information, Equations (S4) and (S5)). Electrochemically determined concentration profiles for c) glycerol, and d) HMF; conditions: pH 8, ν=20 mV s⁻¹, r.t.