In the cyclic voltammetry measurements, the scan rate was 0.02 V/s for the 2N6S and 6AQ measurements and 0.035V/s for the HPTS/MPTS measurements. In chronoamperometry measurements, the time interval was set to 2 s, EDC was -1 V for the experiments at negative potential bias, and 0.5 V for the experiments at positive potential bias. The single-cell configuration was based on a screen-printed electrode with a graphite working electrode with a surface area of 0.079 cm 2 , platinum counter electrode, and silver coated with silver chloride reference electrode. The concentrations of the photoacids/photobases used in the single-cell configuration were: 0.5 mM for 2N6S and 6AQ and 0.2 mM for HPTS and MPTS. The light irradiation in the single-cell configuration was above the sample using a 340 nm LED with a maximum power output of 60 mW (M340L4, ThorLabs) for the excitation of 2N6S and 6AQ or a 405 nm LED with a maximum power output of 540 mW (M405L4, ThorLabs) for the excitation of HPTS and MPTS. Both LEDs were controlled by a T-cube LED driver (LEDD1B, ThorLabs). The H-cell configuration was based on a home-built glass design with a bottom quartz window. The electrodes in the H-cell configuration were graphite working electrode with a surface area of 0.28 cm 2 and the same counter and reference electrodes as described for the single-cell configuration. The concentration of the photoacids/photobases used in the Hcell configuration was 3 mM for both 2N6S and 6AQ. The light irradiation in the H-cell configuration was below the quartz window using a 340 nm LED with a maximum output power of 130 mW (CUD4AF1B, SETi) with a home-built controller.