Fig. 5: Effect of pressure on the front-illuminated 3 J III-V based PEC water splitting cell.
a Schematic illustration of the cell configuration. The three-electrode configuration is constructed with the platinized 3 J III-V photoelectrode as the working electrode, an IrOx/TaOx/Ti mesh serves as the counter electrode, and an Ag/AgCl reference electrode. The photoelectrode is tilted to ~45° from the horizontal plane to ensure a better camera angle for imaging. Linear sweep voltammetry (LSV) curves measured under AM1.5 G 1 sun illumination at different pressures (b) in a 0.1 M KPi solution (pH = 7 ± 0.1) and c in a 0.1 M KPi solution containing 0.5 M Na2S2O8 as electron scavenger. The scan was performed from negative to positive applied bias at a scan rate of 20 mV s-1, with the first ~160 mV measured in dark before turning on the illumination. No iR corrections was conducted for the reported voltammograms. d–g Representative images of gas bubbles on the photoelectrode at 1–8 bar in a pH 7 ± 0.1, 0.1 M KPi solution. h Representative image of the photoelectrode during the reaction in a pH 7 ± 0.1, 0.1 M KPi solution containing 0.5 M Na2S2O8. The scale bars in (d–h) represent 5 mm. i Chronoamperometry measurement at 0 V vs. RHE for 3 h at 1 bar vs. 8 bar in 0.1 M KPi solution (pH = 7 ± 0.1). j Change in photocurrent due to bubble detachment (\(\triangle J\)) and bubble growth time (\(\triangle t\)) at 1 bar vs. 8 bar. The operating pressure of the PEC water splitting cell is increased by supplying compressed N2 gas. The electrolyte flow rate is kept at 4.6 mL s-1. Error bars are the standard deviation of at least three measurements. The measurements were conducted at room temperature (~25 °C).
