Fig. 3: Photoelectrochemical performance of BiVO₄ photoanodes under various solar concentrations at 1 bar.

a Linear sweep voltammetry (LSV) curves for our BiVO₄ photoelectrodes under different solar concentration at a scan rate of 20 mV s^-1, measured without a hole scavenger. A final measurement at 1 sun (dashed curve) was conducted to confirm reproducibility. The electrolyte used is 0.1 M KP_i (pH = 7 ± 0.1). No iR corrections was conducted for the reported voltammograms. b Normalized photocurrents (\({{{{\bf{J}}}}}_{c=x}/{{{{\bf{J}}}}}_{c=1}\)) at 1 bar and 1.23 V vs. RHE under various solar concentrations for our BiVO₄ photoelectrodes in a 0.1 M KP_i solution (w/o hole scavenger, red datapoints) and in a 0.1 M KP_i solution containing 0.5 M Na₂SO₃ (w/ hole scavenger, blue datapoints). A reported measurement from Vilanova et al.²³ (using α-Fe₂O₃ photoelectrodes in 1 M KOH) under the similar solar concentration range is added (orange datapoints) for comparison. For our datapoints, three independent measurements were performed to ensure reproducibility, and the spread of the values is smaller than the size of the circles. The y = x dashed line indicates the linear dependence of \({{{{\bf{J}}}}}_{c=x}/{{{{\bf{J}}}}}_{c=1}\) with the increase in solar concentration (the ideal case). The electrolyte flow rate was fixed at ~4.6 mL s^-1, and the electrolyte temperature was measured using a K-type thermocouple; a temperature variation of less than 2.5 °C between the highest and lowest solar concentrations was observed during the LSV measurements. The measurements were conducted at room temperature (~25 °C).