BiOI–BiVO 4 photoanodes with significantly improved solar water splitting capability: p–n junction to expand solar adsorption range and facilitate charge carrier dynamics

Herein, we report an effective synthesis method of BiOI/BiVO4 p–n junction that greatly improves the performance of BiVO4 for photoelectrochemical water splitting due to a synergistic effect. The photocurrent density of BiOI/BiVO4 photoanodes achieved 3.27 mA cm2 at 1.23 V vs. RHE, which is much higher than those of pristine BiVO4 and BiOI (1.23 mA cm2 and 0.15 mA cm2 at 1.23 V vs. RHE, respectively). At 0.68 eV vs. RHE, BiOI/BiVO4 shows the maximum of applied bias photo-to-current efficiency of 0.97% at 0.68 V vs. RHE. This new BiOI/BiVO4 p–n junction not only facilitates the separation and transfer of photo-generated charges, but also expands the light absorption range, which is the origin for this synergistic effect. The BiOI/BiVO4 p–n junction materials with excellent solar water splitting capability should shed light on designing and fabricating the next-generation photocatalysts.