All Printed Photoanode/Photovoltaic Mini-Module for Water Splitting

Printing a large-area bismuth vanadate photoanode offers a promising approach for cost-effective photoelectrochemical (PEC) water splitting. However, the light absorption trade-off with charge transfer, as well as stability issues always lead to poor PEC efficiency. Here, the solution-processed recipe is advanced with BiI₃ dopant for the printed deposition with controllable crystal growth. The resultant BiVO₄ films prefer (001) orientation with nanorod feature on substrate, allowing a faster charge transfer and improved photocurrent. The BiVO₄ photoanode in tandem with perovskite solar module delivers an operating photocurrent density of 5.88 mA cm^-2 at zero bias in 3.11 cm² active area under AM 1.5 G illumination, yielding a solar-to-hydrogen efficiency as high as 7.02% for unbiased water splitting. Equally important, the stability of the aged BiVO₄ rods has been addressed to distinguish phase segregation at surface. The photocatalysis degradation composes of vanadium loss and Bi₂ O₃ enriching at the surface, opening a lid on the long-term stability of BiVO₄ photoanodes.