Improved Charge Carrier Dynamics by UnconventionalDoping Strategy for BiVO 4 Photoanode

Bismuth vanadate (BiVO 4 ) is one of the promising photoanodes for solar fuelproduction, but it faces the challenge of poor charge separation due to itssluggish charge transport and short diffusion length. The ability to regulatecharge separation is pivotal for obtaining high efficiency of BiVO4 . Herein, anunconventional acceptor doping strategy is proposed for the first time, dem-onstrating its effectiveness in enhancing charge carrier dynamics. Introducingthe Al 3þ ions into BiVO 4 induced a decrease in carrier concentration but anincrease in the diffusion length and carrier lifetime due to the reduced chance ofencountering an electron-hole pair. Furthermore, decreasing carrier concentra-tion leads to a widened space charge layer, enabling facile charge transportand separation. The optimized 0.5 at% Al-doped BiVO 4 (Al:BVO_0.5) exhibited3.5 and 2.6 order of magnitude increase in diffusion length and in carrierlifetime, respectively, compared to pristine BiVO 4 , achieving a photocurrentdensity of 3.02 mA cm2 at 1.23V RHE (V versus reversible hydrogen electrode)under AM 1.5 G illumination. This research provides a new understanding ofsemiconductor physics and design principles for more efficient photoanodes.RESEARCH ARTICLEwww.small-science-journal.comSmall Sci. 2025, 2500051 2500051 (1 of 9) © 2025 The Author(s). Small Science published by Wiley-VCH GmbH