Photocharged molybdenum-doped BiVO4 photoanodes for simultaneous enhancements in charge transport and surface passivation

The two main drawbacks of monoclinic bismuth vanadate (BiVO4: BVO) as a photoanode, i.e., poor charge transport property and fast electron-hole recombination, were improved by simultaneous Mo doping and photocharged surface passivation methods. First, molybdenum-doped BiVO4 (BiVO4: Mo) was prepared to control the donor concentration without producing any secondary phase. Subsequently, photocharging treatment of the Mo-BVO photoanode induced a cathodic shift in onset potential, similar to 0.15 V (0.75-0.6 V vs RHE) and improved the photocurrent density (similar to 2.2-fold). Moreover, the photocharged 2% Mo-BVO photoanode exhibited an enhanced incident photon current efficiency (IPCE) of about 50% compared to only around 30% (440 nm > lambda > 330 nm range) for the non-photocharged photoanode. Mott-Schottky analysis revealed that 2% Mo doping greatly increased the donor concentration (similar to 1000-fold), whereas the photocharging technique only slightly increased the donor concentration (similar to 1.5-fold).