Surface engineering of Bi2MoO6 as an efficient photoanode in tandem water splitting system by pulsed sonoelectrodeposition

The systematic and controlled synthesis of surface vacancies in semiconductors consider as a promising rout to modify their properties. Therefore, synthetic methods that can create these surface defects in nanomaterials are of great interest. Bismuth molybdate with engineered surface defect growing on its different crystal faces can be an excellent candidate for photoelectrochemical (PEC) water splitting. Simultaneously engineering the growth of the desired crystal face and creating surface vacancies on it would be very difficult. Herein, sonoelectrodeposition (SED) applied with continuous and pulse modes. The two different modes of ultrasound led to create two unexpectedly morphologies with different exposed crystal facets. Pulsed sonoelectrodeposition (PSED) method caused raspberry-like morphology with {010} desired exposed facet including high amounts of stabilized Oxygen vacancies (OVs). High efficiencies of PEC and dye sensitized solar cell (DSSC)/PEC with prepared photoanode originated from high amount of stabilized OVs, different exposed crystal facets and morphologies. The solar to hydrogen (STH) conversion in unassisted water splitting system (DSSC)/PEC was about 3.62%. Results confirmed that pulse mode of ultrasound acts as a proper method for simultaneously engineering of desired facet growth and creation of high amount of stabilized OVs on its surface.