Mo6+ Doped BiVO4 with improved Charge Separation and Oxidation Kinetics for Photoelectrochemical Water Splitting

• Published in: Electrochimica acta 2017-12, Vol.256, p.268-277
• Main Authors: Yang, Lin, Xiong, Yuli, Guo, Wenlong, Guo, Jiangna, Gao, Di, Zhang, Yunhuai, Xiao, Peng
• Format: Article
• Language: English
• Subjects: BiVO4; Charge oxidation kinetics; Crystal deformation; Photoelectrochemical; Photovoltage
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2017.09.186

Highly charge separation and oxidation kinetics of Mo doped BiVO4 photoanode is fabricated for photoelectrochemical water splitting. After Mo doped in monoclinic BiVO4, the deformation of crystal with VO4 tetrahedron and decrease the energy of transfer of photogenerated electrons thus help to overcome poor electron mobility intrinsically. Moreover, this structure can create a higher photovoltage and enhance the overall photoelectrochemical performance, and the different lines are BV (black), 3SMo:BV (red), 3AMo:BV (blue), and 10AMo:BV (pink), respectively. [Display omitted] •Mo-doping BiVO4 shows the highest photocurrent (1.91mA/cm2 at 1.23V vs. RHE).•The ηsep (74.42%) and ηox (49.25%) are obtained by 3AMo:BV at 1.23V vs. RHE.•Mo-doped structure is beneficial for the transfer of photogenerated electrons.•Higher photovoltage is beneficial for the charge oxidation kinetics. Monoclinic bismuth vanadate (BiVO4) has been widely applied as a promising n-type semiconductor for photoelectrochemical (PEC) water splitting because of its low cost, environmentally friendly, and relatively narrow band gap of ∼2.4eV. Here, we developed a facile fabrication of Mo doped BiVO4 photoanode on the fluorine-doped tin oxide substrate by electrodeposition method and used these samples to better understand the doping effect for charge separation and charge oxidation kinetics. Compared with the undoped BiVO4 photoanode, the optimized Mo doped BiVO4 (3AMo:BV) produced a much higher photocurrent of 1.91mA/cm2 at 1.23V vs. RHE under AM 1.5G illumination for water oxidation. The results of the photoelectric conversion kinetics for various samples revealed that the charge separation and oxidation kinetics efficiencies for 3AMo:BV sample are 74.42% and 49.25% at 1.23V vs. RHE, while the values for undoped BiVO4 are 48.04% and 32.98%, respectively. The improved PEC performance for Mo doped BiVO4 is mainly ascribed to the crystal deformation caused by larger tetrahedral ionic VO4 and higher photovoltage generated by the interface of photoanode and electrolyte.