Photoelectrochemical performance of a spin coated TiO2 protected BiVO4-Cu2O thin film tandem cell for unassisted solar water splitting

A tandem cell consisting of a Mo-BiVO4/TiO2/FeOOH photoanode-Cu2O/TiO2/MoS2 photocathode was prepared for unassisted solar water splitting. The protective TiO2 layer was prepared by a cost-effective spin coating technique. The individual Mo-BiVO4/TiO2/FeOOH photoanode and the Cu2O/TiO2/MoS2 photocathode yielded a current density of similar to 0.81 mA cm(-2) at 1.23 V vs. RHE and similar to-1.88 mA cm(-2) at 0 V vs. RHE, respectively under 100 mW cm(-2) xenon lamp illumination. From the individual photoelectrochemical analysis, we identify the operating points of the tandem cell as 0.66 V vs. RHE and 0.124 mA cm(-2). The positive current density from the operating points proves the possibility of non-zero operation of the tandem cell. Finally, a two-electrode Mo-BiVO4/TiO2/FeOOH-Cu2O/TiO2/MoS2 tandem cell was constructed and analysed for unassisted operation. The obtained unassisted current density of the tandem cell was similar to 65.3 mu A cm(-2) with better stability compared to the bare BiVO4-Cu2O tandem cell. The results prove that the spin coated TiO2 protective layer can be a viable approach to protect the photoelectrodes from photocorrosion with better stability and enhanced photoelectrochemical (PEC) performance.

Automated summary

In this study, a tandem cell consisting of a Mo-BiVO4/TiO2/FeOOH photoanode-Cu2O/TiO2/MoS2 photocathode was prepared for unassisted solar water splitting. The spin coated TiO2 protective layer demonstrated better stability and enhanced photoelectrochemical performance.