Ultrathin Ti/TiO2/BiVO4 nanosheet heterojunction arrays for photoelectrochemical water oxidation

Abstract

Abstract Bismuth vanadate (BiVO4) photoanode has attracted intensive attention recently due to its narrow band gap and suitable band edges. However, BiVO4 is suffered from slow charge transportation and short carrier diffusion length resulting a low energy conversion efficiency. Herein, we proposed a strategy for fabricating ultrathin Ti/TiO2/BiVO4 nanosheet heterojunction arrays by a sequential ionic layer adsorption reaction (SILAR) method depositing BiVO4 on top of Ti/TiO2 nanosheet arrays. The photocurrent of Ti/TiO2/BiVO4 photoanode prepared at the precursor concentration of 0.04\u202fM is 1.2\u202fμA/cm2 and increase to 5.8\u202fμA/cm2 for that of 0.02\u202fM. The ultrathin Ti/TiO2 nanosheet arrays possess an ideal surface area for coupling nanoscale BiVO4 as much as possible to construct heterojunction interfaces, which not only shorten the charge transfer pathway but also provide a flexible and strong conductive charge collector. Besides, the formation of heterojunctions between ultrathin TiO2 and BiVO4 favors the photoinduced electrons transfer from BiVO4 to TiO2 suppressing the recombination of photogenerated electron-hole pairs effectively.