Effect of BiVO₄ Crystalline Phases on the Photoinduced Carriers Behavior and Photocatalytic Activity

Abstract

A series of different crystalline phases BiVO 4 photocatalysts (tetragonal, monoclinic, and monoclinic/tetragonal heterophase) have been prepared by a coprecipitation and molten salt method. High-resolution transmission electron microscopy (HRTEM) results show that an interface of intimate contact is formed in monoclinic/tetragonal heterophase and monoclinic phase is mainly on the surface of nanoparticles. Surface photovoltage (SPV) and transient photovoltage (TPV) techniques are used to further investigate the transfer process of photoinduced charge carriers. The results show that the behavior of photoinduced charges markedly depend on the crystalline phases of BiVO 4 samples, and the presence of interface in monoclinic/tetragonal heterophase provides a spatial condition for charge transfer, promotes the separation of photoinduced electronÀhole pairs, and changes the migration direction of photoinduced carriers. The relationship between behavior of photoinduced charge carriers and photocatalytic activity was discussed in detail, which would provide a greater insight into the intrinsic reasons of the enhancement in photocatalytic activity.

Improved O2 evolution from a water splitting reaction over Er3+ and Y3+ co-doped tetragonal BiVO4

“…25 These results clearly show that the behaviour of photoinduced charges is markedly dependent on the BiVO 4 crystalline phases. Moreover, the presence of an interface in the monoclinic/tetragonal heterophase provides a spatial condition for charge transfer.…”

Exalted photocatalytic activity of tetragonal BiVO4by Er3+doping through a luminescence cooperative mechanism

“…Thus, Fan et al reported that the particular m-t heterostructured BiVO 4 is expected to promote the separation of photoinduced electron-hole pairs. 24,25 In spite of this, the exalted performance of Er-doped t-BiVO 4 (6.0 × 10 −4 s −1 ) with respect to the t-BiVO 4 (3.0 × 10 −4 s −1 ) system cannot be attributed only to a surface area contribution or the presence of a small amount of monoclinic phase. Indeed, much research has shown that the surface area would play a key role in the final photocatalytic performance.…”

A ternary Er3+-BiVO4/TiO2 complex heterostructure with excellent photocatalytic performance

“…28 The improved photocatalytic performance of m-t heterostructured BiVO 4 has been associated to promotion photoinduced electron-hole pairs separation. 29 Within this framework, Obregón et al reported the unexpected enhanced photocatalytic activity of tetragonal stabilized Ln-doped BiVO 4 . 30,31 Moreover, by changing the precursor addition sequence in the synthesis route, we have obtained a monoclinic-tetragonal heterostructured Er 3+ -BiVO 4 exhibiting notably a high photoactivity under sun-like irradiation.…”