Composite Photocatalysts Containing BiVO4 for Degradation of Cationic Dyes

Abstract

The creation of composite structures is a commonly employed approach towards enhanced photocatalytic performance, with one of the key rationales for doing this being to separate photoexcited charges, affording them longer lifetimes in which to react with adsorbed species. Here we examine three composite photocatalysts using either WO3, TiO2 or CeO2 with BiVO4 for the degradation of model dyes Methylene Blue and Rhodamine B. Each of these materials (WO3, TiO2 or CeO2) has a different band edge energy offset with respect to BiVO4, allowing for a systematic comparison of these different arrangements. It is seen that while these offsets can afford beneficial charge transfer (CT) processes, they can also result in the deactivation of certain reactions. We also observed the importance of localized dye concentrations, resulting from a strong affinity between it and the surface, in attaining high overall photocatalytic performance, a factor not often acknowledged. It is hoped in the future that these observations will assist in the judicious selection of semiconductors for use as composite photocatalysts.

Investigation of photodegradation of rhodamine B over a BiOX (X = Cl, Br and I) photocatalyst under white LED irradiation

“…Moreover, when the energy of the incident photon is larger than the band gap of the semiconductor, the electrons and holes are generated in the conduction band (CB) and valence band (VB) of the semiconductor. Then, the photoexcited electrons and holes may directly react with the dyes or produce the reactive radical species for the degradation of dye molecules (direct photocatalytic process) [36,37]. However, based on the DRS results, the band gaps of BiOCl, BiOBr and BiOI are about 3.30, 2.82 and 1.72 eV, respectively.…”

TiO2-Low Band Gap Semiconductor Heterostructures for Water Treatment Using Sunlight-Driven Photocatalysis

“…% m-BiVO 4 /TiO 2 nanocomposite was prepared by a simple impregnation method and was tested in the degradation of phenol. This system has been tested by other authors using different approaches and modification [31][32][33]. Other semiconductors that have been coupled to TiO 2 to form a type I heterojunction [18] are WO 3 [34,35], Fe 2 O 3 [36], MoS 2 [37] and BiOI [36].…”

Rational Design of 3D Hierarchical Ternary SnO2/TiO2/BiVO4 Arrays Photoanode toward Efficient Photoelectrochemical Performance

“…Besides, the host–guest heterojunction electrode using two or more dissimilar materials to take the task of charge transport and light absorption, respectively, is another popular strategy to promote the charge transport and suppress the recombination of electron–hole pairs . For instance, BiVO 4 as a light absorber has been combined with various other semiconductors to form a type II configuration such as TiO 2 /BiVO 4 , WO 3 /BiVO 4 , SnO 2 /BiVO 4 , and Fe 2 O 3 /BiVO 4 . Among them, TiO 2 is very attractive due to its relatively negative flat band potential and good chemical stability.…”

“…[13][14][15][16][17][18] Nevertheless, the poor charge transport ability, short carrier diffusion lengths (≈70 nm), and high charge recombination rates of BiVO 4 greatly limit its practical PEC performance. [32] For instance, BiVO 4 as a light absorber has been combined with various other semiconductors to form a type II configuration such as TiO 2 /BiVO 4 , [33][34][35][36][37][38] WO 3 /BiVO 4 , [39][40][41][42] SnO 2 /BiVO 4 , [43,44] and Fe 2 O 3 /BiVO 4 . [19][20][21][22][23][24] Nanostructured electrode design is one effective route to enhance the light absorption and charge transport ability.…”