**2.4 Photocatalytic activity of layered perovskite materials**

In the general formula of the RP phase, An−1A2 I BnO3n+1, A and AI are alkali, alkaline earth, or rare earth metals, respectively, while B states to transition metals. A and AI cations are placed in the perovskite layer and boundary with 12-fold cuboctahedral and 9-fold coordination to the anions, respectively, whereas B cations are sited inside the perovskite system with anionic squares, octahedra, and pyramids. The tantalum-based RP phase materials have been examined as photocatalysts for degradation of organic pollutants under UV light irradiation conditions; such materials are K2Sr1.5Ta3O10 [124], Li2CaTa2O7 [125], H1.81Sr0.81Bi0.19Ta2O7 [126], and N-alkyl chain inserted H2CaTa2O7 [127]. A series of various metals and N-doped perovskite materials were synthesized, such as Sn, Cr, Zn, V, Fe, Ni, W, and N-doped K2La2Ti3O10, for photocatalysis studies under UV and visible light irradiation [128–133]. Still, only Sn-doping efficiently decreased the bandgap energy of K2La2Ti3O10 from 3.6 eV to 2.7 eV. The bandgap energy of N-doped K2La2Ti3O10 was measured to be around 3.4 eV. Additional RP phase kind titanates like Sr2SnO4 [134], Sr3Ti2O7 [135], Cr-doped Sr2TiO4 [136], Sr4Ti3O10 [137], Na2Ca2Nb4O13 [138], and Rh- and Ln-doped Ca3Ti2O7 [139] have also been examined. Bi2WO6 (2.8 eV) shows very high oxygen evolution efficacy than Bi2MoO6 (3.0 eV) from aqueous AgNO3 solution under visible-light-driven. Because of the appropriate bandgap energy, comparatively elevated photocatalytic performance, and good constancy, Bi2MO6 materials have been thoroughly examined as the Aurivillius phase kind that acts as photocatalysts under visible light. In this connection, hundreds of publications associated to the Bi2MoO6 and Bi2WO6 act as photocatalysts so far reported. Most of the investigations in the reports are concentrated on the synthesis of various nanostructured Bi2MoO6 and Bi2WO6 as well as nanofibers, nanosheets, ordered arrays, hollow spheres, hierarchical architectures, inverse opals, and nanoplates, etc., by various synthesis techniques like solvothermal, hydrothermal, electrospinning, molten salt, thermal evaporation deposition, and microwave. All these methods of hydrothermal process have been frequently working for the controlled sizes, shapes, and morphologies of the particles. The photocatalytic properties of these perovskite materials are mostly examined by the photodegradation of organic pollutants. Moreover, the investigations on the simple Bi2MoO6 and Bi2WO6, doped with various metals and nonmetals such as Zn, Er, Mo, Zr, Gd, W, F, and N, into Bi2MoO6 and Bi2WO6 was studied for increasing the photocatalytic performance under visible light. Therefore, these Bi2MO6-based photocatalysts is not specified here, due to further full deliberations that can be shown in many reviews [140–142].

ABi2Nb2O9 where A is Ca, Sr, Ba and Pb is other type of the AL-like layered perovskite material [143–150]. The bandgap energy of PbBi2Nb2O9 is 2.88 eV and originally described as an undoped with single-phase layered-type perovskite material used as photocatalyst employed under visible light irradiation [144]. Bi5FeTi3O15 is also Aurivillius (AL) type multi-layered nanostructured perovskite material with a low bandgap energy (2.1 eV) and also shows photocatalytic activity under visible light [151, 152]. Mostly, these materials were synthesized using the hydrothermal method that has been frequently working for the controlled shapes such as flower-like hierarchical morphology, nanoplate-based, and the complete advance process from nanonet-based to nanoplate-based micro-flowers was shown. The photocatalytic activity of Bi5FeTi3O15 was studied by the degradation of rhodamine

*Perovskite and Piezoelectric Materials*

phenol [91, 106, 107]. The other ABBI

Ag(TaNb)O3 [113] have also been studied. Related to AAI

the various materials as mentioned above. More studies on ABBI

existing visible light region then which greater influenced in the photodegradation of organic pollutants. Also, the study of photoluminescence supported improvement of the photocatalytic property due to the effective charge transfer from BiFeO3 to Au. Even though Ba, Ca, Mn, and Gd-doped BiFeO3 nanomaterials have exhibited noticeable photocatalytic property for the degradation of dyes [80–84], several nano-based LaFeO3 with various morphologies such as nanoparticles, nanorods, nanotubes, nanosheets, and nanospheres have also been synthesized for visible light photocatalysts for degradation of organic dyes [85–93]. Sodium bismuth titanate (Bi0.5Na0.5TiO3) has been extensively used for ferroelectric and piezoelectric devices. It was also investigated as a UV-light photocatalyst with a bandgap energy of 3.0 eV [94–97]. Hierarchical micro/nanostructured Bi0.5Na0.5TiO3 was produced by in situ self-assembly of Bi0.5Na0.5TiO3 nanocrystals under precise hydrothermal conditions, through the evolution mechanism was examined in aspect means that during which the growth mechanism was studied [95]. It was anticipated that the hierarchical nanostructure was assembled through a method of nucleation and growth and accumulation of nanoparticles and following in situ dissolution-recrystallization of the microsphere type nanoparticles with extended heating period and enhanced temperature or basic settings. The 3D hierarchical Bi0.5Na0.5TiO3 showed very high photocatalytic activity for the decomposition of methyl orange dye because of the adsorption of dye molecules and bigger surface area. The properties of Bi0.5Na0.5TiO3 were also assessed by photocatalytic degradation of nitric oxide in the gas phase [95]. La0.7Sr0.3MnO3, acting as a photocatalyst, was examined for solar light-based photocatalytic decomposition of methyl orange [96–98]. In addition, La0.5Ca0.5NiO3 [99], La0.5Ca0.5CoO3−δ [100], and Sr1−xBaxSnO3 (x = 0–1) [101] nanoparticles were synthesized for revealing improved photocatalytic degradation of dyes. A-site strontium-based perovskites such as SrTi1−xFexO3−δ, SrTi0.1Fe0.9O3−δ, SrNb0.5Fe0.5O3, and SrCo0.5Fe0.5O3−δ compounds were prepared through solid-state reaction and solgel approaches, and were examined for the degradation of organic pollutants under visible light irradiation [102–105]. Also, some other researchers modified A-site with lanthanum-based perovskites such as LaNi1−xCuxO3 and LaFe0.5Ti0.5O3 were confirmed as effective visible light photocatalysts for the photodegradation of p-chloro-

Ba(ZrSn)O3 [109], Na(BiTa)O3 [110], Na(TiCu)O3 [111], Bi(MgFeTi)O3 [112], and

catalysts are projected to show their new exhilarating photocatalytic efficiency. The mesoporous nature of LaTiO2N of photocatalyst attended due to thermal ammonolysis process of La2Ti2O7 precursor from polymer complex obtained from the solid-state reaction. The oxynitride analysis revealed that the pore size and shape, lattice defects and local defects, and oxidation states' local analysis related between morphology and photocatalytic activity were reported by Pokrant et al. [114]. Due to the high capability of accommodating an extensive array of cations and valences at both A- and B-sites, ABO3-kind perovskite materials are capable materials for fabricating solid-solution photocatalysts. On the other hand, equally the A and B cations can be changed by corresponding cations subsequent in a perovskite with the formula

O3 kind system means that BI-site substitution by a different cation is another option for tuning the physicochemical or photocatalytic properties of perovskites materials as photocatalyst, due to typically the B-position cations in ABO3 mostly regulate the position of the conduction band, moreover to construct the structure of perovskite system with oxygen atoms. The band positions of photocatalyst can be magnificently modified by sensibly coalescing dual or ternary metal cations at the B-position, or changing the ratio of several cations, which has been fine verified by

O3)1−x. Additional solid solution examples with CaZrO3–CaTaO2N

O3 kind photocatalysts with Ca(TiZr)O3 [108],

BO3-type perovskites, the

O3 kind of photo-

**8**

of (ABO3)x(AI

BI

ABBI

B and acetaldehyde under visible light [151]. The La substituted Bi5−xLaxTi3FeO15 (x = 1, 2) Al-type layered materials were synthesized through hydrothermal method and these materials were used for photodegradation of rhodamine B under solarlight irradiation [153]. Among all AL-type perovskite materials, only PbBi2Nb2O9, Bi2MO6 (M = W or Mo), and Bi5Ti3FeO15 are very high photocatalytic active under visible-light-driven due to low bandgap energy and photostability. Another type of layered perovskite material is Dion-Jacobson phase (DJ), a simple example is CsBa2M3O10 (M = Ta, Nb) and oxynitride crystals used for degradation of caffeine from wastewater under UVA- and visible-light-driven [154]. Similarly, another DJ phase material such means Dion–Jacobsen (DJ) as CsM2Nb3O10 (M = Ba and Sr) and also doped with nitrogen used for photocatalysts for degradation of methylene blue [155]. Zhu et al. prepared tantalum-based {111}-layered type of perovskite material such as Ba5Ta4O15 from hydrothermal method, which has been frequently employed for the controlled shape like hexagonal structure with nanosheets and used as photocatalyst for photodegradation of rhodamine B and gaseous formaldehyde [156]. Pola et al. synthesized a layered-type perovskite material constructed on A<sup>I</sup> AIITi2O6 (AI = Na or Ag or Cu and AII = La) structure for the photodegradation of several organic pollutants and industrial wastewater under visible-light-driven [157–162].


**11**

*Significant Role of Perovskite Materials for Degradation of Organic Pollutants*

BiFeO3 SG UV-Vis MO, RhB,

LaFeO3 HT Visible RhB, MB,

Ca or Mn-doped BiFeO3 HT UV-

La0.7Sr0.3MnO3 SG Solar

ATiO3 (A = Fe, Pb) and AFeO3

SrTiO3 nanocube-coated CdS

A(In1/3Nb1/3B1/3)O3 (A = Sr, Ba;

B = Sn, Pb)

(A = Bi, La, Y)

microspheres

**process**

N-doped NaNbO3 SS UV 2-Propanol [186–188] Ru-doped NaNbO3 HT Visible Phenol [189] AgNbO3 SS UV MB [190] La-doped AgNbO3 SS Visible 2-Propanol [191]

Ba-doped BiFeO3 ES Visible CR [79] Ca-doped BiFeO3 ES Visible CR [80] Ba or Mn-doped BiFeO3 ES Visible CR [82]

Gd-doped BiFeO3 SG Visible RhB [83] LaFeO3 Comb. UV Methyl phenol [84] LaFeO3 SG Visible RhB [85]

Ca-doped LaFeO3 SS Visible MB [92] LnFeO3 (Pr,Y) SG Visible RhB [193] SrFeO3−<sup>x</sup> US Visible Phenol [194] SrFeO3 SS Visible MB [195] BaZrO3 SG UV MB [196] BaZrO3 HT UV MO [197]

Zn0.9Mg0.1TiO3 SG Visible MB [199]

Ag/AgCl/CaTiO3 HT Visible RhB [201] TiO2-coupled NiTiO3 SS Visible MB [202] ZnTiO3 HT UV MO and PCP [203] Mg-doped BaZrO3 SS UV MB [204] SrSnO3 MW UV MO [205] LaCoO3 MW Visible MO [206] LaCoO3 Ads. UV MB, MO [207] LaCoO3 ES UV RhB [208] LaNiO3 SG Visible MO [209] Bi0.5Na0.5TiO3 HT UV MO [93]

La0.5Ca0.5NiO3 SG UV RB5 [98] La0.5Ca0.5CoO3 SG UV CR [99] Sr1−xBaxSnO3 SS UV Azo-dye [100] BaCo1/2Nb1/2O3 SG Visible MB [210] Ba(In1/3Pb1/3M1/3)O3 (M = Nb and Ta) SS Visible MB, 4-CP [211]

SrTi1−xFexO3−δ SS Visible MB [102]

**Light source**

Visible

4-CP

**Pollutants References**

RhB [82]

chlorophenol

SG Visible MB [198]

pollutants

MO [97]

HT Visible Antibiotic

light

SS Visible MB, 4-CP [212]

[69– 77]

[86, 90, 91, 192]

[200]

*DOI: http://dx.doi.org/10.5772/intechopen.91680*

**Perovskite system Synthesis** 


#### *Significant Role of Perovskite Materials for Degradation of Organic Pollutants DOI: http://dx.doi.org/10.5772/intechopen.91680*

*Perovskite and Piezoelectric Materials*

**Perovskite system Synthesis** 

Fe-doped SrTiO3 ST Visible

B and acetaldehyde under visible light [151]. The La substituted Bi5−xLaxTi3FeO15 (x = 1, 2) Al-type layered materials were synthesized through hydrothermal method and these materials were used for photodegradation of rhodamine B under solarlight irradiation [153]. Among all AL-type perovskite materials, only PbBi2Nb2O9, Bi2MO6 (M = W or Mo), and Bi5Ti3FeO15 are very high photocatalytic active under visible-light-driven due to low bandgap energy and photostability. Another type of layered perovskite material is Dion-Jacobson phase (DJ), a simple example is CsBa2M3O10 (M = Ta, Nb) and oxynitride crystals used for degradation of caffeine from wastewater under UVA- and visible-light-driven [154]. Similarly, another DJ phase material such means Dion–Jacobsen (DJ) as CsM2Nb3O10 (M = Ba and Sr) and also doped with nitrogen used for photocatalysts for degradation of methylene blue [155]. Zhu et al. prepared tantalum-based {111}-layered type of perovskite material such as Ba5Ta4O15 from hydrothermal method, which has been frequently employed for the controlled shape like hexagonal structure with nanosheets and used as photocatalyst for photodegradation of rhodamine B and gaseous formaldehyde [156]. Pola et al. synthesized a layered-type perovskite material constructed on A<sup>I</sup>

 = Na or Ag or Cu and AII = La) structure for the photodegradation of several organic pollutants and industrial wastewater under visible-light-driven [157–162].

> **Light source**

light

SrTiO3/Fe2O3 HT Visible TC [179] BaTiO3 SG UV Pesticide [36] BaTiO3 SG UV Aromatics [58] BaTiO3 HT UV MO [58] KNbO3 HT Visible RhB [180] KNbO3 HT UV RhB [181] KNbO3 HT Visible MB [182] NaNbO3 SS UV RhB [183] NaNbO3 Imp. UV 2-Propanol [184] NaNbO3 SS UV MB [185]

**process**

NaTaO3 HT UV CH3CHO [163] La-doped NaTaO3 SG UV MB [164] La-doped NaTaO3 HT UV MB [165] Cr-doped NaTaO3 HT UV MB [166] Eu-doped NaTaO3 SS UV MB [167] Bi-doped NaTaO3 SS UV MB [168] N-doped NaTaO3 SS UV MB [169] C-doped NaTaO3 HT Visible NOx [36] N/F co-doped NaTaO3 HT UV RhB [170] SrTiO3 HT UV RhB [42, 43, 171] Fe-doped SrTiO3 SG Visible RhB [172] N-doped SrTiO3 HT Visible MB, RhB, MO [173] F-doped SrTiO3 BM Visible NO [174] Ni/La-doped SrTiO3 SG Visible MG [175] S/C co-doped SrTiO3 SS Visible 2-Propanol [176] N/La-doped SrTiO3 SG Visible 2-Propanol [177]

AIITi2O6

**Pollutants References**

TC [178]

**10**

(AI


*SS: solid state; HT: hydrothermal; SG: sol-gel; BM: ball-milling; ES: electronspun; MW: microwave; Comb.: combustion; US: ultrasonic; MS: molten salt; Imp.: impregnation; Ads.: adsorption; ST: solvothermal; RhB: rhodamine B; MO: methyl orange; MB: methylene blue; 4-cp: 4-chlorophenol; MG: malachite green; CR: congo red; NO: nitrogen monoxide; PA: isopropyl alcohol; TC: tetracycline; and PCP: pentachlorophenol.*

#### **Table 1.**

*Perovskite materials used as photocatalysts (ABO3, AAI BO3, AAI BO3, ABBI O3, AB(ON)3, and AAI BBIIO3) for degradation of pollutants.*

#### **Figure 2.**

*SEM patterns of BiFeO3: (a) microspheres and (b) microcubes. The intensified pictures are revealed in the upper part inserts. Recopied with consent from Ref. [147]. Copyright © 2010, American Chemical Society.*

**13**

**Author details**

Someshwar Pola\* and Ramesh Gade

provided the original work is properly cited.

Hyderabad, Telangana, India

Department of Chemistry, University College of Science, Osmania University,

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to: somesh.pola@gmail.com

*Significant Role of Perovskite Materials for Degradation of Organic Pollutants*

Authors would like to thank DST-FIST schemes and CSIR, New Delhi. One of us (Ramesh Gade) thanks Council of Scientific & Industrial Research (CSIR), New

I am thankful to Department of Chemistry, University College of Science, Osmania University, for their continuous attention in this study and useful discus-

sions, and to Prof. B. Manohar for her support in working on the chapter.

*DOI: http://dx.doi.org/10.5772/intechopen.91680*

Delhi, for the award of Junior Research Fellowship.

**Acknowledgements**

**Thanks**

*Significant Role of Perovskite Materials for Degradation of Organic Pollutants DOI: http://dx.doi.org/10.5772/intechopen.91680*
