Hydrothermally synthesized ternary heterostructured MoS₂/Al₂O₃/g-C₃N₄ photocatalyst

Vattikuti, S.V. Prabhakar,Byon, Chan Elsevier 2017 Materials research bulletin Vol.96 No.3

<P><B>Abstract</B></P> <P>A multifaceted ternary MoS<SUB>2</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB>/g-C<SUB>3</SUB>N<SUB>4</SUB> nanocomposite was prepared from a simple and facile hydrothermal method, which has good photocatalytic performance for the degradation of crystal violet (CV) dye under visible light irradiation. As a result of wide structural features for the charge separation mechanism, the formation of a ternary heterojunction affects the photocatalytic activity of the MoS<SUB>2</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB>/g-C<SUB>3</SUB>N<SUB>4</SUB> nanocomposite remarkably. The photocatalytic activity of ternary nanocomposite was approximately 10.28 and 1.65 times higher than that of pure g-C<SUB>3</SUB>N<SUB>4</SUB> and 20Al-gCN, respectively. More significantly, the ternary nanocomposite also showed good photostability and reusability. The enhanced visible light photocatalytic activity was attributed to the effective photocatalytic mechanism of charge separation of the ternary system, whereas the surface properties were key factors for photodegradation of the CV dye.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Surfactant-free synthetic method for synthesis of MoS<SUB>2</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB>/g-C<SUB>3</SUB>N<SUB>4</SUB> was proposed. </LI> <LI> The optimized synthetic conditions for MoS<SUB>2</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB>/g-C<SUB>3</SUB>N<SUB>4</SUB> nanocomposites were also investigated. </LI> <LI> Possible growth mechanism of the MoS<SUB>2</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB>/g-C<SUB>3</SUB>N<SUB>4</SUB> heterostructure is also reported. </LI> <LI> 2Mo-Al-gCN sample revealed higher specific surface area with formation of mesoporous structure. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced photocatalytic activity of ZnS nanoparticles loaded with MoS₂ nanoflakes by self-assembly approach

Vattikuti, S.V.P.,Byon, C.,Jeon, S. North-Holland 2016 PHYSICA B-CONDENSED MATTER - Vol.502 No.-

A hybrid consisting of ZnS nanoparticles supported on layered MoS<SUB>2</SUB>-ZnS was synthesized by a hydrothermal method based on self-assembly technique without using a template. XRD, SEM-EDX, TEM, HR-TEM, TG-DTA, XPS, N<SUB>2</SUB> adsorption-desorption, and UV-Vis spectroscopies were used to characterize the structural features, morphology, and composition of the MoS<SUB>2</SUB>-ZnS hybrid. The results show that the MoS<SUB>2</SUB>-ZnS hybrid is mainly ZnS nanoparticles on layered MoS<SUB>2</SUB> with a thickness of ca. 5-20nm. The combination of the MoS<SUB>2</SUB> and ZnS hybrid structure is beneficial for enhancing the photocatalytic degradation of rhodamine B (RhB) under visible light irradiation. A possible photoreaction mechanism of the MoS<SUB>2</SUB>-ZnS hybrid in the degradation is proposed. The photoexcited electrons from the ZnS could easily transfer to the conduction band of MoS<SUB>2</SUB>, thus decreasing the recombination of photoinduced carriers and enabling the degradation of RhB under visible light irradiation.

Hydrothermally synthesized Na₂Ti₃O₇ nanotube–V₂O₅ heterostructures with improved visible photocatalytic degradation and hydrogen evolution - Its photocorrosion suppression

Vattikuti, S.V. Prabhakar,Reddy, Police Anil Kumar,NagaJyothi, P.C.,Shim, Jaesool,Byon, Chan Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.740 No.-

<P><B>Abstract</B></P> <P>There is still a need to prepare heterostructure photocatalysts with high activity and recyclability but without using precious metals to reduce the cost of photocatalysts. Thus, a facile and simple method for the synthesis of a Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst via hydrothermal synthesis is reported herein. The chemical composition, morphology, and structural features of the photocatalyst were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), N<SUB>2</SUB> adsorption–desorption specific surface area analysis (BET), and diffuse reflectance absorption (DRS) methods. It was observed that the specific surface area of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst increased with the incorporation of V<SUB>2</SUB>O<SUB>5</SUB>. The Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst was then used for the removal of rhodamine B (RhB) under simulated solar light irradiation. The Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst revealed excellent photocatalytic activity and photodegradation kinetics as compared to pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotubes and V<SUB>2</SUB>O<SUB>5</SUB> photocatalysts. Furthermore, both the photoactivity and long-term stability of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst were superior to those of the pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotubes and V<SUB>2</SUB>O<SUB>5</SUB> photocatalysts. The excellent photocatalytic performance of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst can be ascribed to its high specific surface area (283.71 m<SUP>2</SUP>g<SUP>−1</SUP>), mesoporous structure, highly dispersed V<SUB>2</SUB>O<SUB>5</SUB> nanoparticles, and hindrance of electron–hole pair recombination of Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> due to the V<SUB>2</SUB>O<SUB>5</SUB> incorporation, which is proven by the photoelectrochemical results, including photocurrent and electron impendence spectroscopy results. In addition, during the study of photocatalytic hydrogen evolution, the hydrogen yield of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB>/V<SUB>2</SUB>O<SUB>5</SUB> nanocomposite was 1.83 times that of pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB>, which also exhibited excellent photocatalytic activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Heterojunction of Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs/V<SUB>2</SUB>O<SUB>5</SUB> NPs was developed via hydrothermal method. </LI> <LI> Visible photocatalytic RhB degradation studies were performed over Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs/V<SUB>2</SUB>O<SUB>5</SUB> NPs. </LI> <LI> Improved degradation efficiency was observed over Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs/V<SUB>2</SUB>O<SUB>5</SUB> NPs when compared to pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs. </LI> <LI> V<SUB>2</SUB>O<SUB>5</SUB> NPs were successfully utilized as cocatalyst for pollutant degradation. </LI> <LI> Charge recombination was diminished in the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs by the addition of V<SUB>2</SUB>O<SUB>5</SUB> NPs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Synthesis and Structural Characterization of Al₂O₃-Coated MoS₂Spheres for Photocatalysis Applications

Vattikuti, S. V. Prabhakar,Byon, Chan Hindawi Limited 2015 Journal of nanomaterials Vol.2015 No.-

<P>This paper reports the synthesis of novel monodisperse Al2O3-coated molybdenum disulfide nanospheres (i.e., core-shell structures) using a one-step facile hydrothermal method. XPS analysis confirmed the purity and stable structure of the Al2O3-coated MoS2nanospheres. A possible growth mechanism of the core-shell structure is also reported, along with their influence on the photodegradation process of rhodamine B (RhB). The Al2O3-coated MoS2nanospheres demonstrate good photocatalytic activity and chemical stability compared to MoS2spheres. TG-DTA analysis provided insight into the decomposition process of the precursor solution and the stability of the nanoparticles. The enhanced photocatalytic activity makes the Al2O3-coated MoS2nanospheres a promising candidate as a photocatalyst that could be used in place of traditional Al2O3/MoS2photocatalyst for the removal of pollutants from waste water.</P>

Carbon/CuO nanosphere-anchored g-C₃N₄ nanosheets as ternary electrode material for supercapacitors

Vattikuti, S.V. Prabhakar,Reddy, B. Purusottam,Byon, Chan,Shim, Jaesool Elsevier 2018 Journal of solid state chemistry Vol.262 No.-

<P><B>Abstract</B></P> <P>Novel electrode materials for supercapacitors comprised of carbon and copper oxide (CuO) nanospheres on graphitic carbon nitride (g-C<SUB>3</SUB>N<SUB>4</SUB>) nanosheets, denoted as C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> are self-assembled via a one-step co-pyrolysis decomposition method. The pure g-C<SUB>3</SUB>N<SUB>4</SUB> and C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> were confirmed by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), thermal gravimetric and differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS), N<SUB>2</SUB> adsorption/desorption studies and Fourier-transform infrared spectroscopy (FTIR). The specific capacitance was 247.2 F g<SUP>−1</SUP> in 0.5 M NaOH at a current density of 1 A g<SUP>−1</SUP>, and more than 92.1% of the capacitance was retained after 6000 cycles. The property enhancement was ascribed to the synergistic effects of the three components in the composite. These results suggest that C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> possessed an excellent cyclic stability with respect to their capacity performance as electrode materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An efficient C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> supercapacitor electrode was synthesized. </LI> <LI> A ternary hybrid was developed via co-pyrolysis in situ growth. </LI> <LI> The C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> hybrid exhibits a 247.2 F g<SUP>−1</SUP> at scan rate of 1 Ag<SUP>−1</SUP>. </LI> <LI> Fast charge transfer was observed over the C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> hybrid. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Synthesis of vanadium-pentoxide-supported graphitic carbon nitride heterostructure and studied their hydrogen evolution activity under solar light

Vattikuti, S. V. Prabhakar,Reddy, Police Anil Kumar,Shim, Jaesool,Byon, Chan Springer-Verlag 2018 Journal of materials science. Materials in electro Vol.29 No.21

Co-precipitation synthesis and characterization of faceted MoS2 nanorods with controllable morphologies

Vattikuti, S. V.,Byon, C.,Reddy, C. V.,Shim, J.,Venkatesh, B. Springer Science + Business Media 2015 APPLIED PHYSICS A MATERIALS SCIENCE AND PROCESSING Vol.119 No.3

In situ fabrication of the Bi₂O₃–V₂O₅ hybrid embedded with graphitic carbon nitride nanosheets: Oxygen vacancies mediated enhanced visible-light–driven photocatalytic degradation of organic pollut

Vattikuti, S.V. Prabhakar,Police, Anil Kumar Reddy,Shim, Jaesool,Byon, Chan Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.447 No.-

<P><B>Abstract</B></P> <P>Novel mesoporous ternary hybrids comprising Bi<SUB>2</SUB>O<SUB>3</SUB>/V<SUB>2</SUB>O<SUB>5</SUB> photocatalysts anchored on graphitic carbon nitride (g-C<SUB>3</SUB>N<SUB>4</SUB>) nanosheets were synthesized via an in situ co-pyrolysis approach and characterized by a series of techniques, including X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller analysis, thermogravimetric-differential thermal analysis, Fourier transform infrared spectroscopy, ultraviolet–visible spectrometry, photoluminescence and electron paramagnetic resonance (EPR). The hybrids were subsequently tested as photocatalysts for the degradation of the phenol red (PR) pollutant under visible light irradiation. The well-designed ternary hybrids showed pure and randomly distributed Bi<SUB>2</SUB>O<SUB>3</SUB>/V<SUB>2</SUB>O<SUB>5</SUB> (denoted as BiV) nanoparticles on monodispersed g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets. The as-prepared ternary Bi<SUB>2</SUB>O<SUB>3</SUB>/V<SUB>2</SUB>O<SUB>5</SUB>@g-C<SUB>3</SUB>N<SUB>4</SUB> (i.e., BiV@g-C<SUB>3</SUB>N<SUB>4</SUB>) hybrids demonstrated high specific surface areas with remarkable mesoporous characteristics. The photodegradation efficiencies of the ternary hybrids for PR were 1.2 and 1.8 times higher than those of binary BiV and pristine Bi<SUB>2</SUB>O<SUB>3</SUB>, respectively, at 50 min irradiation time under simulated solar light irradiation. At the end of the phototreatment, the amount of PR pollutant was reduced to 98.1% in 50 min by using the BiV@g-C<SUB>3</SUB>N<SUB>4</SUB> nanocomposites under simulated solar light irradiation and more efficient for photocatalytic H<SUB>2</SUB> production. Based on an electrochemical analysis, we propose a photocatalytic degradation pathway for PR under visible light irradiation. In addition, the BiV@g-C<SUB>3</SUB>N<SUB>4</SUB> nanocomposite photocatalysts exhibited both long-term stability and photocatalytic efficiency for the degradation of the PR dye. The excellent photoelectrochemical performance of the BiV@g-C<SUB>3</SUB>N<SUB>4</SUB> photocatalysts can be ascribed to their highly dispersed V<SUB>2</SUB>O<SUB>5</SUB> and Bi<SUB>2</SUB>O<SUB>3</SUB> nanoparticles, mesoporous structure, and high specific surface area (83.75 m<SUP>2</SUP> g<SUP>−1</SUP>).</P> <P><B>Highlights</B></P> <P> <UL> <LI> BiV@g-C<SUB>3</SUB>N<SUB>4</SUB> photocatalyst was successfully synthesized via co-pyrolysis. </LI> <LI> Synthetic procedure may open up an opportunity to tailor the morphologies of nanocomposites. </LI> <LI> Studied the oxygen vacancies enhanced photocatalytic activity of BiV@g-C<SUB>3</SUB>N<SUB>4.</SUB> </LI> <LI> Photodegradation and H<SUB>2</SUB> evolution mechanism of the BiV@g-C<SUB>3</SUB>N<SUB>4</SUB> photocatalyst is elucidated and discussed. </LI> <LI> BiV@g-C<SUB>3</SUB>N<SUB>4</SUB> photocatalyst demonstrated 21.08 folds higher H<SUB>2</SUB> production rate than pure ones. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Binder-free WS₂/ZrO₂ hybrid as a photocatalyst for organic pollutant degradation under UV/simulated sunlight and tests for H₂ evolution

Vattikuti, S.V. Prabhakar,Devarayapalli, K.C.,Nagajyothi, P.C.,Shim, Jaesool Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.809 No.-

<P><B>Abstract</B></P> <P>Novel photocatalysts based on sunlight-driven active two-dimensional (2D) layered materials have drawn considerable attention because of their structural-to-photoactive properties. In this study, via binder-free electrostatic self-assembly, WS<SUB>2</SUB>/ZrO<SUB>2</SUB> hybrids were synthesized using a two-step hydrothermal process. The catalysts were thoroughly examined using different analysis techniques. The results indicated that in the WS<SUB>2</SUB>/ZrO<SUB>2</SUB> hybrids, ZrO<SUB>2</SUB> nanoparticles (NPs) were randomly grafted on the planar surfaces of WS<SUB>2</SUB> nanosheets (the ZrO<SUB>2</SUB> NPs were tightly anchored to the nanosheets). The WS<SUB>2</SUB>/ZrO<SUB>2</SUB> hybrids could considerably enhance the photocatalytic reactions under ultraviolet (UV) and simulated sunlight irradiation with an increase in the amount of ZrO<SUB>2</SUB> NPs anchored to WS<SUB>2</SUB> nanosheets, which influenced the photodegradation rate of crystal violet (CV) dye and the H<SUB>2</SUB> evolution activity. Notably, the rate of H<SUB>2</SUB> generation via the photolysis of water was 1023.9 μmol g<SUP>−1</SUP> h<SUP>−1</SUP> for the WS<SUB>2</SUB>/ZrO<SUB>2</SUB>-2 catalyst, indicating both the enhanced photocatalytic degradation activity and the H<SUB>2</SUB> advancement performance of the WS<SUB>2</SUB>/ZrO<SUB>2</SUB> hybrid. The photocatalytic H<SUB>2</SUB> advancement rate for the WS<SUB>2</SUB>/ZrO<SUB>2</SUB>-2 catalyst was 5.28 and 1.49 times higher than those for the bare WS<SUB>2</SUB> catalyst under UV and simulated solar illumination, respectively. Additionally, the WS<SUB>2</SUB>/ZrO<SUB>2</SUB>-2 hybrid exhibited high recyclability owing to the highly hydrophobic nature of the 2D WS<SUB>2</SUB>, which was beneficial for the separation of the hybrid photocatalyst from the CV solution. Finally, the results of a scavenger-trapping experiment indicated that active holes (h<SUP>+</SUP>) were mainly responsible for the photocatalytic reaction, rather than ˙O<SUB>2</SUB> <SUP>−</SUP> and ˙OH<SUP>−</SUP>. Plausible photoreaction mechanisms of photocatalytic degradation and H<SUB>2</SUB> production in aqueous solutions of the WS<SUB>2</SUB>/ZrO<SUB>2</SUB> hybrid were elucidated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 2D/0D-WS<SUB>2</SUB>/ZrO<SUB>2</SUB> heterostructure was synthesized via reducing ethanol approach. </LI> <LI> Improved photocurrent response in WS<SUB>2</SUB>/ZrO<SUB>2</SUB> heterostructure is due to suitable band potential of cocatalyst (ZrO<SUB>2</SUB>). </LI> <LI> The introduction of ZrO<SUB>2</SUB> lead to suppress the electron-hole recombination. </LI> <LI> Strong interaction of WS<SUB>2</SUB>/ZrO<SUB>2</SUB> sheets with organic compounds. </LI> <LI> WS<SUB>2</SUB>/ZrO<SUB>2</SUB>-2 exhibited higher photodegradation and H<SUB>2</SUB> evolution rate. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Selective hydrothermally synthesis of hexagonal WS₂ platelets and their photocatalytic performance under visible light irradiation

Vattikuti, S.V.P.,Byon, C.,Chitturi, V. Academic Press 2016 Superlattices and microstructures Vol.94 No.-

<P>Hexagonal WS2 platelets have been synthesized via simple hydrothermal synthesis method. The hexagonal WS2 is formed by the oriented attachment (OA)-self-assembly (SA). The thickness of the WS2 platelets was between similar to 20 and 100 nm. The specific surface area of these platelets is 94.63 m(2) g(-1). The hexagonal WS2 platelets exhibited excellent photocatalytic activity compared to irregular WS2 platelets for the degradation of rhodamine B (RhB) under visible light irradiation. This work paves the method for designing hexagonal shaped WS2 platelets with great potential for a wide spectrum of applications in photocatalysis. Moreover, this synthetic procedure may open up an opportunity to tailor the morphologies of the other nanomaterials especially transition metal sulfides. (C) 2016 Elsevier Ltd. All rights reserved.</P>