Noble metal-free metal-organic framework-derived onion slice-type hollow cobalt sulfide nanostructures: Enhanced activity of CdS for improving photocatalytic hydrogen production

Kumar, D. Praveen,Park, Hanbit,Kim, Eun Hwa,Hong, Sangyeob,Gopannagari, Madhusudana,Reddy, D. Amaranatha,Kim, Tae Kyu Elsevier 2018 Applied catalysis. B, Environmental Vol.224 No.-

<P><B>Abstract</B></P> <P>The hollow materials have played a significant role in cutting-edge innovations for energy conversion due to their peculiar properties and their wide range of potential applications. These materials show great promise for the development of cleaner power sources to address growing environmental concerns at a time of increasing global demand for energy. Noble metal-free MOF-derived onion slice-type hollow structured Co<SUB>4</SUB>S<SUB>3</SUB> was developed and embedded with CdS nanoparticles for photocatalytic hydrogen production. The incorporation of Co<SUB>4</SUB>S<SUB>3</SUB> with the CdS particles effectively accelerated charge separation and transfer in photocatalytic reactions due to the low density, hollow interior, and shell permeability of the onion-type composite. The optimized Co<SUB>4</SUB>S<SUB>3</SUB>/CdS photocatalyst led to an enhanced rate of H<SUB>2</SUB> production of 12,360μmolh<SUP>−1</SUP> g<SUP>−1</SUP> under simulated solar light irradiation; this value is 26-fold greater than that of the pristine CdS nanoparticles. The Co<SUB>4</SUB>S<SUB>3</SUB>/CdS composite exhibited remarkably stable photocatalytic performance for up to 65h and could be reused in five successive cycles. Furthermore, to the best of our knowledge, this is the highest H<SUB>2</SUB> production rate achieved with cobalt sulfide-based CdS nanoparticle photocatalysts in the photocatalysis of water under simulated solar light irradiation. Owing to its low cost and high efficiency, this photocatalytic system should hold great potential for the development of highly efficient photocatalytic materials for use in various fields.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Noble metal-free MOF-derived onion slice-type hollow structured Co<SUB>4</SUB>S<SUB>3</SUB> was developed. </LI> <LI> The Co<SUB>4</SUB>S<SUB>3</SUB> with the CdS particles effectively accelerated charge separation. </LI> <LI> The low density, hollow interior, shell permeability of Co<SUB>4</SUB>S<SUB>3</SUB> improves the transfer property. </LI> <LI> The optimized Co<SUB>4</SUB>S<SUB>3</SUB>/CdS shows high rate of H<SUB>2</SUB> production of 12,360μmolh<SUP>−1</SUP> g<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Noble metal-free MOF-derived onion slice-type hollow cobalt sulfide nanostructures: Enhanced activity of CdS for improving photocatalytic hydrogen production by D.P. Kumar et al.</P> <P>[DISPLAY OMISSION]</P>

Highly efficient hydrogen generation in water using 1D CdS nanorods integrated with 2D SnS₂ nanosheets under solar light irradiation

Rangappa, A. Putta,Kumar, D. Praveen,Gopannagari, Madhusudana,Reddy, D. Amaranatha,Hong, Yul,Kim, Yujin,Kim, Tae Kyu Elsevier 2020 APPLIED SURFACE SCIENCE - Vol.508 No.-

<P><B>Abstract</B></P> <P>The development of low-cost and noble-metal-free catalysts for the photoconversion of water into hydrogen (H<SUB>2</SUB>) is of great interest. Here, 2D tin(IV) sulfide (SnS<SUB>2</SUB>) ultrathin nanosheets as co‐catalysts are coupled with 1D cadmium sulfide (CdS) nanorods for the photosplitting of water into H<SUB>2</SUB>. The design of the catalyst can facilitate the passivation of the physiochemical properties of CdS and enhance H<SUB>2</SUB> evolution activity. The prepared CdS/SnS<SUB>2</SUB> composite catalyst increases the H<SUB>2</SUB> generation activity and exhibits excellent and continuous long-term photostability. The H<SUB>2</SUB> evolution rate of the optimized CdS/SnS<SUB>2</SUB> composite is approximately 9-fold that of pristine CdS nanorods. The characterization results of the CdS/SnS<SUB>2</SUB> composite reveal that the loading of SnS<SUB>2</SUB> can enhance the synergistic effects of the photocatalyst due to the effective separation, large number of exposed catalytic sites, and highly dispersed nature of the layered SnS<SUB>2</SUB>. Several characterization outcomes of CdS/SnS<SUB>2</SUB> are examined in detail (e.g., structural and surface elemental results of transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy). Further, the optoelectrical properties and charge-carrier excitations are investigated via ultraviolet diffuse reflectance spectroscopy, photoluminescence spectroscopy, and photoelectrochemical analysis. The proposed CdS/SnS<SUB>2</SUB> composite is a promising low-cost, noble-metal-free, and high-efficiency catalyst for the photocatalytic water-reduction reaction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Superior hydrogen evolution rate which is nine folds higher than the CdS. </LI> <LI> Excellent separation of photo generated charge carriers on CdS/SnS<SUB>2</SUB> hybrid with SnS<SUB>2</SUB> insertion. </LI> <LI> Excellent photo stability (30 h) of the catalyst for long term practical applications. </LI> <LI> Uniform deposition of ultrathin SnS<SUB>2</SUB> sheets onto CdS by simple methods. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Optimal hydrogen evolution rate of 20.2 mmol h<SUP>−1</SUP> g<SUP>−1</SUP> facilitated by enhanced absorption and prolonged life time of charge carriers by SnS<SUB>2</SUB> as co-catalyst on CdS.</P> <P>[DISPLAY OMISSION]</P>

Hydrothermal synthesis of wurtzite Zn_1-xNi_xS mesoporous nanospheres: With blue-green emissions and ferromagnetic Curie point above room temperature

Amaranatha Reddy, D.,Kim, D.H.,Rhee, S.J.,Jung, C.U.,Lee, B.W.,Liu, C. Elsevier Sequoia 2014 JOURNAL OF ALLOYS AND COMPOUNDS Vol.588 No.-

Wurtzite Zn<SUB>1-x</SUB>Ni<SUB>x</SUB>S (x=0.00, 0.01, 0.02, 0.03, 0.04 and 0.05) mesoporous nanospheres were successfully synthesized via a versatile hydrothermal method with the assistance of ethylenediamine (EN). The as synthesized nanospheres were uniform, mono-dispersed with a spherical shape. Microstructure investigations revealed that these nanospheres were mesoporous clusters of Zn<SUB>1-x</SUB>Ni<SUB>x</SUB>S nanoparticles with the size around 5nm. X-ray Diffraction, X-ray photoelectron spectroscopy, and Energy-dispersive X-ray spectroscopy studies confirmed that the Ni ions substituted into ZnS host lattice without altering the crystal structure. The Fourier-transform infrared spectra confirmed the coupling between the EN molecules and ZnS. The absorption edge in the diffuse reflection spectra shifted towards lower wavelength with increasing Ni concentration, indicating an expansion in the band gap energy that is estimated to be in the range of 3.53-3.60eV. The photoluminescence spectra of the doped and un-doped samples contained a broad emission band covering the range of 350-650nm. Room temperature magnetization studies indicated that the undoped ZnS nanospheres yielded only diamagnetism, whereas the doped samples exhibited ferromagnetism that can be attributed to the Ni<SUP>2+</SUP> dopants. The temperature dependence of magnetization revealed that the Zn<SUB>1-x</SUB>Ni<SUB>x</SUB>S nanospheres have Curie point above room temperature. The intrinsic ferromagnetism and ferromagnetic Curie point above room temperature promise a great deal of potential applications in spintronic devices for Zn<SUB>1-x</SUB>Ni<SUB>x</SUB>S nanospheres.

Designing CdS Mesoporous Networks on Co-C@Co₉ S₈ Double-Shelled Nanocages as Redox-Mediator-Free Z-Scheme Photocatalyst

Reddy, D. Amaranatha,Park, Hanbit,Gopannagari, Madhusudana,Kim, Eun Hwa,Lee, Seunghee,Kumar, D. Praveen,Kim, Tae Kyu Wiley (John WileySons) 2018 ChemSusChem Vol.11 No.1

<P>Designing porous nanostructures with unprecedented functionalities and an effective ability to harvest the maximum energy region of the solar spectrum and suppress the charge-carrier recombination rate offers promising potential for sustainable energy production. Although several functional porous nanostructures have been developed, high-efficiency materials are still needed. Herein, we report a new, highly active, noble-metal-free, and redox-mediator-free Z-scheme photocatalyst, CdS/Co-C@Co9S8, for H-2 production through water splitting under solar irradiation. The designed photocatalytic system contains open 3D CdS mesopores as a light absorber for wider solar-light harvesting. Metal-organicframework-derived cobalt nanocrystal-embedded few-layered carbon@Co9S8 double-shelled nanocages were used as a co-semiconductor to hamper the photo charge-carrier recombination by accelerating the photogenerated electrons and holes from the other semiconductor. The optimized catalyst shows a H-2 evolution rate of 26.69mmolg(-1)h(-1) under simulated solar irradiation, which is 46times higher than that of the as-synthesized CdS mesoporous nanostructures. The apparent quantum yield reached 7.82% at =425nm in 5h. The outstanding photocatalytic activity of CdS/Co-C@Co9S8 reflects the favorable suppression of the charge-carrier recombination rate, as determined by photoluminescence, photocurrent, and impedance analyses. We believe that the findings reported here may inspire the design of new noble-metal-free porous nanohybrids for sustainable H-2 production.</P>

Heterostructured WS₂-MoS₂Ultrathin Nanosheets Integrated on CdS Nanorods to Promote Charge Separation and Migration and Improve Solar-Driven Photocatalytic Hydrogen Evolution

Reddy, D. Amaranatha,Park, Hanbit,Ma, Rory,Kumar, D. Praveen,Lim, Manho,Kim, Tae Kyu Wiley (John WileySons) 2017 ChemSusChem Vol.10 No.7

<P>Solar-driven photocatalytic hydrogen evolution is important to bring solar-energy-to-fuel energy-conversion processes to reality. However, there is a lack of highly efficient, stable, and non-precious photocatalysts, and catalysts not designed completely with expensive noble metals have remained elusive, which hampers their large-scale industrial application. Herein, for the first time, a highly efficient and stable noble-metal-free CdS/WS2-MoS2 nanocomposite was designed through a facile hydrothermal approach. When assessed as a photocatalyst for water splitting, the CdS/WS2-MoS2 nanostructures exhibited remarkable photocatalytic hydrogen-evolution performance and impressive durability. An excellent hydrogen evolution rate of 209.79mmolg(-1)h(-1) was achieved under simulated sunlight irradiation, which is higher than the values for CdS/MoS2 (123.31mmolg(-1)h(-1)) and CdS/WS2 nanostructures (169.82mmolg(-1)h(-1)) and the expensive CdS/Pt benchmark catalyst (34.98mmolg(-1)h(-1)). The apparent quantum yield reached 51.4% at =425nm in 5h. Furthermore, the obtained hydrogen evolution rate was better than those of several noble-metal-free catalysts reported previously. The observed high rate of hydrogen evolution and remarkable stability may be a result of the ultrafast separation of photogenerated charge carriers and transport between the CdS nanorods and the WS2-MoS2 nanosheets, which thus increases the number of electrons involved in hydrogen production. The proposed designed strategy is believed to potentially open a door to the design of advanced noble-metal-free photocatalytic materials for efficient solar-driven hydrogen production.</P>

Tuning Band Alignments and Charge-Transport Properties through MoSe₂ Bridging between MoS₂ and Cadmium Sulfide for Enhanced Hydrogen Production

Kumar, D. Praveen,Kim, Eun Hwa,Park, Hanbit,Chun, So Yeon,Gopannagari, Madhusudana,Bhavani, P.,Reddy, D. Amaranatha,Song, Jae Kyu,Kim, Tae Kyu American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.31

<P>Transition-metal dichalcogenide materials play a major role in the state-of-the-art innovations for energy conversion because of potential applications resulting from their unique properties. These materials additionally show inordinate potential toward the progress of hygienic power sources to deal with increasing environmental disputes at the time of skyrocketing energy demands. Herein, we report earth-abundant, few-layered, MoSe<SUB>2</SUB>-bridged MoS<SUB>2</SUB>/cadmium sulfide (CdS) nanocomposites, which reduce photogenerated electron and hole recombination by effectively separating charge carriers to achieve a high photocatalytic efficiency. Accordingly, the MoSe<SUB>2</SUB>-bridged MoS<SUB>2</SUB>/CdS system produced effective hydrogen (193 μmol·h<SUP>-1</SUP>) as that of water using lactic acid as a hole scavenger with the irradiation of solar light. The presence of few-layered MoSe<SUB>2</SUB> bridges in MoS<SUB>2</SUB>/CdS successfully separates photogenerated charge carriers, thereby enhancing the shuttling of electrons on the surface to active edge sites. To the best of our knowledge, this few-layered MoSe<SUB>2</SUB>-bridged MoS<SUB>2</SUB>/CdS system exhibits the most effective concert among altogether-reported MoS<SUB>2</SUB>-based CdS composites. Notably, these findings with ample prospective for the development of enormously real photocatalytic systems are due to their economically viable and extraordinary efficiency.</P> [FIG OMISSION]</BR>

Effects of Laser Energy Density on Size and Morphology of NiO Nanoparticles Prepared by Pulsed Laser Ablation in Liquid

마로리,D. Amaranatha Reddy,김태규 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.1

Enhanced photocatalytic activity and anti-photocorrosion of AgI nanostructures by coupling with graphene-analogue boron nitride nanosheets

Choi, Jiha,Reddy, D. Amaranatha,Kim, Tae Kyu Elsevier Science B.V., Amsterdam. 2015 Ceramics international Vol.41 No.-

The influence of laser wavelength and fluence on palladium nanoparticles produced by pulsed laser ablation in deionized water

Kim, J.,Amaranatha Reddy, D.,Ma, R.,Kim, T.K. Elsevier 2014 SOLID STATE SCIENCES Vol.37 No.-

Homogeneous spherical palladium (Pd) nanoparticles were synthesized by pulsed laser ablation of a solid Pd foil target submerged in deionized water, without the addition of any external chemical surfactant. The influence of laser wavelength (355, 532, and 1064 nm) and fluence (8.92, 12.74, and 19.90 J/cm<SUP>2</SUP>) on nucleation, growth, and aggregation of Pd nanoparticles were systematically studied. Microstructural and optical properties of the obtained nanoparticles were studied by field emission transmission electron microscopy (FETEM), energy dispersive X-ray spectroscopy, and UV-vis spectroscopy. FETEM micrographs indicate that the average nanocrystallite sizes are relatively low (3-6 nm) and homogeneous for the particles synthesized at the laser wavelengths of 355 and 532 nm. However, at a laser wavelength of 1064 nm, the average nanocrystallite size is relatively large and inhomogeneous in nature. Moreover, we observe that the mean diameter and production rate of particles increases with an increase in laser fluence. The selected area electron diffraction patterns obtained from isolated Pd nanoparticles show the characteristic diffused electron diffraction rings of polycrystalline materials with a face-centered cubic structure. Absorbance spectrum of the synthesized nanoparticle solution shows a broad absorption band, which corresponds to a typical inter-band transition of a metallic system, indicating the production of pure palladium nanoparticles. The present work provides new insights into the effect of laser wavelength and fluence on the control of size and aggregation of palladium nanoparticles in the liquid medium.

Core-shell ZnFe₂O₄/ZnS composites for photocatalytic applications

Pilsun Yoo,D. Amaranatha Reddy,Sang-Eun Bae,Bo Wha Lee,Seong Huh,Chunli Liu 한국자기학회 2015 한국자기학회 학술연구발표회 논문개요집 Vol.2015 No.5