http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Boppella, Ramireddy,Kochuveedu, Saji Thomas,Kim, Heejun,Jeong, Myung Jin,Marques Mota, Filipe,Park, Jong Hyeok,Kim, Dong Ha American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.8
<P>In this contribution we have developed TiO2 inverse opal based photoelectrodes for photoelectrochemical (PEC) water splitting devices, in which Au nanoparticles (NPs) and reduced graphene oxide (rGO) have been strategically incorporated (TiO2@rGO@Au). The periodic hybrid nanostructure showed a photocurrent density of 1.29 mA cm(-2) at 1.23 V vs RHE, uncovering a 2-fold enhancement compared to a pristine TiO2 reference. The Au NPs were confirmed to extensively broaden the absorption spectrum of TiO2 into the visible range and to reduce the onset potential of these photoelectrodes. Most importantly, TiO2@rGO@Au hybrid exhibited a 14-fold enhanced PEC efficiency under visible light and a 2.5-fold enrichment in the applied bias photon-to-current efficiency at much lower bias potential compared with pristine TiO2. Incident photon-to electron conversion efficiency measurements highlighted a synergetic effect between Au plasmon sensitization and rGO-mediated facile charge separation/transportation, which is believed to significantly enhance the PEC activity of these nanostructures under simulated and visible light irradiation. Under the selected operating conditions the incorporation of Au NPs and rGO into TiO2 resulted in a remarkable boost in the H-2 evolution rate (17.8 mu mol/cm(2)) compared to a pristine TiO2 photoelectrode reference (7.6 mu mol/cm(2)). In line with these results and by showing excellent stability as a photoelectrode, these materials are herin underlined to be of promising interest in the PEC water splitting reaction.</P>
Boppella, Ramireddy,Choi, Chi Hun,Moon, Jooho,Ha Kim, Dong Elsevier 2018 Applied Catalysis B Vol.239 No.-
<P><B>Abstract</B></P> <P>Developing photocatalysts with effective charge separation and fast surface reaction kinetics is crucial to realizing efficient photocatalytic water splitting. In this study, we report a strongly coupled two-dimensional-ternary-heterostructured photocatalyst by sequentially introducing reduced graphene oxide (rGO) and NiFe-layered double hydroxide (NiFe-LDH) on the surface of lanthanum titanate (LTO) via a facile hydrothermal and electrostatic self-assembly methodology, respectively. The synthesized 2D-rGO/LTO/NiFe-LDH photocatalyst showed remarkable photocatalytic H<SUB>2</SUB> evolution activity under simulated light irradiation, even without expensive Pt cocatalyst. The enhancement of photocatalytic activity could be attributed to the efficient interfacial charge transfer at the rGO/LTO heterojunction interface, and the enhanced hole (h<SUP>+</SUP>) trapping ability of NiFe-LDH cocatalyst at the LTO/NiFe-LDH interface, respectively. These attributes could effectively enlarge the life time of photo-generated electron-hole pairs, and increase the electron density for hydrogen production. The optimal rGO/LTO/NiFe-LDH nanocomposite remain sustained even after four successive experimental runs, without apparent change in the H<SUB>2</SUB> evolution rate. The present work elucidates a new strategy to maximize the efficiency via synergetic effect of incorporating rGO and NiFe-LDH as dual cocatalysts, and shows a feasible strategy of using earth-abundant materials as cocatalysts to enhance the overall photocatalytic water splitting reactions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel 2D-ternary photocatalysts of NiFe-LDH and rGO co-loaded with ultrathin LTO were synthesized. </LI> <LI> 2D-ternary photocatalyst showed a remarkable photocatalytic H2 activity under simulated light without the need of Pt. </LI> <LI> Synergetic coupling between NiFe-LDH and rGO enhance the charge separation/ transportation and water splitting performance. </LI> <LI> The enhanced photocatalytic mechanism was proposed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Boppella, Ramireddy,Yang, Wooseok,Tan, Jeiwan,Kwon, Hyeok-Chan,Park, Jaemin,Moon, Jooho Elsevier 2019 Applied catalysis. B, Environmental Vol.242 No.-
<P><B>Abstract</B></P> <P>Rational design and engineering of highly active co-catalysts made of stable and earth-abundant elements is essential to boost the photocatalytic water splitting performances. This paper reports a 2D-black phosphorus (BP) supported Ni<SUB>2</SUB>P (2D-Ni<SUB>2</SUB>P@BP) as a non-precious heterostructure co-catalyst coupled with a 2D porous graphitic carbon nitride nanosheet (CN NSs) photocatalyst to induce visible light photocatalytic hydrogen production. The resulting 2D-Ni<SUB>2</SUB>P@BP/CN composite structure exhibits a remarkable visible light photocatalytic H<SUB>2</SUB> evolution activity of 858.2 μmol h<SUP>−1</SUP> g<SUP>−1</SUP>, revealing ∼50- and ∼5-fold enhancement compared to that of a pristine CN reference and Pt/CN sample, respectively. The dramatic advancement in H<SUB>2</SUB> evolution could be ascribe to the superior hydrogen evolution reduction (HER) activity of Ni<SUB>2</SUB>P@BP. The excellent HER activity arises from the synergetic effect between BP and Ni<SUB>2</SUB>P in which BP, with its superior electron mobility, is believed to accelerate the charge separation/transfer by mediating the photogenerated electrons from CN NSs to the surface of the catalytically active sites of Ni<SUB>2</SUB>P, while Ni<SUB>2</SUB>P promotes the surface reduction reaction by lowering the H<SUB>2</SUB>-evolution overpotential. It is considered that this work provides a new paradigm for designing advanced, stable, and cost-effective photocatalyst systems for the practical implementation of solar hydrogen production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 2D black phosphorus (BP) supported Ni<SUB>2</SUB>P is proposed as a H<SUB>2</SUB> evolution co-catalyst. </LI> <LI> 2D Ni<SUB>2</SUB>P@BP was coupled with 2D C<SUB>3</SUB>N<SUB>4</SUB> photocatalyst to form a strong interfacial 2D-2D contact. </LI> <LI> 2D hybrid Ni<SUB>2</SUB>P@BP/C<SUB>3</SUB>N<SUB>4</SUB> showed excellent photocatalytic H<SUB>2</SUB> production under visible light irradiation </LI> <LI> Ni<SUB>2</SUB>P@BP/C<SUB>3</SUB>N<SUB>4</SUB> hybrid exhibited 50-fold enhancement in H<SUB>2</SUB> evolution compare to pristine C<SUB>3</SUB>N<SUB>4</SUB>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A novel 2D black phosphorus supported Ni<SUB>2</SUB>P co-catalyst is rationally integrated with graphitic nitride photocatalyst for the first time, exhibiting ∼50 times higher H<SUB>2</SUB> production than that of pristine CN. The remarkable activity arises from the cooperative effect between BP and Ni<SUB>2</SUB>P as co-catalysts, which serve as electron transporter and a source of active proton reduction sites, respectively.</P> <P>[DISPLAY OMISSION]</P>
Design and engineering of photoelectrode materials for photoelectrochemical water splitting
( Rami Reddy Boppella ),김동하 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
Photoelectrochemical (PEC) cell is the one most elegant, practical and potentially more efficient route to convert the solar energy to stored chemical energy through the splitting of raw water into molecular oxygen and hydrogen. In this regard, various semiconductor metal oxides including TiO2, Fe2O3, WO3 and BiVO4 gained much attention as a photoelectrode material for H2 production. However, most of these metal oxides do not meet the optoelectronic properties that lead to both low light harvesting efficiencies and required large over potential to drive water oxidation. Therefore developing new robust energy materials that can efficiently harvest a large portion of the solar spectrum with better charge transporting properties is an ultimate challenge nowadays.In this perspective, our present research efforts devoted not only designing photoelectrode materials with high photocurrent but also reducing the over potential with surface treatments. In addition, the primary goal of our research is to fabricate an efficient photoelectrochemical water splitting device (PEC) that can split water directly on semiconductor surface without requiring over potential to realize the means of “The need for clean energy”.
Shanmugasundaram, Arunkumar,Boppella, Ramireddy,Jeong, Yun-Jin,Park, Jongsung,Kim, Young-Bae,Choi, Byungchul,Park, Su Han,Jung, Seunghun,Lee, Dong-Weon Elsevier 2018 Materials chemistry and physics Vol.218 No.-
<P><B>Abstract</B></P> <P>Herein, we present a facile hydrothermal route for the preparation of hierarchical mesoporous zinc oxide (ZnO) and reduced graphene oxide-zinc oxide (ZnO<SUB>rGO</SUB>) composites for degradation of organic pollutants from natural water resources. Morphologies of the as-synthesized materials were carried out by electron microscopy in scanning and transmission modes. Thermal stability of the as-prepared products was characterised by thermogravimetric-differential thermal analysis. Crystal structure and phase purity of the materials was characterised by powder x-ray diffraction, micro-Raman, and X-ray photoelectron spectroscopy analysis. Optical properties of the as-prepared materials were investigated by ultra violet-diffused reflectance and photoluminescence spectroscopy analysis. Photocatalytic activity of the as-prepared materials was estimated by evaluating the degradation kinetics of methylene blue (MB) dye in aqueous solution under standard solar light illumination. The calculated rate constant of the Zn<SUB>rGO</SUB> is found to be ∼2.831 h<SUP>−1</SUP> which is ∼6.3 times higher than the estimated rate constant of the as-prepared pristine ZnO (0.455 h<SUP>−1</SUP>). The exceptional photocatalytic activity of the as-prepared Zn<SUB>rGO</SUB> composites is attributed to the account of their synergetic effect, porous structure, and effective separation of charge carriers. Finally, based on the obtained experimental results viable photocatalytic mechanism has been proposed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new one-step approach yields ZnO/rGO hybrids with <I>in-situ</I> formation of heterojunctions. </LI> <LI> Ethanolamine used to mineralize the ZnO precursor and also facilitates the reduction GO <I>in-situ</I>. </LI> <LI> The ZnO/rGO heterojunctions show improved photo catalytic activity under solar light illumination. </LI> <LI> Plausible photo catalysis mechanism has been proposed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
권한나,정경화,( Ramireddy Boppella ),( Saji Thomas Kochuveedu ),장유진,윤민지,김동하 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
Recently, the environmental pollution became more serious problem.One of the ways involves the use of photocatalysts along with mesoporous TiO2 considering its high photocatalytic activity. However, its absorption spectrum shares only UV region with the broad sunlight spectrum. Mesoporous carbon is a characteristic nanostructure that can be formed by carbonization of self-assembled block copolymer-TiO2 nanohybrids. It has been reported that the presence of carbonaceous moieties in mesoporous TiO2 can increase the power conversion efficiency by up to 60%. To increase the solar absorption is the use of UCNs that can utilize IR and NIR spectral range. Certain pairs of lanthanides elements are capable of absorbing IR/NIR and converting it to visible light or UV by a process called upconversion. We focus on the integration of UCN into m-TiO2 or mC-TiO2 in a single system in order to maximize the photocatalytic performance by bringing the synergy effect from the constituent elements.
( Filipe Marques Mota ),( Ramireddy Boppella ),( Keiji Tanaka ),김동하 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
To harvest low energy photons, we investigated a 3D composite photoanode integrating visible-responsive plasmonic Au nanoparticles and NIR-responsive upconversion nanocrystals (UCN) into 3D TiO<sub>2</sub> inverse-opals (Au/UCN/TiO<sub>2</sub>) with extended solar energy utilization in the UV-vis-NIR range for photoelectrochemical (PEC) water splitting platforms. The NIR-responsive properties of NaYF<sub>4</sub>:Yb<sup>3+</sup> UCN nanocrystals doped with Er<sup>3+</sup> or Tm<sup>3+</sup> ions, and the effect of an alternating sequential introduction of UCN and Au were also investigated. Our Au/Er-UCN/TiO<sub>2</sub> hybrid revealed a 10-fold photocurrent density enhancement under UV-vis-NIR against the pristine TiO<sub>2</sub>.