Solution combustion synthesis of SnO2-NiO p-n heterojunction nanocomposite for photocatalytic application

Babu, Bathula,Harish, V. V. N.,Shim, Jaesool,Reddy, Chandragiri Venkata Springer-Verlag 2018 Journal of materials science Materials in electron Vol.29 No.19

Bandgap tuning and XPS study of SnO₂ quantum dots

Babu, Bathula,Neelakanta Reddy, I.,Yoo, Kisoo,Kim, Dongseob,Shim, Jaesool Elsevier 2018 Materials letters Vol.221 No.-

<P><B>Abstract</B></P> <P>In this study, we investigated the influence of annealing temperature on ultra-small SnO<SUB>2</SUB> quantum dots (SQDs) prepared by a simple chemical reduction process. The structural and optical properties of annealed SQDs were systematically studied by different techniques. Our results show that the crystallinity and average crystallite size of annealed SQDs increased gradually with annealing temperature. The average crystallite size was maintained below 10 nm even for high annealing temperatures. XPS peak fitting analysis yielded information on the presence of mixed ionic states of Sn<SUP>2+</SUP> and Sn<SUP>4+</SUP> in SQDs and further revealed that the number of Sn<SUP>2+</SUP> ions decreased at high temperature. Band-edge shifts were estimated from XPS data. It was possible to shift the bandgap of annealed SQDs from UV to the visible wavelength region, which is likely to have a beneficial impact on many applications of optoelectronic devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SnO<SUB>2</SUB> QDs were successfully synthesized by an in-situ chemical reduction process. </LI> <LI> The band gap of SnO<SUB>2</SUB> QDs were tuned to visible region by post-annealing. </LI> <LI> The modification of VB and CB edge potentials of SnO<SUB>2</SUB> QDs were systematically studied through XPS study. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced visible-light-active photocatalytic performance using CdS nanorods decorated with colloidal SnO₂ quantum dots: Optimization of core–shell nanostructure

Babu, Bathula,Harish, V.V.N.,Koutavarapu, Ravindranadh,Shim, Jaesool,Yoo, Kisoo Elsevier 2019 Journal of industrial and engineering chemistry Vol.76 No.-

<P><B>Abstract</B></P> <P>We report a novel fabrication method for CdS nanorods (NRs) @ SnO<SUB>2</SUB> quantum dots (SQDs) core–shell NR (CdS@SnO<SUB>2</SUB> core–shell NR) heterojunction photocatalysts using a simple two-step process involving hydrothermal and ultrasonication techniques. The surface of the fabricated CdS NRs was completely decorated with colloidal SQDs. The amount of colloidal SQDs on the surface of the CdS NRs was optimized to achieve the maximum degradation efficiency. The superior performance of these NRs in dye degradation was attributed to the synergetic effect of the colloidal SQDs, which protected the surface of the CdS NRs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 1D core–shell nanorods were fabricated via a sonochemical approach. </LI> <LI> CdS nanorods were coated with colloidal SQDs, and the SQD quantity was optimized. </LI> <LI> CdS@SnO<SUB>2</SUB> core–shell NRs exhibited highly efficient and stable catalytic activity. </LI> <LI> Degradation efficiency of C–S 1.0 was ∼6.8 times higher than that of bare CdS NRs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Facile one-step synthesis of pellet-press-assisted saddle-curl-edge-like g-C₃N₄ nanosheets for improved visible-light photocatalytic activity

Babu, Bathula,Akkinepally, Bhargav,Shim, Jaesool,Yoo, Kisoo Elsevier 2019 CERAMICS INTERNATIONAL Vol.45 No.12

<P><B>Abstract</B></P> <P>Graphitic carbon nitride (g-C<SUB>3</SUB>N<SUB>4</SUB>) has attracted increasing interest as a visible-light-active photocatalyst. In this study, saddle-curl-edge-like g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets were prepared using a pellet presser (referred to as g-CN P nanosheets). Urea was used as the precursor for the preparation of g-C<SUB>3</SUB>N<SUB>4</SUB>. Thermal polymerization of urea in a pellet form significantly affected the properties of g-C<SUB>3</SUB>N<SUB>4</SUB>. Systematic investigations were performed, and the results for the modified g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets are presented herein. These results were compared with those for pristine g-C<SUB>3</SUB>N<SUB>4</SUB> to identify the factors that affected the fundamental properties. X-ray diffraction analysis and high-resolution transmission electron microscopy revealed a crystallinity improvement in the g-CN P nanosheets. Fourier-transform infrared spectroscopy provided clear information regarding the fundamental modes of g-C<SUB>3</SUB>N<SUB>4</SUB>, and X-ray photoelectron spectroscopy (XPS) peak-fitting investigations revealed the variations of C and N in detail. The light-harvesting property and separation efficiency of the photogenerated charge carriers were examined via optical absorption and photoluminescence studies. The valence band edge and conduction band edge potentials were calculated using XPS, and the results indicated a significant reduction in the bandgap for the g-CN P nanosheets. The Brunauer–Emmett–Teller surface area increased for the g-CN P nanosheets. The photocatalytic degradation performance of the g-CN P nanosheets was tested by applying a potential and using the classical dye Rhodamine B (RhB). The RhB dye solution was almost completely degraded within 28 min. The rate constant of the g-CN P nanosheets was increased by a factor of 3.8 compared with the pristine g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets. The high crystallinity, enhanced light absorption, reduced bandgap, and increased surface area of the saddle-curl-edge-like morphology boosted the photocatalytic performance of the g-CN P nanosheets.</P>

Synthesis and characterization of pure tetragonal ZrO₂ nanoparticles with enhanced photocatalytic activity

Reddy, Ch. Venkata,Babu, Bathula,Reddy, I. Neelakanta,Shim, Jaesool Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.6

<P><B>Abstract</B></P> <P>Tetragonal zirconia (t-ZrO<SUB>2</SUB>) nanoparticles were successfully prepared by a hydrothermal method and characterized by various measurement techniques. The tetragonal crystalline structure of ZrO<SUB>2</SUB> nanoparticles were confirmed by X-ray diffraction analysis. The binding energies of Zr and O were confirmed from the XPS spectrum. The band gap energy was estimated using optical absorption spectroscopy, found to be 4.8eV. The UV (360nm) and visible (403nm and 537nm) emissions were observed from PL spectrum. The thermal stability of the prepared ZrO<SUB>2</SUB> nanoparticles was studied by TG-DTA analysis. The photocatalytic degradation of the as-prepared ZrO<SUB>2</SUB> nanoparticles was studied under UV light irradiation using methyl orange (MO) as a model organic pollutant. Results showed that 99% degradation was achieved within 50min. Photoelectrochemical studies were also supported the photocatalytic activities.</P>

Control of copper nanowire network properties and application to transparent conducting layer in LED

Yoon, Hahnjoo,Shin, Dong Su,Babu, Bathula,Kim, Taek Gon,Song, Keun Man,Park, Jinsub Elsevier 2017 Materials & Design Vol.132 No.-

<P><B>Abstract</B></P> <P>We report the control of structural, optical, and electrical properties of solution processed copper (Cu) nanowires (NWs) by varying the capping agent concentration and demonstrating the enhanced light extraction of GaN-based light-emitting diodes (LEDs) using Cu NWs. Cu NWs were prepared by a simple solvothermal method, and the capping agent concentration effects on the growth of Cu NWs were systematically investigated. The different diameters of Cu NWs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible absorption, and conductivity measurements. All characterization results showed high aspect ratio nanowires with efficient transmittance and conductivity properties. When the synthesized Cu NWs were adopted as a transparent conducting layer, the electroluminescence intensity was improved by its spreading effects. This work will elucidate the influence of capping agents on the physical properties, optical properties, and electrical conductivity of Cu NWs for use as a transparent conductor in optoelectronic devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Suitable amount of capping agent (HDA) is 50mM for the standard synthesis method of Cu NWs. </LI> <LI> 50μL of H50 Cu NWs show the transmittance and sheet resistance of 88.1%T and 15.8Ω□<SUP>−1</SUP>, respectively. </LI> <LI> LED with Cu NWs electrode shows 2.2 times enhanced EL intensity compared with one without Cu NWs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

메조다공성 알루미나에 담지된 팔라듐 촉매의 메탄 연소 반응

김민석(Minseok Kim),임수현(Suhyun Lim),바툴라 하리 바부(Hari Babu Bathula),허일정(Iljeong Heo),김정랑(Jeong-Rang Kim),이진희(Jin Hee Lee),서영웅(Young-Woong Suh) 한국자동차공학회 2020 한국 자동차공학회논문집 Vol.28 No.5

Methane has 21 times more global warming potential than carbon dioxide. Particularly, slipped methane after burning fossil fuel, natural gas, and shale gas is one of the major sources of CH₄, and must be mitigated by methane combustion over heterogeneous catalysts(typically, Pd/Al₂O₃). Herein, we have prepared a mesoporous palladium alumina catalyst(MPdA) with one-pot solvent deficient precipitation(SDP), in which the calcination temperature varies from 400 to 1000 °C with a step of 100 °C. Among the prepared MPdA catalysts, the best catalytic performance was achieved with the one calcined at 800 °C, which is supported by the results of the Pd dispersion. Since the developed catalyst was examined as superior to conventional Pd/Al₂O₃, the SDP method is significant in synthesizing an active catalyst for methane combustion.