Enhanced photocatalytic performance at a Au/N–TiO₂ hollow nanowire array by a combination of light scattering and reduced recombination

Sudhagar, P.,Devadoss, Anitha,Song, Taeseup,Lakshmipathiraj, P.,Han, Hyungkyu,Lysak, Volodymyr V.,Terashima, C.,Nakata, Kazuya,Fujishima, A.,Paik, Ungyu,Kang, Yong Soo The Royal Society of Chemistry 2014 Physical chemistry chemical physics Vol.16 No.33

<P>We demonstrate one-step gold nanoparticle (AuNP) coating and the surface nitridation of TiO<SUB>2</SUB> nanowires (TiO<SUB>2</SUB>-NWs) to amplify visible-light photon reflection. The surface nitridation of TiO<SUB>2</SUB>-NW arrays maximizes the anchoring of AuNPs, and the subsequent reduction of the band gap energy from 3.26 eV to 2.69 eV affords visible-light activity. The finite-difference time-domain (FDTD) simulation method clearly exhibits the enhancement in the strengths of localized electric fields between AuNPs and the nanowires, which significantly improves the photocatalytic (PC) performance. Both nitridation and AuNP decoration of TiO<SUB>2</SUB>-NWs result in beneficial effects of high (e<SUP>−</SUP>/h<SUP>+</SUP>) pair separation through healing of the oxygen vacancies. The combined effect of harvesting visible-light photons and reducing recombination in Au/N-doped TiO<SUB>2</SUB>-NWs promotes the photocatalytic activity towards degradation of methyl orange to an unprecedented level, ∼4 fold (1.1 × 10<SUP>−2</SUP> min) more than does TiO<SUB>2</SUB>-NWs (2.9 × 10<SUP>−3</SUP> min<SUP>−1</SUP>). The proposed AuNP decoration of nitridated TiO<SUB>2</SUB>-NW surfaces can be applied to a wide range of n-type metal oxides for photoanodes in photocatalytic applications.</P> <P>Graphic Abstract</P><P>Maximizing the Au nanoparticle decoration on TiO<SUB>2</SUB> nanowire through nitrogen doping for simultaneous enhancement in visible light scattering and electron–hole charge separation. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cp02009j'> </P>

Modulating the interaction between gold and TiO₂ nanowires for enhanced solar driven photoelectrocatalytic hydrogen generation

Sudhagar, P.,Song, Taeseup,Devadoss, Anitha,Lee, Jung Woo,Haro, Marta,Terashima, Chiaki,Lysak, Volodymyr V.,Bisquert, Juan,Fujishima, Akira,Gimenez, Sixto,Paik, Ungyu The Royal Society of Chemistry 2015 Physical chemistry chemical physics Vol.17 No.29

<P>The interaction strength of Au nanoparticles with pristine and nitrogen doped TiO<SUB>2</SUB> nanowire surfaces was analysed using density functional theory and their significance in enhancing the solar driven photoelectrocatalytic properties was elucidated. In this article, we prepared 4-dimethylaminopyridine capped Au nanoparticle decorated TiO<SUB>2</SUB> nanowire systems. The density functional theory calculations show {101} facets of TiO<SUB>2</SUB> as the preferred phase for dimethylaminopyridine–Au nanoparticles anchoring with a binding energy of −8.282 kcal mol<SUP>−1</SUP>. Besides, the interaction strength of Au nanoparticles was enhanced nearly four-fold (−35.559 kcal mol<SUP>−1</SUP>) at {101} facets <I>via</I> nitrogen doping, which indeed amplified the Au nanoparticle density on nitrided TiO<SUB>2</SUB>. The Au coated nitrogen doped TiO<SUB>2</SUB> (N–TiO<SUB>2</SUB>–Au) hybrid electrodes show higher absorbance owing to the light scattering effect of Au nanoparticles. In addition, N–TiO<SUB>2</SUB>–Au hybrid electrodes block the charge leakage from the electrode to the electrolyte and thus reduce the charge recombination at the electrode/electrolyte interface. Despite the beneficial band narrowing effect of nitrogen in TiO<SUB>2</SUB> on the electrochemical and visible light activity in N–TiO<SUB>2</SUB>–Au hybrid electrodes, it results in low photocurrent generation at higher Au NP loading (3.4 × 10<SUP>−7</SUP> M) due to light blocking the N–TiO<SUB>2</SUB> surface. Strikingly, even with a ten-fold lower Au NP loading (0.34 × 10<SUP>−7</SUP> M), the synergistic effects of nitrogen doping and Au NPs on the N–TiO<SUB>2</SUB>–Au hybrid system yield high photocurrent compared to TiO<SUB>2</SUB> and TiO<SUB>2</SUB>–Au electrodes. As a result, the N–TiO<SUB>2</SUB>–Au electrode produces nearly 270 μmol h<SUP>−1</SUP> cm<SUP>−2</SUP> hydrogen, which is nearly two-fold higher than the pristine TiO<SUB>2</SUB> counterpart. The implications of these findings for the design of efficient hybrid photoelectrocatalytic electrodes are discussed.</P> <P>Graphic Abstract</P><P>The interaction strength of Au nanoparticles with pristine and nitrogen doped TiO<SUB>2</SUB> nanowire surfaces was analysed using density functional theory and their significance in enhancing the solar driven photoelectrocatalytic properties was elucidated. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5cp01175b'> </P>

Synergistic Metal–Metal Oxide Nanoparticles Supported Electrocatalytic Graphene for Improved Photoelectrochemical Glucose Oxidation

Devadoss, Anitha,Sudhagar, P.,Das, Santanu,Lee, Sang Yun,Terashima, C.,Nakata, K.,Fujishima, A.,Choi, Wonbong,Kang, Yong Soo,Paik, Ungyu American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.7

<P>We report the fabrication of graphene–WO<SUB>3</SUB>–Au hybrid membranes and evaluate their photocatalytic activity towards glucose oxidase mediated enzymatic glucose oxidation. The dual-functionality of gold nanoparticles in the reinforcement of visible light activity of graphene–WO<SUB>3</SUB> membranes and improving the catalytic activity of immobilized enzymes for unique photoelectrochemical sensing application is demonstrated. This work provides new insights into the fabrication of light-sensitive hybrid materials and facilitates their application in future.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-7/am4058925/production/images/medium/am-2013-058925_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am4058925'>ACS Electronic Supporting Info</A></P>

An Improved Design and Performance Enhancement of Y-Source DC-DC Boost Combined Phase Shifted Full Bridge Converter for Electric Vehicle Battery Charging Applications

Anitha P.,Kumar K. Karthik,Kamaraja A. S. 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.4

In the conventional scheme of power converters for electric vehicle battery charging applications from Solar Photo Voltaic System (SPV), the boost converter is preferred at the front end followed by a full-bridge converter with a discrete switches design. The effect of circuit parasites considerably contributes to power losses and degrades performance. An attempt is made on the entire scheme by integrating the Y-Source Boost Converter (YSBC) with the Phase Shifted Full Bridge Converter (PSFBC) to perform better with the high-power density and minimum effects of circuit parasites. The total system were digitally controlled incorporating the effective MPPT with boost solutions for solar conversion and Zero Voltage Switching (ZVS) on the full-bridge conversion through full protection features. The thermal design of the system were carried out to achieve effective power density. The system voltage conversion boosted from SPV voltage of 20VDC to 60VDC to charge a battery bank of 48 V with a typical system specification of (300–350) W was targeted with a switching frequency of 12.5 kHz at the boost stage and 100 kHz at the full-bridge stage for optimum performance. The solar efficiency of the system is improved using the Incremental Conductance (IC) MPPT methodology.

Mechanical Ventilator Pressure and Volume Control Using Classifier Machine Learning Algorithm for Medical Care

Anitha T.,Gopu G.,Arun Mozhi Devan P. 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.4

The mechanical ventilation technique is crucial for saving the lives of critically ill patients in the Intensive Care Unit. However, there can be a mismatch between the patient’s needs and the ventilator settings, which can cause patient-ventilator asynchrony. Our research aims to tackle this issue by implementing a novel current cyclic feedback type iterative learning PID controller (ILCPID) to achieve the desired pressure and volume. The research also provides a concise and comprehensive study to identify the most eff ective machine learning methodology for developing adequate ventilation models. In addition, the ILCPID controller’s accuracy and eff ectiveness are further validated using machine learning-based classifi ers that can predict and identify the best model for the diff erent ventilator modes, reducing the risk of mechanically ventilated patients. Among the diff erent classifi ers, the proposed narrow neural network achieved an accuracy of 92.4% and 89.29% for pressure and volume, respectively. Other techniques, such as wide neural networks, coarse trees, K-nearest neighbours, and decision trees, were also compared for accuracy, training duration, specifi city, and sensitivity.

Influence of vermiculite and sintered fly ash in robustness and hardened properties of light weight self-compacting concrete

A. Anitha,V.G. Kalpana,P. Muthupriya 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.1

The performance of Light Weight Self-Compacting Concrete (LWSCC) incorporated with Sintered Fly Ash and Vermiculiteare investigated in this study. The robustness and hardened properties of the LWSCC is investigated at diverse proportioningrates where Cement, Fine Aggregate and Coarse Aggregate are replaced with Fly Ash (FA) (25%), Vermiculite (1-9%) andSintered Fly Ash (SFA) (10-50%) respectively. The workability properties such as Filling ability, Passing ability, viscosity andthe mechanical properties such as density, compressive strength, tensile strength, flexural strength, ultrasonic pulse velocity,acid and sulphate resistance were studied. The percentage loss in weight and loss in compressive strength due to Acid attackand Sulphate attack at the age of 28 days of LWSCC were observed by immersing in 10% of HNO3, magnesium sulphate andsodium sulphate solutions. Vermiculite with SFA considerably boosted the workability and mechanical properties of LWSCCmixes. The presence of lightweight aggregates reduced the strength loss caused by sodium and magnesium sulphate ions. Acombination of 5% of Vermiculite and 30% of SFA resulted with the best robustness and hardened property of concrete