Interconnected Pt-Nanodendrite/DNA/Reduced-Graphene-Oxide Hybrid Showing Remarkable Oxygen Reduction Activity and Stability

Tiwari, Jitendra N.,Kemp, Kingsley Christian,Nath, Krishna,Tiwari, Rajanish N.,Nam, Hong-Gil,Kim, Kwang S. American Chemical Society 2013 ACS NANO Vol.7 No.10

<P>Controlling the morphology and size of platinum nanodendrites (PtDs) is a key factor in improving their catalytic activity and stability. Here, we report the synthesis of PtDs on genomic-double-stranded-DNA/reduced-graphene-oxide (gdsDNA/rGO) by the NaBH<SUB>4</SUB> reduction of H<SUB>2</SUB>PtCl<SUB>6</SUB> in the presence of plant gdsDNA. Compared to industrially adopted catalysts (<I>i.e.</I>, state-of-the-art Pt/C catalyst, Pt/rGO, Pt<SUB>3</SUB>Co, <I>etc.</I>), the as-synthesized PtDs/gdsDNA/rGO hybrid displays very high oxygen reduction reaction (ORR) catalytic activities (much higher than the 2015 U.S. Department of Energy (DOE) target values), which are the rate-determining steps in electrochemical energy devices, in terms of onset-potential, half-wave potential, specific-activity, mass-activity, stability, and durability. Moreover, the hybrid exhibits a highly stable mass activity for the ORR over a wide pH range of 1–13. These exceptional properties would make the hybrid applicable in next-generation electrochemical energy devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2013/ancac3.2013.7.issue-10/nn4038404/production/images/medium/nn-2013-038404_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn4038404'>ACS Electronic Supporting Info</A></P>

Titanium Dioxide Nanomaterials and its Derivatives in the Remediation of Water: Past, Present and Future

Tiwari, Alka,Shukla, Alok,Tiwari, Diwakar,Choi, Suk Soon,Shin, Hyun-Gon,Lee, Seung-Mok The Korean Society of Industrial and Engineering C 2019 공업화학 Vol.30 No.3

The aim of this review article is to summarize the role of titanium oxide ($TiO_2$) nanomaterials in the remediation of the aquatic environment contaminated with various emerging pollutants. The advanced oxidation process led by the semiconductor $TiO_2$ is an impetus in the remediation technology. Therefore, a vast number of literature works are available in this area. Further, the role of modified $TiO_2$ or thin film materials were discussed in the review. Also, the Localized Surface Plasmon Resonance (LSPR) effect of using noble metaldoped $TiO_2$ played an interesting role in the remediation process.

Au-nanoparticle/nanopillars TiO2 meso-porous thin films in the degradation of tetracycline using UV-A light

Alka Tiwari,Alok Shukla,Lalliansanga,Diwakar Tiwari,이승목 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.69 No.-

Novel meso-porous nanoparticles Au/TiO2 thin films were obtained by template synthesis using polyethylene glycol as filler medium. The materials were characterized by advanced analytical methods. The photocatalysts were employed for the photocatalytic degradation of tetracycline from aqueous solutions using UV-A light (λmax 330 nm). Various physico-chemical parametric studies enabled to deduce the mechanism of degradation. A significant percentage of tetracycline was mineralized by the treatment. The stability of thin film was evidenced with the repeated use of thin film. The degradation of tetracycline was proceeded predominantly by the OH radicals generated at the valance and conduction band of semiconductor.

Titanium Dioxide Nanomaterials and its Derivatives in the Remediation of Water: Past, Present and Future

( Alka Tiwari ),( Alok Shukla ),( Diwakar Tiwari ),( Suk Soon Choi ),( Hyun-gon Shin ),( Seung-mok Lee ) 한국공업화학회 2019 공업화학 Vol.30 No.3

The aim of this review article is to summarize the role of titanium oxide (TiO₂) nanomaterials in the remediation of the aquatic environment contaminated with various emerging pollutants. The advanced oxidation process led by the semiconductor TiO₂ is an impetus in the remediation technology. Therefore, a vast number of literature works are available in this area. Further, the role of modified TiO₂ or thin film materials were discussed in the review. Also, the Localized Surface Plasmon Resonance (LSPR) effect of using noble metaldoped TiO₂ played an interesting role in the remediation process.

Chemical strain formation through anion substitution in Cu₂WS₄ for efficient electrocatalysis of water dissociation

Tiwari, Anand P.,Azam, Ashraful,Novak, Travis G.,Prakash, Om,Jeon, Seokwoo The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.17

<P>Researchers have revealed that the electrocatalytic activity can be improved by creation of defects in the crystal lattice of 2D layered transition metal dichalcogenides (TMDCs) or ternary metal chalcogenides (TMCs) such as MoS2 or Cu2MoS4, respectively. However, the role of anion substitution in the enhancement of overall electrocatalytic activity in TMCs remains unproven. Here, we show the substitution of anion atom sulfur (S) with selenium (Se) in a new electrocatalyst Cu2WS4 for efficient hydrogen evolution reaction (HER) activity. The higher electrocatalytic activity of Cu2WS4 after anion atom substitution can be attributed to the creation of chemical strain in the lattice, which causes an increase of active sites for hydrogen adsorption and desorption. Experimentally, the anion substituted Cu2W(SySe1 − y)4 samples show superior electrocatalytic activities with a low onset potential of −0.320 V at 10 mA cm<SUP>−2</SUP> for the HER, which is two-fold lower than that of the pristine Cu2WS4 (−0.650 V at 10 mA cm<SUP>−2</SUP>) sample. In addition, after 1000 cycles with continuous electrolysis in an acid electrolyte for 12 h, the anion substituted samples Cu2W(SySe1 − y)4 preserve their structure and robust catalytic activity perfectly. As a result, our work demonstrates a new approach for developments of real applications of TMCs in energy conversion.</P>

Highly active and stable layered ternary transition metal chalcogenide for hydrogen evolution reaction

Tiwari, Anand P.,Kim, Doyoung,Kim, Yongshin,Prakash, Om,Lee, Hyoyoung Elsevier 2016 Nano energy Vol.28 No.-

<P><B>Abstract</B></P> <P>Layered ternary transition metal chalcogenides (TTMCs) material has great potentials that can overcome to the limitation of active sites which is challenging in binary transition metal chalcogenides (BTMC), such as MoS<SUB>2</SUB>, towards electrochemical hydrogen production. Here, we demonstrate TTMC material which contains two transition metals Cu and Mo with chalcogen S. The TTMC, Cu<SUB>2</SUB>MoS<SUB>4</SUB> has been successfully synthesized by a facile solution-processed method. Moreover, by anion doping such as Se in as the synthesized Cu<SUB>2</SUB>MoS<SUB>4</SUB>, it has been found that TTMC can be exfoliated into single layer nanosheets. Furthermore, by controlling the number of layers, single layers TTMC exhibit the highest electrocatalytic activity towards hydrogen evolution reaction (HER) because the single layers can provide more catalytic active sites than multilayers and bulk. The onset potential for hydrogen generation is −96mV for single layer TTMC electrode material with corresponding Tafel slope 52mV/decade. After 1000 cycles with continuous electrolysis in acid electrolyte for 15h, the electrode material preserves its structure and robust catalytic activity perfectly. Our new TTMC materials show highly active electrocatalytic performance and high stability which overcome the intrinsic limitation of BTMC. As a result, our work can guide new strategy for the developments of real applications of TMCs in HER.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Single layered ternary transition metal chalcogenides have been synthesized for highly active and stable electrocatalyst. </LI> <LI> Se-doping plays an essential role to exfoliate Cu<SUB>2</SUB>Mo(S<SUB>1-y</SUB>Se<SUB>y</SUB>)<SUB>4</SUB> for high electrochemical active surface. </LI> <LI> Se-doping strategy can be implemented to exfoliate and enhance electrocatalytic activity of transition metals chalcogens. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Effective approaches to synthesis of single layered ternary transition metal chalcogenide (TTMC) have been developed to produce highly active and stable electrocatalyst towards hydrogen evolution reaction. The single layered TTMC are achieved by Se-doping in Cu<SUB>2</SUB>MoS<SUB>4</SUB> which can be applicable for other transition metal chalcogenide (TMC).</P> <P>[DISPLAY OMISSION]</P>

ON RELATIONSHIPS AMONG INTUITIONISTIC FUZZY APPROXIMATION OPERATORS, INTUITIONISTIC FUZZY TOPOLOGY AND INTUITIONISTIC FUZZY AUTOMATA

Tiwari, S.P. The Korean Society for Computational and Applied M 2010 Journal of applied mathematics & informatics Vol.28 No.1

This paper is a study about the relationships among topologies and intuitionistic fuzzy topology induced, respectively, by approximation operators and an intuitionistic fuzzy approximation operator associated with an approximation space (X, R), when the relation R on X is precisely reflexive and transitive. In particular, we consider an intuitionistic fuzzy approximation operator on an approximation space X (i.e., a set X with a reflexive and transitive relation on it), which turns out to be an intuitionistic fuzzy closure operator. This intuitionistic fuzzy closure operator gives rise to two saturated fuzzy topologies on X and it turns out that all the level topologies of one of the fuzzy topology coincide and equal to the topology analogously induced on X by a crisp approximation operator. These observations are then applied to intuitionistic fuzzy automata.

Prisoners' Perception of Tobacco Use and Cessation in Chhatisgarh, India - The Truth from Behind the Bars

Tiwari, Ram Vinod,Megalamanegowdru, Jayachandra,Parakh, Abhinav,Gupta, Anjali,Gowdruviswanathan, Shailarani,Nagarajshetty, Praveen Malavalli Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.1

Background: Prisoners represent a population group that is disadvantaged, socially deprived and underprivileged, needing particular attention with regard to provision of necessary oral health care, health promotion and motivation and tobacco cessation. Considering the situation in prisons, smoking and tobacco chewing are burning issues related to health deterioration and economic loss that seem to be overlooked by the public health sectors. Aim: To assess prisoners' perception of tobacco use and cessation in Chhatisgarh, India. Materials and Methods: A pre-tested, close ended questionnaire was administered in the form of extensive face to face interviews, to assess perceptions regarding tobacco use and cessation in the central jail of Durg District of Chhattisgarh state, India. Results: Prevalence of tobacco usage amongst the prisoners was found to be 61%. Some 27% reported smoking, 44% used tobacco in the chewable form and 29% indulged in consuming tobacco in both forms i.e. smoked as well as chewed. Results suggest several recommendations for policy relevance such as provision of a prison dentist, a tobacco cessation counseling program and targeted eradication of oral cancer by educating the prisoners. Conclusions: Health is a fundamental human "right of everyone to the enjoyment of the highest attainable standard of physical and mental well-being". This applies to prisoners just as it does to every other human being. The alarming findings in the study suggest the need for dental treatment facilities and tobacco cessation counseling in prisons.

Point-Wise Fusion of Distributed Gaussian Process Experts (FuDGE) Using a Fully Decentralized Robot Team Operating in Communication-Devoid Environment

Tiwari, Kshitij,Jeong, Sungmoon,Chong, Nak Young IEEE 2018 IEEE TRANSACTIONS ON ROBOTICS Vol.34 No.3

<P>In this paper, we focus on large-scale environment monitoring by utilizing a fully decentralized team of mobile robots. The robots utilize the resource constrained-decentralized active sensing scheme to select the most informative (uncertain) locations to observe while conserving allocated resources (battery, travel distance, <I>etc.</I>). We utilize a distributed Gaussian process (GP) framework to split the computational load over our fleet of robots. Since each robot is individually generating a model of the environment, there may be conflicting predictions for test locations. Thus, in this paper, we propose an algorithm for aggregating individual prediction models into a single globally consistent model that can be used to infer the overall spatial dynamics of the environment. To make a prediction at a previously unobserved location, we propose a novel gating network for a mixture-of-experts model wherein the weight of an expert is determined by the responsibility of the expert over the unvisited location. The benefit of posing our problem as a centralized fusion with a distributed GP computation approach is that the robots never communicate with each other, individually optimize their own GP models based on their respective observations, and off-load all their learnt models on the base station only at the end of their respective mission times. We demonstrate the effectiveness of our approach using publicly available datasets.</P>

Hybrid materials in the remediation of arsenic contaminated waters: a physico-chemical study

Tiwari, Diwakar,Lee, Seung-Mok Taylor Francis 2016 Desalination and water treatment Vol.57 No.5

<P>Hybrid materials are obtained by the organic modification of sericite using the organic cations viz. tetramethylammonium chloride (TMA or T) and dimethyldioctadecylammonium chloride as (DDDMA or D) by a simple wet cation exchange process. Surface morphology of these solids is discussed with the Scanning Electron Microscopic images. Moreover, the materials are characterized by the X-ray diffraction and Fourier Transform-Infrared analytical techniques. Removal behavior of these organo-modified sericite samples is assessed for arsenite and arsenate from aqueous solutions under the batch and column reactor operations. The batch reactor experiments show that increasing the sorptive concentration (1-20mg/L) and pH (2-10) is caused to decrease the percent uptake of arsenite and arsenate significantly. Increasing the background electrolyte concentrations from 0.0001 to 0.1mol/L NaNO3 causes a significant decrease in percent removal of As(III) which infers that As(III) is sorbed onto the solid surface, primarily, by weak electrostatic or by van der Waals forces hence, forming an outer-sphere complexes at the solid surface. On the other hand As(V) uptake is insignificantly affected in presence of background electrolyte concentrations. This indicates that As(V) is sorbed by a strong chemical force and forming an inner sphere complexes onto the solid surface. The equilibrium state modeling shows that the data is fitted well to the Freundlich and Langmuir adsorption isotherms. The sorption capacities of these solids are calculated under these equilibrium conditions which indicate that organo-modified-sericite samples possess significantly higher removal capacity comparing to the virgin sericite. The leaching of the organic molecules (T or D) are also conducted in the sorption process of As(III) or As(V) and shows that almost negligible amount of T or D leaches in the bulk solutions since the Total Organic Carbon value of the bulk solution is not increased. Further, the breakthrough curves are obtained for these oxyanions under the column experimentations and the data is fitted well to the Thomas equation hence, the maximum loading capacity for arsenic is estimated under the dynamic conditions.</P>