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Nano Catalyst

Sara Fernández, Lu Gao, Jan Philipp Hofmann, Jérôme Carnis, Stéphane Labat, Gilbert A Chahine, Arno J F van Hoof, M W G M Tiny Verhoeven, Tobias U Schülli, Emiel J M Hensen, Olivier Thomas, Marie-Ingrid Richard
The catalytic activity of metal nanoparticles can be altered by applying strain, which changes the crystalline lattice spacing and modifies the electronic properties of the metal. Understanding the role of elastic strain during catalytic reactions is thus crucial for catalyst design. Here, we show how single highly faceted Pt nanoparticles expand or contract upon interaction with different gas atmospheres using in situ nano-focused coherent X-ray diffraction imaging. We also demonstrate inter-particle heterogeneities, as they differ in development of strain under CO oxidation reaction conditions...
December 11, 2018: Nanoscale
Mebrahtu Melake Mezgebe, Anqi Ju, Gang Wei, Daniel K Machariya, Shanyi Guang, Hongyao Xu
The nano-sized copper sulfides (CuS) with different morphologies were prepared by hydrothermal method without any surfactant or template. The morphology and structure of CuS were characterized by powder X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectra (XPS), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) and ultraviolet-visible (UV-vis) absorption spectroscopy. FESEM results show that four morphologies of CuS (flower-like nanospheres, cross-linked nanodisks, cross-linked nanoplates and nanosheets) were prepared simply by changing the hydrothermal solvent...
December 10, 2018: Nanotechnology
Gibaek Lee, Hyeonji Choi, Yongsug Tak
In this study, the degradation of different cathode carbon supports is investigated in PEMFCs. A platinum catalyst is synthesized using various carbon supports, such as Vulcan XC-72, graphite nano powder, and carbon nanotube, which are evaluated based on the fabrication of membrane-electrode-assemblies (MEAs). During the start-up and shutdown of PEMFCs, the individual electrode potential can be measured in-situ using a dynamic hydrogen electrode (DHE). The cathode potential increases instantaneously to 1.4 V in one attempt, when H2/air boundaries are developed on the anode side during the fuel starvation, leading to significant carbon corrosion...
November 28, 2018: Nanotechnology
Mariam Ameen, Mohammad Tazli Azizan, Anita Ramli, Suzana Yusup, Mohamad Sahban Alnarabiji
Hydrodeoxygenation is one of the promising technologies for the transformation of triglycerides into long-chain hydrocarbon fuel commonly known as green diesel. The hydrodeoxygenation (HDO) of rubber seed oil into diesel range (C15 -C18 ) hydrocarbon over non-sulphided bimetallic (Ni-Mo/γ-Al2 O3 solid catalysts were studied. The catalysts were synthesized via wet impregnation method as well as sonochemical method. The synthesized catalysts were subjected to characterization methods including FESEM coupled with EDX, XRD, BET, TEM, XPS, NH3 -TPD, CO-chemisorption and H2 -TPR in order to investigate the effects of ultrasound irradiations on physicochemical properties of the catalyst...
March 2019: Ultrasonics Sonochemistry
Cui Ma, Pengfei Yuan, Shengyong Jia, Yaqi Liu, Xingjun Zhang, Sen Hou, Hanxu Zhang, Zhengguang He
In this work, the biologically pre-treated leachate was subjected to catalytic micro-ozonation using cow-dung ash composites loaded with Fe3 O4 nanoparticles (nano-Fe3 O4 @CDA) as the catalyst. The optimal conditions used were nano-Fe3 O4 @CDA dosage of 0.8 g/L, input ozone of 3.0 g/L, and reaction time of 120 min. This environment yielded the following results: The COD and color number (CN) removal reached 53% and 89%, respectively, and the BOD5 /COD increased from 0.05 to 0.32. The catalytic micro-ozonation partially degraded the refractory substances into intermediates with lower molecular weight...
January 2019: Waste Management
Jun Xu, Shengli Guo, Lei Jia, Wensheng Zhang
In this work, AuPd alloy palygorskite based Pal-NH₂@AuPd nano-catalysts were prepared and used as catalysts for the reduction of nitroarenes and dyes at room temperature. The surface of palygorskite (Pal) was first modified with 3-aminpropyltriethoxysilane, and then covered with AuPd alloy nanoparticles through co-reduction of HAuCl₄ and K₂PdCl₄. The morphology and structures of the Pal-NH₂@AuPd nano-catalysts were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM)...
December 3, 2018: Nanomaterials
Ke Fan, Haiyuan Zou, Yue Lu, Hong Chen, Fusheng Li, Jinxuan Liu, Licheng Sun, Lianpeng Tong, Michael F Toney, Manling Sui, Jiaguo Yu
As one of the most remarkable oxygen evolution reaction (OER) electrocatalysts, metal chalcogenides have been intensively reported due to their high OER activities during the past few decades. It has been reported that electron-chemical conversion of metal chalcogenides into oxides/hydroxides would take place after OER. However, the transition mechanism of such unstable structures, as well as the real active sites and catalytic activity during OER for these electrocatalysts, has not been understood yet, which urgently needs a direct observation for the electrocatalytic water oxidation process, especially at nano or even angstrom scale...
December 3, 2018: ACS Nano
Tanu Kaushal, Gaurava Srivastava, Ashok Sharma, Arvind Singh Negi
Quinoxalines are benzopyrazines containing benzene and pyrazine rings fused together. In the recent past, quinoxalines have attracted Medicinal Chemists considerably for their syntheses and chemistry due to their distinct pharmacological activities. Diverse synthetic protocols have been developed via multicomponent reactions, single pot synthesis and combinatorial approach using efficient catalysts, reagents, and nano-composites etc. Further, the versatility of the quinoxaline core and its reasonable chemical simplicity devise it extremely promising source of bioactive compounds...
November 15, 2018: Bioorganic & Medicinal Chemistry
N Babitha, L Srimathi Priya, S Rosy Christy, A Manikandan, A Dinesh, M Durka, S Arunadevi
Semiconductor ZnO samples with two different morphologies such as nanoparticles (ZnO-NPs) and nano-sheets (ZnO-NSs) was successfully prepared by microwave heating (MHM) and modified sol-gel (SGM) method, respectively using Pedalium Murex plant extract as the bio-reducing agent. Structural, purity and morphology of the samples was examined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis. Optical property analysis and band gap calculation were carried out by UV-Visible diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy techniques...
May 1, 2019: Journal of Nanoscience and Nanotechnology
Brindha Appavu, Sivakumar Thiripuranthagan, Thamaraiselvi Kanagaraj, Sakthivel Kumaravel, Elangovan Erusappan
In this study, we report the synthesis of NiWO₄/nitrogen doped reduced graphene oxide nano composite by one-pot hydrothermal method. The NiWO₄ nano particles were dispersed uniformly on graphene sheets. The as prepared NiWO₄, NiWO₄/5% rGO and NiWO₄/N-5% rGO composites were analytically characterized by Powder X-ray diffraction (XRD), Raman spectroscopy, Diffuse reflectance spectroscopy (DRS-UV), Scanning electron microscopy (SEM) and N₂ adsorption-desorption isotherm. The photocatalytic performances of the synthesized composites were evaluated towards the photo degradation of congo red (CR) under visible light radiation...
May 1, 2019: Journal of Nanoscience and Nanotechnology
J Amala Infant Joice, S Aishwarya, T Sivakumar
Titania by sol gel and Ni-Ru titania catalysts by wet impregnation methods were prepared and characterized by XRD, UV-DRS, BET and TEM techniques. Catalytic activities of the photocatalysts were evaluated towards the degradation of three widely used neonicotinoids type insecticides namely acetamiprid, imidacloprid and thiamethoxam under UV, Visible and solar irradiations. The reaction parameters such as initial concentration of the insecticide, weight of the catalyst and pH of the system were found to influence the reaction rate...
May 1, 2019: Journal of Nanoscience and Nanotechnology
Ting Zhang, Di Zhang, Xinghua Han, Ting Dong, Xinwen Guo, Chunshan Song, Rui Si, Wei Liu, Yuefeng Liu, Zhongkui Zhao
Developing single-atom catalysts with porous micro-/nano-structures for high active-site accessibility is of great significance but still remains a challenge. Herein, we for the first time report a novel template-free preassembly strategy to fabricate the single Cu atoms mounted porous hollow graphitic carbonitride spheres via thermal polymerization of supramolecular preassemblies composed of melamine-Cu complex and cyanuric acid. Atomically dispersed Cu-N3 moieties were unambiguously confirmed by the spherical aberration correction electron microscopy and extended X-ray absorption fine structure spectroscopy...
November 30, 2018: Journal of the American Chemical Society
Giuseppe Gallo, Luana Presta, Elena Perrin, Michele Gallo, Davide Marchetto, Anna Maria Puglia, Renato Fani, Franco Baldi
BACKGROUND: Klebsiella oxytoca DSM 29614 - isolated from acid mine drainages - grows anaerobically using Fe(III)-citrate as sole carbon and energy source, unlike other enterobacteria and K. oxytoca clinical isolates. The DSM 29614 strain is multi metal resistant and produces metal nanoparticles that are embedded in its very peculiar capsular exopolysaccharide. These metal nanoparticles were effective as antimicrobial and anticancer compounds, chemical catalysts and nano-fertilizers. RESULTS: The DSM 29614 strain genome was sequenced and analysed by a combination of in silico procedures...
November 27, 2018: BMC Microbiology
Gabriela Kratošová, Veronika Holišová, Zuzana Konvičková, Avinash P Ingle, Swapnil Gaikwad, Kateřina Škrlová, Aleš Prokop, Mahendra Rai, Daniela Plachá
Chemical, physical and mechanical methods of nanomaterial preparation are still regarded as mainstream methods, and the scientific community continues to search for new ways of nanomaterial preparation. The major objective of this review is to highlight the advantages of using green chemistry and bionanotechnology in the preparation of functional low-cost catalysts. Bionanotechnology employs biological principles and processes connected with bio-phase participation in both design and development of nano-structures and nano-materials, and the biosynthesis of metallic nanoparticles is becoming even more popular due to; (i) economic and ecologic effectiveness, (ii) simple one-step nanoparticle formation, stabilisation and biomass support and (iii) the possibility of bio-waste valorisation...
November 24, 2018: Biotechnology Advances
Xin Jin, Tianqi Fang, Jinyao Wang, Mengyuan Liu, Siyuan Pan, Bala Subramaniam, Jian Shen, Chaohe Yang, Raghunath V Chaudhari
Conversion of biomass to chemicals provides essential products to human society from renewable resources. In this context, achieving atom-economical and energy-efficient conversion with high selectivity towards target products remains a key challenge. Recent developments in nanostructured catalysts address this challenge reporting remarkable performances in shape and morphology dependent catalysis by metals on nano scale in energy and environmental applications. In this review, most recent advances in synthesis of heterogeneous nanomaterials, surface characterization and catalytic performances for hydrogenation and oxidation for biorenewables with plausible mechanism have been discussed...
November 26, 2018: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Shriram Janghela, Nagendra Singh Neeraj, Neha Agarwal, Kavita Agarwal, Debmalya Roy, Kingsuk Mukhopadhyay, Namburi Eswara Prasad
Micron long carbon nanofibers (CNFs) were grown on porous carbon beads to give an active surface for rapid immobilization of guest molecules. The fabrication of nanostructures using a catalytic route involving chemical vapour deposition on a porous substrate was accomplished by the controlled synthesis of iron nanoclusters on the surface of porous carbon beads. The challenge of catalyst nanoparticle diffusion into the porous substrate was addressed by using iron coordinated ligand complexes and optimizing the loading percentage of metal salts onto beads...
November 23, 2018: Physical Chemistry Chemical Physics: PCCP
Hirofumi Kishi, Tomokazu Sakamoto, Koichiro Asazawa, Susumu Yamaguchi, Takeshi Kato, Barr Zulevi, Alexey Serov, Kateryna Artyushkova, Plamen Atanassov, Daiju Matsumura, Kazuhisa Tamura, Yasuo Nishihata, Hirohisa Tanaka
Platinum group metal-free (PGM-free) catalysts based on transition metal-nitrogen-carbon nanomaterials have been studied by a combination of ex situ and in situ synchrotron X-ray spectroscopy techniques; high-resolution Transmission Electron Microscope (TEM); Mößbauer spectroscopy combined with electrochemical methods and Density Functional Theory (DFT) modeling/theoretical approaches. The main objective of this study was to correlate the HO₂- generation with the chemical nature and surface availability of active sites in iron-nitrogen-carbon (Fe-N-C) catalysts derived by sacrificial support method (SSM)...
November 22, 2018: Nanomaterials
Jumeng Wei, Min Zhou, Anchun Long, Yanming Xue, Hanbin Liao, Chao Wei, Zhichuan J Xu
The hydrogen evolution reaction (HER) is a half-cell reaction in water electrolysis for producing hydrogen gas. In industrial water electrolysis, the HER is often conducted in alkaline media to achieve higher stability of the electrode materials. However, the kinetics of the HER in alkaline medium is slow relative to that in acid because of the low concentration of protons in the former. Under the latter conditions, the entire HER process will require additional effort to obtain protons by water dissociation near or on the catalyst surface...
2018: Nano-micro letters
Palle R Murthy, Parasuraman Selvam
Ordered mesoporous carbon (OMC) supported gold nanoparticles of size 3-4 nm having uniform dispersion were synthesized by sol-immobilization method. OMCs such as CMK-3 and NCCR-56 with high surface area and uniform pore size were obtained, respectively, using ordered mesoporous silicas such as SBA-15 and IITM-56 as hard templates, respectively. The resulting OMC supported monodispersed nano-gold, i. e., Au/CMK-3 and Au/NCCR-56, exhibited excellent performance as mild-oxidizing catalysts for oxidation of glycerol with high hydrothermal stability...
November 21, 2018: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Min Tian, Feng Li, Haiguo Hu, Jiantai Ma, Jun Jin
The catalyst with high atom utilization efficiency accompanied by improved reactivity and durability is highly desired. Metallic MoO2 with small size is easy to agglomerate, making it difficult to water splitting for hydrogen by electrolysis. Here, the nano-Cu-mediated multi-sites method is proposed for the first time to prepare ultrafine MoO2 nanoparticles (NPs) dispersed on poly (diallyldimethylammonium chloride) decorated-reduced graphene oxide (denoted as MoO2/PDDA-rGO). The introduction of Cu NPs increases the number of growing sites for MoO2 on PDDA-rGO and simultaneously promotes the growing rate of MoO2 on PDDA-rGO...
November 20, 2018: ChemSusChem
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