scholarly journals The Effect of Carbon Content on Methanol Oxidation and Photo-Oxidation at Pt-TiO2-C Electrodes

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 248 ◽  
Author(s):  
Athanasios Papaderakis ◽  
Olga Spyridou ◽  
Nikolaos Karanasios ◽  
Aikaterini Touni ◽  
Angeliki Banti ◽  
...  
Keyword(s):  
Carbon Content ◽  
High Surface ◽  
Electronic Conductivity ◽  
High Surface Area ◽  
Deposition Process ◽  
Atom Ratio ◽  
Catalyst Film ◽  
Uv Illumination ◽  
Oxidation Of Methanol ◽  
Pt Electrodes

The oxidation of methanol is studied at TiO2-supported Pt electrodes of varied high surface area carbon content (in the 30-5% w/w range) and C÷Ti atom ratio (in the 3.0-0.4 ratio). The Pt-TiO2 catalyst is prepared by a photo-deposition process and C nanoparticles (Vulcan XC72R) are added by simple ultrasonic mixing. The optimum C÷Ti atom ratio of the prepared catalyst for methanol electro-oxidation is found to be 1.5, resulting from the interplay of C properties (increased electronic conductivity and methanol adsorption), those of TiO2 (synergistic effect on Pt and photo-activity), as well as the catalyst film thickness. The intrinsic catalytic activity of the best Pt-TiO2/C catalyst is better than that of a commercial Pt/C catalyst and could be further improved by nearly 25% upon UV illumination, whose periodic application can also limit current deterioration.

scholarly journals Design and stabilisation of a high area iron molybdate surface for the selective oxidation of methanol to formaldehyde

2016 ◽  
Vol 188 ◽  
pp. 115-129 ◽  
Author(s):  
Stephanie Chapman ◽  
Catherine Brookes ◽  
Michael Bowker ◽  
Emma K. Gibson ◽  
Peter P. Wells
Keyword(s):  
Surface Area ◽  
Selective Oxidation ◽  
High Surface ◽  
High Surface Area ◽  
Fold Increase ◽  
Catalytic Performance ◽  
Iron Molybdate ◽  
Oxidation Of Methanol ◽  
Bulk Catalyst ◽  
Temperature Programmed

The performance of Mo-enriched, bulk ferric molybdate, employed commercially for the industrially important reaction of the selective oxidation of methanol to formaldehyde, is limited by a low surface area, typically 5–8 m2 g−1. Recent advances in the understanding of the iron molybdate catalyst have focused on the study of MoOx@Fe2O3 (MoOx shell, Fe2O3 core) systems, where only a few overlayers of Mo are present on the surface. This method of preparing MoOx@Fe2O3 catalysts was shown to support an iron molybdate surface of higher surface area than the industrially-favoured bulk phase. In this research, a MoOx@Fe2O3 catalyst of even higher surface area was stabilised by modifying a haematite support containing 5 wt% Al dopant. The addition of Al was an important factor for stabilising the haematite surface area and resulted in an iron molybdate surface area of ∼35 m2 g−1, around a 5 fold increase on the bulk catalyst. XPS confirmed Mo surface-enrichment, whilst Mo XANES resolved an amorphous MoOx surface monolayer supported on a sublayer of Fe2(MoO4)3 that became increasingly extensive with initial Mo surface loading. The high surface area MoOx@Fe2O3 catalyst proved amenable to bulk characterisation techniques; contributions from Fe2(MoO4)3 were detectable by Raman, XAFS, ATR-IR and XRD spectroscopies. The temperature-programmed pulsed flow reaction of methanol showed that this novel, high surface area catalyst (3ML-HSA) outperformed the undoped analogue (3ML-ISA), and a peak yield of 94% formaldehyde was obtained at ∼40 °C below that for the bulk Fe2(MoO4)3 phase. This work demonstrates how core–shell, multi-component oxides offer new routes for improving catalytic performance and understanding catalytic activity.

scholarly journals Toolbox for atomic layer deposition process development on high surface area powders

2021 ◽  
Vol 92 (2) ◽  
pp. 025115
Author(s):  
K. Knemeyer ◽  
R. Baumgarten ◽  
P. Ingale ◽  
R. Naumann d’Alnoncourt ◽  
M. Driess ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Surface Area ◽  
Process Development ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Layer ◽  
Deposition Process ◽  
Atomic Layer Deposition Process ◽  
Layer Deposition

scholarly journals Cinnamon-Derived Hierarchically Porous Carbon as an Effective Lithium Polysulfide Reservoir in Lithium–Sulfur Batteries

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1220 ◽  
Author(s):  
Ranjith Thangavel ◽  
Aravindaraj G. Kannan ◽  
Rubha Ponraj ◽  
Karthikeyan Kaliyappan ◽  
Won-Sub Yoon ◽  
...  
Keyword(s):  
Surface Area ◽  
Porous Carbon ◽  
Pore Volume ◽  
High Surface ◽  
Electronic Conductivity ◽  
High Surface Area ◽  
High Energy ◽  
Superior Performance ◽  
Lithium Sulfur Batteries ◽  
Lithium Sulfur

Lithium–sulfur batteries are attractive candidates for next generation high energy applications, but more research works are needed to overcome their current challenges, namely: (a) the poor electronic conductivity of sulfur, and (b) the dissolution and migration of long-chain polysulfides. Inspired by eco-friendly and bio-derived materials, we synthesized highly porous carbon from cinnamon sticks. The bio-carbon had an ultra-high surface area and large pore volume, which serves the dual functions of making sulfur particles highly conductive and acting as a polysulfide reservoir. Sulfur was predominantly impregnated into pores of the carbon, and the inter-connected hierarchical pore structure facilitated a faster ionic transport. The strong carbon framework maintained structural integrity upon volume expansion, and the unoccupied pores served as polysulfide trapping sites, thereby retaining the polysulfide within the cathode and preventing sulfur loss. These mechanisms contributed to the superior performance of the lithium-sulfur cell, which delivered a discharge capacity of 1020 mAh g−1 at a 0.2C rate. Furthermore, the cell exhibited improved kinetics, with an excellent cycling stability for 150 cycles with a very low capacity decay of 0.10% per cycle. This strategy of combining all types of pores (micro, meso and macro) with a high pore volume and ultra-high surface area had a synergistic effect on improving the performance of the sulfur cathode.

scholarly journals Effect of porosity on GaN for hydrogen gas sensing

2014 ◽  
Vol 8 (1) ◽  
Author(s):  
Aishah Zarzali Shah ◽  
Nurul Huda Mohd Noor ◽  
Zainuriah Hassan ◽  
Ainorkhilah Mahmood ◽  
Yam Fong Kwong
Keyword(s):  
Gas Sensing ◽  
High Surface ◽  
High Surface Area ◽  
Schottky Contact ◽  
Hydrogen Sensor ◽  
Hydrogen Gas ◽  
Force Microscopy ◽  
Uv Illumination ◽  
Atomic Force ◽  
Bandgap Semiconductors

Porous wide bandgap semiconductors have been widely studied in the last decade due to their unique properties compared to the bulk crystals. The high surface area, shift of bandgap, luminescence intensity enhancement and efficient photoresponse when porosity is formed can be tailored to fabricate new sensing devices. In this work, porous GaN was prepared by ultraviolet (UV) assisted electroless chemical etching method. The commercial Si doped n-type GaN film grown on two inches diameter sapphire (0001) substrate with GaN thickness of 5.5 μm was used in this study. The wafer was then cleaved into few pieces, and these samples were etched in HF:H2O2:CH3OH under UV illumination for 60 minutes. The structural properties was characterized using Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM). Hydrogen sensor was subsequently fabricated by depositing Pt Schottky contact onto the porous GaN sample. The effect of sensing dilute H2 gas with different concentration which is 1% and 2% H2 in a N2 gas ambient was analyzed. The Schottky barrier height of the gas sensor samples was reduced upon exposure to gas. The porous GaN resulted better sensitivity compared to the as grown GaN sample in H2 gas sensing

scholarly journals New insights in polydopamine formation via surface adsorption

2022 ◽  
Author(s):  
Hamoon Hemmatpour ◽  
Oreste De Luca ◽  
Dominic Crestani ◽  
Alessia Lasorsa ◽  
Patrick van der Wel ◽  
...  
Keyword(s):  
Reaction Pathway ◽  
High Surface ◽  
High Surface Area ◽  
Coupling Reaction ◽  
Deposition Process ◽  
Halloysite Nanotubes ◽  
Systematic Investigation ◽  
Main Reaction ◽  
Oxidative Coupling Reaction ◽  
Initial Stage

Abstract Polydopamine is a biomimetic self-adherent polymer, which can be easily deposited on a wide variety of materials. Despite the rapidly increasing interest in polydopamine-based coatings, the polymerization mechanism and the key intermediate species formed during the deposition process are still controversial. Herein, we report a systematic investigation of polydopamine formation on halloysite nanotubes; the negative charge and high surface area of halloysite nanotubes favour the capture of intermediates that are involved in polydopamine formation and decelerate the kinetics of the process, to unravel the various polymerization steps. Data from X-ray photoelectron and solid-state nuclear magnetic resonance spectroscopies demonstrate that in the initial stage of polydopamine deposition, oxidative coupling reaction of the dopaminechrome molecules is the main reaction pathway that leads to formation of polycatecholamine oligomers as an intermediate and the post cyclization of the linear oligomers occurs subsequently. Furthermore, Tris molecules are incorporated into the initially formed oligomers.

LiMBO3 (M=Fe, Mn): Potential Cathode for Lithium Ion Batteries

2002 ◽  
Vol 730 ◽  
Author(s):  
Jan L. Allen ◽  
Kang Xu ◽  
Sam S. Zhang ◽  
T. Richard Jow
Keyword(s):  
High Surface ◽  
Electronic Conductivity ◽  
Specific Capacity ◽  
High Surface Area ◽  
Lithium Ion ◽  
Composite Electrodes ◽  
Electrically Conductive ◽  
Manganese Phosphate ◽  
Redox Active ◽  
Active Metal

AbstractRecently discovered borates, LiMBO3 (M=Fe, Mn), share similarities with LiFe(Mn)PO4. They are polyanion structures, contain extractable lithium and suffer from low electronic conductivity. They are attractive to replace expensive, less abundant redox metals in current use in cathodes with environmentally friendly iron or manganese. Phosphate or borate groups adjacent to the redox active metal increase the voltage of the redox couple through an inductive effect. The LiFeBO3 discharge curve shows a pseudo-plateau around 2.6 V for the Fe(II) / Fe(III) couple. This study brings to bear techniques to improve electrode conductivity to produce LiMBO3 composite electrodes thus allowing access to some of the high, theoretical specific capacity. At low current, up to 70 percent of lithium could be extracted from LiFeBO3 that was prepared in the presence of high surface area, highly electrically conductive carbon black. Attempts to improve the cathode properties of LiMnBO3 were less successful.

scholarly journals Nanostructured TiO2 Doped with Nb as a Novel Support for PEMFC

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Edgar Valenzuela ◽  
Victor Ramos-Sanchez ◽  
Alejandro Adolfo Lambert Arista ◽  
Oumarou Savadogo
Keyword(s):  
Surface Area ◽  
High Surface ◽  
Electronic Conductivity ◽  
Catalyst Support ◽  
High Surface Area ◽  
Particle Dispersion ◽  
Metallic Oxide ◽  
Oxide Support ◽  
The Stability

Nowadays, one of the major issues of the PEMFC concerns the durability. Historically, carbon has been used as a catalyst support in PEMFC; nevertheless, under the environmental conditions of the cell, the carbon is oxidized, leaving the catalyst unsupported. In order to increase the stability and durability of the catalyst in the PEMFC, a novel nanostructured metallic oxide support is proposed. In this work, TiO2 was doped with Nb to obtain a material that combines chemical stability, high surface area, and an adequate electronic conductivity in order to be a successful catalyst support candidate for long-term PEMFC applications. The TiO2-Nb nanostructured catalyst support was physically and electrochemically characterized. According to the results, the TiO2-Nb offers high surface area and good particle dispersion; also, the electrochemical activity and stability of the support were evaluated under high potential conditions, where the TiO2-Nb proved to be much more stable than carbon.

scholarly journals Salt-Mediated Au-Cu Nanofoam and Au-Cu-Pd Porous Macrobeam Synthesis

Molecules ◽  
2018 ◽  
Vol 23 (7) ◽  
pp. 1701 ◽  
Author(s):  
Fred Burpo ◽  
Enoch Nagelli ◽  
Lauren Morris ◽  
Kamil Woronowicz ◽  
Alexander Mitropoulos
Keyword(s):  
Surface Area ◽  
Electrochemical Impedance ◽  
High Surface ◽  
Electronic Conductivity ◽  
High Surface Area ◽  
Three Dimensional ◽  
Synthesis Methods ◽  
X Ray ◽  
Sensing Applications ◽  
Metal Composition

Multi-metallic and alloy nanomaterials enable a broad range of catalytic applications with high surface area and tuning reaction specificity through the variation of metal composition. The ability to synthesize these materials as three-dimensional nanostructures enables control of surface area, pore size and mass transfer properties, electronic conductivity, and ultimately device integration. Au-Cu nanomaterials offer tunable optical and catalytic properties at reduced material cost. The synthesis methods for Au-Cu nanostructures, especially three-dimensional materials, has been limited. Here, we present Au-Cu nanofoams and Au-Cu-Pd macrobeams synthesized from salt precursors. Salt precursors formed from the precipitation of square planar ions resulted in short- and long-range ordered crystals that, when reduced in solution, form nanofoams or macrobeams that can be dried or pressed into freestanding monoliths or films. Metal composition was determined with X-ray diffraction and energy dispersive X-ray spectroscopy. Nitrogen gas adsorption indicated an Au-Cu nanofoam specific surface area of 19.4 m2/g. Specific capacitance determined with electrochemical impedance spectroscopy was 46.0 F/g and 52.5 F/g for Au-Cu nanofoams and Au-Cu-Pd macrobeams, respectively. The use of salt precursors is envisioned as a synthesis route to numerous metal and multi-metallic nanostructures for catalytic, energy storage, and sensing applications.

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