Hydrogen in Nanostructured, Carbon-Related, and Metallic Materials

MRS Bulletin ◽  
2002 ◽  
Vol 27 (9) ◽  
pp. 705-711 ◽  
Author(s):  
Andreas Züttel ◽  
Shin-ichi Orimo
Keyword(s):  
Hydrogen Atom ◽  
Carbon Atom ◽  
Hydrogen Adsorption ◽  
Theoretical Calculations ◽  
High Surface ◽  
High Surface Area ◽  
Metallic Materials ◽  
Hydrogen Atoms ◽  
Hydrogen Interaction ◽  
Recent Developments

AbstractRecent developments in hydrogen interaction with carbonaceous materials are reviewed in this article. The interaction is based on van der Waals attractive forces (physisorption), or the overlap of the highest occupied molecular orbitals of carbon with the hydrogen electron, overcoming the activation-energy barrier for hydrogen dissociation (chemisorption). While the physisorption of hydrogen limits the hydrogen-to-carbon ratio to less than one hydrogen atom per two carbon atoms (i.e., 4.2 mass%), in chemisorption, a ratio of two hydrogen atoms per one carbon atom is realized (e.g., in polyethylene). However, the materials with large hydrogen-to-carbon ratios only liberate the hydrogen at elevated temperature. No evidence, apart from theoretical calculations, was found for a new hydrogen-adsorption phenomenon on carbon nanotubes (CNTs), as compared with high-surface-area graphite. The curvature of CNTs and fullerenes increases the reactivity of these materials with hydrogen and leads more easily to the formation of hydrocarbons, as compared with graphite. Nanocrystalline or amorphous carbon exhibits an intermediate state for hydrogen between physisorption and chemisorption and absorbs up to one hydrogen atom per carbon atom. Nanostructured carbonaceous and metallic materials offer a large potential for hydrogen storage and must therefore be investigated in more detail.

scholarly journals Design Considerations for Borehole Thermal Energy Storage (BTES): A Review with Emphasis on Convective Heat Transfer

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-26 ◽  
Author(s):  
Helge Skarphagen ◽  
David Banks ◽  
Bjørn S. Frengstad ◽  
Harald Gether
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Theoretical Calculations ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Thermal Recovery ◽  
Conductive Heat ◽  
Geological Environment

Borehole thermal energy storage (BTES) exploits the high volumetric heat capacity of rock-forming minerals and pore water to store large quantities of heat (or cold) on a seasonal basis in the geological environment. The BTES is a volume of rock or sediment accessed via an array of borehole heat exchangers (BHE). Even well-designed BTES arrays will lose a significant quantity of heat to the adjacent and subjacent rocks/sediments and to the surface; both theoretical calculations and empirical observations suggest that seasonal thermal recovery factors in excess of 50% are difficult to obtain. Storage efficiency may be dramatically reduced in cases where (i) natural groundwater advection through the BTES removes stored heat, (ii) extensive free convection cells (thermosiphons) are allowed to form, and (iii) poor BTES design results in a high surface area/volume ratio of the array shape, allowing high conductive heat losses. The most efficient array shape will typically be a cylinder with similar dimensions of diameter and depth, preferably with an insulated top surface. Despite the potential for moderate thermal recovery, the sheer volume of thermal storage that the natural geological environment offers can still make BTES a very attractive strategy for seasonal thermal energy storage within a “smart” district heat network, especially when coupled with more efficient surficial engineered dynamic thermal energy stores (DTES).

Hydrogen adsorption on high surface area Cr2 O3 materials

2013 ◽  
Vol 210 (9) ◽  
pp. 1920-1924 ◽  
Author(s):  
Jinglian Fan ◽  
Yongxiang Cheng ◽  
Zunyun Xie ◽  
Lingyun Jin ◽  
Gengshen Hu ◽  
...  
Keyword(s):  
Surface Area ◽  
Hydrogen Adsorption ◽  
High Surface ◽  
High Surface Area

scholarly journals Enzymatic Bioreactors: An Electrochemical Perspective

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1232
Author(s):  
Simin Arshi ◽  
Mehran Nozari-Asbemarz ◽  
Edmond Magner
Keyword(s):  
Direct Electron Transfer ◽  
High Surface ◽  
High Surface Area ◽  
Enzyme Engineering ◽  
Future Perspective ◽  
Enzymatic System ◽  
Reaction Conditions ◽  
Flow Reactors ◽  
Recent Developments ◽  
Enzyme Cascades

Biocatalysts provide a number of advantages such as high selectivity, the ability to operate under mild reaction conditions and availability from renewable resources that are of interest in the development of bioreactors for applications in the pharmaceutical and other sectors. The use of oxidoreductases in biocatalytic reactors is primarily focused on the use of NAD(P)-dependent enzymes, with the recycling of the cofactor occurring via an additional enzymatic system. The use of electrochemically based systems has been limited. This review focuses on the development of electrochemically based biocatalytic reactors. The mechanisms of mediated and direct electron transfer together with methods of immobilising enzymes are briefly reviewed. The use of electrochemically based batch and flow reactors is reviewed in detail with a focus on recent developments in the use of high surface area electrodes, enzyme engineering and enzyme cascades. A future perspective on electrochemically based bioreactors is presented.

Mechanism and stereochemistry of enzymic reactions involved in porphyrin biosynthesis

1976 ◽  
Vol 273 (924) ◽  
pp. 117-136 ◽  
Keyword(s):  
Schiff Base ◽  
Hydrogen Atom ◽  
Carbon Atom ◽  
Pyridoxal Phosphate ◽  
Hydrogen Atoms ◽  
Bond Forming ◽  
Aminolaevulinic Acid

5-Aminolaevulinate synthetase catalyses the condensation of glycine and succinyl-CoA to give 5-aminolaevulinic acid. At least two broad pathways may be considered for the initial C—C bond forming step in the reaction. In pathway A the Schiff base of glycine and enzyme bound pyridoxal phosphate ( a ) undergoes decarboxylation to give the carbanion ( b ) which then condenses with succinyl-CoA with the retention of both the original C2 hydrogen atoms of glycine. In pathway B, loss of a C2 hydrogen atom gives another type of carbanion ( c ) that reacts with succinyl-CoA. Evidence has been presented to show that the initial C—C bond forming event occurs via pathway B which involves the removal of the pro R hydrogen atom of glycine. Subsequent mechanistic and stereochemical events occurring at the carbon atom destined to become C5 of 5-aminolaevulinate have also been delineated.

Concluding remarks: there's nowt so queer as carbon electrodes

2014 ◽  
Vol 172 ◽  
pp. 521-532 ◽  
Author(s):  
Patrick R. Unwin
Keyword(s):  
Carbon Materials ◽  
Local Density ◽  
High Surface ◽  
High Surface Area ◽  
Carbon Electrodes ◽  
Key Points ◽  
Recent Developments ◽  
History Of ◽  
History Of Use ◽  
The Impact

This contribution provides a personal overview and summary of Faraday Discussion 172 on “Carbon in Electrochemistry”, covering some of the key points made at the meeting within the broader context of other recent developments on carbon materials for electrochemical applications. Although carbon electrodes have a long history of use in electrochemistry, methods and techniques are only just becoming available that can test long-established models and identify key features for further exploration. This Discussion has highlighted the need for a better understanding of the impact of surface structure, defects, local density of electronic states, and surface functionality and contamination, in order to advance fundamental knowledge of various electrochemical processes and phenomena at carbon electrodes. These developments cut across important materials such as graphene, carbon nanotubes, conducting diamond and high surface area carbon materials. With more detailed pictures of structural and electronic controls of electrochemistry at carbon electrodes (and electrodes generally), will come rational advances in various technological applications, from sensors to energy technology (particularly batteries, supercapacitors and fuel cells), that have been well-illustrated at this Discussion.

ChemInform Abstract: HYDROGEN ADSORPTION ON HIGH SURFACE AREA PLATINUM CRYSTALLITES

1974 ◽  
Vol 5 (11) ◽  
pp. no-no
Author(s):  
K. KINOSHITA ◽  
J. LUNDQUIST ◽  
P. STONEHART
Keyword(s):  
Surface Area ◽  
Hydrogen Adsorption ◽  
High Surface ◽  
High Surface Area

Template-Method Synthesis of High-Surface-Area Monolithic Carbon Aerogels and Their Applications for Hydrogen and Deuterium Adsorption

2017 ◽  
Vol 16 (05n06) ◽  
pp. 1750010 ◽  
Author(s):  
Bowei Chen ◽  
Xiaojun Wang ◽  
Jiayi Zhu ◽  
Yutie Bi ◽  
Xuan Luo ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Surface Area ◽  
Hydrogen Adsorption ◽  
High Surface ◽  
High Surface Area ◽  
Carbon Aerogel ◽  
Molar Ratio ◽  
Template Method ◽  
Carbon Aerogels ◽  
Polymer Templates

In this work, novel monolithic carbon aerogels obtained by using a polymer template method were characterized and evaluated for their applications in the hydrogen and deuterium adsorption capacity. The properties (i.e., surface area, pore size distribution, hydrogen and deuterium adsorption capacities, etc.) of the carbon aerogels were affected by the polymer templates. The results showed that the carbon aerogel with the molar ratio of polyacrylic acid (PAA) to zinc chloride (ZnCl2) being 0.75:40 was featured the highest surface area (1806 m2/g) and had the highest hydrogen adsorption capacity. Moreover, the deuterium adsorption capacity of the carbon aerogel was to be further elucidated.

Cs-P Oxide Catalysts for Aldol Condensation to Produce Methyl Acrylate

2015 ◽  
Vol 1104 ◽  
pp. 51-56 ◽  
Author(s):  
Shi Feng Jiang ◽  
Zhen Qiu Li ◽  
Hong Nan Chen ◽  
Er Qiang Wang
Keyword(s):  
Methyl Acrylate ◽  
Circulating Fluidized Bed ◽  
Aldol Condensation ◽  
Theoretical Calculations ◽  
High Surface ◽  
High Surface Area ◽  
Fixed Bed ◽  
Catalyst Particle ◽  
Raw Material ◽  
Cold Model

In this research, methyl acrylate has been synthesized from industrial raw material methyl acetate through highly efficient and eco-friendly method, One-step aldol condensation, using acid-base bifunctional catalyst Cs, P and K as catalysts. Carbon deposits and other issues led to the catalysts deactivation in the process of fixed bed, which led to the production interruption. While, the process of circulating fluidized bed can overcome this defect and the catalyst can maintain good catalytic activity in the whole process. Cs (8%), P (5%), K (2%)/γ-Al2O3/ catalyst showed better performance due to its high surface area and more weak basicity and acidity. In addition, theoretical calculations and cold model experiments were also conducted in this work to determine the catalyst particle size，operation gas velocity and gas distributor plate.

Recent developments in the use of nanoparticles for treatment of biofilms

2017 ◽  
Vol 6 (5) ◽  
pp. 383-404 ◽  
Author(s):  
Chendong Han ◽  
Nicholas Romero ◽  
Stephen Fischer ◽  
Julia Dookran ◽  
Aaron Berger ◽  
...  
Keyword(s):  
Health Care Systems ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Chronic Infections ◽  
Recent Developments ◽  
Care Systems ◽  
Biofilm Bacteria ◽  
Biofilm Disruption ◽  
Unique Chemical

AbstractChronic infections have posed a tremendous burden on health care systems worldwide. Approximately 60% of chronic infections are estimated to be related to biofilms, in large part due to the extraordinary antibiotic resistance of biofilm bacteria. Nanoparticle (NP)-based therapies are viable approaches to treat biofilm-associated infections due to NPs’ unique chemical and physical properties, granted by their high surface area to volume ratio. The mechanism underlying the anti-biofilm activity of various types of NPs is actively under investigation. Simply comparing biofilm disruption or reduction rates is not adequate to describe the effectiveness of NPs; many other factors need to be taken into account, such as the NP type, bacterial strain, concentration of NPs, quantification methods, and the biofilm culture environment. This review focuses on recent research on the creation, characterization, and evaluation of NPs for the prevention or treatment of biofilm infections.

scholarly journals Recent Developments in All-Solid-State Micro-Supercapacitors Based on Two-Dimensional Materials

2020 ◽  
Author(s):  
Minu Mathew ◽  
Sithara Radhakrishnan ◽  
Chandra Sekhar Rout
Keyword(s):  
Solid State ◽  
Mechanical Stability ◽  
2D Materials ◽  
High Surface ◽  
High Surface Area ◽  
Diffusion Path ◽  
Redox Activity ◽  
Good Surface ◽  
Recent Developments ◽  
On Chip

Owing to their unique features such as high surface area, rich electroactive sites, ultrathin thickness, excellent flexibility and mechanical stability and multiple surface functionalities enables outstanding electrochemical response which provides high energy and power density supercapacitors based on them. Also, the Van der Waals gap between layered 2D materials encourages the fast ion transport with shorter ion diffusion path. 2D materials such as MXenes, graphene, TMDs, and 2D metal–organic frame work, TMOs/TMHs materials, have been described with regard to their electrochemical properties for MSCs. We have summarized the recent progress in MSC based on well-developed 2D materials-based electrodes and its potential outcomes with different architectures including interdigitated pattern, stacked MSC and 3D geometries for on-chip electronics. This chapter provides a brief overview of the recent developments in the field of 2D material based all-solid-state microsupercapacitors (MSCs). A brief note on the MSC device configuration and microfabrication methods for the microelectrodes have been discussed. Taking advantage of certain 2D materials such as 2D MXenes, TMDs, TMOs/TMHs that provide good surface chemistry, tunable chemical and physical properties, intercalation, surface modification (functionalization), heterostructures, phase transformations, defect engineering etc. are beneficial for enhancement in pseudocapacitance as it promotes the redox activity.

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