Improving the Activity of Fe/C/N ORR Electrocatalyst Using Double Ammonia Promoted CO2 Laser Pyrolysis

Recently, we reported the use of CO2 laser pyrolysis for the synthesis of promising Fe/C/N electrocatalysts for Oxygen Reduction Reaction (ORR) in fuel cells. The set-up used single laser pyrolysis of an aerosolized solution of iron acetylacetonate in toluene with ammonia, both as laser energy transfer agent and nitrogen source. In the present paper, we investigate the effect of a second ammonia promoted CO2 laser pyrolysis on the feature and ORR activity of Fe/C/N electrocatalysts. Indeed, compared to single pyrolysis, the second ammonia promoted CO2 laser pyrolysis could be an interesting way to synthesize in one-step performing ORR electrocatalysts on a large scale. For this comparison, a two-stage reactor was built, allowing both single ammonia-induced CO2 laser pyrolysis as reported previously or double ammonia-induced CO2 laser pyrolysis. In the latter configuration, the catalyst nanopowder flow is formed at the first stage of the reactor, then mixed with a second ammonia flow and allowed to cross a second CO2 laser beam, thus undergoing a second ammonia-induced CO2 laser pyrolysis before being collected on filters. It is found that the second ammonia-induced CO2 laser pyrolysis significantly improves the ORR performances of the materials prepared by single CO2 laser pyrolysis. The effect is demonstrated for three different catalysts for which the onset potentials for the ORR from single-stage to double-stage configuration increase from 625 mV to 845 mV, 790 mV to 860 mV, and 800 mV to 885 mV, respectively. The selectivity of the ORR was determined at 600 mV/SHE and lie between 3.41 and 3.72. These promising performances suggesting potentialities for the one-step formation of highly active Fe/C/N ORR electrocatalysts are discussed, based on results of surface analysis by XPS, specific surface area measurements, and Raman spectroscopy.

Download Full-text

Global Reaction Model to Describe the Kinetics of Catalytic Pyrolysis of Coffee Grounds Waste

Materials Science Forum ◽

10.4028/www.scientific.net/msf.899.173 ◽

2017 ◽

Vol 899 ◽

pp. 173-178 ◽

Cited By ~ 1

Author(s):

Ronydes Batista Jr. ◽

Bruna Sene Alves Araújo ◽

Pedro Ivo Brandão e Melo Franco ◽

Beatriz Cristina Silvério ◽

Sandra Cristina Danta ◽

...

Keyword(s):

Thermal Decomposition ◽

Large Scale ◽

Catalytic Pyrolysis ◽

Petroleum Products ◽

Reaction Model ◽

Heating Rates ◽

Coffee Grounds ◽

One Step ◽

Global Reaction ◽

The One

In view of the constant search for new sources of renewable energy, the particulate agro-industrial waste reuse emerges as an advantageous alternative. However, despite the advantages of using the biomass as an energy source, there is still strong resistance as the large-scale replacement of petroleum products due to the lack of scientifically proven efficient conversion technologies. In this context, the pyrolysis is presented as one of the most widely used thermal decomposition processes. The knowledge of aspects of chemical kinetics, thermodynamics these will, heat and mass transfer, are so important, since influence the quality of the product. This paper presents a kinetic study of slow pyrolysis of coffee grounds waste from dynamic thermogravimetric experiments (TG), using different powder catalysts. The primary thermal decomposition was described by the one-step reaction model, which considers a single global reaction. The kinetic parameters were estimated using nonlinear regression and the differential evolution method. The coffee ground waste was dried at 105°C for 24 hours. The sample in nature was analyzed at different heating rates, being 10, 15, 20, 30 and 50 K/min. In the catalytic pyrolysis, about 5% (w/w) of catalyst were added to the sample, at a heating rate of 30 K/min. The results show that the one-step model does not accurately represent the data of weight loss (TG) and its derivative (DTG), but can do an estimative of the activation energy reaction, and can show the differences caused by the catalysts. Although no one can say anything about the products formed with the addition of the catalyst, it would be necessary to micro-pyrolysis analysis, we can say the influence of the catalyst in the samples, based on the data obtained in thermogravimetric tests.

Download Full-text

An approach combining additive manufacturing and dielectrophoresis for 3D-structured flexible lead-free piezoelectric composites for electromechanical energy conversion

Journal of Materials Chemistry A ◽

10.1039/d1ta07475j ◽

2021 ◽

Author(s):

Zehuan Wang ◽

Jin Cheng ◽

Renchao Hu ◽

Xiaoting Yuan ◽

Zhonghui Yu ◽

...

Keyword(s):

Additive Manufacturing ◽

Large Scale ◽

Lead Free ◽

Piezoelectric Composites ◽

Additive Manufacturing Technology ◽

Electromechanical Energy Conversion ◽

Electromechanical Energy ◽

One Step ◽

The One ◽

Piezoelectric Devices

Additive manufacturing technology has promoted the development of piezoelectric devices, from the one-step moulding of micro-miniature devices to large-scale devices.

Download Full-text

Characterization of highly active 2-keto-3-deoxy-L-arabinonate and 2-keto-3-deoxy-D-xylonate dehydratases in terms of the biotransformation of hemicellulose sugars to chemicals

Applied Microbiology and Biotechnology ◽

10.1007/s00253-020-10742-5 ◽

2020 ◽

Vol 104 (16) ◽

pp. 7023-7035

Author(s):

Samuel Sutiono ◽

Bettina Siebers ◽

Volker Sieber

Keyword(s):

Racemic Mixture ◽

Highly Active ◽

Key Points ◽

Deoxy Sugar ◽

Weimberg Pathway ◽

One Step ◽

The One ◽

Increased Activity ◽

Enzyme Class

Abstract2-keto-3-L-arabinonate dehydratase (L-KdpD) and 2-keto-3-D-xylonate dehydratase (D-KdpD) are the third enzymes in the Weimberg pathway catalyzing the dehydration of respective 2-keto-3-deoxy sugar acids (KDP) to α-ketoglutaric semialdehyde (KGSA). The Weimberg pathway has been explored recently with respect to the synthesis of chemicals from L-arabinose and D-xylose. However, only limited work has been done toward characterizing these two enzymes. In this work, several new L-KdpDs and D-KdpDs were cloned and heterologously expressed in Escherichia coli. Following kinetic characterizations and kinetic stability studies, the L-KdpD from Cupriavidus necator (CnL-KdpD) and D-KdpD from Pseudomonas putida (PpD-KdpD) appeared to be the most promising variants from each enzyme class. Magnesium had no effect on CnL-KdpD, whereas increased activity and stability were observed for PpD-KdpD in the presence of Mg2+. Furthermore, CnL-KdpD was not inhibited in the presence of L-arabinose and L-arabinonate, whereas PpD-KdpD was inhibited with D-xylonate (I50 of 75 mM), but not with D-xylose. Both enzymes were shown to be highly active in the one-step conversions of L-KDP and D-KDP. CnL-KdpD converted > 95% of 500 mM L-KDP to KGSA in the first 2 h while PpD-KdpD converted > 90% of 500 mM D-KDP after 4 h. Both enzymes in combination were able to convert 83% of a racemic mixture of D,L-KDP (500 mM) after 4 h, with both enzymes being specific toward the respective stereoisomer. Key points• L-KdpDs and D-KdpDs are specific toward L- and D-KDP, respectively.• Mg2+affected activity and stabilities of D-KdpDs, but not of L-KdpDs.• CnL-KdpD and PpD-KdpD converted 0.5 M of each KDP isomer reaching 95 and 90% yield.• Both enzymes in combination converted 0.5 M racemic D,L-KDP reaching 83% yield.

Download Full-text

Microwave Assisted Synthesis of Ru3Pd6Pt Cathode Catalyst in a PEM Fuel Cell

Journal of New Materials for Electrochemical Systems ◽

10.14447/jnmes.v16i3.3 ◽

2013 ◽

Vol 16 (3) ◽

pp. 147-150 ◽

Cited By ~ 1

Author(s):

F. Leyva-Noyola ◽

O. Solorza-Feria

Keyword(s):

Fuel Cell ◽

Large Scale ◽

High Pressures ◽

Cost Effective ◽

Pem Fuel Cell ◽

Reduction Reaction ◽

Microwave Assisted Synthesis ◽

Microwave Assisted ◽

Long Time ◽

Set Up

Nanoparticles of Ru3Pd6Pt have been previously produced by different synthesis routes that involve high temperatures and relative high pressures and long time. The usage of a conventional microwave assisted synthesis reduces environmental risk impact as well as the cost effective production in large scale with minimum set up modifications. These features are the motivations for the use of microwaves in the synthesis of the Ru3Pd6Pt catalyst for PEM fuel cell applications to reduce the Pt loading. In this communication a tri-metallic electrocatalyst was produced by the reduction of the corresponding metallic salts, RuCl3, PdCl2, and H2PtCl6 in ethylene glycol using a modified conventional microwave device. Oxygen reduction reaction kinetic analysis results conducted to a Tafel slope, (-b = 41.2 ± 1.7 mV dec-1) at low overpotential, and exchange current density (i0 = 3.01 ± 0.39 × 10-5 mA cm-2) in 0.5M H2SO4. This electrocatalyst exhibited good performance and stability in a single H2/O2PEM fuel cell.

Download Full-text

A Simple and Effective Method for the Preparation of Porous Graphene Nanosheets

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.719-720.123 ◽

2015 ◽

Vol 719-720 ◽

pp. 123-126

Author(s):

Jin Sun ◽

Qing Zhong Xue ◽

Yong Gang Du ◽

Fu Jun Xia ◽

Qi Kai Guo

Keyword(s):

Large Scale ◽

Graphene Nanosheets ◽

Scale Production ◽

Green Method ◽

Porous Graphene ◽

Large Scale Production ◽

Potential Applications ◽

One Step ◽

Autogenous Pressure ◽

The One

Porous graphene is a collection of graphene-related materials which exhibits properties distinct from those of graphene, and it has widespread potential applications in various fields. Several approaches have been developed to produce porous graphene. However, the large-scale production of porous graphene nanosheets still remains a great challenge. Moreover, the costs of some methods are prohibitive for its commercial production and the processes are too complicated and time-consuming. In this work, we propose a simple and green method by which graphene nanosheets can be etched by sodium hydroxide under autogenous pressure at 180 °C. The morphologies and surface elements of the porous graphene nanosheets and sizes of pores were characterized. It is demonstrated that the one-step etching of graphene nanosheets is an effective method to obtain large-scale porous graphene nanosheets with high and uniform porosity. The pores in the porous graphene nanosheets were 6 nm depth (the same as the thickness of the graphene nanosheets) and 30-50 nm width.

Download Full-text

One-step synthesis of trimetallic Pt–Pd–Ru nanodendrites as highly active electrocatalysts

RSC Advances ◽

10.1039/c5ra01981h ◽

2015 ◽

Vol 5 (39) ◽

pp. 31147-31152 ◽

Cited By ~ 44

Author(s):

Kamel Eid ◽

Victor Malgras ◽

Pei He ◽

Kunmiao Wang ◽

Ali Aldalbahi ◽

...

Keyword(s):

Oxygen Reduction Reaction ◽

Oxygen Reduction ◽

Methanol Oxidation ◽

Oxidation Reaction ◽

Reduction Reaction ◽

Methanol Oxidation Reaction ◽

Highly Active ◽

One Step

Trimetallic Pt–Pd–Ru nanodendrites synthesized by a one-step route are highly active electrocatalysts for methanol oxidation reaction and oxygen reduction reaction.

Download Full-text

Tin dioxide facilitated truncated octahedral Pt3Ni alloy catalyst: synthesis and ultra highly active and durable electrocatalysts for oxygen reduction reaction

RSC Advances ◽

10.1039/c6ra02452a ◽

2016 ◽

Vol 6 (31) ◽

pp. 26323-26328 ◽

Cited By ~ 5

Author(s):

Na Zhang ◽

Lei Du ◽

Chunyu Du ◽

Geping Yin

Keyword(s):

Oxygen Reduction Reaction ◽

Oxygen Reduction ◽

Tin Dioxide ◽

Reduction Reaction ◽

Ni Catalysts ◽

Catalyst Synthesis ◽

Highly Active ◽

Ni Alloy ◽

Orr Activity ◽

Alloy Catalyst

This work firstly synthesized SnO2 modified truncated octahedral Pt3Ni alloy nanoparticle electrocatalyst using neat FPD as the solvent, ORR activity and durability of which is 2.4 times and 2.5 times that of Pt3Ni catalysts.

Download Full-text

Africa — Latin America — Asia and Pacific — Middle East

International Review of the Red Cross ◽

10.1017/s0020860400022749 ◽

1986 ◽

Vol 26 (251) ◽

pp. 115-124

Keyword(s):

Latin America ◽

Middle East ◽

Large Scale ◽

The Other ◽

Displaced Persons ◽

Assistance Programme ◽

Medical Teams ◽

Set Up ◽

The One ◽

Voluntary Agencies

In January and February, the ICRC reduced, as planned, the level of its relief activities in Ethiopia. This reduction was made possible, on the one hand, by an increase in food supplies for the population in the northern provinces of that country affected by conflict and drought and, on the other, by more intensive activity on the part of other voluntary agencies in the area. While leaving in place the structures which would enable it rapidly to set up a large-scale assistance programme if the need were to appear in a given region, the ICRC has lowered the volume of its general relief distributions. In December 1985, 10,700 tonnes were distributed to 830,000 persons. This was reduced to 5,000 tonnes for 424,300 persons in January, and further to 2,800 tonnes for 181,000 persons in February in the provinces of Eritrea, Tigray, Wollo, Gondar and Hararge. The last three therapeutic feeding centres were closed on 16 January (Wukro), and on 16 and 27 February (Idaga Hamus and Adwa). However, ICRC medical teams continued to monitor the health of the populations living in provinces which were receiving assistance, concentrating their activities on groups of displaced persons in Eritrea (in the region between Keren and Barentu), Tigray (in the region between Aksum and Adwa and the region of Mehony), Wollo (in the region of Sekota) and Hararge (Wobera Woreda; Habro Woreda), all areas with major security problems.

Download Full-text

Ensemble Kalman Filtering with One-Step-Ahead Smoothing

Monthly Weather Review ◽

10.1175/mwr-d-17-0175.1 ◽

2018 ◽

Vol 146 (2) ◽

pp. 561-581 ◽

Cited By ~ 3

Author(s):

Naila F. Raboudi ◽

Boujemaa Ait-El-Fquih ◽

Ibrahim Hoteit

Keyword(s):

Data Assimilation ◽

Large Scale ◽

Sequential Data ◽

Bayesian Filtering ◽

Error Statistics ◽

Background Error ◽

One Step ◽

The One ◽

Lorenz 96 ◽

Ensemble Kalman Filtering

The ensemble Kalman filter (EnKF) is widely used for sequential data assimilation. It operates as a succession of forecast and analysis steps. In realistic large-scale applications, EnKFs are implemented with small ensembles and poorly known model error statistics. This limits their representativeness of the background error covariances and, thus, their performance. This work explores the efficiency of the one-step-ahead (OSA) smoothing formulation of the Bayesian filtering problem to enhance the data assimilation performance of EnKFs. Filtering with OSA smoothing introduces an updated step with future observations, conditioning the ensemble sampling with more information. This should provide an improved background ensemble in the analysis step, which may help to mitigate the suboptimal character of EnKF-based methods. Here, the authors demonstrate the efficiency of a stochastic EnKF with OSA smoothing for state estimation. They then introduce a deterministic-like EnKF-OSA based on the singular evolutive interpolated ensemble Kalman (SEIK) filter. The authors show that the proposed SEIK-OSA outperforms both SEIK, as it efficiently exploits the data twice, and the stochastic EnKF-OSA, as it avoids observational error undersampling. They present extensive assimilation results from numerical experiments conducted with the Lorenz-96 model to demonstrate SEIK-OSA’s capabilities.

Download Full-text