Hybrid chitosan derivative-carbon suport for oxygen reduction reactions

New hybrid chitosan derivative-carbon black was prepared and used as support for Pt nanoparticles. These catalysts improved the activity toward oxygen reduction reaction (ORR), compared with those of commercial Pt/C catalyst. The biopolymer chitosan provided an efficient and sustainable surface nitrogen source associated with the superior performance of the catalysts.Peer reviewe

Synthesis of biodiesel from Nigella sativa seed oil using surfactant-Brønsted acidic-combined ionic liquid as catalyst

Two acidic ionic liquids based on 1-benzyl-1H-imidazole have been synthesized and characterized by FT-IR, 1H NMR, 13C NMR and CHNS analyses. The ionic liquids have been used for transesterification of Nigella sativa seed oil as newer sources of oil with methanol. We determined relative fatty acid content, iodine and saponification values of seed oil and estimated cetane number of produced biodiesel based on the chemical composition of oil. Also, the effect of reaction temperature, type and amount of catalyst, molar ratio and reaction time were investigated. The results show that the ILH2 ionic liquid has the higher catalytic activity under the optimized reaction conditions. Thus, this ionic liquid is able to catalyze the transesterification of N. sativa seed oil to its methyl esters in 6 h with yields of more than 93%. The catalytic activity of ILH2 for the transesterification of other vegetable oils and alcohols has also been studied.We would like to thank the Research Council of Islamic Azad University, Shahrekord Branch for supporting this work.Peer Reviewe

Electrocatalysts for low temperature fuel cells

Low temperature fuel cells technologies are currently shifting very fast from fundamental research to real growth. The development of electrocatalysts plays a vital role in the electrocatalytic reactions involved in these devices, because the catalyst determines the overall reaction efficiency, durability and cost. This article review progress in the research and development of electrocatalysts for low temperature fuel cells technologies, with especial attention in the contribution of our research teams over the last 15 years or so. The intensive research efforts in reducing or replacing Pt-based electrodes in fuel cells have been focus in the use of carbon nanomaterials as electrocatalytic supports, including carbon nanostructures tailored by surface modification or building in particular dopants/defects. Recent research effort has also led to the use of electronic conductivity noncarbon support materials. In addition, carbon-composite materials are proving to be a robust, inexpensive and active electrocatalysts, where the synergetic effect between the carbon nanomaterials and the ceramic or polymer nanostructures can lead to a superior electrocatalytic performance and durability for low temperature fuel cells. Perspectives on these catalysts and possible pathways to address current remaining challenges are also discussed.Authors thank the Ministry of Economy and Competitiveness (MINECO) and FEDER through the Project ENE2014-52158-C2-1-R for financial support.Peer reviewe

Recent progress on bimetallic NiCo and CoFe based electrocatalysts for alkaline oxygen evolution reaction: A review

16 figures, 10 tables.The deployment of hydrogen as an energy carrier is found to be a vital alternative fuel for the future. It is expected that water electrolysis, powered by renewable energy sources, be able to scale‐up hydrogen production. However, the reaction kinetic of oxygen evolution reaction (OER) is a sluggish process, which predominantly limits the efficiency of water electrolysis. This review recapitulates the recent progress and efforts made in the design and development of two selected earth-abundant bimetallic electrocatalysts (NiCo and CoFe) for alkaline OER. Each bimetal electrocatalyst is thoroughly outlined and discussed in five sub-sections, including bimetal (oxy) hydroxides, Layered double hydroxides (LDHs) structures, oxides, composites, alloy and nanostructured electrocatalysts, and assembled with heteroatoms. Furthermore, a brief introduction to an in situ/operando characterization techniques and advantages for monitoring the structure of the electrocatalysts is provided. Finally, a summary outlining the challenges and conceivable approaches to advance OER performance is highlighted and discussed.Financial support from the European Union’s Horizon 2020 Research and Innovation programme under the Marie Skłodowska-Curie Actions-Innovative Training Networks (MSCA-ITN) Grant Agreement 813748 (Bike project) are gratefully acknowledged. The authors also wish to acknowledge the Ministerio de Ciencia, Innovación y Universidades (MICINN), and FEDER for the received funding in the project of reference ENE2017-83976-C2-1-R.Peer reviewe

Synthesis and characterization of Au nanocatalyst on modifed bentonite and silica and their applications for solvent free oxidation of cyclohexene with molecular oxygen

In the present work, the selective liquid phase oxidation of cyclohexene mainly to 2-cyclohexe-1-one has been investigated over gold nanoparticles (GNPs) with molecular oxygen in a solvent-free condition. Gold nanoparticles were synthesised on two modified supports of silica and bentonite. In this respect the surface of silica and bentonite was modified with organic ligands consist of thiol and thioester groups. The catalysts were characterized by TEM, XPS, N2 adsorption/desorption, FT-IR, and CHNS techniques. TEM images show that the gold nanoparticles over modified bentonite and silica have diameters in the range 0f 50 and less than 10 nm, respectively. The results show that the catalytic activity of gold nanoparticles over modified silica, SiO2-pA-Acrylate-Thioamide-Au (0), is much better than the gold nanoparticles immobilized on the modified bentonite, MEDPT@CP-bentonite-Au (0). The catalytic activity over SiO2-pA-Acrylate-Thioamide-Au (0) recycled catalyst remained at a satisfactory state after at least 4 cycles. Activity tests were carried out in an autoclave under solvent-free conditions. In order to obtain maximum conversion, the reaction parameters such as reaction temperature and time were optimized. Under optimized conditions, a maximum of 92% conversion and 97% selectivity was achieved with the SiO2-pA-Acrylate-Thioamide-Au (0) catalyst.Thanks are due to the Iranian Nanotechnology Initiative and the Research Council of Isfahan University of Technology and Centre of Excellence in the Chemistry Department of Isfahan University of Technology for supporting of this work.Peer Reviewe

Non-precious melamine/chitosan composites for the oxygen reduction reaction: effect of the transition metal

7 figures, 2 tables.The development of active and low-cost electrocatalysts for the oxygen reduction reaction (ORR) is crucial for the sustainable commercialization of fuel cell technologies. In this study, we have synthetized Me/Mo2C (Me = Fe, Co, Cu)-based composites embedded in N- and P-dual doped carbon by means of inexpensive industrial materials, such as melamine and chitosan, as C and N sources, and the heteropolyacid H3PMo12O40 as P and Mo precursor. The effect of the transition metal (Fe, Co, and Cu) on the ORR in alkaline medium has been investigated. The physicochemical properties of the electrocatalysts were performed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy (TEM). Activity towards ORR was carried out in a three-electrode cell using a ring-disk electrode in 0.1M NaOH. The results obtained clearly show the important role played by each transition metal (Fe, Co, and Cu) in the electrochemical activity. Among them, Fe gives rise to the best performing composite in carrying out the oxygen reduction reaction. The formation Fe3C/Mo2C species embedded in N- and P-dual doped carbon seems to be the determining role in the increase of the ORR performance.The authors acknowledge the Ministerio de Ciencia, Innovación y Universidades (MCIU), and FEDER for the funding received for the project, with references ENE2017-83976-C2-1-R, Spanish National Research Council COOPB20202, and MERC project 721399002.Peer reviewe

Titanium carbide and carbonitride electrocatalyst supports: Modifying Pt-Ti interface properties by electrochemical potential cycling

Titanium carbide and carbonitride are expected to be good materials to replace carbon as electrocatalyst supports, since they are chemically stable in acidic media and possess high electrical conductivity. However, they eventually can be transformed to titanium oxide, which is a thermodynamically stable compound, at potentials higher than 0.9 V (vs. RHE) in acidic media. In this communication, we report an enhanced catalytic activity towards CO and methanol electrooxidation on TiC and TiCN materials induced by surface oxides at the Pt/support interface. In particular, the current density obtained for Pt/TiC, activated up to 1.0 V, is 2-fold higher than that achieved with the commercial PtRu/C catalyst, which is accepted to be one of the best catalysts for methanol oxidation reaction.This work was supported by the Spanish Science and Innovation Ministry under project CTQ2011-28913-CO2-O2. MR acknowledges the FPU-2012 program for nancial support.Peer Reviewe

Recycling the spent bleaching earth waste material into electrocatalytic component

1 figure.-- Talk delivered at the CESEP’19 Conference: 8th International Conference on Carbon for Energy Storage and Environment Protection, October 20-24th, Alicante (Spain).-- © Universidad de Alicante.The design of electrocatalytic materials with high efficiency and without noble metals for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are essential for the development of new emerging electrochemical energy storage and conversion devices [1]. Spent bleaching earth (SBE) is a worthless oil refinery waste material containing a notable percentage of residual oil. New applications are urgent such as converting SBE into catalysts, according to the circular economy concept. In this work SBE has been used as electrocatalytic component for the reversible oxygen electrode. SBE was chemically treated to obtain based-carbon compounds. Then, cobalt, iron and/or tungsten heteropolyacid were added to the carbon-based SBE compounds to obtain different composites. The textural, structural and surface chemistry properties of the composites materials were analysed along with electrochemical characterization in a three electrode cell in alkaline medium. Electrochemical results evidenced Co/SBE catalyst proved to be a valuable bifunctional competitor for ORR and OER showing activity in both reactions (Figure 1) and a better stability than Pt in accelerated tests.By the Spanish Ministry of Science, Innovation and Universities, through project ENE2017- 83976-C2-1-R (co-founded by FEDER), the Spanish National Research Council (CSIC) through project iCOOP20202 and MERC grant project 99392002. D. F.I. also thanks the CSIC for his JAE-Intro grant.Peer reviewe

Hybrid Chitosan-Carbon as New Electrocatalyst Support for Direct Methanol Fuel Cells

Trabajo presentado en la European Hydrogen Energy Conference - EHEC, celebrada en Sevilla (España) del 12 al 14 de mayo de 2014.Peer Reviewe

In situ FTIR and Raman study on the distribution and reactivity of surface vanadia species in V2O5/CeO2 catalysts

The surface structure and reactivity of vanadia supported on ceria catalysts were studied by Raman spectroscopy and methanol adsorption and temperature-programmed surface reaction (TPRS) of the adsorbed species monitored in situ by infrared spectroscopy. Monomeric and polymeric vanadia surface species and CeVO4 were identified on the catalysts. Methanol adsorption reveled that mostly reduced Ce3+ sites are present in the surface of the catalysts, produced as a result of the reductive solid reaction of VOx species with the ceria surface. Adsorbed methanol/methoxy decomposed stepwise to formate and, finally, carbonate/carbon dioxide. The reactivity is linked to interphase sites, Ce–O–V, which could favor the abstraction of hydrogen during the methoxy transformation to formates.The authors acknowledge the financial support of the National Agency for Scientific and Technological Promotion (projects PICT-2012-1280, PICT-2010-0836 and PME 311/06), the Universidad Nacional del Litoral (grants CAI+D 2011 PI 50120110100311 and 50120110100100) and Spanish Ministry (grant CTQ2011- 25517-E).Peer Reviewe