Grafenos como carbocatalizadores y soporte de nanopartículas metálicas orientadas

Tesis por compendioA lo largo de los últimos años, el grafeno ha despertado un gran interés entre la comunidad científica debido las numerosas aplicaciones que ha encontrado dentro del campo de las industrias electrónica, informática y automovilística, así como en ciencia de los materiales. Dadas las extraordinarias propiedades físico-químicas que presenta el grafeno, se pueden desarrollar materiales con altas conductividades y durezas, además de propiedades interesantes en muchos campos de investigación. El empleo de grafeno como soporte o como catalizador sostenible libre de metales, está siendo un tema de interés en muchos grupos de investigación actualmente. Teniendo en cuenta la tendencia al desarrollo de procesos químicos nuevos basados en el empleo de biomasa como fuente de materia prima en sustitución de hidrocarburos fósiles, el grafeno se presenta como un candidato a tener un papel importante en este campo. En este contexto, en la presente tesis doctoral se describe el desarrollo de nuevas metodologías de preparación de distintos tipos de grafeno enfocando su posterior empleo en catálisis. La actividad del grafeno y grafenos dopados en ausencia de metales como carbocatalizadores para la reacción de reformado en fase acuosa de polioles, la preparación de partículas metálicas soportadas en grafeno por un proceso en una sola etapa, generándose una fuerte interacción metal-grafeno con orientación cristalográfica preferente del metal, su actividad como catalizadores altamente activos en procesos de interés en síntesis orgánica, intermedios en química fina o en la reacción de reformado en fase acuosa comentada anteriormente, serán objeto de estudio en la presente tesis doctoral.Over the past few years, graphene has increasingly attracted the attention of the scientific community due to the numerous applications that it has found within the field of electronics, computer and automotive industries, as well as in materials science. Given the extraordinary physicochemical properties of graphene, materials with high conductivities and hardnesses, as well as interesting properties for many research fields can be developed. The use of graphene as support or as metal-free sustainable catalyst is currently a topic of interest in many research groups. Taking into account the trend towards the development of new chemical processes based on the use of biomass as a source of raw material in substitution of fossil hydrocarbons, graphene is a promising candidate to play an important role in this field. On this basis, the present doctoral thesis discloses the development of new methodologies for the preparation of different types of graphene focusing on their subsequent use in catalysis. Herein, we disclose the activity of graphene and doped graphene in the absence of metals as carbocatalysts for the reaction of aqueous phase reforming of polyols. Another target is the preparation of metal particles supported on graphene by one-step process, results in a strong metal-graphene interaction with a preferential crystallographic orientation of the metal. Its activity as highly active catalysts in processes of interest in organic synthesis, as intermediates in fine chemistry, and in the reaction of aqueous phase reforming, will also be studied in this doctoral thesis.Al llarg dels últims anys, el grafè ha despertat un gran interès entre la comunitat científica degut a les nombroses aplicacions que ha trobat dins del camp de les industries electrònica, informàtica i automobilística, així com en la ciència del materials. Degut a les extraordinàries propietats físico-químiques que presenta el grafè, es poden desenvolupar materials amb altes conductivitats i duresa, a més de propietats interesants en molts camps d'investigació. L'ús de grafè com a suport o com a catalitzador sostenible lliure de metalls, esta sent un tema d'interès en molts grups de recerca en l'actualitat. Tenint en compte la tendència al desenvolupament de processos químics nous, basats en l'ús de biomassa com a font de matèria prima en substitució del hidrocarburs fòssils, el grafè es presenta com a candidat a tenir un paper important en aquest camp de recerca. En aquest context, en la present tesis doctoral es descriu el desenvolupament de noves metodologies de preparació de diferents tipus de grafè enfocant el seu posterior us en catàlisis. L'activitat del grafè i grafè dopat en absència de metalls com a carbocatalitzadors per a la reacció del reformat de poliols en fase aquosa, la preparació de partícules metàl·liques suportades en grafè mitjançant un procés en una sola etapa, generant-se una forta interacció metall-grafè amb orientació cristal·logràfica preferent del metall, la seua activitat como a catalitzadors altament actius en processos d'interès en síntesis orgànica, intermedis en química fina o en la reacció de reformat en fase aquosa comentada anteriorment, seran objecte d'estudi en la present tesis doctoral.Esteve Adell, I. (2018). Grafenos como carbocatalizadores y soporte de nanopartículas metálicas orientadas [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/99569TESISCompendi

Aqueous phase reforming of glycerol using doped graphenes as metal-free catalysts

[EN] Boron-doped graphene obtained by pyrolysis at 900 degrees C of the boric acid ester of alginate was found to be the most active graphene among a series of doped and co-doped graphenes to promote the aqueous phase reforming of glycerol at 250 degrees C. This reaction is of interest in the context of valorization of the aqueous wastes of carbohydrate syrups. Control experiments adding to undoped graphene 1 wt% of triphenylborane, tris(pentafluorophenyl) borane or bis(pinacolyl)diborane as models of possible boron atom types present in B-doped graphene, and boric acid that could be present in a residual amount after pyrolysis, show in all cases an increase in the catalytic activity of graphene. B-doped graphene has also activity for glucose aqueous phase reforming. B-doped graphene undergoes deactivation upon reuse, probably due to B leaching. The results show that graphenes are promising metal-free catalysts for aqueous phase reforming and are alternatives to those containing platinum.Financial support from the Spanish Ministry of Economy and Competitiveness (Severo Ochoa, Grapas and CTQ2015-69153-CO2-R1) and Generalitat Valenciana (Prometeo 2013-014) is gratefully acknowledged. I. E.-A. acknowledges the Spanish Ministry of Science for PhD scholarships. This research was funded partly by the EU-5SPS joint initiative through the NOVACAM project (Grant agreement no. 604319).Esteve-Adell, I.; Crapart, B.; Primo Arnau, AM.; Serp, P.; García Gómez, H. (2017). Aqueous phase reforming of glycerol using doped graphenes as metal-free catalysts. Green Chemistry. 19(13):3061-3068. https://doi.org/10.1039/c7gc01058cS30613068191

Graphene as Metal-Free Catalyst for Aqueous Phase Reforming of Ethylene Glycol

[EN] Graphene obtained by pyrolysis of alginate shows in the absence of any metal, catalytic activity towards the decomposition of ethylene glycol into hydrogen and carbon dioxide at 250 8C due to the presence of hydrogenating/dehydrogenating sites. This reaction has interest in the context of valorization of waste waters from cellulose depolymerization and it is typically catalyzed by platinum and other transition metals. In this regard, the use of graphene as metal-free catalyst may have a considerable advantage from the point of sustainability of the catalyst. Based on the influence of the presence of acids and bases and the lack of influence of quenchers of reactive oxygen species, it is proposed that the active sites on the graphene could be frustrated acid-base Lewis pairs acting as dehydrogenating centers. Controls with oxalic acid and glyoxal have shown that if ethylene glycol is converted into these a-dicarbonylic compounds, spontaneous decarboxylation would occur totally (oxalic acid) or in some extent (glyoxal. 30%). In the last case, decarboxylation is also assisted by graphene.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-69153-CO2-R1) and Generalitat Valenciana (Prometeo 2013-014) is gratefully acknowledged. I. E.-A. thank to Spanish Ministry of Science for PhD scholarships. This research is partly funded by the EU-JSPS joint initiative through the NOVACAM project.Esteve-Adell, I.; Bakker, N.; Primo Arnau, AM.; Hensen, EJM.; García Gómez, H. (2017). Graphene as Metal-Free Catalyst for Aqueous Phase Reforming of Ethylene Glycol. ChemistrySelect. 2(22):6338-6343. https://doi.org/10.1002/slct.201701138S6338634322

Innovative preparation of MoS2-graphene heterostructures based on alginate containing (NH4)2MoS4 and their photocatalytic activity for H2 generation

Films and particles of MoS2 on graphene (G) showing synergy for photocatalytic H-2 evolution due to the strong interaction between the two layered components have been obtained by pyrolysis at 900 degrees C under argon flow of ammonium alginate, films or powders, containing variable proportions of (NH4)(2)MoS4. X-ray diffraction shows that under these conditions (NH4)(2)MoS4 decomposes to MoS2, while simultaneously alginate forms few layers G or graphitic carbon residues. Sonication of MoS2-G powders in water produces exfoliation of the material leading to few-layers platelets of MoS2-G heterostructures. MoS2 is considered as an alternative of noble metals for H-2 evolution in dye-sensitized photocatalytic systems. In the present case, MoS2-G heterostructures exhibit more than double photocatalytic activity for H-2 generation than pristine MoS2 particles. (C) 2014 Elsevier Ltd. All rights reserved.Financial support by Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ-2012-32315) and Generalidad Valenciana (Prometeo 2012-13) is gratefully acknowledged. ML-S and IE-A thank the Spanish Ministry for postgraduate scholarships.Latorre Sánchez, M.; Esteve Adell, I.; Primo Arnau, AM.; García Gómez, H. (2015). Innovative preparation of MoS2-graphene heterostructures based on alginate containing (NH4)2MoS4 and their photocatalytic activity for H2 generation. Carbon. 81:587-596. https://doi.org/10.1016/j.carbon.2014.09.093S5875968

Grafeno: obtención, tipos y su aplicación como sensor para detección de gases y sensor de presión

[ES] El grafeno, un material bidimensional (2D) de espesor atómico, que presenta extraordinarias propiedades electrónicas, mecánicas y elevada área superficial, ha despertado un gran interés en la fabricación de sensores. En la presente revisión se revisan los avances en sensores basados en grafeno con potencial de aplicación en el ámbito medioambiental para la detección de gases tóxicos. Además se muestra el auge de los sensores de presión basados en grafeno como sensores ¿wearable¿ en el ámbito de la salud humana, el Internet of Things o la inteligencia artificial.[EN] Graphene is a 2D layered carbon material with atomic thickness. This material exhibits remarkable electronic and mechanical properties and many of these properties are interesting for sensing applications. The present work reviews the potential application of graphene-based sensors on environmental field, for toxic gases detection. Moreover, the increasing research interest of graphene-based pressure sensors as key components in wearable electronic sensing devices for application in the field of human health, Internet of Thing and artificial intelligence is discussed.Los autores agradecen al Ministerio de Ciencia, Innovación y Universidades por la financiación recibida a través del Subprograma Torres-Quevedo del Programa Estatal de Promoción del Talento y su Empleabilidad 2013-2016 en el marco del proyecto eGRAF (PTQ-17-09497).Esteve-Adell, I.; Gil Agustí, MT.; Zubizarreta Saenz De Zaitegui, L.; Quijano-Lopez, A.; García Pellicer, M. (2020). Grafeno: obtención, tipos y su aplicación como sensor para detección de gases y sensor de presión. Avances en Quimica. 15(2):57-72. http://hdl.handle.net/10251/166201577215

Graphene Film-Supported Oriented 1.1.1 Gold(0) Versus 2.0.0 Copper(I) Nanoplatelets as Very Efficient Catalysts for Coupling Reactions

[EN] Few-layered graphene-supported 1.1.1 and 2.0.0 oriented Au and Cu2O nanoplatelets were prepared by one-step pyrolysis of the corresponding metal salts embedded in chitosan at 900 degrees C under inert atmosphere. These nanometric films containing oriented nanoplatelets were investigated in a series of reactions as Ullmann-type homocoupling, C-N cross-coupling and Michael addition. The catalysts exhibited turnover numbers (TONs) three to six ord(e)rs of magnitude higher than those of analogous graphene-supported unoriented metal nanoparticles. In addition it has been found that oriented Cu2O and Au nanoplatelets grafted on defective graphene also exhibit activity to promote the Michael addition of compounds with active methylene and methine hydrogens to alpha,beta-conjugated ketone. An exhaustive characterization of these materials using spectroscopic and electron microscopy analyses has been carried out. CO2 thermoprogrammed desorption measurements show that films of these two graphene supported catalysts exhibit some basicity that can explain their activity to promote Michael addition.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-69153-CO2-R1) and Generalitat Valenciana (Prometeo 2017-083) is gratefully acknowledged. I.E.-A. and A.P thanks the Spanish Ministry for a postgraduate scholarship and for a Ramon y Cajal research associate contract, respectively.Candu, N.; Simion, A.; Coman, SM.; Primo Arnau, AM.; Esteve-Adell, I.; Parvulescu, VI.; García Gómez, H. (2018). Graphene Film-Supported Oriented 1.1.1 Gold(0) Versus 2.0.0 Copper(I) Nanoplatelets as Very Efficient Catalysts for Coupling Reactions. Topics in Catalysis. 61(14):1449-1457. https://doi.org/10.1007/s11244-018-1043-xS144914576114Tao F (2016) Metal nanoparticles for catalysis: advances and applications. RSC Catalysis Series, CambridgeWildgoose GG, Banks CE, Compton RG (2006) Metal nanoparticles and related materials supported on carbon nanotubes: methods and applications. Small 2:182–193Ding M, Tang Y, Star A (2013) Understanding interfaces in metal–graphitic hybrid nanostructures. J Phys Chem Lett 4:147–160Primo A, Esteve I, Blandez JF, Dhakshinamoorthy A, Alvaro M, Candu N, Coman S, Parvulescu VI, Garcia H (2015) High catalytic activity of oriented 2.0.0 copper(I) oxide grown on graphene film. Nat Commun 6:8561Ravi Kumar MNV (2000) A review of chitin and chitosan applications. React Funct Polym 46:1–27Rinaudo M (2006) Chitin and chitosan: properties and applications. Prog Polym Sci 31:603–632Rinaudo M (2008) Main properties and current applications of some polysaccharides as biomaterials. Polym Int 57:397–430Primo A, Atienzar P, Sanchez E, Delgado JM, Garcia H (2012) From biomass wastes to large-area, high-quality, N-doped graphene: catalyst-free carbonization of chitosan coatings on arbitrary substrates. Chem Commun 48:9254–9256Primo A, Sánchez E, Delgado JM, Garcia H (2014) High-yield production of N-doped graphitic platelets by aqueous exfoliation of pyrolyzed chitosan. Carbon 68:777–783Primo A, Forneli A, Corma A, Garcia H (2012) From biomass wastes to highly efficient CO2 adsorbents graphitisation of chitosan and alginate biopolymers. ChemSusChem 5:2207–2214Li X, Cai W, An J, Kim S, Nah J, Yang D, Piner R, Velamakanni A, Jung I, Tutuc E, Banerjee SK, Colombo L, Ruoff RS (2009) Large-area synthesis of high-quality and uniform graphene films on copper foils. Science 324:1312–1314Takagi D, Kobayashi Y, Hlbirio H, Suzuki S, Homma Y (2008) Mechanism of gold-catalyzed carbon material growth. Nano Lett 8:832–835Reina A, Jia X, Ho J, Nezich D, Son H, Bulovic V, Cresselhaus MS, Kong J (2008) Large area, few-layer graphene films on arbitrary substrates by chemical vapor deposition. Nano Lett 9:30–35Wei D, Liu Y, Zhang H, Huang L, Yu G (2009) Synthesis of N-doped graphene by chemical vapor deposition and its electrical properties. Nano Lett 9:1752–1758Kim KS, Zhao Y, Jang H, Lee SY, Kim JM, Kim KS, Ahn J-H, Choi J-Y, Hong BH (2009) Large-scale pattern growth of graphene films for stretchable transparent electrodes. Nature 457:706–710Gao L, Guest JR, Guisinger NP (2010) Epitaxial graphene on Cu(111). Nano Lett 10:3512–3516Zhao L, Rim KT, Zhou H, He R, Heinz TF, Pinczuk A, Flynn GW, Pasupathy AN (2011) Influence of copper crystal surface on the CVD growth of large area monolayer graphene. Solid State Commun 151:509–513Wood JD, Schmucker SW, Lyons AS, Pop E, Lyding JW (2011) Effects of polycrystalline Cu substrate on graphene growth by chemical vapor deposition. Nano Lett 11:4547–4554Primo A, Esteve-Adell I, Candu N, Coman S, Parvulescu V, Garcia H (2016) One-step pyrolysis preparation of 1.1.1 oriented gold nanoplatelets supported on graphene and six orders of magnitude enhancement of the resulting catalytic activity. Angew Chem-Int Ed 55:607–612Perlmutter P (1992) Conjugate addition reactions in organic synthesis. Pergamon Press, ElmsfordChristoffers J (1998) Transition-metal catalysis of the Michael reaction of 1,3-dicarbonyl compounds and acceptor-activated alkenes. Eur J Org Chem 7:1259–1266Comelles J, Moreno-Mañas M, Vallribera A (2005) Michael additions catalysed by transition metals and lanthanide species. A review. Arkivoc 9:207–238Saegusa T, Ito Y, Tomitra S, Kinoshita H (1972) Synthetic reactions by complex catalysts. XXIV. A new catalyst of copper-isocyanide complex for the Michael addition. Bull Chem Soc Jpn 45:496–499Hidehiko K, Masahiro S, Nagata C (1999) Acceleration of Michael addition reaction by microwave irradiation in the presence of metal acetylacetonate catalysts. Nippon Kagaku Kaishi 2:145–148Oh E, Susumu K, Blanco-Canosa JB, Medintz IL, Dawson PE, Mattoussi H (2010) Preparation of stable maleimide-functionalized Au nanoparticles and their use in counting surface ligands. Small 6:1273–1278Ba H, Rodriguez-Fernández J, Stefani FD, Feldman J (2010) Immobilization of gold nanoparticles on living cell membranes upon controlled lipid binding. Nano Lett 10:3006–3012Hartlen KD, Ismaili H, Zhu J, Workentin MS (2012) Michael addition reactions for the modification of gold nanoparticles facilitated by hyperbaric conditions. Langmuir 28:864–87

Oriented 2.0.0 Cu2O nanoplatelets supported on few-layers graphene as efficient visible light photocatalyst for overall water splitting

[EN] Cu2O nanoplatelets with preferential 2.0.0 facet orientation supported on few layers graphene were prepared as films in a single step by pyrolysis at 900 degrees C under inert atmosphere of Cu2+-chitosan precursor. (Cu2O) over bar /fl-G films exhibit a photocatalytic activity for overall water splitting of 19.5 mmol/g(cu+G) h. This value is about 4 orders of magnitude higher than the photocatalytic activity measured for unoriented Cu2O nanoparticles on few-layers graphene or than commercial Cu2O nanoparticles and about three orders of magnitude higher than the activity reported in the literature for Cu2O nanoparticles. In addition Cu2O nanoparticles on few-layers graphene retain about 50% of its photocatalytic activity after 6 days of continuous irradiation. It is proposed that this activity and stability arises from the combination of features derived from the pyrolysis preparation procedure including strong Cu2O-graphene grafting, the role of graphene as cocatalyst and preferential 2.0.0 facet orientation. (C) 2016 Elsevier B.V. All rights reserved.Finantial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-69153-CO2-1-R) and Generalitat Valenciana (Prometeo 2013-019) is gratefully acknowledged. D. M. M. and I. E. A thank to the Technical University of Valencia and the Spanish Ministry of Science for PhD scholarshipsMateo-Mateo, D.; Esteve-Adell, I.; Albero-Sancho, J.; Primo Arnau, AM.; García Gómez, H. (2017). Oriented 2.0.0 Cu2O nanoplatelets supported on few-layers graphene as efficient visible light photocatalyst for overall water splitting. Applied Catalysis B Environmental. 201:582-590. https://doi.org/10.1016/j.apcatb.2016.08.033S58259020

Oriented Pt Nanoparticles Supported on Few-Layers Graphene as Highly Active Catalyst for Aqueous-Phase Reforming of Ethylene Glycol

Pt nanoparticles (NPs) strongly grafted on few layers graphene (G) have been prepared by pyrolysis under inert atmosphere at 900 degrees C of chitosan films (70-120 rim thickness) containing adsorbed H2PtCl6. Preferential orientation of exposed Pt facets was assessed by X-ray diffraction of films having high Pt loading where the 111 and 222 diffraction lines were observed and also by SEM imaging comparing elemental Pt mapping with the image of the 111 oriented particles. Characterization techniques allow determination of the Pt content (from 45 ng to 1 mu g cm(-2), depending on the preparation conditions), particle size distribution (9 +/- 2 nm), and thickness of the films (12-20 nm). Oriented Pt NPs on G exhibit at least 2 orders of magnitude higher catalytic activity for aqueous-phase reforming of ethylene glycol to H-2 and CO2 compared to analogous samples of randomly oriented Pt NPs supported on preformed graphene. Oriented (Pt) over bar /fl-G undergoes deactivation upon reuse, the most probable cause being Pt particle growth, probably due to the presence of high concentrations of carboxylic acids acting as mobilizing agents during the course of the reaction.Financial support by the Spanish Ministry of Economy and Competitiveness (Severn Ochoa and CTQ2015-69153-CO2-R1) and Generalitat Valenciana (Prometeo 2013-019) is gratefully acknowledged. I.E.-A. thanks the Spanish Ministry of Science for Ph.D. scholarships.Esteve-Adell, I.; Bakker, N.; Primo Arnau, AM.; Hensen, E.; García Gómez, H. (2016). Oriented Pt Nanoparticles Supported on Few-Layers Graphene as Highly Active Catalyst for Aqueous-Phase Reforming of Ethylene Glycol. ACS Applied Materials and Interfaces. 8(49):33690-33696. https://doi.org/10.1021/acsami.6b11904S336903369684

Cucurbit[7]uril-stabilized gold nanoparticles as catalysts of the nitro compound reduction reaction

[EN] The catalytic performance of cucurbit[7]uril-protected gold nanoparticles is reported for the first time for the reductive degradation of the banned but still used antibacterial compound nitrofurantoin. The cucurbit[7]uril-protected gold nanoparticles were produced by Au(III) reduction by sodium borohydride and subsequent addition of cucurbit[7]uril as a ligand. Working in this way, 5.7 nm gold nanoparticles were obtained and characterised by spectrophotometric and high-resolution transmission electron microscopic techniques. For a 1 : 100 nitro compound : sodium borohydride molar ratio, a normalised pseudo-first order apparent constant of 0.27 L s(-1) m(-2) at 25 degrees C and an activation energy of 34 kJ mol(-1) were obtained. For comparative purposes, the reduction reaction of the pollutant 4-nitrophenol was also studied and an apparent kinetic constant of 0.12 L s(-1) m(-2) at 25 degrees C and an activation energy of 68 kJ mol-1 were obtained, data that, when compared with recently reported work, demonstrates that these nanoparticles are an efficient catalyst.The authors would like to thank the Comunidad Aut´onoma de Madrid (S2013/MIT-3029, NANOAVANSENS).Blanco, E.; Esteve-Adell, I.; Atienzar Corvillo, PE.; Casas, J.; Hernández, P.; Quintana, C. (2016). Cucurbit[7]uril-stabilized gold nanoparticles as catalysts of the nitro compound reduction reaction. RSC Advances. 6(89):86309-86315. doi:10.1039/c6ra07168fS863098631568

Aplicaciones del grafeno en sistemas de almacenamiento de energía

The increase of renewable energy consumption, together with the growing demand of smart electronic devices, requires the development of energy storage systems with potential to store power over long duration of time and tailor-made functionalities. Graphene, due to its extraordinary electronic and mechanical properties, has the potential to revolutionize energy storage devices. In the present review, the main advances in graphene-based energy storage systems are highlighted, summarizing the benefits that this material brings in Li-ion batteries and supercapacitors.La transición energética actual hacia energías renovables, junto con la creciente demanda de dispositivos electrónicos inteligentes, requiere del desarrollo de sistemas de almacenamiento de energía que posean mayores capacidades y con funcionalidades hechas a medida. El grafeno, gracias a sus extraordinarias propiedades electrónicas y mecánicas, tiene potencial para revolucionar los dispositivos de almacenamiento de energía. En este contexto en la presente revisión, se destacan los principales avances en sistemas de almacenamiento de energía basados en grafeno, resumiendo los beneficios que aporta este material en las baterías de Li-ion y supercondensadores