Influence of Capping Ligands on Metal-Nanoparticle-Driven Hydrogen Evolution and CO2 Reduction Reactions

Nuria Romero, Karine Philippot

ABSTRACT
This chapter looks into the influence of the functionalization of the surface of metal nanoparticles (MNPs) with ligands on their catalytic performance in two crucial reactions, the hydrogen evolution reaction (HER) and the CO2 reduction reaction (CO2RR). The birth of the surface functionalization of MNPs with ligands was greatly inspired by the advanced knowledge accumulated on molecular metal catalysts, whose physical and chemical properties can be tuned by coordinating appropriate ligands to the metal active center. This field of research has profited from the progress in the synthetic methods for the generation of MNPs and the evolution of the spectroscopic and analytical techniques for their exhaustive characterization, as well as the improvement of the computational techniques. Relevant examples will illustrate how the functionalization of the surface of MNPs allow to modulate the energy profile of catalytic intermediate species through electronic effects and regulate the product selectivity through hydrophobic/hydrophilic effects. Another key parameter is the tuning of the number of surface-active sites as a function of the metal to ligand ratio and the chemical nature of the coordinating ligand. Furthermore, in some peculiar cases, second coordination sphere effects have even been described in analogy to biological enzymes.

Contact:
Karine Philippot Karine.Philippot(at)lcc-toulouse.fr

Reference:
Influence of Capping Ligands on Metal-Nanoparticle-Driven Hydrogen Evolution and CO2 Reduction Reactions
Martí G., Lozano-Roche A., Romero N., Francàs L., Philippot K., Bofill R., García-Antón J., Sala X.
in Topics in Organometallic Chemistry. Surface Functionalized Metal Catalysts, L. M. Martínez-Prieto (Ed.), Springer International Publishing: Cham, 2024, vol. 75, pp. 105-132. (978-3-031-73841-8).
https://doi.org/10.1007/3418_2024_116
https://hal.science/hal-04821235

Design of ruthenium nanoparticles for better performance in catalysis

Nuria Romero, Rosa Axet, Karine Philippot

Share link (until December 09, 2023)

ABSTRACT
This chapter focus on recent advances in the design of ruthenium-based nanoparticles using organometallic complexes as the metal source, for their application in catalysis. The aim is to illustrate the advantages of the organometallic approach to achieve nanoparticles with controlled characteristics. The adjustment of the morphology (size, shape, crystalline structure) and of the surface state of metal nanoparticles, are key parameters for the tuning of their catalytic properties. Study and rationalize the effects of these parameters provides interesting perspectives to improve the performance of nanocatalysts. At the laboratory scale, the accurate design of metal nanoparticles is feasible by an adequate choice of the reaction conditions including the nature of the metal precursor (organometallic complex with appropriate kinetics of decomposition), the nature of the stabilizer (polymers, dendrimers, ligands, ionic liquids, etc.), the addition of a second metal for a synergy effect or the use of a support that will bring other properties (stability, conductivity, electronic effects by phosphorus- or nitrogen doping, confinement effect). The challenge is to find the best compromise to achieve robust metal nanoparticles with high catalytic performance, both in terms of activity and selectivity. This will be illustrated through recent examples of ruthenium nanoparticles implemented in catalytic reactions that can find applications in fine chemistry and energy. The complementarity between computational and experimental chemistries, when available, will be underlined, being a powerful way to precisely understand the catalytic properties of nanoparticles and then, improve performance.

Contacts:
Rosa Axet Rosa.Axet(at)lcc-toulouse.fr and Karine Philippot Karine.Philippot(at)lcc-toulouse.fr

Ru-based nanoparticles supported on carbon nanotubes for electrocatalytic hydrogen evolution: structural and electronic effects

Nuria Romero*^ab, Dídac A. Fenoll^a, Laia Gil^a, Sergi Campos^a, Jordi Creus^ab, Gerard Martí^a, Javier Heras-Domingo^a, Vincent Collière^b, Camilo A. Mesa^c, Sixto Giménez^c, Laia Francàs^a, Luis Rodríguez-Santiago^a, Xavier Solans-Monfort*^a, Mariona Sodupe^a, Roger Bofill^a, Karine Philippot*^b, Jordi García-Antón^a and Xavier Sala*^a

^a Departament de Química, Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès, 08193, Catalonia, Spain. E-mail: xavier.sala@uab.cat; xavier.solans@uab.cat
^b CNRS, LCC (Laboratoire de Chimie de Coordination), UPR8241, Université de Toulouse, UPS, INPT, F-31077 Toulouse cedex 4, France. E-mail: nuria.romero@lcc-toulouse.fr; karine.philippot@lcc-toulouse.fr
 ^cInstitute of Advanced Materials (INAM), Universitat Jaume I, Avenida de Vicent Sos Baynat, s/n, 12006 Castelló de la Plana, Castellón, Spain

Inorg. Chem. Front., 2023, 10, 5885-5896
DOI: 10.1039/D3QI00698K

The performance of Ru-based nanoparticles (NPs) in the hydrogen evolution reaction (HER) relies on both their structural properties and the oxidation state of the metal. Herein, the versatility of the organometallic approach for the synthesis of metal-based nanostructures is combined with thermal oxidation treatments to prepare carbon-nanotube (CNT)-supported Ru-containing nanomaterials for their use as electrocatalysts after dropcasting onto a glassy carbon rotating disk electrode. This strategy allowed access to a series of hybrid nanomaterials of different Ru/RuO₂ compositions and different structural order. Linear sweep voltammetry experiments show that the relative disposition of the Ru/RuO₂ phases, their interconversion under reductive turnover conditions and the degree of structural order affect the HER electrocatalytic performance of different materials. The electrode containing NPs consisting of a RuO₂ core and metallic Ru at the surface outperforms that containing either pure RuO₂ NPs or Ru NPs. Impedance spectroscopy studies and DFT calculations suggest that this catalytic activity enhancement arises from improved charge transport properties and from the structure of the exposed metallic Ru shell, which is partially oxidized and highly amorphous.

Contacts:
Nuria Romero Nuria.Romero(at)lcc-toulouse.fr and Karine Philippot Karine.Philippot(at)lcc-toulouse.fr

Ruthenium Nanoparticles Stabilized with Methoxy-Functionalized Ionic Liquids: Synthesis and Structure–Performance Relations in Styrene Hydrogenation

Krishnan, D.; Schill, L.; Axet, M.R.; Philippot, K.; Riisager, A.

Nanomaterials 2023, 13, 1459. 

https://doi.org/10.3390/nano13091459

In situ study of the evolution of NiFe nanocatalysts in reductive and oxidative environments upon thermal treatments

François Robert, Pierre Lecante, Jean-Sébastien Girardon, Robert Wojcieszak, Éric Marceau, Valérie Briois, Catherine Amiens and Karine Philippot

Faraday Discuss., 2023,242, 353-373

https://doi.org/10.1039/D2FD00095D

The conversion of biomass as a sustainable path to access valuable chemicals and fuels is very attractive for the chemical industry, but catalytic conversions still often rely on the use of noble metals. Sustainability constraints require developing alternative catalysts from abundant and low-cost metals. In this context, NiFe nanoparticles are interesting candidates. In their reduced and supported form, they have been reported to be more active and selective than monometallic Ni in the hydrogenation of the polar functions of organic molecules, and the two metals are very abundant. However, unlike noble metals, Ni and Fe are easily oxidized in ambient conditions, and understanding their transformation in both oxidative and reductive atmospheres is an important though seldom investigated issue to be addressed before their application in catalysis. Three types of NiFe nanoparticles were prepared by an organometallic approach to ensure the formation of ultrasmall nanoparticles (<3.5 nm) with a narrow size distribution, controlled composition and chemical order, while working in mild conditions: Ni2Fe1 and Ni1Fe1, both with a Ni rich core and Fe rich surface, and an alloy with a Ni1Fe9 composition. Supported systems were obtained by the impregnation of silica with a colloidal solution of the preformed nanoparticles. Using advanced characterization techniques, such as wide-angle X-ray scattering (WAXS) and X-ray absorption spectroscopy (XAS) in in situ conditions, this study reports on the evolution of the chemical order and of the oxidation state of the metals upon exposure to air, hydrogen, and/or increasing temperature, all factors that may affect their degree of reduction and subsequent performance in catalysis. We show that if oxidation readily occurs upon exposure to air, the metals can revert to their initial state upon heating in the presence of H₂ but with a change in structure and chemical ordering.

Contributors:

• CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP 44099, F- 31077 Toulouse Cedex 4, France. E-mail: catherine.amiens@lcc-toulouse.fr
• Université de Toulouse, UPS, INPT, F-31077 Toulouse Cedex 4, France
• CNRS, CEMES (Centre d’Elaboration des Matériaux et d’Etudes Structurales), 29 Rue Jeanne Marvig, BP 4347, F-31055 Toulouse Cedex 4, France
• Univ. Lille, CNRS, Centrale Lille, Univ. Artois, UMR 8181 – UCCS – Unité de Catalyse et Chimie du Solide, F-59000 Lille, France
• Synchrotron SOLEIL, CNRS-UR1, L’Orme des Merisiers, BP48, Saint-Aubin, F-91192 Gif-sur Yvette, France

Fundings:

• Agence Nationale de la Recherche, Projet ANR “NobleFreeCat”, ANR- 17-CE07-0022-01 https://noblefreecat.univ-lille.fr/en/,
• Région Occitanie (ALDOCT 000355)
• CNRS,
• Université de Toulouse Paul-Sabatier,
• SOLEIL synchrotron (project no. 20200224).

Ru nanoparticles supported on alginate-derived graphene as hybrid electrodes for the hydrogen evolution reaction

Laura Mallón, Christian Cerezo-Navarrete, Nuria Romero,  Marta Puche, Jordi García-Antón, Roger Bofill, Karine Philippot, Luis M. Martínez-Prieto and Xavier Sala
New J. Chem., 2022, 46, 49
DOI: 10.1039/d1nj05215b

Contacts:
Nuria Romero Nuria.Romero(at)lcc-toulouse.fr and Karine Philippot Karine.Philippot(at)lcc-toulouse.fr