Sara Cavaliere | Université de Montpellier (original) (raw)

Papers by Sara Cavaliere

One of the greatest challenges of our time is to mitigate the global climate change caused by ant... more One of the greatest challenges of our time is to mitigate the global climate change caused by anthropogenic emission of greenhouse gases, mainly generated by use of fossil fuels. A critical part of the solution is to substitute energy generation based on fossil fuels by the more renewable energy sources (solar, wind, geothermal power and others) and one of the main issues is to provide efficient energy storage for a large subset of intermittent energy sources. This can be achieved by various means, such as physical storage (e.g. pump hydro storage, flywheels, compressed air) and/or chemical conversion (e.g. batteries, hydrogen and ammonia generation and storage, artificial carbon-based fuels) (Figure 1). The second family of the energy storage solutions is close to maturity for commercial deployment, therefore research and development proceeds at a fast pace and enjoys significant investments at all levels. For this reason, it is foreseen that the activities in this direction will b...

HAL (Le Centre pour la Communication Scientifique Directe), 2015

International audienc

ECS Transactions, 2015

Nickel nanofibres were prepared by electrospinning followed by specific thermal treatments. Pt/Ni... more Nickel nanofibres were prepared by electrospinning followed by specific thermal treatments. Pt/Ni fibrous electrocatalysts were obtained by galvanic displacement of the metal surface atoms with platinum. A novel, very fast Ni displacement assisted by microwaves is described. The Pt/Ni nanofibres were characterised for their activity towards oxygen reduction for their application in PEMFC electrodes.

HAL (Le Centre pour la Communication Scientifique Directe), Mar 15, 2011

ACS Catalysis, May 18, 2023

HAL (Le Centre pour la Communication Scientifique Directe), 2005

ABSTRACT Amine functionalized platinum nanoparticles have been modified by over-grafting two diff... more ABSTRACT Amine functionalized platinum nanoparticles have been modified by over-grafting two different molecules, 2-thiophenecarbonyl chloride (Pt-1) and 1-hexyl-4-(4-isothiocyanatophenyl)-bicyclo (2, 2, 2) octane (Pt-2). Cyclic voltammetry was performed at gold electrodes coated with Langmuir–Blodgett (LB) mixed films of Pt-1 and Pt-2 nanoparticles, and behenic acid. From five layers the electrochemical response was essentially provided by the last LB component. The electrochemical responses towards the [Fe(CN)6]3−/4− couple were strongly influenced by the nature of the over-grafted molecules: films of Pt-2 presented an almost complete blocking effect, while films of Pt-1 allowed the redox reaction to occur on Pt nanoparticles. In order to understand the reasons for such different behaviors we built up hetero-nanostructures by superposing Pt-1 and Pt-2 LB layers in different ways, yielding different kinds of “sandwich” structures. The electrochemical response depended on the electrode ending. When Pt-1 nanoparticles were in the outer layer, in contact with the electrolyte solution, the electrode was electroactive toward the redox probe, while when Pt-2 layers were in the outer layer no electroactivity was detected. For sandwiches made of Pt-1, with a variable thickness of an intercalated film of Pt-2, the electrode response to [Fe(CN)6]3−/4− was modulated by the thickness of the inter-layer: the thicker the layer, the lower the response.

Zenodo (CERN European Organization for Nuclear Research), Nov 23, 2021

Nature Energy, Jun 13, 2023

HAL (Le Centre pour la Communication Scientifique Directe), 2011

Meeting abstracts, Jul 23, 2018

Many fuel cell membranes are highly heterogeneous systems comprising mechanical and chemical rein... more Many fuel cell membranes are highly heterogeneous systems comprising mechanical and chemical reinforcing components, including porous polymer sheets, nanofibers or nanoparticles, as well as radical scavengers or hydrogen peroxide decomposition catalysts. In the last 10 years, significant attention has been devoted to 1D nanomaterials obtained by electrospinning. Several chemistries and compositions ranging from aliphatic or aromatic polymers to metal oxides and phosphates and morphologies from nanofibers to nanotubes have been employed to prepare nanocomposite membranes. Despite the significant advances realized, further improvements in ionomer membrane durability under operation are still required. In particular, it is crucial to control the heterogeneity induced by the nanofiber component and to strengthen the interface between them and the matrix. Specific interactions can improve the fiber/matrix interface with overall improvement of dimensional and mechanical properties. This presentation will briefly review the different approaches to fuel cell membrane reinforcement based on electrospun polymers and describe our recent advances with polybenzimidazole reinforcement of PFSAs.

Chemcatchem, Aug 9, 2022

The development of highly active and long-term stable electrocatalysts for the cathode of proton-... more The development of highly active and long-term stable electrocatalysts for the cathode of proton-exchange membrane fuel cells (PEMFC) is a paramount requirement for high performance and durable PEMFC stacks. In this regard, alloying Pt with rare earth metals (REM) has emerged as a promising approach. This short review summarizes and discusses the most relevant advances on Pt-REM alloy electrocatalysts, from bulk polycrystalline surfaces to carbon supported nanostructures, for the oxygen reduction reaction (ORR), and their implementation in PEMFCs, and is a starting point to establish the challenges in synthesis and design and properties goals for novel Pt-REM alloys.

ChemElectroChem, Jul 14, 2023

A Pt‐free cathode catalyst is necessary for proton‐exchange membrane fuel cell (PEMFC) to enable ... more A Pt‐free cathode catalyst is necessary for proton‐exchange membrane fuel cell (PEMFC) to enable the widespread use of these environmentally friendly energy conversion devices at affordable price. Herein, a pyrolyzed electrospun carbon nanofibre (CNF) catalyst is prepared embedded with cobalt(II) phthalocyanine and iron(II) phthalocyanine compounds to provide the transition metal N4‐macrocyclic complex‐derived sites (MNX) possessing better electrocatalytic oxygen reduction reaction (ORR) activity. The physical characterisation showed the nanofibrous structure of catalyst with rough surface texture and considerable amount of N, Fe, and Co. The D−MN4−CNF−IL−A catalyst prepared using ionic liquid as a porogen displayed the best electrocatalytic activity for O2 electroreduction proceeding via 4e− pathway in 0.5 M H2SO4 electrolyte solution with the ORR onset and half‐wave potential of 0.83 and 0.71 V vs reversible hydrogen electrode (RHE), respectively.

HAL (Le Centre pour la Communication Scientifique Directe), 2007

Meeting abstracts, Jul 7, 2022

HAL (Le Centre pour la Communication Scientifique Directe), Jun 1, 2022

Les piles à combustible convertissent directement l'énergie chimique en énergie électrique. Cepen... more Les piles à combustible convertissent directement l'énergie chimique en énergie électrique. Cependant, les catalyseurs actuels à base de métaux précieux et rares induisent un coût élevé et menacent la pérennité de cette technologie. Cet article présente les avancées et défis restant pour remplacer le platine par des catalyseurs bio-inspirés, à base de fer, azote et carbone (Fe-N-C). De leur synthèse à leur intégration dans les dispositifs, en passant par l'identification des sites catalytiques à un atome de fer, cet article se concentre sur une application des Fe-N-C en piles à combustible à membrane conductrice de protons, mais nous abordons également celles à membrane conductrice d'anions, une technologie émergente et prometteuse. Mots-clés Piles à combustible, électrocatalyse, réduction de l'oxygène, fer, membrane échangeuse de protons, membrane échangeuse d'anions

ACS Catalysis, Dec 6, 2022

Journal of The Electrochemical Society, Mar 1, 2022

The selectivity of CO2 electrolyzers has hitherto mainly been associated with the cathode selecti... more The selectivity of CO2 electrolyzers has hitherto mainly been associated with the cathode selectivity. A few recent studies have shown that the nature of the polymer membrane can impact the system ionic selectivity, with anion exchange membranes (AEM) leading to high crossover of (bi)carbonates during operation and a CO2 pumping effect. In the present work, we investigate and compare CO2 crossover during operation through an AEM and a bipolar membrane (BPM) in a flow cell fed with gaseous CO2. With AEM, starting with 1 M KHCO3 catholyte and 1 M KOH anolyte, the anolyte pH rapidly drops from 14 to 8. This triggers an increase of 1.2 V in cell voltage at 45 mA·cm−2, due to increased OER overpotential and anolyte resistance. Steady-state operation at 45 mA·cm−2 with the AEM results in a CO2/O2 ratio of 3.6 at the anode. With BPM, the anolyte pH decreases more slowly, and the CO2/O2 ratio at the anode under steady-state at 45 mA·cm−2 is only 0.38. Overall, the cell voltage is lower with the BPM than with the AEM at steady-state. These results show the potential of BPMs to mitigate carbon crossover, which could be further reduced by optimizing their design.

Springer eBooks, 2018

International audienc

One of the greatest challenges of our time is to mitigate the global climate change caused by ant... more One of the greatest challenges of our time is to mitigate the global climate change caused by anthropogenic emission of greenhouse gases, mainly generated by use of fossil fuels. A critical part of the solution is to substitute energy generation based on fossil fuels by the more renewable energy sources (solar, wind, geothermal power and others) and one of the main issues is to provide efficient energy storage for a large subset of intermittent energy sources. This can be achieved by various means, such as physical storage (e.g. pump hydro storage, flywheels, compressed air) and/or chemical conversion (e.g. batteries, hydrogen and ammonia generation and storage, artificial carbon-based fuels) (Figure 1). The second family of the energy storage solutions is close to maturity for commercial deployment, therefore research and development proceeds at a fast pace and enjoys significant investments at all levels. For this reason, it is foreseen that the activities in this direction will b...

HAL (Le Centre pour la Communication Scientifique Directe), 2015

International audienc

ECS Transactions, 2015

Nickel nanofibres were prepared by electrospinning followed by specific thermal treatments. Pt/Ni... more Nickel nanofibres were prepared by electrospinning followed by specific thermal treatments. Pt/Ni fibrous electrocatalysts were obtained by galvanic displacement of the metal surface atoms with platinum. A novel, very fast Ni displacement assisted by microwaves is described. The Pt/Ni nanofibres were characterised for their activity towards oxygen reduction for their application in PEMFC electrodes.

HAL (Le Centre pour la Communication Scientifique Directe), Mar 15, 2011

ACS Catalysis, May 18, 2023

HAL (Le Centre pour la Communication Scientifique Directe), 2005

ABSTRACT Amine functionalized platinum nanoparticles have been modified by over-grafting two diff... more ABSTRACT Amine functionalized platinum nanoparticles have been modified by over-grafting two different molecules, 2-thiophenecarbonyl chloride (Pt-1) and 1-hexyl-4-(4-isothiocyanatophenyl)-bicyclo (2, 2, 2) octane (Pt-2). Cyclic voltammetry was performed at gold electrodes coated with Langmuir–Blodgett (LB) mixed films of Pt-1 and Pt-2 nanoparticles, and behenic acid. From five layers the electrochemical response was essentially provided by the last LB component. The electrochemical responses towards the [Fe(CN)6]3−/4− couple were strongly influenced by the nature of the over-grafted molecules: films of Pt-2 presented an almost complete blocking effect, while films of Pt-1 allowed the redox reaction to occur on Pt nanoparticles. In order to understand the reasons for such different behaviors we built up hetero-nanostructures by superposing Pt-1 and Pt-2 LB layers in different ways, yielding different kinds of “sandwich” structures. The electrochemical response depended on the electrode ending. When Pt-1 nanoparticles were in the outer layer, in contact with the electrolyte solution, the electrode was electroactive toward the redox probe, while when Pt-2 layers were in the outer layer no electroactivity was detected. For sandwiches made of Pt-1, with a variable thickness of an intercalated film of Pt-2, the electrode response to [Fe(CN)6]3−/4− was modulated by the thickness of the inter-layer: the thicker the layer, the lower the response.

Zenodo (CERN European Organization for Nuclear Research), Nov 23, 2021

Nature Energy, Jun 13, 2023

HAL (Le Centre pour la Communication Scientifique Directe), 2011

Meeting abstracts, Jul 23, 2018

Many fuel cell membranes are highly heterogeneous systems comprising mechanical and chemical rein... more Many fuel cell membranes are highly heterogeneous systems comprising mechanical and chemical reinforcing components, including porous polymer sheets, nanofibers or nanoparticles, as well as radical scavengers or hydrogen peroxide decomposition catalysts. In the last 10 years, significant attention has been devoted to 1D nanomaterials obtained by electrospinning. Several chemistries and compositions ranging from aliphatic or aromatic polymers to metal oxides and phosphates and morphologies from nanofibers to nanotubes have been employed to prepare nanocomposite membranes. Despite the significant advances realized, further improvements in ionomer membrane durability under operation are still required. In particular, it is crucial to control the heterogeneity induced by the nanofiber component and to strengthen the interface between them and the matrix. Specific interactions can improve the fiber/matrix interface with overall improvement of dimensional and mechanical properties. This presentation will briefly review the different approaches to fuel cell membrane reinforcement based on electrospun polymers and describe our recent advances with polybenzimidazole reinforcement of PFSAs.

Chemcatchem, Aug 9, 2022

The development of highly active and long-term stable electrocatalysts for the cathode of proton-... more The development of highly active and long-term stable electrocatalysts for the cathode of proton-exchange membrane fuel cells (PEMFC) is a paramount requirement for high performance and durable PEMFC stacks. In this regard, alloying Pt with rare earth metals (REM) has emerged as a promising approach. This short review summarizes and discusses the most relevant advances on Pt-REM alloy electrocatalysts, from bulk polycrystalline surfaces to carbon supported nanostructures, for the oxygen reduction reaction (ORR), and their implementation in PEMFCs, and is a starting point to establish the challenges in synthesis and design and properties goals for novel Pt-REM alloys.

ChemElectroChem, Jul 14, 2023

A Pt‐free cathode catalyst is necessary for proton‐exchange membrane fuel cell (PEMFC) to enable ... more A Pt‐free cathode catalyst is necessary for proton‐exchange membrane fuel cell (PEMFC) to enable the widespread use of these environmentally friendly energy conversion devices at affordable price. Herein, a pyrolyzed electrospun carbon nanofibre (CNF) catalyst is prepared embedded with cobalt(II) phthalocyanine and iron(II) phthalocyanine compounds to provide the transition metal N4‐macrocyclic complex‐derived sites (MNX) possessing better electrocatalytic oxygen reduction reaction (ORR) activity. The physical characterisation showed the nanofibrous structure of catalyst with rough surface texture and considerable amount of N, Fe, and Co. The D−MN4−CNF−IL−A catalyst prepared using ionic liquid as a porogen displayed the best electrocatalytic activity for O2 electroreduction proceeding via 4e− pathway in 0.5 M H2SO4 electrolyte solution with the ORR onset and half‐wave potential of 0.83 and 0.71 V vs reversible hydrogen electrode (RHE), respectively.

HAL (Le Centre pour la Communication Scientifique Directe), 2007

Meeting abstracts, Jul 7, 2022

HAL (Le Centre pour la Communication Scientifique Directe), Jun 1, 2022

Les piles à combustible convertissent directement l'énergie chimique en énergie électrique. Cepen... more Les piles à combustible convertissent directement l'énergie chimique en énergie électrique. Cependant, les catalyseurs actuels à base de métaux précieux et rares induisent un coût élevé et menacent la pérennité de cette technologie. Cet article présente les avancées et défis restant pour remplacer le platine par des catalyseurs bio-inspirés, à base de fer, azote et carbone (Fe-N-C). De leur synthèse à leur intégration dans les dispositifs, en passant par l'identification des sites catalytiques à un atome de fer, cet article se concentre sur une application des Fe-N-C en piles à combustible à membrane conductrice de protons, mais nous abordons également celles à membrane conductrice d'anions, une technologie émergente et prometteuse. Mots-clés Piles à combustible, électrocatalyse, réduction de l'oxygène, fer, membrane échangeuse de protons, membrane échangeuse d'anions

ACS Catalysis, Dec 6, 2022

Journal of The Electrochemical Society, Mar 1, 2022

The selectivity of CO2 electrolyzers has hitherto mainly been associated with the cathode selecti... more The selectivity of CO2 electrolyzers has hitherto mainly been associated with the cathode selectivity. A few recent studies have shown that the nature of the polymer membrane can impact the system ionic selectivity, with anion exchange membranes (AEM) leading to high crossover of (bi)carbonates during operation and a CO2 pumping effect. In the present work, we investigate and compare CO2 crossover during operation through an AEM and a bipolar membrane (BPM) in a flow cell fed with gaseous CO2. With AEM, starting with 1 M KHCO3 catholyte and 1 M KOH anolyte, the anolyte pH rapidly drops from 14 to 8. This triggers an increase of 1.2 V in cell voltage at 45 mA·cm−2, due to increased OER overpotential and anolyte resistance. Steady-state operation at 45 mA·cm−2 with the AEM results in a CO2/O2 ratio of 3.6 at the anode. With BPM, the anolyte pH decreases more slowly, and the CO2/O2 ratio at the anode under steady-state at 45 mA·cm−2 is only 0.38. Overall, the cell voltage is lower with the BPM than with the AEM at steady-state. These results show the potential of BPMs to mitigate carbon crossover, which could be further reduced by optimizing their design.

Springer eBooks, 2018

International audienc