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Romain Moury

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Papers by Romain Moury

Reversible transition of an amorphous Cu-Al oxyfluoride into a highly active electrocatalyst for nitrate reduction to ammonia

The electrochemical conversion of nitrate (NO3-) to ammonia (NH3) is an emerging alternative to v... more The electrochemical conversion of nitrate (NO3-) to ammonia (NH3) is an emerging alternative to valorize this aqueous pollutant to an essential chemical feedstock and potential fuel. Underpinning the maturation of the field and eventual viability of this technology is the discovery of efficient electrocatalysts, coupled with fundamental insights into the reaction mechanism. Until now, fluorinated materials have not yet been explored in this direction. In this work, we present the first fluorinated catalyst used for electrochemical NO3- reduction to NH3. A new copper-based oxyfluoride, Cu3Al2OF10, prepared through a facile coprecipitation and annealing of the corresponding hydrated fluoride r-Cu3Al2F12(H2O)12, was found to be exceptionally active, attaining a NH3 Faradaic Efficiency (FE) of up to 57% for the 8-electron NO3- to NH3 pathway (-0.4 VRHE) with a mass activity of up to 1220 A.g-1 at -0.6 VRHE, the highest yet recorded. Additionally, Cu3Al2OF10 continually produced NH3 for ...

Correction: Experimental investigation of Mg(B3H8)2 dimensionality, materials for energy storage applications

Dalton Transactions

Correction for ‘Experimental investigation of Mg(B3H8)2 dimensionality, materials for energy stor... more

Alkali metal hydrazinidoboranes as solid-state hydrogen storage materials

L'hydrazine borane et ses dérivés, nouveaux matériaux pour le stockage chimique de l'hydrogène

Dans ce manuscrit, nous trouverons l'etude et la caracterisation de 3 nouveaux materiaux pour... more Dans ce manuscrit, nous trouverons l'etude et la caracterisation de 3 nouveaux materiaux pour le stockage chimique de l'hydrogene : l'hydrazine borane (N2H4BH3, HB avec 15.3 % m H) et les hydrazinidoboranes de lithium (LiN2H3BH3, LiHB avec 11.6 % m H) et de sodium (NaN2H3BH3, NaHB avec 8.8 % m H). Ces materiaux font partie de la famille des boranes, recemment envisages comme des materiaux prometteurs pour le stockage chimique de l'hydrogene. Comme exemple type, nous pouvons citer l'ammoniaborane (NH3BH3, AB avec 19.6 % m H), car il possede une capacite massique theorique en hydrogene elevee et debute sa deshydrogenation a une temperature moderee (122°C). Cependant, la cinetique de deshydrogenation de AB est lente. En outre, des gaz nocifs a la pile a combustible, tel que de la borazine, sont emis au cours de la thermolyse. Dans ce contexte, des derives, a savoir les amidoboranes, ont ete synthetises pour ameliorer les performances de AB. En effet, les amidoborane...

Thermal Conversion of Unsolvated Mg(B3H8)2 to BH4– in the Presence of MgH2

ACS Applied Energy Materials, 2021

In the search for energy storage materials, metal octahydrotriborates, M(B3H8)n, n=1,2, are promi... more In the search for energy storage materials, metal octahydrotriborates, M(B3H8)n, n=1,2, are promising candidates for applications such as stationary hydrogen storage and all solid-state batteries. Therefore, we studied the thermal conversion of unsolvated Mg(B3H8)2 to BH4-: as synthesized, and in the presence of MgH2. The conversion of our unsolvated Mg(B3H8)2 starts at ~100˚C and yields ~22 wt% of BH4along with the formation of (closo-hydro)borates and volatile boranes. This loss of boron (B) is a sign of poor cyclability of the system. However, the addition of activated MgH2 to unsolvated Mg(B3H8)2 drastically increases the thermal conversion to 85-88wt% of BH4while simultaneously decreasing the amounts of B-losses. Our results strongly indicate that the presence of activated MgH2 substantially decreases the formation of (closo-hydro)borates and provides the necessary H2 for the B3H8-to-BH4 conversion. This is the first report of a metal octahydrotriborate system to selectively convert to BH4under moderate conditions of temperature (200 °C) in less than 1h, making the MgB3H8-MgH2 system very promising for energy storage applications. Recently, this class of compounds has been demonstrated to be promising candidate as solid-state electrolytes for all-solid-state batteries. 6-10 For example, KB3H8 was reported to reach a maximum conductivity of 3.4 × 10-7 S.cm −1 at 150 °C, 11 and that of unsolvated Mg(B3H8)2 to be 1.4×10-4 Scm-1 at 80 °C. 12 Compounds based on B3H8anion have also been studied as nonflammable hydrogen carriers at room temperature in order to address the flammability issues related to the transport of gasoline. Borohydride based ionic liquids, such as C(NH2)3B3H8 and Li(NH3)B3H8, are considered due to their melting point <-10 °C and their liquid nature at room temperature. While C(NH2)3B3H8 releases ~7 mol% of H2 at 83 °C, Li(NH3)B3H8 releases ~95 mol% of H2 at 133 °C along with the liberation of minor B2H6 and B5H9 amounts. 13-14 By adding metal chlorides, MClx (x=2-4, M=Al, Zn, Zr), the H2 evolution of the Li(NH3)B3H8 was improved to ~97 mol%, 98 mol%, and 96 mol% at 109-119 °C. 14 B3H8compounds, such as NaB3H8 (13 wt% H), KB3H8 (5 wt% H), were also recently studied for long-term solid state hydrogen storage. 11, 15-17 In the case of NaB3H8, it has a high solubility in water (74 wt%) at room temperature, therefore possibilities exist for it to be used as a liquid hydrogen carrier in solution. Huang et al. found that the use of CoCl2 can act as a catalyst to enhance the hydrogen evolution up to ~7 wt% in the case of NaB3H8. 18 Compounds based on B3H8are also potential materials in preparing metal borides (MBx, x =1, 2) with chemical vapor deposition methods. For instance, Cr(B3H8)2, Mg(B3H8)2(Et2O)2 and Mg(B3H8)2(MeO)2 were used to synthesize CrB2 and MgB2. However, the evolution of pentaborane (B5H9) from heating these precursors affects the purity of the deposited metal boride films. 19-20 Mg(B3H8)2 was first observed experimentally as a dehydrogenation intermediate of magnesium borohydride, Mg(BH4)2, at 200 °C in vacuo after 5 weeks. 21 This result pioneered the research initiatives to determine the reversible re-hydrogenation of Mg(B3H8)2 to Mg(BH4)2 according to the following reaction: 1 3 Mg(B3H8)2 + 2 3 MgH2 + 2 3 H2 → Mg(BH4)2. To investigate the reversible hydrogenation of Mg(BH4)2 from Mg(B3H8)2, Chong et al. used tetrahydrofuran (THF) and studied the hydrogenation of solvated Mg(B3H8)2•2THF. 22 The authors found that the system Mg(B3H8)2•2THF-MgH2 yielded a 9 mol%-conversion to BH4at 200 °C under 50 bar of H2. However, the role of MgH2 and THF in the hydrogenation of Mg(B3H8)2•2THF-MgH2 was not clarified. The finding boosted the development of synthetic procedures for B3H8compounds and the study of its properties. Initially, synthetic routes of M(B3H8)n, n=1,2 involved the use of toxic chemicals (e.g. Hg, B2H6, B4H10 and BF3O(C2H5)2), 23-30 while the more recent synthetic strategies reported are solvent-free for M(B3H8)n with n=1,2 and M= Mg, Li, Na, K, Rb, Cs. 12, 31-34 Theoretical calculations based on prototype electrostatic ground state search method and density functional theory suggested that unsolvated Mg(B3H8)2 had an unfavorable enthalpy of reaction to be a decomposition product of Mg(BH4)2, since it was estimated to be +180 kJ/mol H2 for the following reaction: Mg(BH4)2 → 1 3 Mg(B3H8)2 + 2 3 MgH2 + 2 3 H2. 35 However, the authors used a computed crystal structure of Mg(B3H8)2 due to the lack of experimental data at that time. Recently, Moury et al. revealed that unsolvated Mg(B3H8)2 was mainly amorphous. 12 This finding will open more opportunities in studying unsolvated Mg(B3H8)2 and its chemical and physical properties in view of energy storage material. One of the greatest challenges encountered by these materials is the ability to de-/rehydrogenate because: i) they lose boron in the form of gas-phase boranes in their thermal decomposition, ii) they are not selective in their decomposition products as species like B10H10 2are produced, and iii) they form solid-state species regarded as thermodynamic sinks, such as B12H12 2-. For example, the thermal decomposition of KB3H8 occurs in the temperature range of 150-250 °C with a mass loss of 11 wt%, with the generation of several gaseous byproducts such as B2H6, B5H9 and B6H10 and solid products B12H12 2-, B10H10 2and BH4-. 17 To date the reported hydrogen cycling capacity of Mg(B3H8)2 formed from dehydrogenation of Mg(BH4)2 is ~ 2.5 wt% due to the

Destabilization of Boron-Based Compounds for Hydrogen Storage in the Solid-State: Recent Advances

Energies, 2021

Boron-based materials have been widely studied for hydrogen storage applications. Examples of the... more Boron-based materials have been widely studied for hydrogen storage applications. Examples of these compounds are borohydrides and boranes. However, all of these present some disadvantages that have hindered their potential application as hydrogen storage materials in the solid-state. Thus, different strategies have been developed to improve the dehydrogenation properties of these materials. The purpose of this review is to provide an overview of recent advances (for the period 2015–2021) in the destabilization strategies that have been considered for selected boron-based compounds. With this aim, we selected seven of the most investigated boron-based compounds for hydrogen storage applications: lithium borohydride, sodium borohydride, magnesium borohydride, calcium borohydride, ammonia borane, hydrazine borane and hydrazine bisborane. The destabilization strategies include the use of additives, the chemical modification and the nanosizing of these compounds. These approaches were a...

Highly efficient water oxidation via a bimolecular reaction mechanism on rutile structured mixed-metal oxyfluorides

Mixed-metal oxides are generally considered to be the highest-performance catalysts for alkaline ... more Mixed-metal oxides are generally considered to be the highest-performance catalysts for alkaline water oxidation. Despite significant efforts dedicated to understanding and accelerating their efficiency, most works have been limited investigations of Ni, Co, and Fe oxides, thus overlooking beneficial effects of hetero-anion incorporation. To this end, we report on the development of Co0.5Fe0.5O0.5F1.5 oxyfluoride materials featuring a rutile crystal structure and porous morphology via a scalable and green synthetic route. The catalyst surface, enhanced through electron withdrawing effects imparted by the fluoride ions, give rise to highly effective catalytic sites for electrochemical water oxidation. In particular, their performance across metrics of Tafel slope (27 mV/dec), mass activity (846 A/g at 1.53 V vs. RHE), turnover frequency (21/s at 1.53 V vs. RHE), overpotential (220 mV for 10 mA/cm2), and stability (27 days of continuous operation) largely surpasses most known Co-based...

Amorphous Iron–Manganese Oxyfluorides, Promising Catalysts for Oxygen Evolution Reaction under Acidic Media

ACS Applied Energy Materials, 2021

The development of earth-abundant catalysts for the oxygen evolution reaction (OER) in acidic med... more

Controlled Morphology Synthesis of Nanostructured β-AlF3–x(OH)x with Tunable Specific Surface Area

Crystal Growth & Design, 2021

27 Al isotropic chemical shift ranges and quadrupolar coupling constants of the various AlF6y(OH)... more

Amidoboranes and hydrazinidoboranes: State of the art, potential for hydrogen storage, and other prospects

International Journal of Hydrogen Energy, 2020

Four types of adverse events resembling immunological reactions have been reported in patients un... more Four types of adverse events resembling immunological reactions have been reported in patients undergoing chronic maintenance hemodialysis: anaphylaxis [1], hypereosinophilia [1-5], asthmatic attacks [4-6], and pulmonary leukostasis with compromised pulmonary function [7-10]. We evaluated three successive chronic dialysis patients who had developed acute hypersensitivity reactions manifested by increased airway obstruction in response to hemodialysis. Each patient also had a non-acute reaction to dialysis, hypereosinophilia, and one patient had urticaria. All dialyzers were ethylene oxide sterilized and none were reused. In these three patients the adverse reactions abated after changing from dialyzers containing Cuprophan (ENKA Ag, Wuppertal, Germany) to dialyzers not containing Cuprophan. In each patient a second exposure to Cuprophan caused recurrence of one or more of the adverse reactions. These case studies and our re-examination of previous observations [1-61 suggest that in some patients both acute and chronic adverse reactions may be related to the use of Cuprophan. Methods and Results. Patient 1. A 50-year-old black female with renal failure secondary to hypertension began chronic hemodialysis in December 1975. It is uncertain which dialyzers were used during the first 10 months of dialysis, but during her ninth and tenth months of dialysis differential counts showed 18 and 20% eosinophils (Fig. 1). In October 1976, a one antigenmatched cadaver kidney transplant was attempted but was rejected and, 3 weeks later, removed. Hemodialysis was continued using coil dialyzers containing Cuprophan (ENKA Ag)

Experimental investigation of Mg(B3H8)2 dimensionality, materials for energy storage applications

Dalton Transactions, 2020

We synthesized and studied the dimensionality of Mg(B3H8)2, a controversial intermediate in the t... more

Stabilization of a mixed iron vanadium based hexagonal tungsten bronze hydroxyfluoride HTB–(Fe0.55V0.45)F2.67(OH)0.33 as a positive electrode for lithium-ion batteries

Dalton Transactions, 2020

The first mixed iron vanadium hydroxyfluoride with a Hexagonal Tungsten Bronze (HTB) structure as... more

Crystallization of closo-borate electrolytes from solution enabling infiltration into slurry-casted porous electrodes for all-solid-state batteries

Energy Storage Materials, 2019

Crystallization of closo-borate electrolytes from solution enabling infiltration into slurrycaste... more

Direct Solution‐Based Synthesis of Na 4 (B 12 H 12 )(B 10 H 10 ) Solid Electrolyte

ChemSusChem, 2019

All-solid-state batteries (ASSBs) promise higher power and energy density compared to 390 360 330... more

An alternative approach to the synthesis of NaB3H8 and Na2B12H12 for solid electrolyte applications

International Journal of Hydrogen Energy, 2017

Alkaline or alkaline earth octahydrotriborate M(B 3 H 8) x and dodecahydro-closo-dodecaborate M x... more Alkaline or alkaline earth octahydrotriborate M(B 3 H 8) x and dodecahydro-closo-dodecaborate M x B 12 H 12 (M ¼ Li, Na, Mg or Ca with x ¼ 1 or 2) have recently attracted a lot of interest for hydrogen storage and solid electrolyte applications. Nevertheless, their syntheses are still a roadblock for large scale applications. In this paper we propose a novel approach for their syntheses starting from the cheapest borohydride NaBH 4. The process involves first the solvothermal synthesis of tetrabutylammonium octahydrotriborate (C 4 H 9) 4 NB 3 H 8 (TBAB 3 H 8) being the basis for the syntheses of the others boranes. Starting from TBAB 3 H 8 , we have synthesized pure and unsolvated NaB 3 H 8 by salt metathesis reaction with sodium tetraphenylborate. Then, we have successfully obtained Na 2 B 12 H 12 by solvothermal decomposition of NaB 3 H 8. This approach has shown to be quantitative and reproducible, which could lead to the development of these boranes in real life applications.

Demonstration of Mg2FeH6 as heat storage material at temperatures up to 550 °C

Applied Physics A, 2016

The storage of heat at high temperatures, which can be used to generate electricity after sunset ... more The storage of heat at high temperatures, which can be used to generate electricity after sunset in concentrating solar power plants, is one of the most challenging technologies. The use of metal hydride could be one possibility to solve the problem. During the endothermic heat storage process, the metal hydride is decomposed releasing hydrogen, which then can be stored. During the exothermic reaction of the metal with the hydrogen gas, the stored heat is then released. Previous research had shown that Mg and Fe powders can be used at temperatures up to 550°C for heat storage and shows excellent cycle stability over hundreds of cycles without any degradation. Here, we describe the results of testing of a tube storage tank that contained 211 g of Mg and Fe powders in 2:1 ratio. Twenty-three dehydrogenations (storage) and 23 hydrogenations (heat release) in the temperature range between of 395 and 515°C and pressure range between 1.5 and 8.6 MPa were done. During the dehydrogenation, 0.41-0.42 kWh th kg-1 of heat based on material 2 Mg/Fe can be stored in the tank. After testing, mainly Mg 2 FeH 6 was observed and small amounts of MgH 2 and Fe metal can be detected in the hydride samples. This means that the heat storage capacity of the system could be further increased if only Mg 2 FeH 6 is produced during subsequent cycles.

$Research paper thumbnail of In situ thermodiffraction to monitor synthesis and thermolysis of hydrazine borane-based materials$

In situ thermodiffraction to monitor synthesis and thermolysis of hydrazine borane-based materials

Journal of Alloys and Compounds, 2016

Hydrazine borane N 2 H 4 BH 3 (HB) and its alkali metal derivatives, i.e. sodium hydrazinidoboran... more Hydrazine borane N 2 H 4 BH 3 (HB) and its alkali metal derivatives, i.e. sodium hydrazinidoborane NaN 2 H 3 BH 3 (NaHB) and lithium hydrazinidoborane b-LiN 2 H 3 BH 3 (b-LiHB), are novel materials under investigation for solid-state chemical hydrogen storage. Herein, we report in situ thermodiffraction experiments developed to monitor synthesis of NaHB at low temperatures (from À173 C) and a thermolysis of each of the boranes, manifesting the following main observations. (i) Dehydrogenation of HB starts with the liquid phase and dehydrocoupling involves the formation of a crystalline intermediate (at 90e197 C). (ii) NaHB forms from À38 C, melts at ca. 60 C, and decomposes upon melting at higher temperatures. (iii) b-LiHB dehydrogenates to a small extent starting from 40 C, but mostly transforms to the high-temperature phase a-LiHB at 91 C; up to around 150 C, the two crystalline phases dehydrogenate according to a complex stepwise mechanism. Our results help in gaining insight in synthesis and thermolysis of the aforementioned novel hydrazine borane-based materials.

Development of Hydrogen Storage Tank Systems Based on Complex Metal Hydrides

Materials, 2015

This review describes recent research in the development of tank systems based on complex metal h... more This review describes recent research in the development of tank systems based on complex metal hydrides for thermolysis and hydrolysis. Commercial applications using complex metal hydrides are limited, especially for thermolysis-based systems where so far only demonstration projects have been performed. Hydrolysis-based systems find their way in space, naval, military and defense applications due to their compatibility with proton exchange membrane (PEM) fuel cells. Tank design, modeling, and development for thermolysis and hydrolysis systems as well as commercial applications of hydrolysis systems are described in more detail in this review. For thermolysis, mostly sodium aluminum hydride containing tanks were developed, and only a few examples with nitrides, ammonia borane and alane. For hydrolysis, sodium borohydride was the preferred material whereas ammonia borane found less popularity. Recycling of the sodium borohydride spent fuel remains an important part for their commercial viability.

$Research paper thumbnail of Anin situpowder diffraction cell for high-pressure hydrogenation experiments using laboratory X-ray diffractometers$

Anin situpowder diffraction cell for high-pressure hydrogenation experiments using laboratory X-ray diffractometers

Journal of Applied Crystallography, 2015

Anin situdiffraction cell is presented which has been designed and constructed for in-house powde... more Anin situdiffraction cell is presented which has been designed and constructed for in-house powder diffraction experiments under high gas pressures up to 30 MPa. For a proof of principle, thein situcell has been tested for several hydrogenation experiments under elevated pressures and temperatures. LaNi5was chosen as an example for hydrogenation, applying simultaneously 5.5 MPa H2pressure at a temperature of 423 K. For testing the high-pressure–temperature suitability of thein situcell, pressure–temperature experiments up to 14 MPa at 373 K were performed, studying the rehydrogenation of NaH and Al to NaAlH4. The experimental setup enables recording ofin situX-ray diffraction data on laboratory instruments with short data acquisition times at elevated hydrogen pressures and temperatures.

Hydrazine Borane and Hydrazinidoboranes as Chemical Hydrogen Storage Materials

Energies, 2015

Hydrazine borane N2H4BH3 and alkali derivatives (i.e., lithium, sodium and potassium hydrazinidob... more Hydrazine borane N2H4BH3 and alkali derivatives (i.e., lithium, sodium and potassium hydrazinidoboranes MN2H3BH3 with M = Li, Na and K) have been considered as potential chemical hydrogen storage materials. They belong to the family of boron-and nitrogen-based materials and the present article aims at providing a timely review while focusing on fundamentals so that their effective potential in the field could be appreciated. It stands out that, on the one hand, hydrazine borane, in aqueous solution, would be suitable for full dehydrogenation in hydrolytic conditions; the most attractive feature is the possibility to dehydrogenate, in addition to the BH3 group, the N2H4 moiety in the presence of an active and selective metal-based catalyst but for which further improvements are still necessary. However, the thermolytic dehydrogenation of hydrazine borane should be avoided because of the evolution of significant amounts of hydrazine and the formation of a shock-sensitive solid residue upon heating at >300 °C. On the other hand, the alkali hydrazinidoboranes, obtained by reaction of hydrazine borane with alkali hydrides, would be more suitable to thermolytic dehydrogenation, with improved properties in comparison to the parent borane. All of these aspects are surveyed herein and put into perspective.