Catalytic effect of TiF4 in improving hydrogen storage properties of MgH2

Jangir, Mukesh; Jain, Ankur; Yamaguchi, Shotaro; Ichikawa, Takayuki; Lal, Chhagan; Jain, I.P.

doi:10.1016/j.ijhydene.2016.06.238

Cited by 79 publications

(24 citation statements)

References 26 publications

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“…2 The binding energy of 459.9 eV is significantly higher than the ones of pure TiO2 and can be explained by the influence of the Fanions. 3 The intensity ratio between this Ti 4+ component and the main Ti 4+ 2p3/2 signal decreased from 0.3 for TiO2 n-sh to ca. 0.1 for the other samples, in agreement with the evolution of the electronic properties highlighted by UV-Vis-NIR-MIR spectroscopy and with the progressive decrease of Fcontent (see Table 2 in the main text).…”

Section: Tof-simsmentioning

confidence: 93%

Beyond Shape Engineering of TiO₂ Nanoparticles: Post-Synthesis Treatment Dependence of Surface Hydration, Hydroxylation, Lewis Acidity and Photocatalytic Activity of TiO₂ Anatase Nanoparticles with Dominant {001} or {101} Facets

Mino

Pellegrino

Rades

et al. 2018

ACS Appl. Nano Mater.

112

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TiO2 anatase nanoparticles are among the relevant players in the field of light-responsive semiconductor nanomaterials used to face environmental and energy issues. In particular, shape-engineered TiO2 anatase nanosheets with dominant {001} basal facets gained momentum because of the possibility to exploit different and/or improved functional behaviors with respect to usual bipyramidal TiO2 anatase nanoparticles, mainly exposing {101} facets. Nevertheless, such behavior depends in a significant extent on the physicochemical features of surfaces exposed by nanosheets. They can vary in dependence on the presence or removal degree of capping agents, namely, fluorides, used for shape-engineering, and experimental investigations in this respect are still a few. Here we report on the evolution of interfacial/surface features of TiO2 anatase nanosheets with dominant {001} facets from pristine nanoparticles fluorinated both in the bulk and at their surface to nanoparticles with F– free surfaces by treatment in a basic solution and to totally F– free nanoparticles by calcination at 873 K. The nanoparticles fluorine content and its subsequent evolution is determined by complementary techniques (ion chromatography, TOF-SIMS, XPS, AES, SEM-EDX), probing different depths. In parallel, the evolution of the electronic properties and the Ti valence state is monitored by UV–vis spectroscopy and XPS. The calcination treatment results in {001} facets poorly hydroxylated, hydrated, and hydrophilic, which appear as surface features consequent to the expected (1 × 4) reconstruction. Moreover, IR spectroscopy of CO adsorbed as probe molecule indicates that the Lewis acidity of Ti4+ sites exposed on (1 × 4) reconstructed {001} facets of calcined TiO2 nanosheets is weaker than that of cationic centers on {101} facets of bipyramidal TiO2 anatase nanoparticles. The samples have also been tested in phenol photodegradation highlighting that differences in surface hydration, hydroxylation, and Lewis acidity between TiO2 nanoparticles with nanosheet (freed by F– by calcination at 873 K) and bipyramidal shape have a strong impact on the photocatalytic activity that is found to be quite limited for the nanoparticles mainly exposing (1 × 4) reconstructed {001} facets.

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Section: Tof-simsmentioning

confidence: 93%

Beyond Shape Engineering of TiO₂ Nanoparticles: Post-Synthesis Treatment Dependence of Surface Hydration, Hydroxylation, Lewis Acidity and Photocatalytic Activity of TiO₂ Anatase Nanoparticles with Dominant {001} or {101} Facets

Mino

Pellegrino

Rades

et al. 2018

ACS Appl. Nano Mater.

112

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“…Inspired by the merits of F ions, several researchers have developed different fluoride materials such as CeF 4 , NbF 5 , ZrF 4 , TiF 3 , TiF 4 etc. [129][130][131][132][133]. An assumption has been proposed on the basis of intermediate H δ− -Nb δ+ bond formation, which is favored by large electronic delocalization of the Nb-F bond.…”

Section: Metal Halide Catalystsmentioning

confidence: 99%

Catalytic Tuning of Sorption Kinetics of Lightweight Hydrides: A Review of the Materials and Mechanism

2018

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Hydrogen storage materials have been a subject of intensive research during the last 4 decades. Several developments have been achieved in regard of finding suitable materials as per the US-DOE targets. While the lightweight metal hydrides and complex hydrides meet the targeted hydrogen capacity, these possess difficulties of hard thermodynamics and sluggish kinetics of hydrogen sorption. A number of methods have been explored to tune the thermodynamic and kinetic properties of these materials. The thermodynamic constraints could be resolved using an intermediate step of alloying or by making reactive composites with other hydrogen storage materials, whereas the sluggish kinetics could be improved using several approaches such as downsizing and the use of catalysts. The catalyst addition reduces the activation barrier and enhances the sorption rate of hydrogen absorption/desorption. In this review, the catalytic modifications of lightweight hydrogen storage materials are reported and the mechanism towards the improvement is discussed.

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“…17 A more recent and detailed XPS investigation 18 revealed the formation of TiH 2 and Ti-Mg-F species during the milling as well as the dehydrogenation process and proved the contribution of F anion to promote the dehydrogenation/re-hydrogenation reactions of MgH 2. 17 A more recent and detailed XPS investigation 18 revealed the formation of TiH 2 and Ti-Mg-F species during the milling as well as the dehydrogenation process and proved the contribution of F anion to promote the dehydrogenation/re-hydrogenation reactions of MgH 2.…”

Section: Introductionmentioning

confidence: 98%

“…In our recent study, the effect of TiF 4 additive on hydrogenation of MgH 2 was investigated, and results show that hydrogen decomposition of MgH 2 with the TiF 4 takes place at comparatively low temperature than the as-received MgH 2 and 2-h milled MgH 2. 17 A more recent and detailed XPS investigation 18 revealed the formation of TiH 2 and Ti-Mg-F species during the milling as well as the dehydrogenation process and proved the contribution of F anion to promote the dehydrogenation/re-hydrogenation reactions of MgH 2. The above results suggest the essential formation of TiH 2 even if the reaction starts with other titanium compounds.…”

Section: Introductionmentioning

confidence: 98%

The enhanced de/re-hydrogenation performance of MgH₂ with TiH₂ additive

Jangir¹,

Jain

Agarwal

et al. 2017

Int J Energy Res

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Summary Catalytic effects of TiH2 on hydrogenation/dehydrogenation kinetics of MgH2 were investigated in this study. The TG analysis showed that the addition of the x wt% TiH2 exhibited lower onset temperature of 160°C which is 100°C and 190°C lower than as‐milled and as‐received MgH2. The dehydrogenation and hydrogenation kinetics were significantly improved compared with the pure MgH2. The activation energy for the hydrogen desorption of MgH2 was reduced from −137.13 to −77.58 kJ/mol by the addition of TiH2. XRD and XPS results showed that the phase of TiH2 remained same during the dehydrogenation without any intermediate formation confirming its role as catalyst.

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Catalytic effect of TiF4 in improving hydrogen storage properties of MgH2

Cited by 79 publications

References 26 publications

Beyond Shape Engineering of TiO₂ Nanoparticles: Post-Synthesis Treatment Dependence of Surface Hydration, Hydroxylation, Lewis Acidity and Photocatalytic Activity of TiO₂ Anatase Nanoparticles with Dominant {001} or {101} Facets

Beyond Shape Engineering of TiO₂ Nanoparticles: Post-Synthesis Treatment Dependence of Surface Hydration, Hydroxylation, Lewis Acidity and Photocatalytic Activity of TiO₂ Anatase Nanoparticles with Dominant {001} or {101} Facets

Catalytic Tuning of Sorption Kinetics of Lightweight Hydrides: A Review of the Materials and Mechanism

The enhanced de/re-hydrogenation performance of MgH₂ with TiH₂ additive

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Catalytic effect of TiF4 in improving hydrogen storage properties of MgH2

Cited by 79 publications

References 26 publications

Beyond Shape Engineering of TiO2 Nanoparticles: Post-Synthesis Treatment Dependence of Surface Hydration, Hydroxylation, Lewis Acidity and Photocatalytic Activity of TiO2 Anatase Nanoparticles with Dominant {001} or {101} Facets

Beyond Shape Engineering of TiO2 Nanoparticles: Post-Synthesis Treatment Dependence of Surface Hydration, Hydroxylation, Lewis Acidity and Photocatalytic Activity of TiO2 Anatase Nanoparticles with Dominant {001} or {101} Facets

Catalytic Tuning of Sorption Kinetics of Lightweight Hydrides: A Review of the Materials and Mechanism

The enhanced de/re-hydrogenation performance of MgH2 with TiH2 additive

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Product

Resources

About

Beyond Shape Engineering of TiO₂ Nanoparticles: Post-Synthesis Treatment Dependence of Surface Hydration, Hydroxylation, Lewis Acidity and Photocatalytic Activity of TiO₂ Anatase Nanoparticles with Dominant {001} or {101} Facets

Beyond Shape Engineering of TiO₂ Nanoparticles: Post-Synthesis Treatment Dependence of Surface Hydration, Hydroxylation, Lewis Acidity and Photocatalytic Activity of TiO₂ Anatase Nanoparticles with Dominant {001} or {101} Facets

The enhanced de/re-hydrogenation performance of MgH₂ with TiH₂ additive