- Email: [email protected]
Synthesis and characterization of layered FePS3 for hydrogen uptake
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
Available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/he
Synthesis and characterization of layered FePS3 for hydrogen uptake N. Ismail a,*, A.A. El-Meligi a, Y.M. Temerk b, M. Madian a a
National Research Center, Physical Chemistry Department, Center of Excellence for Advanced Science, Renewable Energy Group, Cairo, Egypt b Assiut University, Faculty of Science, Chemistry Department, Assuit, Egypt
article info
abstract
Article history:
Iron phosphorus trisulfide FePS3 is related to the chalcogenides. It is characterized by
Received 16 January 2010
layered structure. FePS3 powder was prepared by solid state reaction and heated up to
Received in revised form
650 C using two different heating rates 1 C/min and 40 C/min. The results showed that
2 May 2010
the FePS3 produced with slow heating rate was highly ordered single crystalline phase
Accepted 12 May 2010
while the powder produced with the fast heating rate was poly crystalline phase. The
Available online 17 June 2010
surface morphology and the grain size were influenced by the heating rate used for preparation. The thermal resistance of the highly ordered crystalline phase extended till
Keywords:
680 C while the less ordered one extended to 660 C. The products at 900 C revealed
Metal phosphorous trisulfide
partial decomposition of FePS3 with subsequent formation of iron sulfide phases poorer
Hydrogen sorption
with sulfur element. The FePS3 of single crystalline phase exhibited higher hydrogen
Layered material
sorption capacity at different temperatures than the less ordered crystalline phase. Hydrogen capacity was reduced by cycling as the interlayer gap shrinks. ª 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
1.
Introduction
Research over the last decade focused on chemical and physical hydrogen storage based materials poses possible mechanisms for reversible storage. Plenty of materials are tested, among them, metal hydrides light and complex [1], nitridesimides-amides [2e5], multicomponent systems [6], zeolites [7] and recently metal organic frameworks (MOFs) [8,9]. Nevertheless, intensive efforts have been pushed to meet the practical demands required of a solid state storage system, namely high storage density together with favorable sorption thermodynamics and kinetics and prolonged cycle ability and lifetime, significant challenges remain keeping safe, efficient hydrogen storage far from mobile application concerns [10,11]. Materials with layered structure attract attention because of two dimensional structure features. It gives rise to strong anisotropies in the physical properties [12e15]. Transition
metal chalcogenides MPX3 (M^first row transition metals; X^S or Se) show fascinating structure, electric and magnetic properties [16e18]. The unit cell containing a group Fe2P2S6 is shown in Fig. 1 [19], where hexagonal sulfur sheets are arranged along the c axis in an ABCABC stacking planes. The “Van der Waals” weak bonded empty gaps between planes are easily intercalated by molecules or ions either by the reduction of the host or substitution of the metal cations [20,21]. This adds interesting feature to these compounds is their application as cathode materials for rechargeable high-energy-density lithium batteries [22,23]. As a consequence of intercalation is the increase in the layer spacing due to the insertion of guest material into the “Van der Waals” gap. Our idea is based on using the “Van der Waals” gap to occupy hydrogen and to evaluate the FePS3 as a hydrogen storage material.
* Corresponding author. Fax: þ20 233370931. E-mail address: [email protected] (N. Ismail). 0360-3199/$ e see front matter ª 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2010.05.061
7828
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
were mixed thoroughly. The mixed brown powders were sealed in two silica ampoules under vacuum of 102 bar. These ampoules were put in a programmable heating rate furnace. The first ampoule was heated from room temperature to 650 C using 40 C/min heating rate. The temperature was then remained at 650 C for 6 days [24]. The other ampoule followed the same experimental sequence using a heating rate 1 C/min. Then the silica ampoules were left to cool inside the furnace till room temperature. The ampoules were broken and the synthesized FePS3 black powders were ground. This is the first time to study the preparation of MPS3 compounds with different heating rates and its influence on the material structure. In this article, we point out to sample prepared using 40 C/min heating rate as sample (A) and the sample prepared by 1 C/min as sample (B).
S2 S5
S4 P2
M1 S1
S3 S6 M2
Fig. 1 e The unit cell of FePS3 where M^Fe.
2.2.
In this work we propose new family Transition metal chalcogenides, not suggested before, to the field of hydrogen storage. To our knowledge this class of materials is not studied before for the purpose of hydrogen energy storage. FePS3 is not expensive and its preparation is feasible.
2.
Experimental methods
2.1.
Synthesis
Two black samples of powder FePS3 compound were prepared by solid state reaction between stoichiometric amounts of the elemental powders, Fe, P and S of purity 99.98%. The elements
Techniques
Powder X-ray diffractograms (XRDs) were recorded in the range 5 < 2q > 70 , and time 2 s per step with Philips X0 pert A) instrument of CuKa radiation (l ¼ 1.5418 The IR spectrum of the powder was recorded in KBr disks containing a small amount of the compound, with a JASCO FT/ IR 6300. The thermal stability of the prepared materials and its decomposition temperature were determined from its thermogravimetric analysis (TGA) curves for 10 mg of the black powder by an apparatus “DSC Q 600”-V 20.5 under nitrogen flow atmosphere using a heating rate 10 C/min. Surface morphology of FePS3 powder was studied by scanning electron microscopy (SEM) JEOL JXA-840A. The powder was spread over double face scotch tapes attached to the holder and sputtered with gold. The voltage used was 30 kV and the magnification was 3500.
Intensity (a.u.)
(001)
(b) (a)
5
10
15
20
25
30
35
40
45
50
55
60
2 deg. ) Fig. 2 e XRD patterns of FePS3 powder, (a) sample A as-prepared (b) sample B as-prepared.
65
70
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
7829
Fig. 3 e The Atomic building of FePS3.
The transmission electron microscopy (TEM) experiments were carried out at room temperature, on JEOL-1230 microscope running at 120 kV with a tungsten cathode. The sample was prepared by adding minute amount of the powder to deionized water. Then ultra-sonication was performed to obtain a suspension of thin particles. One droplet of this dispersion was deposited on a holey carbon grid and after evaporation of water, the particles stuck to the carbon film. The specific surface area (SBET), the total pore volume (Vp) and the mean pore radius (r) of various adsorbents were determined from nitrogen adsorption isotherms measured at 196 C using NOVA automated gas sorbometer. The values of Vp were computed using the relation Vp ¼ 15:45 104 Vst cm3 =g
(1)
where Vst is the volume of nitrogen adsorbed at P/P tends to unity. The values of r were determined from equation (2) r ¼
2Vp A 104 SBET
(2)
The determination of hydrogen content was carried out by the measurement of pressure-composition isotherms (PCI) by
Intensity (a.u.)
(a) (b)
441
570 1000
950
900
Fig. 5 e SEM images of FePS3 (a) sample A; (b) sample B.
850
800
750
700
650
600
550
500
450
400
Fig. 4 e IR spectra of FePS3, (a) sample A as-prepared (b) sample B as-prepared.
a volumetric method using an AMC PCI-HP 1200 equipment. Temperature was controlled with a precision of 0.1 C. The accuracy of hydrogen content measurements was 0.04 wt%. In order to minimize contamination from air the compound powder was degassed at 200 C for 1 h under dynamic vacuum before test. Pressure-composition isothermal (PCI) plots were traced under the above mentioned conditions. In addition, the sorption kinetics at 193 C was evaluated.
3.
Results and discussion
3.1.
X-ray powder diffraction (XRD)
The structure of the prepared samples A and B is identified by X-ray diffractograms shown in Fig. 2(A) and (B). All characteristic diffraction lines of the FePS3 phase are observed, indicating the formation of the compound. The sharpness of the different peaks suggests the formation of big size crystals of FePS3 of [001] line reflection [25]. The peak area of Sample B is nearly five-fold sample A. The main peak of sample A is shifted to lower Bragg’s angle (2q) than sample B so that, the main peak of sample A lies at 2q ¼ 13.87 and d spacing equals 6.37 while the main peak of sample B lies at 2q ¼ 13.77 and
7830
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
Fig. 6 e TEM images of FePS3 powder; (a) particle dispersion (b), (c) and (d) of sample B; (e) and (f) of sample A; (g),(h) Electron diffraction pattern of samples B and A respectively.
d spacing equals 6.42. It is deduced that the slow heating rate during preparation enhances well crystalline ordered phase and widen the interlayer distances. According to standard 1998- JCPDS card 78-0496, the XRD patterns are indexed in the monoclinic unit cell space group C2/
m in which the calculated parameters by a least-squares refinement of the observed reflections, are a ¼ 5.947 A, b ¼ 10.300 A, c ¼ 6.7222 A, and b ¼ 107.16 . The atomic building of the FePS3 layers is shown in Fig. 3. It has been performed using “Atoms” software program, as explained in previous literature [24].
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
3.3.
100
Sample B Sample A
95 90
weight, %
85 80 75 70 65 60 55 50 100
200
300
400
500
600
700
800
900
1000
Temperature, °C
Fig. 7 e Thermogravimetric plots of FePS3. The crystal size values estimated from XRD patterns for different types of iron phosphorus trisulfide samples were obtained using Scherrer method [26] relating the crystallite size to peak broadening introduced in equation (3). d ¼ Klb1=2 cosq
(3)
The crystal sizes of sample A of the three main peaks are 106.7, 79.5 and 90.02 nm respectively, The crystal sizes of sample B are 133, 111.2 and 136.4 nm respectively. It is clear that using heating rate 1 C/min in preparation of FePS3 leads to increase the crystallite size.
3.2.
Infrared spectroscopy (IR)
The IR spectrum of pure FePS3 samples A and B (see Fig. 4(A) and (B) respectively) show the presence of the n(PS3)2 asymmetric stretching band at 570 cm1. This band is characteristic for phosphorous trisulfide transition metal compound [27]. Additionally, in the medium infra red band at 441 cm1 a peak appears that corresponds to the y(PeP) bands 0 or T z(PS3). These studies confirm the formation of the desired species.
7831
SEM and TEM investigations
Scanning electron microscopy images taken to A and B samples are revealed in Fig. 5(A) and (B). Comparison between both images from the first blink shows a significant difference in surface morphology. The heating rate during synthesis plays role in the surface architecture and size. The relatively fast heating rate (40 C/min) enhances the formation of thin transparent agglomerated platelets. On the other hand, the slow heating rate (1 C/min) in image (b), gives rise to coarse undefined separated shapes, the lateral direction in some of them looks like compact layers as it is marked by the arrows in the image. The grain size in image (b) varies from 9 to 18 mm while its thickness varies from 0.6 to 1 mm. The slow heating rate induces the formation of coarse grains. TEM images of FePS3 powders are shown in Fig. 6. Image (a) informs homogeneous dispersion of particles. The images of sample B are shown in (b), (c) and (d), and the images of the sample A are provided by (e) and (f). Image (b) shows the formation of planes located over each other. In another location in the same sample, image (c) and (d) clearly show the formation of branched chains formed from regular spheres almost the same size. Image (e) views the formation of layered platelet clusters while image (f) views the formation of the branched chain formed from spheres. The particle size estimated for the regular spheres in sample A is 18e20 nm, sample B shows coarser particle size than sample A of 30e65 nm. One may conclude that the relatively fast heating rate of the preparation is twilling the particle size. The electron diffraction pattern in image (g) for sample B confirms the preparation of a single crystalline phase (001) FePS3. While the fast heating rate (Sample A) enduces the formation of poly crystalline phase as shown in image (h).
3.4.
Thermal resistance
Thermogravimetric analysis (TGA) curves of A and B are introduced in Fig. 7. A slight weight loss of about 5 wt% appears at 200 C in sample A. Probably this is due to some humidity present in the sample. The onset decomposition
Fig. 8 e XRD pattern of FePS3 at 900 C.
7832
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
2.2 2.0
Sample A at -193 °C
1.8
1.8
1.6
Hydrogen content (wt%)
Hydrogen content (wt%)
2.0
Sample B at -193 C Sample A at -193 C
1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2
1.4 1.2 1.0
Cycle1 Cycle2 Cycle3 Cycle4 Cycle5
0.8 0.6 0.4 0.2
0.0 0
2
4
6
8
10
12
14
16
18
0.0
20
0
2
4
6
Hydrogen pressure (bar)
Fig. 9 e PCI curves of FePS3 sample A and B performed at L193 C.
temperatures of sample A and sample B are 660 C and 680 C respectively followed by abrupt decrease of weight that ends almost at the temperatures 765 C and 785 C respectively. The total amount of weight loss at these temperatures is about 45%. Conclusion may be driven out from these results that the preparation with relatively slow heating rate results in formation of single crystalline phase, which improves the thermal resistance of FePS3 powder so that the onset and the final decomposition temperatures are shifted to higher temperature values. In order to figure out the change occurred that causes the abrupt decrease in weight, the products of sample A and B after thermal analysis till 900 C were X-rayed and the diffraction patterns of both samples are similar and displayed in Fig. 8. This pattern reveals that partial decomposition of FePS3 occurred and the decomposition products are Fe7S8 as minor compound and FeS2 as trace existing compound beside the FePS3 as the major existing compound. The abrupt decrease in weight shown in Fig. 7 could be due to the release
10
12
14
16
18
20
Fig. 11 e PCI isotherms at L193 C of FePS3 prepared with fast heating rate.
of sublimated sulfur during the partial decomposition of FePS3 with subsequent formation of iron sulfide phase(s) relatively poorer with sulfur element.
3.5.
Hydrogen storage characteristics of FePS3
The hydrogen sorption isotherm curves of FePS3 powder at 193 C are recorded in Fig. 9. Up to 20 bar, the isotherm shows a linear progression over the investigated pressure range. The hydrogen adsorption content reaches 2.2 wt% in sample B of single crystalline phase and 1.7 wt% in sample A of poly crystalline phase. Most probably molecular hydrogen is adsorbed within the interplaner gap of Van der Waals forces that may induce hydrogen adsorption within. More studies were performed at different temperatures. At room temperature (25 C) and up to 20 bar hydrogen pressure, sample A and B were able to store minute amounts of hydrogen 0.1 wt% and 0.2 wt% respectively. Decreasing the temperature till 100 C,
2.2
0.6
2.0
-100 °C 0.5
Sample B at -193 °C
1.8
Sample A Sample B
Hydrogen content (wt%)
Hydrogen content wt%
8
pressure (bar)
0.4
0.3
0.2
0.1
1.6 1.4 1.2
Cycle1 Cycle2 Cycle3 Cycle4 Cycle5
1.0 0.8 0.6 0.4 0.2 0.0
0.0 0
2
4
6
8
10
12
14
16
18
20
Hydrogen pressure (bar)
Fig. 10 e PCI curves of FePS3 sample A and B performed at L100 C.
0
2
4
6
8
10
12
14
16
18
20
Pressure (bar)
Fig. 12 e PCI cycles of FePS3 prepared with slow heating rate performed at L193 C.
Hydrogen content, wt%
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
(a)
3.2 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0
(b) -193 °C
The rate of hydrogen adsorption is studied for sample B at 193 C and presented in Fig. 13. At 20 bar, the powder adsorbs 2.2 wt% within 30 min but the desorption rate is rather slow so that it desorbs this amount of hydrogen thoroughly within 75 min. At 30 bar, the powder adsorbs 3 wt% of hydrogen within 30 min then it continues to adsorb more hydrogen with slow rate. At 85 min the sample adsorbs about 3.2 wt%. Its desorption rate is similar to the desorption rate of the 20 bar but till 90 min. The powder does not undergo full desorption and about 0.1 wt% hydrogen remains in it.
4. 0
10
20
30
40
50
60
70
80
7833
Conclusion
90
time, min
Fig. 13 e The rate of hydrogen adsorption (solid symbol) and its desorption (hallow symbol) of sample B at (a) 30 bar; (b) 20 bar.
the amount of molecular hydrogen adsorbed reached 0.35 wt% for sample A, and 0.6 wt% for sample B up to the same hydrogen pressure. Fig. 10 displays the isotherms at 100 C. Quite obvious that the single crystalline phase of relatively wider d spacing distance is able to uptake more hydrogen in the interlayer space distance at varies temperatures than the polyscrystalline phase. The specific surface area and the apparent micropore volume were calculated from the physisorption isotherm data of N2 at 196 C on the basis of BrunauereEmmetteTeller (BET) theory [28]. BET analysis for sample B has specific surface area (60 m2/g), the apparent micropore volume A. On obtained is 19 103 cc/g and the mean pore radius is 6.3 the other hand, Sample A yields a relative smaller specific surface area and less micropore volume so that the specific surface area is 28 m2/g, the apparent micropore volume A. obtained is 8 103 cc/g, and the mean pore radius is 5.7 These results are in agreement with the hydrogen sorption capacities as the increase in surface area and pore volume should increase the physically adsorbed hydrogen. In order to study the efficiency of hydrogen cycling, five adsorption/desorption cycles were performed at 193 C and up to 20 bar for both samples A and B. The results are displayed in Fig. 11 and 12. After each adsorption isotherm, the powder undergoes full desorption. In both samples, cycling reduces the hydrogen capacity by increasing the cycle number, in a way that the hydrogen capacity of the fifth cycle of sample A has been reduced by 17% while that of sample B has been reduced by 9%. The samples after cycling exhibit the same XRD patterns as in Fig. 2 but the estimated d spacing values were lower so that in sample A the d spacing became 6.3 and in sample B became 6.38. The slight decrease in the interlayer gap distance by desorption may be the reason of the observed reduction in the amount of hydrogen adsorbed by hydrogen cycling. The IR spectra of the samples after hydrogen cycling did not trace any change in sample A and B compared with the asprepared samples.
Preparation of FePS3 layered material with different heating rates has influenced the crystallinity of the product as well as the interplanar gap in a way that slow heating rate results in better well ordered single crystalline phase and wider interplanar space. This advantage allows the powder to store more hydrogen in its interplanar space. Yet, hydrogen cycling is reduced by increasing the number of cycles because the interlayer distance shrinks. To our knowledge this is the first time to examine FePS3 for hydrogen sorption and to study the preparation with different heating rates.
Acknowledgments N. Ismail, A. A. El-Meligi and M. Madian are deeply grateful to Prof. Hany El-Nazer and Prof. Nihad El-Chazly for their administrative support. The Egyptian Science and Technology Development Fund (STDF) is acknowledged for funding this work.
references
[1] Sakintuna Billur, Lamari-Darkrim Farida, Hirscher Michael. Metal hydride materials for solid hydrogen storage: a review. Int J Hydrogen Energy 2007;32:1121e40. [2] Luo Kun, Liu Yongfeng, Wang Fenghuai, Gao Mingxia, Pan Hongge. Hydrogen storage in a LieAleN ternary system. Int J Hydrogen Energy 2009;34:8101e7. [3] Palumbo Oriele, Paolone Annalisa, Cantelli Rosario, Chandra Danesh. Lithium nitride as hydrogen storage material. Int J Hydrogen Energy 2008;33:3107e10. [4] Chen Yong, Wu Cheng-Zhang, Wang Ping, Cheng Hui-Ming. Structure and hydrogen storage property of ball-milled LiNH2/MgH2 mixture. Int J Hydrogen Energy 2006;31:1236e40. [5] Song Y, Yang R. Decomposition mechanism of magnesium amide Mg(NH2)2. Int J Hydrogen Energy 2009;34:3778e83. [6] Jain Ankur, Jain RK, Agarwal Shivani, Jain IP. Structural and thermodynamical investigations of La0.23Ni0.34Co0.33Nd0.08Ti0. 01Al0.01 hydrogen storage alloy. Int J Hydrogen Energy 2008; 33:356e9. [7] Dong Jinxiang, Wang Xiaoyan, Xu Hong, Zhao Qiang, Li Jinping. Hydrogen storage in several microporous zeolites. Int J Hydrogen Energy 2007;32:4998e5004. [8] Wang Ying, Fang Ming, Li Yi, Liang Jing, Shi Wei, Chen Jun, et al. A porous 3de4f heterometallic metal-organic
7834
[9]
[10]
[11] [12]
[13]
[14]
[15]
[16]
[17]
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
framework for hydrogen storage. Int J Hydrogen Energy; 2010 [on line]. Zou Xiaolong, Cha Moon-Hyun, Kim Seungchul, Nguyen Manh Cuong, Zhou Gang, Duan Wenhui, et al. Hydrogen storage in Ca-decorated, B substituted metal organic framework. Int J Hydrogen Energy 2010;35:198e203. Winter Carl-Jochen. Hydrogen energy e abundant, efficient, clean: a debate over the energy-system-of-change. Int J Hydrogen Energy 2009;34:S1e52. Ahluwalia RK, Hua TQ, Peng JK. Automotive storage of hydrogen in alane. Int J Hydrogen Energy 2009;34:7731e40. Brec Raymond. Review on structural and chemical properties of transition metal phosphorous tri sulfidesMPS3. Solid State Ionics 1986;22:3e30. Grasso V, Silipigni L. Low-dimensional materials. The MPX3 family, physical features and potential future applications. Rivista del Nuovo Cimento della Societa Italiana di Fisica 2002;25(6):1e102. Benedek G, Marra GL, Miglio L, Scagliotti M, Jouanne M. Lattice dynamics of layered crystals in the class transition metal (M) phosphorus trichalcogenide (X) MPX3 (M ¼ iron, manganese; X ¼ selenium, sulfur). Physica Scripta 1988;37(5):759e61. Balkanski M, Jouanne M, Ouvrard G, Scagliotti M. Effects due to spin ordering in layered MPX3 compounds revealed by inelastic light scattering. J Phys C: Solid State Phys 1987;20 (27):4397e413. Takano Y, Arai N, Arai A, Takahashi Y, Takase K, Sekizawa K. Magnetic properties and specific heat of MPS3 (M ¼ Mn, Fe, Zn). J Magn Magn Mater 2004;272e276:E593e5. Noriyuki Kurita, Kenji Nakao. Band structures and physical properties of magnetic layered semiconductors MPS3. J Phys Soc Jpn 1989;58(2):610e21.
[18] Helmut Tributsch. Photoelectrochemical studies on intercalation and semiconducting intercalation compounds. Solid State Ionics 1983;9-10:41e57. [19] Bernasconi M, Benedek G, Miglio L. Lattice dynamics of lithium-intercalated iron phosphorus trisulphide. Mater Sci Eng B 1989;3:167e76. [20] Westreich Philippe, Yang Datong, Frindt Robert F. Host layer buckling in the compounds formed by exfoliation and restacking of cadmium phosphorus trisulphide with adenosine monophosphate included. Mater Res Bull 2006;41:502e14. [21] Brec R, Schleich DM, Ouvrard G, Louisy A, Rouxel J. Physical properties of lithium intercalation compounds of the layered transition-metal chalcogenophosphites. Inorg Chem 1979;18 (7):1814e8. [22] Kuzminskii YV, Voronin BM, Redin NN. Iron and nickel phosphorus trisulfides as electroactive materials for primary lithium batteries. J Power Sources 1995;55(2):133e41. [23] Ye V, Kuz’minskii BM, Voronin IM, Petrushina NN, Redin GP, Prikhodko. Nickel phosphorus trisulfide: an electroactive material for medium-temperature lithium batteries. J Power Sources 1995;55:1e6. [24] El-Meligi AA. Synthesizing layered material of FePS3 and its intercalation with pyridine. Mater Chem Phys 2005;89:253e9. [25] Ruiz-Leo`n D, Manrı´quez V, Kazaneva J, Avila RE. Insertion of trivalent cations in the layered MPS3 (Mn, Cd) materials. Mater Res Bull 2002;37:981. [26] Cullity BD. Elements of X-ray diffraction. 2nd ed.; 1978. [27] Joy P, Vasudevan PA. Infrared (700e100 cm1) vibrational spectra of the layered transition metal thiophosphates MPS3 (M ¼ Mn, Fe and Ni). J Phys Chem Solids 1993;54(3):343e8. [28] Brunauer S, Emmett PH, Teller E. Adsorption of gases in multimolecular layers. J Am Chem Soc 1938;60:309.
Available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/he
Synthesis and characterization of layered FePS3 for hydrogen uptake N. Ismail a,*, A.A. El-Meligi a, Y.M. Temerk b, M. Madian a a
National Research Center, Physical Chemistry Department, Center of Excellence for Advanced Science, Renewable Energy Group, Cairo, Egypt b Assiut University, Faculty of Science, Chemistry Department, Assuit, Egypt
article info
abstract
Article history:
Iron phosphorus trisulfide FePS3 is related to the chalcogenides. It is characterized by
Received 16 January 2010
layered structure. FePS3 powder was prepared by solid state reaction and heated up to
Received in revised form
650 C using two different heating rates 1 C/min and 40 C/min. The results showed that
2 May 2010
the FePS3 produced with slow heating rate was highly ordered single crystalline phase
Accepted 12 May 2010
while the powder produced with the fast heating rate was poly crystalline phase. The
Available online 17 June 2010
surface morphology and the grain size were influenced by the heating rate used for preparation. The thermal resistance of the highly ordered crystalline phase extended till
Keywords:
680 C while the less ordered one extended to 660 C. The products at 900 C revealed
Metal phosphorous trisulfide
partial decomposition of FePS3 with subsequent formation of iron sulfide phases poorer
Hydrogen sorption
with sulfur element. The FePS3 of single crystalline phase exhibited higher hydrogen
Layered material
sorption capacity at different temperatures than the less ordered crystalline phase. Hydrogen capacity was reduced by cycling as the interlayer gap shrinks. ª 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
1.
Introduction
Research over the last decade focused on chemical and physical hydrogen storage based materials poses possible mechanisms for reversible storage. Plenty of materials are tested, among them, metal hydrides light and complex [1], nitridesimides-amides [2e5], multicomponent systems [6], zeolites [7] and recently metal organic frameworks (MOFs) [8,9]. Nevertheless, intensive efforts have been pushed to meet the practical demands required of a solid state storage system, namely high storage density together with favorable sorption thermodynamics and kinetics and prolonged cycle ability and lifetime, significant challenges remain keeping safe, efficient hydrogen storage far from mobile application concerns [10,11]. Materials with layered structure attract attention because of two dimensional structure features. It gives rise to strong anisotropies in the physical properties [12e15]. Transition
metal chalcogenides MPX3 (M^first row transition metals; X^S or Se) show fascinating structure, electric and magnetic properties [16e18]. The unit cell containing a group Fe2P2S6 is shown in Fig. 1 [19], where hexagonal sulfur sheets are arranged along the c axis in an ABCABC stacking planes. The “Van der Waals” weak bonded empty gaps between planes are easily intercalated by molecules or ions either by the reduction of the host or substitution of the metal cations [20,21]. This adds interesting feature to these compounds is their application as cathode materials for rechargeable high-energy-density lithium batteries [22,23]. As a consequence of intercalation is the increase in the layer spacing due to the insertion of guest material into the “Van der Waals” gap. Our idea is based on using the “Van der Waals” gap to occupy hydrogen and to evaluate the FePS3 as a hydrogen storage material.
* Corresponding author. Fax: þ20 233370931. E-mail address: [email protected] (N. Ismail). 0360-3199/$ e see front matter ª 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2010.05.061
7828
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
were mixed thoroughly. The mixed brown powders were sealed in two silica ampoules under vacuum of 102 bar. These ampoules were put in a programmable heating rate furnace. The first ampoule was heated from room temperature to 650 C using 40 C/min heating rate. The temperature was then remained at 650 C for 6 days [24]. The other ampoule followed the same experimental sequence using a heating rate 1 C/min. Then the silica ampoules were left to cool inside the furnace till room temperature. The ampoules were broken and the synthesized FePS3 black powders were ground. This is the first time to study the preparation of MPS3 compounds with different heating rates and its influence on the material structure. In this article, we point out to sample prepared using 40 C/min heating rate as sample (A) and the sample prepared by 1 C/min as sample (B).
S2 S5
S4 P2
M1 S1
S3 S6 M2
Fig. 1 e The unit cell of FePS3 where M^Fe.
2.2.
In this work we propose new family Transition metal chalcogenides, not suggested before, to the field of hydrogen storage. To our knowledge this class of materials is not studied before for the purpose of hydrogen energy storage. FePS3 is not expensive and its preparation is feasible.
2.
Experimental methods
2.1.
Synthesis
Two black samples of powder FePS3 compound were prepared by solid state reaction between stoichiometric amounts of the elemental powders, Fe, P and S of purity 99.98%. The elements
Techniques
Powder X-ray diffractograms (XRDs) were recorded in the range 5 < 2q > 70 , and time 2 s per step with Philips X0 pert A) instrument of CuKa radiation (l ¼ 1.5418 The IR spectrum of the powder was recorded in KBr disks containing a small amount of the compound, with a JASCO FT/ IR 6300. The thermal stability of the prepared materials and its decomposition temperature were determined from its thermogravimetric analysis (TGA) curves for 10 mg of the black powder by an apparatus “DSC Q 600”-V 20.5 under nitrogen flow atmosphere using a heating rate 10 C/min. Surface morphology of FePS3 powder was studied by scanning electron microscopy (SEM) JEOL JXA-840A. The powder was spread over double face scotch tapes attached to the holder and sputtered with gold. The voltage used was 30 kV and the magnification was 3500.
Intensity (a.u.)
(001)
(b) (a)
5
10
15
20
25
30
35
40
45
50
55
60
2 deg. ) Fig. 2 e XRD patterns of FePS3 powder, (a) sample A as-prepared (b) sample B as-prepared.
65
70
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
7829
Fig. 3 e The Atomic building of FePS3.
The transmission electron microscopy (TEM) experiments were carried out at room temperature, on JEOL-1230 microscope running at 120 kV with a tungsten cathode. The sample was prepared by adding minute amount of the powder to deionized water. Then ultra-sonication was performed to obtain a suspension of thin particles. One droplet of this dispersion was deposited on a holey carbon grid and after evaporation of water, the particles stuck to the carbon film. The specific surface area (SBET), the total pore volume (Vp) and the mean pore radius (r) of various adsorbents were determined from nitrogen adsorption isotherms measured at 196 C using NOVA automated gas sorbometer. The values of Vp were computed using the relation Vp ¼ 15:45 104 Vst cm3 =g
(1)
where Vst is the volume of nitrogen adsorbed at P/P tends to unity. The values of r were determined from equation (2) r ¼
2Vp A 104 SBET
(2)
The determination of hydrogen content was carried out by the measurement of pressure-composition isotherms (PCI) by
Intensity (a.u.)
(a) (b)
441
570 1000
950
900
Fig. 5 e SEM images of FePS3 (a) sample A; (b) sample B.
850
800
750
700
650
600
550
500
450
400
Fig. 4 e IR spectra of FePS3, (a) sample A as-prepared (b) sample B as-prepared.
a volumetric method using an AMC PCI-HP 1200 equipment. Temperature was controlled with a precision of 0.1 C. The accuracy of hydrogen content measurements was 0.04 wt%. In order to minimize contamination from air the compound powder was degassed at 200 C for 1 h under dynamic vacuum before test. Pressure-composition isothermal (PCI) plots were traced under the above mentioned conditions. In addition, the sorption kinetics at 193 C was evaluated.
3.
Results and discussion
3.1.
X-ray powder diffraction (XRD)
The structure of the prepared samples A and B is identified by X-ray diffractograms shown in Fig. 2(A) and (B). All characteristic diffraction lines of the FePS3 phase are observed, indicating the formation of the compound. The sharpness of the different peaks suggests the formation of big size crystals of FePS3 of [001] line reflection [25]. The peak area of Sample B is nearly five-fold sample A. The main peak of sample A is shifted to lower Bragg’s angle (2q) than sample B so that, the main peak of sample A lies at 2q ¼ 13.87 and d spacing equals 6.37 while the main peak of sample B lies at 2q ¼ 13.77 and
7830
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
Fig. 6 e TEM images of FePS3 powder; (a) particle dispersion (b), (c) and (d) of sample B; (e) and (f) of sample A; (g),(h) Electron diffraction pattern of samples B and A respectively.
d spacing equals 6.42. It is deduced that the slow heating rate during preparation enhances well crystalline ordered phase and widen the interlayer distances. According to standard 1998- JCPDS card 78-0496, the XRD patterns are indexed in the monoclinic unit cell space group C2/
m in which the calculated parameters by a least-squares refinement of the observed reflections, are a ¼ 5.947 A, b ¼ 10.300 A, c ¼ 6.7222 A, and b ¼ 107.16 . The atomic building of the FePS3 layers is shown in Fig. 3. It has been performed using “Atoms” software program, as explained in previous literature [24].
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
3.3.
100
Sample B Sample A
95 90
weight, %
85 80 75 70 65 60 55 50 100
200
300
400
500
600
700
800
900
1000
Temperature, °C
Fig. 7 e Thermogravimetric plots of FePS3. The crystal size values estimated from XRD patterns for different types of iron phosphorus trisulfide samples were obtained using Scherrer method [26] relating the crystallite size to peak broadening introduced in equation (3). d ¼ Klb1=2 cosq
(3)
The crystal sizes of sample A of the three main peaks are 106.7, 79.5 and 90.02 nm respectively, The crystal sizes of sample B are 133, 111.2 and 136.4 nm respectively. It is clear that using heating rate 1 C/min in preparation of FePS3 leads to increase the crystallite size.
3.2.
Infrared spectroscopy (IR)
The IR spectrum of pure FePS3 samples A and B (see Fig. 4(A) and (B) respectively) show the presence of the n(PS3)2 asymmetric stretching band at 570 cm1. This band is characteristic for phosphorous trisulfide transition metal compound [27]. Additionally, in the medium infra red band at 441 cm1 a peak appears that corresponds to the y(PeP) bands 0 or T z(PS3). These studies confirm the formation of the desired species.
7831
SEM and TEM investigations
Scanning electron microscopy images taken to A and B samples are revealed in Fig. 5(A) and (B). Comparison between both images from the first blink shows a significant difference in surface morphology. The heating rate during synthesis plays role in the surface architecture and size. The relatively fast heating rate (40 C/min) enhances the formation of thin transparent agglomerated platelets. On the other hand, the slow heating rate (1 C/min) in image (b), gives rise to coarse undefined separated shapes, the lateral direction in some of them looks like compact layers as it is marked by the arrows in the image. The grain size in image (b) varies from 9 to 18 mm while its thickness varies from 0.6 to 1 mm. The slow heating rate induces the formation of coarse grains. TEM images of FePS3 powders are shown in Fig. 6. Image (a) informs homogeneous dispersion of particles. The images of sample B are shown in (b), (c) and (d), and the images of the sample A are provided by (e) and (f). Image (b) shows the formation of planes located over each other. In another location in the same sample, image (c) and (d) clearly show the formation of branched chains formed from regular spheres almost the same size. Image (e) views the formation of layered platelet clusters while image (f) views the formation of the branched chain formed from spheres. The particle size estimated for the regular spheres in sample A is 18e20 nm, sample B shows coarser particle size than sample A of 30e65 nm. One may conclude that the relatively fast heating rate of the preparation is twilling the particle size. The electron diffraction pattern in image (g) for sample B confirms the preparation of a single crystalline phase (001) FePS3. While the fast heating rate (Sample A) enduces the formation of poly crystalline phase as shown in image (h).
3.4.
Thermal resistance
Thermogravimetric analysis (TGA) curves of A and B are introduced in Fig. 7. A slight weight loss of about 5 wt% appears at 200 C in sample A. Probably this is due to some humidity present in the sample. The onset decomposition
Fig. 8 e XRD pattern of FePS3 at 900 C.
7832
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
2.2 2.0
Sample A at -193 °C
1.8
1.8
1.6
Hydrogen content (wt%)
Hydrogen content (wt%)
2.0
Sample B at -193 C Sample A at -193 C
1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2
1.4 1.2 1.0
Cycle1 Cycle2 Cycle3 Cycle4 Cycle5
0.8 0.6 0.4 0.2
0.0 0
2
4
6
8
10
12
14
16
18
0.0
20
0
2
4
6
Hydrogen pressure (bar)
Fig. 9 e PCI curves of FePS3 sample A and B performed at L193 C.
temperatures of sample A and sample B are 660 C and 680 C respectively followed by abrupt decrease of weight that ends almost at the temperatures 765 C and 785 C respectively. The total amount of weight loss at these temperatures is about 45%. Conclusion may be driven out from these results that the preparation with relatively slow heating rate results in formation of single crystalline phase, which improves the thermal resistance of FePS3 powder so that the onset and the final decomposition temperatures are shifted to higher temperature values. In order to figure out the change occurred that causes the abrupt decrease in weight, the products of sample A and B after thermal analysis till 900 C were X-rayed and the diffraction patterns of both samples are similar and displayed in Fig. 8. This pattern reveals that partial decomposition of FePS3 occurred and the decomposition products are Fe7S8 as minor compound and FeS2 as trace existing compound beside the FePS3 as the major existing compound. The abrupt decrease in weight shown in Fig. 7 could be due to the release
10
12
14
16
18
20
Fig. 11 e PCI isotherms at L193 C of FePS3 prepared with fast heating rate.
of sublimated sulfur during the partial decomposition of FePS3 with subsequent formation of iron sulfide phase(s) relatively poorer with sulfur element.
3.5.
Hydrogen storage characteristics of FePS3
The hydrogen sorption isotherm curves of FePS3 powder at 193 C are recorded in Fig. 9. Up to 20 bar, the isotherm shows a linear progression over the investigated pressure range. The hydrogen adsorption content reaches 2.2 wt% in sample B of single crystalline phase and 1.7 wt% in sample A of poly crystalline phase. Most probably molecular hydrogen is adsorbed within the interplaner gap of Van der Waals forces that may induce hydrogen adsorption within. More studies were performed at different temperatures. At room temperature (25 C) and up to 20 bar hydrogen pressure, sample A and B were able to store minute amounts of hydrogen 0.1 wt% and 0.2 wt% respectively. Decreasing the temperature till 100 C,
2.2
0.6
2.0
-100 °C 0.5
Sample B at -193 °C
1.8
Sample A Sample B
Hydrogen content (wt%)
Hydrogen content wt%
8
pressure (bar)
0.4
0.3
0.2
0.1
1.6 1.4 1.2
Cycle1 Cycle2 Cycle3 Cycle4 Cycle5
1.0 0.8 0.6 0.4 0.2 0.0
0.0 0
2
4
6
8
10
12
14
16
18
20
Hydrogen pressure (bar)
Fig. 10 e PCI curves of FePS3 sample A and B performed at L100 C.
0
2
4
6
8
10
12
14
16
18
20
Pressure (bar)
Fig. 12 e PCI cycles of FePS3 prepared with slow heating rate performed at L193 C.
Hydrogen content, wt%
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
(a)
3.2 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0
(b) -193 °C
The rate of hydrogen adsorption is studied for sample B at 193 C and presented in Fig. 13. At 20 bar, the powder adsorbs 2.2 wt% within 30 min but the desorption rate is rather slow so that it desorbs this amount of hydrogen thoroughly within 75 min. At 30 bar, the powder adsorbs 3 wt% of hydrogen within 30 min then it continues to adsorb more hydrogen with slow rate. At 85 min the sample adsorbs about 3.2 wt%. Its desorption rate is similar to the desorption rate of the 20 bar but till 90 min. The powder does not undergo full desorption and about 0.1 wt% hydrogen remains in it.
4. 0
10
20
30
40
50
60
70
80
7833
Conclusion
90
time, min
Fig. 13 e The rate of hydrogen adsorption (solid symbol) and its desorption (hallow symbol) of sample B at (a) 30 bar; (b) 20 bar.
the amount of molecular hydrogen adsorbed reached 0.35 wt% for sample A, and 0.6 wt% for sample B up to the same hydrogen pressure. Fig. 10 displays the isotherms at 100 C. Quite obvious that the single crystalline phase of relatively wider d spacing distance is able to uptake more hydrogen in the interlayer space distance at varies temperatures than the polyscrystalline phase. The specific surface area and the apparent micropore volume were calculated from the physisorption isotherm data of N2 at 196 C on the basis of BrunauereEmmetteTeller (BET) theory [28]. BET analysis for sample B has specific surface area (60 m2/g), the apparent micropore volume A. On obtained is 19 103 cc/g and the mean pore radius is 6.3 the other hand, Sample A yields a relative smaller specific surface area and less micropore volume so that the specific surface area is 28 m2/g, the apparent micropore volume A. obtained is 8 103 cc/g, and the mean pore radius is 5.7 These results are in agreement with the hydrogen sorption capacities as the increase in surface area and pore volume should increase the physically adsorbed hydrogen. In order to study the efficiency of hydrogen cycling, five adsorption/desorption cycles were performed at 193 C and up to 20 bar for both samples A and B. The results are displayed in Fig. 11 and 12. After each adsorption isotherm, the powder undergoes full desorption. In both samples, cycling reduces the hydrogen capacity by increasing the cycle number, in a way that the hydrogen capacity of the fifth cycle of sample A has been reduced by 17% while that of sample B has been reduced by 9%. The samples after cycling exhibit the same XRD patterns as in Fig. 2 but the estimated d spacing values were lower so that in sample A the d spacing became 6.3 and in sample B became 6.38. The slight decrease in the interlayer gap distance by desorption may be the reason of the observed reduction in the amount of hydrogen adsorbed by hydrogen cycling. The IR spectra of the samples after hydrogen cycling did not trace any change in sample A and B compared with the asprepared samples.
Preparation of FePS3 layered material with different heating rates has influenced the crystallinity of the product as well as the interplanar gap in a way that slow heating rate results in better well ordered single crystalline phase and wider interplanar space. This advantage allows the powder to store more hydrogen in its interplanar space. Yet, hydrogen cycling is reduced by increasing the number of cycles because the interlayer distance shrinks. To our knowledge this is the first time to examine FePS3 for hydrogen sorption and to study the preparation with different heating rates.
Acknowledgments N. Ismail, A. A. El-Meligi and M. Madian are deeply grateful to Prof. Hany El-Nazer and Prof. Nihad El-Chazly for their administrative support. The Egyptian Science and Technology Development Fund (STDF) is acknowledged for funding this work.
references
[1] Sakintuna Billur, Lamari-Darkrim Farida, Hirscher Michael. Metal hydride materials for solid hydrogen storage: a review. Int J Hydrogen Energy 2007;32:1121e40. [2] Luo Kun, Liu Yongfeng, Wang Fenghuai, Gao Mingxia, Pan Hongge. Hydrogen storage in a LieAleN ternary system. Int J Hydrogen Energy 2009;34:8101e7. [3] Palumbo Oriele, Paolone Annalisa, Cantelli Rosario, Chandra Danesh. Lithium nitride as hydrogen storage material. Int J Hydrogen Energy 2008;33:3107e10. [4] Chen Yong, Wu Cheng-Zhang, Wang Ping, Cheng Hui-Ming. Structure and hydrogen storage property of ball-milled LiNH2/MgH2 mixture. Int J Hydrogen Energy 2006;31:1236e40. [5] Song Y, Yang R. Decomposition mechanism of magnesium amide Mg(NH2)2. Int J Hydrogen Energy 2009;34:3778e83. [6] Jain Ankur, Jain RK, Agarwal Shivani, Jain IP. Structural and thermodynamical investigations of La0.23Ni0.34Co0.33Nd0.08Ti0. 01Al0.01 hydrogen storage alloy. Int J Hydrogen Energy 2008; 33:356e9. [7] Dong Jinxiang, Wang Xiaoyan, Xu Hong, Zhao Qiang, Li Jinping. Hydrogen storage in several microporous zeolites. Int J Hydrogen Energy 2007;32:4998e5004. [8] Wang Ying, Fang Ming, Li Yi, Liang Jing, Shi Wei, Chen Jun, et al. A porous 3de4f heterometallic metal-organic
7834
[9]
[10]
[11] [12]
[13]
[14]
[15]
[16]
[17]
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 5 ( 2 0 1 0 ) 7 8 2 7 e7 8 3 4
framework for hydrogen storage. Int J Hydrogen Energy; 2010 [on line]. Zou Xiaolong, Cha Moon-Hyun, Kim Seungchul, Nguyen Manh Cuong, Zhou Gang, Duan Wenhui, et al. Hydrogen storage in Ca-decorated, B substituted metal organic framework. Int J Hydrogen Energy 2010;35:198e203. Winter Carl-Jochen. Hydrogen energy e abundant, efficient, clean: a debate over the energy-system-of-change. Int J Hydrogen Energy 2009;34:S1e52. Ahluwalia RK, Hua TQ, Peng JK. Automotive storage of hydrogen in alane. Int J Hydrogen Energy 2009;34:7731e40. Brec Raymond. Review on structural and chemical properties of transition metal phosphorous tri sulfidesMPS3. Solid State Ionics 1986;22:3e30. Grasso V, Silipigni L. Low-dimensional materials. The MPX3 family, physical features and potential future applications. Rivista del Nuovo Cimento della Societa Italiana di Fisica 2002;25(6):1e102. Benedek G, Marra GL, Miglio L, Scagliotti M, Jouanne M. Lattice dynamics of layered crystals in the class transition metal (M) phosphorus trichalcogenide (X) MPX3 (M ¼ iron, manganese; X ¼ selenium, sulfur). Physica Scripta 1988;37(5):759e61. Balkanski M, Jouanne M, Ouvrard G, Scagliotti M. Effects due to spin ordering in layered MPX3 compounds revealed by inelastic light scattering. J Phys C: Solid State Phys 1987;20 (27):4397e413. Takano Y, Arai N, Arai A, Takahashi Y, Takase K, Sekizawa K. Magnetic properties and specific heat of MPS3 (M ¼ Mn, Fe, Zn). J Magn Magn Mater 2004;272e276:E593e5. Noriyuki Kurita, Kenji Nakao. Band structures and physical properties of magnetic layered semiconductors MPS3. J Phys Soc Jpn 1989;58(2):610e21.
[18] Helmut Tributsch. Photoelectrochemical studies on intercalation and semiconducting intercalation compounds. Solid State Ionics 1983;9-10:41e57. [19] Bernasconi M, Benedek G, Miglio L. Lattice dynamics of lithium-intercalated iron phosphorus trisulphide. Mater Sci Eng B 1989;3:167e76. [20] Westreich Philippe, Yang Datong, Frindt Robert F. Host layer buckling in the compounds formed by exfoliation and restacking of cadmium phosphorus trisulphide with adenosine monophosphate included. Mater Res Bull 2006;41:502e14. [21] Brec R, Schleich DM, Ouvrard G, Louisy A, Rouxel J. Physical properties of lithium intercalation compounds of the layered transition-metal chalcogenophosphites. Inorg Chem 1979;18 (7):1814e8. [22] Kuzminskii YV, Voronin BM, Redin NN. Iron and nickel phosphorus trisulfides as electroactive materials for primary lithium batteries. J Power Sources 1995;55(2):133e41. [23] Ye V, Kuz’minskii BM, Voronin IM, Petrushina NN, Redin GP, Prikhodko. Nickel phosphorus trisulfide: an electroactive material for medium-temperature lithium batteries. J Power Sources 1995;55:1e6. [24] El-Meligi AA. Synthesizing layered material of FePS3 and its intercalation with pyridine. Mater Chem Phys 2005;89:253e9. [25] Ruiz-Leo`n D, Manrı´quez V, Kazaneva J, Avila RE. Insertion of trivalent cations in the layered MPS3 (Mn, Cd) materials. Mater Res Bull 2002;37:981. [26] Cullity BD. Elements of X-ray diffraction. 2nd ed.; 1978. [27] Joy P, Vasudevan PA. Infrared (700e100 cm1) vibrational spectra of the layered transition metal thiophosphates MPS3 (M ¼ Mn, Fe and Ni). J Phys Chem Solids 1993;54(3):343e8. [28] Brunauer S, Emmett PH, Teller E. Adsorption of gases in multimolecular layers. J Am Chem Soc 1938;60:309.