Synthesis of hierarchical mesoporous Ln2Ti2O7 (Ln = Y, Tb-Yb) pyrochlores and uranyl sorption properties

doi:10.1016/j.jmst.2021.10.020

Abstract

Abstract:

Mesoporous structured metal oxides exhibit many active applications. However, the synthesis of crystalline metal oxides with a ternary composition while maintaining satisfactory pore features is challenging. Typically, high temperatures are required which inhibit control of pore structure properties including surface area, pore volume, and pore size. Herein, the synthesis of ternary metal oxides Ln₂Ti₂O₇ possessing pyrochlore crystal structure is achieved using a novel technique which combines ‘soft’ and hard colloid templating strategies. The formed materials are of submicron size and composed of ∼ 25-30 nm product ‘building blocks’ with good chemical and phase stability. The polycrystalline powders have a high specific surface area (up to 70 m²·g^-1) and pore volume (∼ 0.35 cm³·g^-1) which result in a good adsorption capacity (U uptake closing to 60 mg·g^-1). Remarkably, the material exhibits a significant portion of mesopores (mainly 10-40 nm) which facilitate fast adsorption of the cations due to high accessibility. The synthetic methodology described herein produces highly homogenous powders and can be applied to other compositions and structures.

Key words: Porous ternary metal oxides, Dual template synthesis, Lanthanide titanate, Pyrochlore, Uranium adsorption

Linggen Kong, Inna Karatchevtseva, Tao Wei, Nicholas Scales. Synthesis of hierarchical mesoporous Ln₂Ti₂O₇ (Ln = Y, Tb-Yb) pyrochlores and uranyl sorption properties[J]. J. Mater. Sci. Technol., 2022, 113: 22-32.

Figures/Tables 11

Fig. 1. Schematic diagram for the fabrication of hierarchical porous crystal metal oxides.

Fig. 2. XRD patterns of (YTi)-complex powders calcined for 6 h at (a) 600 °C, (b) 700 °C, (c) 800 °C, (d) 900 °C, (e) 1050 °C, (f) 1150 °C, (g) 1250 °C. The blue vertical markers beneath the pyrochlore patterns show the peak positions expected in the crystal structure.

Table 1. Cell parameters by Le Bail method fitting of X-ray data for Y2Ti2O7 pyrochlores with different template to pyrochlore weight ratios (w/w).

Empty Cell	with template			template leached
w/w	cell size (Å)	R_p (%)	R_wp (%)	cell size (Å)	R_p (%)	R_wp (%)
0	10.0987	2.10	3.02	10.0953	2.01	2.85
1:4	10.0923	1.47	1.83	10.0837	1.41	1.77
1:2	10.0957	2.25	2.79	10.0835	2.01	2.56
3:4	10.0989	2.42	3.10	10.0864	1.26	1.61
1:1	10.0988	2.98	3.88	10.0869	1.32	1.70

Fig. 3. XRD patterns of the powders A) before and B) after template leaching with pyrochlore composition as Ln2Ti2O7, Ln = (a) Tb, (b) Dy, (c) Y, (d) Ho, (e) Er, (f) Yb. Template is 12.4 nm (Φ) colloidal silica with template to pyrochlore weight ratio as 1:2. (*): Ln4.67(SiO4)3O apatite, (q) SiO2 quartz.

Fig. 4. SEM images of the Y2Ti2O7 pyrochlore particulates after leaching of 12.4 nm (Φ) colloidal silica as template. Template to pyrochlore weight ratio is (a) 1:4, (b) 1:2, (c, d) 3:4, (e) 1:1.

Fig. 5. Bright field TEM images of the Y2Ti2O7 pyrochlore particles after leaching of 12.4 nm (Φ) colloidal silica as template. Template to pyrochlore weight ratio is (a) 1:4, (b) 1:2, (c) 3:4, (d) 1:1. (e) SAED pattern [011] zone axis from sample b, showing the strong diffractions, e.g. (2 -2 2) plane and weak diffractions, e.g. (-1 -3 3) plane. (f) Electron diffraction rings obtained from the pyrochlore nano-grains in sample c. (g) TEM image at high magnification showing the lattices structure in sample c. (h) HRTEM image for the location marked ‘D’ in g and inserted FFT image in [011] zone. (i) EDS spectrum of sample b after soaking with uranyl at initial U concentration 600 ppm for 48 h.

Fig. 6. Nitrogen isotherms (a, b, c, d), the corresponding pore size distribution and cumulate pore volume based on DFT analysis for leached Y2Ti2O7 sample (e, f, g, h). Hard template is colloidal silica 12.4 nm (Φ) and template to pyrochlore weight ratio is (a, e) 1:4, (b, f) 1:2, (c, g) 3:4, (d, h) 1:1.

Table 2. Pore structure data and surface hydroxyl group analyzing of powders after leaching Φ 12.4 nm template at various SiO2 to Y2Ti2O7 pyrochlore weight ratios.

Sample	Empty Cell	WR1-4	WR1-2	WR3-4	WR1-1
SiO₂ to Y₂Ti₂O₇ wt. ratio	0	1:4	1:2	3:4	1:1
SiO₂ to Y₂Ti₂O₇ mol. ratio		1.60:1	3.21:1	4.81:1	6.42:1
SiO₂ to Y₂Ti₂O₇ vol. ratio		0.57:1	1.13:1	1.70:1	2.26:1
BET surface area (m²·g^-1)	7.79	61.3	70.9	63.4	60.8
DFT surface area (m²·g^-1)	7.48	63.2	68.8	57.1	58.4
BET pore volume (cm³·g^-1)^a)	0.102	0.204	0.332	0.414	0.479
DFT pore volume (cm³·g^-1)	0.068	0.168	0.265	0.321	0.367
Average pore diameter (nm)^b)	52.3	13.3	18.7	26.1	31.6
DFT pore diameter (nm)	29.4	10.5	16.1	20.6	29.4
DFT micropores (%)^c)	0	1.79	0.73	0	0.20
DFT mesopores (%)^d)	56.5	78.4	77.1	75.0	68.2
D_OH (OH nm^-2)^e)	7.13	5.18	5.12	4.94	4.76
OH (x10²⁰·g^-1)^f)	0.56	3.18	3.63	3.13	2.89
OH (mmol·g^-1)^g)	0.092	0.528	0.603	0.520	0.480

Table 3. Langmuir constants for uranyl sorption capacity studies of the Y2Ti2O7 porous pyrochlores.

Sample	SiO₂^a) (nm)	Ratio^b)	q_max (mg·g^-1)	q_max (mmol·g^-1)	q_max (μmol·m²)	b	R²
Φ8WR1-4	6.8-8.5	1:4	56.3	0.236	4.96	0.325	0.999
Φ8WR3-4	6.8-8.5	3:4	52.2	0.219	5.40	0.320	0.999
WR1-4	12.4	1:4	57.0	0.240	3.91	0.515	0.999
WR1-2	12.4	1:2	59.1	0.248	3.50	0.311	0.997
WR3-4	12.4	3:4	59.4	0.249	3.93	0.276	0.997
Φ20WR1-4	20.3	1:4	53.6	0.225	4.35	0.558	0.999
Φ20WR3-4	20.3	3:4	59.9	0.252	3.66	0.446	0.998

Fig. 7. Uranium uptake adsorption isotherms (a, b, c) and kinetics (d, e, f) for pyrochlore powders using 12.4 nm (Φ) colloidal silica as template with template to pyrochlore weight ratio at (a, d) 1:4, (b, e) 1:2 and (c, f) 3:4. Blue bold lines represent Langmuir fits for isotherms and pseudo-second-order fits for kinetics with initial U concentration 457 ppm. pH = 3.8, V/m = 100 mL·g-1. The experimental data points are expressed as (average ± 3σ, N = 2) and where not visible are smaller than the markers.

Table 4. Uranyl adsorption pseudo-second-order kinetic constants of the Y2Ti2O7 porous pyrochlores.a).

Sample	Ratio^b)	q_e (mg·g^-1)	q_e (mmol·g^-1)	k₂ (g·mg^-1·h^-1)	h₀ (×10) (mg·g^-1·h^-1)	R²
C_i = 100 ppm
WR1-4	1:4	9.92	0.0417	4.72	46.5	1.00
WR1-2	1:2	9.93	0.0417	8.62	85.0	1.00
WR3-4	3:4	9.95	0.0418	25.7	254	1.00
C_i = 457 ppm
WR1-4	1:4	39.5	0.166	0.0134	2.09	0.997
WR1-2	1:2	41.2	0.173	0.0106	1.79	0.996
WR3-4	3:4	42.1	0.177	0.0127	2.26	0.998

References 66

[1]	Y. Zhang, L. Tao, C. Xie, D. Wang, Y. Zou, R. Chen, Y. Wang, C. Jia, S. Wang, Adv. Mater. 32 (2020) 1905923.
[2]	A. Huang, Y. He, Y. Zhou, Y. Zhou, Y. Yang, J. Zhang, L. Luo, Q. Mao, D. Hou, J. Yang, J. Mater. Sci. 54 (2019) 949-973. DOI
[3]	R.L. Vekariya, A. Dhar, P.K. Paul, S. Roy, Ionics (Kiel) 24 (2018) 1-17.
[4]	W. Li, J. Liu, D. Zhao, Nature Rev. Mater. 1 (2016) 16023.
[5]	H. Zhao, M. Zhou, L. Wen, Y. Lei, Nano Energy 13 (2015) 790-813. DOI URL
[6]	X. Zhou, X. Cheng, Y. Zhu, A.A. Elzatahry, A. Alghamdi, Y. Deng, D. Zhao, Chin. Chem. Lett. 29 (2018) 405-416.
[7]	T. Wagner, S. Haffer, C. Weinberger, D. Klaus, M. Tiemann, Chem. Soc. Rev. 42 (2013) 4036-4053. DOI URL
[8]	H. Chen, X. Liang, Y. Liu, X. Ai, T. Asefa, X. Zou, Adv. Mater. 32 (2020) 2002435. DOI URL
[9]	Y. Cui, X. Lian, L. Xu, M. Chen, B. Yang, C. Wu, W. Li, B. Huang, X. Hu, Materials (Basel) 12 (2019) 276. DOI URL
[10]	M. Moritz, M. Geszke-Moritz, Mater. Sci. Eng. C 49 (2015) 114-151. DOI URL
[11]	C. Barbé, J. Bartlett, L. Kong, K. Finnie, H.Q. Lin, M. Larkin, S. Calleja, A. Bush, G. Calleja, Adv. Mater. 16 (2004) 1959-1966. DOI URL
[12]	N. Fontanals, R.M. Marcé, F. Borrull, Separations 6 (2019) 56. DOI URL
[13]	Y. Xie, C. Chen, X. Ren, X. Wang, H. Wang, X. Wang, Prog. Mater. Sci. 103 (2019) 180-234. DOI
[14]	H.-. C. zur Loye, T. Besmann, J. Amoroso, K. Brinkman, A. Grandjean, C. H. Henager, S. Hu, S.T. Misture, S.R. Phillpot, N.B. Shustova, H. Wang, R.J. Koch, G. Morrison, E. Dolgopolova, Chem. Mater. 30 (2018) 4475-4488. DOI URL
[15]	P. Makowski, X. Deschanels, A. Grandjean, D. Meyer, G. Toquer, F. Goettmann, New J. Chem. 36 (2012) 531-541. DOI URL
[16]	D. Mao, J. Wan, J. Wang, D. Wang, Adv. Mater. 31 (2018) 1802874. DOI URL
[17]	C. Jo, J. Hwang, W.-.G. Lim, J. Lim, K. Hur, J. Lee, Adv. Mater. 30 (2018) 1703829. DOI URL
[18]	J. Wei, Z. Sun, W. Luo, Y. Li, A.A. Elzatahry, A.M. Al-Enizi, Y. Deng, D. Zhao, J. Am. Chem. Soc. 139 (2017) 1706-1713. DOI URL
[19]	A. Feinle, M.S. Elsaesser, N. Hüsing, Chem. Soc. Rev. 45 (2016) 3377-3399. DOI PMID
[20]	L.-.B. Sun, X.-.Q. Liu, H.-.C. Zhou, Chem. Soc. Rev. 44 (2015) 5092-5147. DOI URL
[21]	D. Gu, F. Schüth, Chem. Soc. Rev. 43 (2014) 313-344. DOI URL
[22]	A. Walcarius, Chem. Soc. Rev. 42 (2013) 4098-4140. DOI PMID
[23]	V. Valtchev, L. Tosheva, Chem. Rev. 113 (2013) 6734-6760. DOI URL
[24]	W. Li, D. Zhao, Chem. Commun. 49 (2013) 943-946. DOI URL
[25]	W. Li, Q. Yue, Y. Deng, D. Zhao, Adv. Mater. 25 (2013) 5129-5152. DOI URL
[26]	Y. Ren, Z. Ma, P.G. Bruce, Chem. Soc. Rev. 41 (2012) 4909-4927. DOI PMID
[27]	F. Qu, W. Shang, D. Wang, S. Du, T. Thomas, S. Ruan, M. Yang, ACS Appl. Mater. Interfaces 10 (2018) 15314-15321. DOI URL
[28]	G. Wang, X. Zhou, J. Qin, Y. Liang, B. Feng, Y. Deng, Y. Zhao, J. Wei, ACS Appl. Mater. Interfaces 11 (2019) 35060-35067. DOI URL
[29]	G. Wang, J. Qin, Y. Feng, B. Feng, S. Yang, Z. Wang, Y. Zhao, J. Wei, ACS Appl. Mater. Interfaces 12 (2020) 45155-45164. DOI URL
[30]	L. Zhang, L. Jin, B. Liu, J. He, Frontier Chem. 7 (2019) 22.
[31]	X. Deng, K. Chen, H. Tüysüz, Chem. Mater. 29 (2017) 40-52. DOI URL
[32]	Z. Ma, B. Zhou, Y. Ren, Front.Environ. Sci. Eng. 7 (2013) 341-355.
[33]	J.-.H. Smått, F.M. Sayler, A.J. Grano, M.G. Bakker, Mater. 14 (2012) 1059-1073. DOI URL
[34]	A.-.H. Lu, F. Schüth, Adv. Mater. 18 (2006) 1793-1805. DOI URL
[35]	H. Yang, D. Zhao, J. Mater. Chem. 15 (2005) 1217-1231. DOI URL
[36]	O.D. Velev, E.W. Kaler, Adv. Mater. 12 (2000) 531-534. DOI URL
[37]	M.A. Subramanian, G. Aravamudan, G.V. Subba Rao, Prog. Solid State Chem. 15 (1983) 55-143. DOI URL
[38]	J. Shamblin, M. Feygenson, J. Neuefeind, C.L. Tracy, F. Zhang, S. Finkeldei, D. Bosbach, H. Zhou, R.C. Ewing, M. Lang, Nature Mater 15 (2016) 507-511. DOI URL
[39]	M.J.P. Gingras, P.A. McClarty, Rep. Prog. Phys. 77 (2014) 056501. DOI URL
[40]	X.M. Ge, S.H. Chan, Q.L. Liu, Q. Sun, Adv. Energy Mater. 2 (2012) 1156-1181. DOI URL
[41]	J.S. Gardner, M.J.P. Gingras, J.E. Greedan, Rev. Modern Phys. 82 (2010) 53-107. DOI URL
[42]	D.R. Modeshia, R.I. Walton, Chem. Soc. Rev. 39 (2010) 4303-4325. DOI PMID
[43]	R.C. Ewing, W.J. Weber, J. Lian, J. Appl. Phys. 95 (2004) 5949-5971. DOI URL
[44]	S.T. Bramwell, M. J.P. Gingras, Science 294 (2001) 1495-1501. PMID
[45]	K.E. Sickafus, L. Minervini, R.W. Grimes, J.A. Valdez, M. Ishimaru, F. Li, K.J. Mc-Clellan, T. Hartmann, Science 289 (2000) 748-750. PMID
[46]	K. Vellingiri, K.-.H. Kim, A. Pournara, A. Deep, Prog. Mater. Sci. 94 (2018) 1-67. DOI URL
[47]	T.Le Nedelec, A. Charlot, F. Calard, F. Cuer, A. Leydier, A. Grandjean, New J. Chem. 42 (2018) 14300-14307. DOI URL
[48]	E. Rosenberg, G. Pinson, R. Tsosie, H. Tutu, E. Cukrowska, Johnson Matthey Technol. Rev. 60 (2016) 59-77. DOI URL
[49]	M. Gao, G. Zhu, C. Gao, Energy Environ. Focus 3 (2014) 219-226. DOI URL
[50]	L. Chen, H. Xin, Y. Fang, C. Zhang, F. Zhang, X. Cao, C. Zhang, X. Li, J. Nanomater.(2014) 793610 2014.
[51]	R.K. Eby, R.C. Ewing, R.C. Birtcher, J. Mater. Res. 7 (1992) 3080-3102. DOI URL
[52]	Y. Lou, S. Dourdain, C. Rey, Y. Serruys, D. Simeone, N. Mollard, X. Deschanels, Micropor. Mesopor. Mater. 251 (2017) 146-154. DOI URL
[53]	K. Zhu, C. Chen, H. Wang, Y. Xie, M. Wakeel, A. Wahid, X. Zhang, J. Colloid Interface Sci. 535 (2019) 265-275. DOI URL
[54]	S. Huang, H. Pang, L. Li, S. Jiang, T. Wen, L. Zhuang, B. Hu, X. Wang, Chem. Eng. J. 353 (2018) 157-166. DOI URL
[55]	W. Chouyyok, C.L. Warner, K.E. Mackie, M.G. Warner, G.A. Gill, R. Shane Addle- man, Ind. Eng. Chem. Res. 55 (2016) 4195-4207. DOI URL
[56]	M. Chee Kimling, N. Scales, T.L. Hanley, R.A. Caruso, Environ. Sci. Technol. 46 (2012) 7913-7920.
[57]	G.L. Drisko, M. Chee Kimling, N. Scales, A. Ide, E. Sizgek, R.A. Caruso, V. Luca, Langmuir 26 (2010) 17581-17588. DOI URL
[58]	D.G. Sizgek, C.S. Griﬃth, E. Sizgek, V. Luca, Langmuir 25 (2009) 11874-11882. DOI URL
[59]	W.M. Haynes, CRC Handbook of Chemistry and Physics, 92nd ed., CRC Press, Boca Raton, FL, 2011.
[60]	C.J. Brinker, G.W. Scherer, Sol-Gel Science: The Physics and Chemistry of Sol-Gel Processing, Academic Press, San Diego, 1990.
[61]	L. Kong, I. Karatchevtseva, M. Blackford, I. Chironi, G. Triani, J. Am. Ceram. Soc. 95 (2012) 816-822. DOI URL
[62]	S. Wang, W. Li, S. Wang, J. Jiang, Z. Chen, Micropor. Mesopor. Mater. 221 (2016) 32-39. DOI URL
[63]	Z. Zheng, Chem. Commun. 24 (2001) 2521-2529.
[64]	S.A. Hindocha, L.J. McIntyre, A.M. Fogg, J. Solid State Chem. 182 (2009) 1070-1074. DOI URL
[65]	R.D. Shannon, Acta Cryst A 32 (1976) 751-767. DOI URL
[66]	V.V. Popov, A.P. Menushenkov, B.R. Gaynanov, A.A. Ivanov, F. d’Acapito, A. Puri, I. V. Shchetinin, M.V. Zheleznyi, M.M. Berdnikova, A.A. Pisarev, A.A. Yastrebtsev, N.A. Tsarenko, L.A. Arzhatkina, O.D. Horozova, I.G. Rachenok, K.V. Ponkratov, J. Alloys Compd. 746 (2018) 377-390. DOI URL

Synthesis of hierarchical mesoporous Ln₂Ti₂O₇ (Ln = Y, Tb-Yb) pyrochlores and uranyl sorption properties

RichHTML

PDF (PC)

Knowledge

Abstract

Cite this article

share this article

Figures/Tables 11

References 66

Related Articles 5

Recommended Articles

Metrics

Comments

[1]	Wei Fan, Yu Bai, Yanfen Liu, Taotao Li, Binmao Li, Lei Zhang, Chenmin Gao, Shiyu Shan, Haocen Han. Principal element design of pyrochlore-fluorite dual-phase medium- and high-entropy ceramics [J]. J. Mater. Sci. Technol., 2022, 107(0): 149-154.
[2]	Junwei Che, Xiangyang Liu, Xuezhi Wang, Quan Zhang, Erhu Zhang, Gongying Liang, Shengli Zhang. Ultralow oxygen ion diffusivity in pyrochlore-type La₂(Zr_0.7Ce_0.3)₂O₇ [J]. J. Mater. Sci. Technol., 2022, 102(0): 174-185.
[3]	Juanli Zhao, Yuchen Liu, Yun Fan, Wei Zhang, Chengguan Zhang, Guang Yang, Hongfei Chen, Bin Liu. Native point defects and oxygen migration of rare earth zirconate and stannate pyrochlores [J]. J. Mater. Sci. Technol., 2021, 73(0): 23-30.
[4]	Chun Li, Chaolong Ren, Yue Ma, Jian He, Hongbo Guo. Effects of rare earth oxides on microstructures and thermo-physical properties of hafnia ceramics [J]. J. Mater. Sci. Technol., 2021, 72(0): 144-153.
[5]	G. Karthick, Lavanya Raman, B.S. Murty. Phase evolution and mechanical properties of novel nanocrystalline Y₂(TiZrHfMoV)₂O₇ high entropy pyrochlore [J]. J. Mater. Sci. Technol., 2021, 82(0): 214-226.