ảnh hưởng của W(VI) đến cấu trúc và hoạt tính quang xúc tác của bột w tio2 kích thước nano được điều chế bằng phương pháp thủy phân

TAP CHI

H6A

HOC

T. 50(4) 492-497

THANG 8 NAM 2012

ANH HU'6'NG CUA W(VI) D £ N CAU TRUC VA HOAT T I N H QUANG
XUC TAC CUA B Q T W-TiOz KJCH THU-b-C NANO DWgC DltU CH^
B A N G PHU'aNG P H A P T H U Y PHAN
Nguyen Vfln Hung'', NgdSp Luvng^
'Khoa Hda hgc, Trudng Dgi hgc Ddng Thdp
^Khoa Hda bgc. Trudng Dgi hgc Khoa hgc Tu nhien, DHQG Hd Ndi
Din Tdasogn 22-4-2012
Abstract
Nano-sized W(VI)-dopcd TiOj and pure TiOj powders were synlheslzed successfully by hydrolysis method from
precursors TiOSO^ and {NH4)6H;W|20jo wiih presenting urea The prepared products were characterized by XRD, UVVIS, TEM. BET and XPS methods. Experimental results showed that the obtained W-TiOj powders were single phase
anatase, small particle size (-13-14 nm), regular particle distribution and large specific surface area (67.4 m'/g).
Moreover, the existing of W(VI) in the crystal lattice had been narrowed significantly ihc band gap energy of TiOj (Eg
in ^out 2.25-2.28 eV). Sample W-Ti02 with W/TiOj molar ratio = 0.1% had the highest pholo-calalytic activity.
Methylene blue in aqueous solution was nearly completely decomposed after irradiation in Ih and 1.65 times higher
than TiO^ sample without doping.
Keywords: Titanium dioxide, photocatalyst, hydrolysis, W-T1O2. doping, W(V1).
I.GIOITHIEU
Ti02 Id chit quang xue tdc (QXT) hua h?n nhat
cho viec xu ly d nhilm mdi trudng vd gidi quyet van
de khiing hoang ndng lupng trong tuong lai [1]. Tuy
nhien, do nang lupng viing cam cua Ti02 khd Idn

(3,05 eV ddi vdi anata vd 3,25 eV doi vdi rutin) n6n
chi ho^t dpng QXT trong vijng tu ngo?i gan vd do
dd ban che khd ndng tdn dyng nguon ndng lupng m$t
trdi vd gidi han ung dyng thyc tiln cua nd. ,Yi vgy,
nhi6u ion kim lo^i, ddc bi^t Id cdc ion kim lo^i
chuyen tilp da dupe su dyng de biln tinh cdc d^ng
thill hinh khac nhau ciia Ti02 nh5m ndng cao hon
niJa hogt tinh QXT cCia TiO: trong vung dnh sdng
nhin thdy.
Do bdn kinh ion W(VI) (0,065 nm) tuong d6ng
vdi bdn kinh ion Ti(IV) (0,062 nm) [2] nen ion
Ti(IV) dl ddng dupe thay the bdi ion W(VI) trong
mfuig ludi Ti02, gay ra nhiing thay doi cd vl tinh
chdt bl mdt ldn d3c tinh cau true trong ldng hgt xiic
tdc vd do dd cd thi giiip TiOz hogt dpng QXT hi?u
qud hon trong viing dnh sdng khd kien. A. Kubacka
[3] da dilu che cdc vgt li?u TiOz dupe bien tfnh bdi
(V, Mo, Nb, W) bdng phuong phdp vi nhu tuong.
K6t qud cho thdy, W(V1) de dang thav the Ion Ti(IV)
trong ludi T1O2 de hinh thdnh lien kit dgng Ti-W vd
dd thu h?p ddng ke ndng lupng viing cam ciia Ti02.
Tat cd cdc mau Ti02 dupe biln tinh vdi cdc ion tren
deu cd khd ndng phan hQy quang dung djch toluen

cao hon so vdi mlu TiO: khdng biln tinh dudi hue
xa cua dnh sdng mdt trdi.
Cd nhieu phuong phdp dilu chi vgt Ii?u Ti02
bien tinh, nhung phuong phdp thCiy phdn dong thi
dung djch muoi vd co chua Ti(lV) (TiCU
TiOS04,..) cd mdt ure Id phuong phdp don gidn, co

the dl ddng thyc thi trong san xu^t, tgo ra ch4t QXT
cd gid thdnh thap, di?n tich be mdt Idn vd khd ndng
QXT cao [4]. Vi?c chpn ch^t dau Id TiOS04 va tien
hdnh thuy phdn trong dilu ki§n cd mjt ur6 theo chung
tdi cd mOt s6 uu diem ndi trpi. Thu nhdt, sy cd mdt
cua ion S04^" cd the giup cdi thi^n di^n tich bl m$t va
tdng cudng tinh axit tren be m$t TiOi. Cac kit qua
ndy tgo dieu ki^n thudn Ipi dl TiO] hap phy H2O len
bl m$t vd chuyen chiing thdnh cdc goc hydroxyl hogt
dOng (•OH) nfin tdng cudng hogt tinh QXT cila Ti02.
Thu hai, khdc vdi qud trinh ihiiy phan bdi cdc chit ket
tiia bazo nhu NaOH, dung djch NH3..., cdc phdn tii
ure CO(NH2)2 do cd nhdm -NH2 ddng vai trd nhu la
chit hogt dOng be mjt va khi bj dun ndng se phdn hiij;
cho NH3 mpt cdch tir ti> vd ddng dlu trong toan bO thi
tich dung djch nen trdnh dupe hi^n tupng kit tua
viing, d6ng thdi cd the ldm gidm kfch thudc hgt, tdng
di?n tich be mdt vd miic dp ket tinh ciia sdn phim bOt •
Ti02 dieu che dupe. Tuy nhiSn, vi?c dilu chi bpt
TiOj biln tinh bdi W(VI) bdng phuong phdp thCiy
phan van chua dirpc cdng b6.

492

Trong cdng trinh ndy, chfing tdi thdng bdo m8t


TCHH, T. 50(4), 2012
s6 kit qud nghiSn cuu ve dnh hudng ciia n^ng dO urd
vd W(VI) den cau tr6c vd tinh chdt ciia bpt TiO^

dupe dilu chi b^ng phuong phdp thiiy phdn dhng
the dung djch TiOS04 cd m§t urfi vd ddnh gid hogt
tinh QXT ciia nd thdng qua khd ndng phdn hiiy dung
djch metylen xanh dudi biic xg din compact.

Nguyen Vdn Hung vd cgngsu
ddng nhi?t hap phy-gidi hip nito tgi 77 K tren thiet
bj Micromeritics (My).
Gid tri ndng lupng lien kit vd trgng thdi oxi hda
ciia cdc nguyen to dude ghi phi XPS tren mdy
S-Prob!e TM2803 dudi ngudn phdt xg tia X AIK,,
vdi VLing ndng lupng qua tii 0-1000 eV.

2. PHUONG PHAP NGHIEN CllRj

3. KfiT QUA VA T H A O L U A N

2.1. Th^c nghiem

3.1. Anh hirdng ciia nSng dp ure

Cac hda chat dupe sCr dyng trong thyc nghiem
deu d dgng tinh khiet md khdng can chi hda bo
sung.
Hda tan 4,0 gam TiOS04 vdo 50 ml dung djch
H2SO4 0,018 M. Cho tilp lupng urfi vd mu6i amoni
vonframat xdc djnh vdo dung djch TiOS04 vira thu
dupe, khudy dlu trong khodng 15 phiit. Dung djch
h6n hpp dupe pha lodng bdng nude cit hai lin din
220 ml vd tiln hdnh thuy phdn d 100°C trong 3 gid

dudi dilu ki§n khuiy trpn mgnh, diu dupe huyen
phu. Huyin phii dupe rua vdi lan bdng nude cit vd
sau do la etanol cho din khi khdng cdn phdt hif n ion
S04^" trong nude nia (thu vdi dung djch BaCb 0,2
M). Sdy khd huyIn phii d 110°C trong 24 gid vd
nung d 500''C trong 4 gid, thu dupe sdn phdm bdt
W-Ti02. Mdu TiOi khdng biln tinh dupe dilu chi
tucmg tu nhung khdng cd su bd lupng mudi amoni
vonframat.
Hoat tinh QXT ciia cdc mdu dupe thCr bdng each
tron 0,15 g bpt sdn phdm vdi 200 ml dung dich
metylen xanh cd ndng dp 10 mg/l, khudy trpn hdn
hpp 30 phut trong bdng toi dl cdn bdng hap phy-gidi
hap trudc khi chilu xg bdng den compact Golstar
40 W vdi 3 viing budc sdng ddc trung la 435 nm,
545 nm vd 610 nm, thdi gian chilu xa 1 gid. Hieu
sudt phdn iing QXT dupe xdc dinh bdng cdch so
sanh dp hdp thu quang (Abs) ciia dich trudc vd sau
phdn ling d eye dai hap thy X = 663 nm.

De khdo sdt dnh hudng ciia nong dp ur6, lupng
ure dupe cho vdo dung dich thiiy phan sao cho iing
vdi cdc nong dp ure khdc nhau: 0,30, 0,45, 0,60,
0,75 vd 0,90 M. Cdc mlu dupe ki hi?u tucmg iing tir
TPWU4 din TPWU12. Gidn dh XRD ciia cdc mdu d
cdc n6ng dd ur€ khac nhau dupe dua ra d hinh 1. Gid
trj kfch thudc hgt trung binh vd hi?u suit phan hdy
quang ciia ch6ng dupe trinh bdy trong bdng I.

2.2. Cac phinmg phdp xac dinh

Gian dd XRD ciia b^t Ti02 dupe ghi tren nhilu
xg kl tia X D8 Advance Brucker (Diic) vdi tia CuK^
c6 X = 0,154056 nm, nhi?t dp ghi 25°C, gdc 29: 10
-70°, tdc dp quet 0,037s. Kich thudc hgt trung binh
dugc xac djnh dya vdo pic d§c trung tren gidn do
XRD theo cong thiic Scherrer.
Phd UV-VIs ciia san phdm dupe ghi tren mdy
JASCO-V670 (Nhat Bdn), budc sdng qu6t tir
250-i-800 nm, tdc dO quet 400 nm/phut. Cdc anh
TEM ciia sdn phdm bOt Ti02 dupe chyp tr6n kinh
hiln vi di?n tu truyin qua JEMlOlO (JEOL-Nhgt
Ban) cd he so phdng dgi M = x50 den xdOO.OOO, dp
phdn giai 5 = 3 A, di6n ap gia toe U = 40 din 100
kV. Di^n tich bl m#t BET dupe xdc dinh tir dudng

Anatase

Analase
1

1.TPW4
2.TPW6
3.TPW8
4.TPW10
5.TPW12

.

j!

,,

,

-.u

w|Lwv/L«-.^2

-J

JL-/UJ\.I
4D
SO
2-Theta-Scale

Hinh 1: Gian dd XRD ciia cac mdu
W-Ti02 d ndng dp ure khac nhau
Bdng 1. Anh hudng cua ndng dp UT% din kich thudc
hat trung binh va hieu suit phan hiiy quang cua cdc
mdu W-Ti02
Kf hi?u
mlu

N6ng do ure,
M

r,
nm

H,

TPWU4
TPWU6
TPWU8
TPWUlO
TPWU12

0,30
0,45
0,60
0,75
0,90

15,7
14,9
13,8
14,2
15,5

87,73
92,54
97,98
94,21
90,40

%

Til hinh 1 va bang 1 cho thay, tat ca cac mlu d6u
a dang don pha anata vdri dinh pic dac tnmg img vdi
goc 26 ~ 25,3°. Khi tang din n6ng dp ure tir 0,30 d6n

0,60 M thi kich thuoc hat trung binh giam va dat gia
trj cue tieu img voi mlu c6 n6ng dp ui€ la 0,60 M.


TCHH, T. 50(4), 2012

Anh hudng ciia W(VL) din cdu triic...

Neu tiep tyc tdng n6ng dp urfi > 0,60 M thi kich
thudc hgt trung binh tdng. Dilu ndy cd thi gidi thfch,
do ure cd nhdm -NH^ nen cd thi xem nd nhu Id chit
hogt dpng bl m^t. M$t khdc, trong su6t qud trinh
phan hiiy cdc ion NH4"' dupe tgo ra tir tir vd phdn b6
dong deu trong todn b$ the tich ciia dung djch n6n
trdnh dupe hi?n tupng kit tiia vCing. Do dd, khi tflng
dan ning dp urS kich thudc hgt trung binh gidm. Tuy
nhien, khi ning dp ure qud Idn din den sy thiiy phdn
mgnh ciia cdc cation kim logi nen Idm tdng kich
thudc hgt. Nhmig nhin chung, vdt li§u W-Ti02 dilu
chi dupe cd kich thudc hgt khd bi (khodng 14 den
16 nm). Bdng 1 cdn cho thiy sy phii hpp giOa quv
lugt bien dii kich thudc hgt trung binh vd hi^u suit
phan hiiy quang. Mdu W-TiO; img vdi ning dp urS
0,6 M cd kich thudc hgt trung binh hi nhit vd cho
hi$u suit phdn buy quang dung djch metylen xanh
Idn nhit.

sy [5] gidi thich, do cd sy tuong ding vl bdn kfnh
git^a ion W(VI) vd Ti(IV) nSn W(VI) dl ddng thay
till Ti(iV) trong ciu triic mgng ludi Ti02 de hinh

thdnh dung djch rdn WxTi|.x02.
Thdnh phin, thdng si mgng ludi, kich thudc hgt
trung binh vd hi^u sudt phdn hiiy quang cCia cdc mlu
theo ty I? mol W/T1O2 khdc nhau dupe trinh bdy trong
bdng 2. Tir bdng 2 cho thiy, khi tdng din t;J' I? mol
wn"i02 kich thudc hgt trung binh gidm. Dilu ndy
chimg td, sy cd mdt ciia W(VI) trong mgng ludi TiC^
da ire chi sy phdt triln hgt vd Idm gidm ddng kl kfch
thudc hgt ciia cdc mlu W-TiOj so vdi mlu TiOj khong
biln tfnh. Quy lu^t gidm din kfch thudc hgt 1102 khi
tdng din n6ng dd W(V1) cung dd dupe cdng bl trong
cdc cdng trinh nghien cim [5,6].
Bdng 2: Thdnh phin, thdng so mgng ludi, kfch thudc
hgt trung binh vd hi^u suat phan hiiy quang ciia cdc
mlu d ty I? mol W/Ti02 khdc nhau

3.2. Anh hudng cua ly 1$ mol W/TiOi
Ndng dp ion biln tinh Id m0t trong nhChig ylu tl
quyet dinh den cau triic vd hogt tinh QXT ciia Ti02.
De khao sdt dnh hudng ciia nong dp W(VI), lupng
amoni vonframat dupe cho vdo dung djch thCiy phdn
sao cho ling vdi cdc ty I? mol W/TiO: khdc nhau: 0,
0,05, 0,1, 0,15, 0,2 vd 0,25%. Cdc mau dupe kl hi?u
tuong img tir TPWO din TPW0,25. Gidn do XRD
cua chiing dupe dua ra d hinh 2.
—1.TPW0
2.TPW0,05
3.TPW0,10
4.TPW0.15
5.TPW0,2O

6.TPW0,25

Anatase

dlr~ArTt

J L 3

6
5

\3

2-Theta-Scale

Hinh 2- Gidn dl XRD ciia cdc mdu d ty 1?
mol W/TiOj khdc nhau
Tir hinh 2 cho thay, tit cd cdc mau deu d dgng
don pha anata. Dinh pic ddc trung cho pha anata ciia
cac mdu W/Ti02 ling vdi gdc 20 -25,3° vd mdu Ti02
khdng biln tinh iing vdi gdc 29 -25,32°. Kit qud ndy
chiing td cac vdt li?u W-TiO; cd kich thudc hgt
trung binh hi hon so vdi mdu Ti02 khdng biln tinh.
Ngodi pic ddc trung cho pha anata khdng thiy xuat
hi§n pic cho pha WO3 hodc pha Ig ndo khdc trong
mdu. Dilu ndy cd thi W(VI) da tham gia vdo cau
true mgng ludi ciia Ti02. Haiyan Song vd cdc c^ng

Ki hi$u
mau

TPWO
TPW0,05
TPWO.IO
TPWO, 15
TPW0,20
TPW0,25

Thong so
Tyl?
mol
m^ng ludi
W^iO,, a = b,
c,

%

0
0,05
0,10
0,15
0,20
0,25

A

A

3,782
3,784
3,785

3,787
3,790
3,787

9,504
9,507
9,505
9,511
9,502
9,509

r,
nm

H,

19,4
14,9
13,7
11,8
11,4
10,6

60,43
84,70
99,4«
93,55
89,70
85,13

%

Tir bdng 2 cho thiy, cd sy sai khdc thdng si
mgng ludi giOa cdc mau W/TiOj so vdi mlu Ti02
khdng bien tfnh. Kit qud nay chiing td, W(VI) dd
tham gia vdo cau tnic mgng ludi TiO:. Sy sai khdc
ndy theo chilu hudng cdc mdu W-Ti02 cd cdc hdng
so mgng a va c Idn hon so vdi mlu Ti02 khdng bien
tinh khi tdng din ty 1? mol W/TiOi. Dilu ndy Leo'nRamos [7] cho rdng, do tuong tdc ddy giiia cdc ion
W(VI) trong mgng ludi TiOj.
Bdng 2 cdn cho thiy, khi tdng dan ty 1^ mol
W/TiOi hi$u suit phan buy quang tdng vd dgt gia hi
eye dgi d mlu cd ty l§ mol W/TiOz 0,1%. NIU tilp
tyc tdng ty 1? ndy > 0,1% thi hi$u suat phdn bdy
quang giam. Kit qua ndy cung phii hpp vdi kit qud
dd cdng bo d cdng trinh [8], khi dilu chi vgt li§u
W/Ti02 bdng phuong phdp thiiy phdn dung djch
TiCl4 vdi cdc ty 1? mol W/Ti02 khdc nhau: 0,1, 0,5,
1,0 vd 10%. Lee [8] nh§n thiy. niu tdng ty 1? mol
Wrri02 > 0,1 % thi hi?u suit phdn hiiy quang gidnu j
Theo H. Tian [9] thi W(VI) trong mgng ludi TiOz d l 3
ddng bi khii xuong W(V), cdc electron bj kich thlf^
quang trong viing ddn cCia Ti02 cd thi dupe nhan bdi
W(VI) theo phuong trinh (1):
W(VI) + e ( - ^ j ^ ^ W ( V )

(1)

Trong trudng hpp ndy, biln tfnh W(VI) giiip bdy

TCHH, T. 50(4), 2012
cSc di§n tii quang sinh nhIm giim sv tii kit hpp
gitta cic di|n tir va la trong nen ting cuimg host tinh
QXT. Tuy nhien, bien tinh W(VI) 6 n6ng dp qui
cao, n6 sg_hoat dpng nhu cic tam tai kit hprp cua c$p
electron-16 tr6ng (lim giam hi$u suit phan hiiy
quang) theo hai phuong trinh (2) vi (3):
W(VI) + e,>,au->W(V)
V'Cih
• W(V1)

Nguyen Vdn Hung vd cdng su
tuong img d hinh 4 vi 5. Kit qua tinh toin cho thiy
m^au img vdi ty Ip W/TiOi 0,1% cd nSng lupng vijng
cam (-2,25-2,88 eV) h6 hon so vdi mlu TiO; khdng
bien tinh (-2,93 eV). Nhu vjy, s(r hipn dipn cua
W(VI) trong mang ludi TiOi da thu hpp ding ki
ning lupng vimg elm ciia n6.

(2)

Ph6 UV-VIS cua cic mlu theo tj 1? mol W/TiOj
khic nhau dupe dua ra a hinh 3. Tir hlnh 3 cho thiy,
tit ci cic mlu W-Ti02 diu c6 dO hip thy quang
trong vimg anh sing nhin thiy cao hon so v6i mlu
TiO: IdiOng biln tinh, Khi ting din ty 1^ mol
WA'iO: thi dp hip thu quang trong vimg c6 bu6c
s6ng Idioin^ 450 den 600 nm ting vi d^t gii trj hip
thy ldn nhat ung vdi mlu c6 t^ Ip mol W/TiOi

0,15%. Neu tiep tyc ting ty le mol W/TiOj > 0,15%
thi dp hip thy quang cd phan giim.
Ph6 UV-VIS va m6 hinh tinh toin gii trj ning
lupng viing elm cua mlu TiO: khdng bien tinh vi
mlu W-Ti02 d ty Ip mol W/TiOi 0,1% dupe dua ra

Hmh 3: Pho UV-VIS cua cac mlu o ty Ip
mol W/Ti02 khic nhau

MnR dlfdc bie'nllnh
^ — M i u Hat vdi ly Ifi muJ
W/T1O2 = «,i %

/

423 nm
= 1240/423 = 2,93 eV

1 1 = 430 nm
g = 1240/430 = 2,88 eV

1^
/

^=5S0nni
Eg = 1240/5SO = 2,25 eV

500

Birdc song, nm

Hmh 4: Phd UV-VIS ciia mlu TiOj
khdng dupe biin tinh W(V1)
Anh TEM ciia mdu Ti02 khdng biln tfnh vd mlu
W-TiOi dty le mol W/TiOj 0,1% dupe duara.tuong
6ng d hinh 6 vd 7. Tii cdc dnh TEM cho thiy, mlu
W-TiOj d ty le mol WA'i02 0,1 % cd kfch thudc hgt
b^ (~ 13-14 nm) vd phan bo dong dlu hon so vdi
mlu Tp2 khdng biln tinh (~19-20 nm).
Mlu Ti02 khdng biln tfnh vd mlu W-Ti02 d ty
1| mol WA'i02 0,1% dupe tiln hdnh ghi ddng nhi$t
hip phu - gidi hip phy N2 (BET). Ket qud BET cho
thdy, mlu W-Ti02 d t j 1$ mol W/TiOj 0,1 % cd di?n
tfch bl mat (67,3 m^/g) ldn hon so vdi mlu TiO:
khfing biln tfnh (43,5 mVg). Nhu vdy, sy hi?n di$n
ciia W(VI) trong mgng ludi Ti02 da cdi thi^n dang
kl di^n tfch be mgt ciia nd.
, Mdu Ti02 khdng biln tfnh vd mlu W-Ti02 d ty
1| mol V/TTiOi 0,1% dupe chiing tdi tiln hdnh ghi

600

700

BOD

BiTdc s6ng, nm

Hinh 5: Phd UV-VIS ciia mdu W-Ti02 d
tylemol W/TiO2 0,l%

phd XPS nham xdc dinh ndng lupng lien ket (BE) vd
trang thai oxi hda ciia cdc nguySn td cd mdt trong
mdu. Gidn dl XPS ciia cac mau ndy dupe dua ra d
hinh 8. Tir hinh 8 cho thi);, mdu Ti02 kh6ng biln
tinh cd mdt cac nguyen td Ti, O, N vd C, Mdu
W-Ti02 ngodi sy cd mat ciia nhimg nguySn to ndy
cdn c6 them nguy8n td W. Mdu Ti02 khdng biln
tinh vd mlu W-Ti02 cd pic C 1 s iing vdi cac gid trj
BE tuong img Id 285,7 vd 285,4 eV. Kit qua nay cd
thi Id do su hifu chinh bdi phd trgng thai C-C ciia
chinh dyng cu do XPS. Pic N Is ciia mdu Ti02
khdng biln tfnh vd mdu W-Ti02 cd gia trj BE img
vdi 400,7 vd 400,8 eV. Sir xuit hien pic N Is cd th^
Id do N cdn ldn lgi trong mdu ma chua the logi bo
hit sau qua trinh thiiy phan.


/inh hudng ciia W(VI) ten cdu triici

TCllH.T. ."^0(4). 2012

Hlnh 7: Anh TEM cua mlu Wrt'lO: 6
tyl?molWn-iO2 0,l%

Hmh 6: Anh TEM ciia mlu TiOj
khdng dupe bien tinh W(V1)

i "
|til.t¥l,u

i""

|z

1*3

1:

a

MniluVni|Wnli(l.cV

, 018

WTiOiJ

wu

i\

,;

247,8

"
1
261 ,S

(C)

WSp

&

(D|
B2,S

i:.»

V.A
"4^5/2

/\530.B

;^ m,^

t'»

W4d3;2
•^

.1

' , W Gpl

Hinh 8- Cac phd XPS ciia 0,1 % W/Ti02 (a) vd T i a khdng biln tfnh (b):
(A) Ti 2p, (B) O 1 s, (C) W 4d vd (D) W 5p
Gid trj BE Ti 2p3;i vd Ti 2pi,'2 ciia mlu TiO:
khdng biln tfnh tuong img la 459,5 vd 465,5 eV vd
cua mlu W/Ti02 Id 459,6 va 465,6 eV. Cdc gid trj

BE nay cung gdn vdi cdc gid trj dd dupe cdng bo d
cdc cdng trinh [2] va quy gdn cho Ti(IV). Nhu v|y,
cd sy chuyln djch theo chilu hudng BE Ti 2p3,2 vd
Ti 2pi/2 ciia mdu W-TiOz ldn hon so vdi mau Ti02
khong bien tinh (hinh 8A). Dilu ndy cd thi dd hlnh
thanh lien kit dang W-O-Ti trong mgng ludi Ti02
[2]. Ddng thdi, cudng dp ddng electron Ti 2p3/2 vd Ti
2pi/2 ctia mlu W-Ti02 thip hon so vdi mdu TiOj
khdng biln tinh. Ket qud ndy [2] cho rdng, cdc ion
W(VI) dd kit hpp vao trong cau true mgng ludi Ti02
bdng cdch thay thi ion Ti(IV) (do cd sy tuong ding

vl bdn kinh ion giChi chung) va tgo lifin ket dgng W0-Ti. Tuong ty. hinh 8B cho thiy, gid trj BE O Is
cita mlu w m O j (530,9 eV, Hgn kit W-O-Ti) Idn
hon vd cd cudng d$ ddng electron ciia O Is thip htm
so vdi mlu Ti02 khdng biln tfnh (530,8 eV, lifin kit
Ti-0). Vi§c chuyln djch BE theo chieu hudng ldn
hon ndy cd thi suy ra liSn kit W-O-Ti dupe hinh
thdnh vd cd sy ddng gdp t& cd hai liSn kit Ti-0 va
W-0[2].
Do sv tuong tdc obitan-spin md trgng thdi nang
lupng ciia cdc phSn Idp 4d cOa W bj tdch thdnh cac
miic ndng lupng W 4ds;2, W Adia, tiromg ihig vdi cdc,
gid trj BE Id 247,8 vd 261,5 eV (hinh 8C). Ngodi %,
mlu W/Ti02 cdn cho thiy xuit hi?n pic W 5pl e5~


TCHH, T. 50(4), 2012

Nguyen

gia trj BE Id 52,5 e V (hinh 8D). Cdc gid trj BE ndy
d§c trung cho W d trgng thdi oxi hda (VI) [3]. M$t
khdc, c i u hlnh electron cdc Idp ngodi ciia W(0) vd
Ti(0) tuong Cmg Id: [Xe] 4f^^Sd^6s^ va [Ar] 3 d M s l
Pho XPS tr6n hlnh 8 khdng t h i y cdc pic ciia cdc
electron d cdc phdn Idp 5d, 6s (Ti02 biln tinh
WJVl)) vd 3d, 4s (cho cd TiOj khdng bien tfnh vd cd
bien tfnh W(VI)). D i l u ndy chimg td khdng cd trgng
thdi W(a), W(IV), Ti(0) vd Ti(III) md chii y l u ton tgi
dgng W(V1) vd Ti(IV) trong m l u d i l u c h i ciia
chung tdi.

Da dilu c h i thdnh cdng v§t li§u W-TiOj bdng
phucmg phdp thiiy phdn trong d i l u ki^n cd mdt ure
vdi cac chit ddu Id TiOS04 vd amoni vonframat. K i t
qua nghien cim cho thiy, d i l u ki§n thich hpp d l tiln
hanh dilu c h i bao g i m : nong dO T i O S 0 4 0,12 M (4 g
TiOSO4/220 ml dung djch thCiy phdn), ndng d§ ure
0,60 M, ty I§ mol W/TiOj 0 , 1 % , dung djch dupe tiln
hanh thuy phdn d lOOT trong 3 gid, s l y khd kit tiia d
110°C trong 24 gid vd nung d SOOT trong 4 gid. Vdi
dilu cdc ki^n ndy, sdn p h i m W-TiOj thu dupe Id don
pha anata, cd kfch thudc hgt b6 (-13-14 nm), cdc hgt
phan b l ddng d l u vd cd di^n tfch b l mat khd Idn
(67,3 mVg). Ngoai ra, svr cd m$t ciia W(VI) trong
mgng ludi Ti02 cho thiy, dd thu h?p ddng k l ndng
lupng viing cam ciia T i 0 2 (Eg khodng 2,25-2,88 eV).
Mlu W-TiOj d t j I§ mol W/Ti02 0,1 % cd dp h i p thy
quang mgnh nhit trong vimg dnh sang khd kiln vd cd

hifu suat phdn buy quang cao nhdt. Metylen xanh
trong dung djch nude gdn n h u bi phdn hiiy hodn toan
chi sau Igid chieu sdng vd cao hon khodng 1,65 ldn
so vdi mdu Ti02 khdng d u p e biln tinh.
TAI LIEU THAM BCHAO
1. X. Chen

and

S.

S.

Mao.

Titanium

Dioxide

Vdn Hung vd cgng su

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