TAP CHI HOA HOC 7.51(1)64-66 THANG 2 NAM 2013
T O N G H O P C U S C A U TRUC COVELlT B A N G P H L T O N G P H A P K ^ T TOA Nguyen Dure Van', Dao Nggc Nhi^m, Doan Trung Dung vk Liru Minh Dai
Vi?n Khoa hgc vdt li?u. Vi?n Hdn lam Khoa hgc vd Cdng ngh? Vi?t Nam Den Tda sogn 8-10-2012
Abstract
Covellite-type CuS nanocryslals were synthesized by precipitate method from copper(II) nitrate and ammonium sulfide, followed by further thermal treatment at 105"C for 8 h in air. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy. The results showed that the single crystalline phase of covellite-type CuS was obtained with average size of nanocryslals < 70 nm. The effects of preparative parameters, namely, precipitation pH value, temperature of precipitation, molar ratio of Cu^VS^' on structure and particle size of covellite-type CuS nanocryslals were also investigated and discussed.
Keywords: Copper sulfide (CuS), nanoparlicles, precipitate method 1. MO DAU
Trong thdi gian gan day viec nghien ciiru che tao vat lieu nano CuS da va dang thu hiit sy quan tam ctia nhieu nha khoa hgc tren the gidi do vat lieu nay cd cac tinh chat ly thii va cd tiem nang irng dung phong phil [1-8]. Vat lieu CuS dugc irng dung trong nhieu ITnh vuc nhu quang xiic tac, pin khd, vat lieu dan dien, vat lieu hap Ihu sdng radio, vat lieu quang hgc ... [1, 2]. Dgc biet, vat lieu CuS kich thudc nano vdi cau triic covelil theo Monajjemi va cac cdng su cd linh dan dien nhu kim logi [1], Cho den nay, da cd nhieu phuang phap che tao vat lieu nano CuS da duac sir dung nhu thuy nhiet [9], phan ung pha rSn [10]. Trong bai bao nay chiing tdi trinh bay kit qua khao sat mdt so yeu Id de tdng hgp dan pha CuS cd kich thudc nanomet vdi cau triic covelit biing phuang phap ket tiia.
2. THUC NGHIEM 2.1. Hoa chat, dung cu
Cac hda chat dung djch (NH4)iS, Cu(N03)2 3H2O, HNO3 va NH3 dIu ed do sgch phan tich.
- May khuay tir gia nhiet ARE (Y), tii sdy MD- 400 (Dire) va mgt sd dung cy thi nghiem thuy tinh khac.
2.2. Tong hgp vat lieu bang phiro-ng phap ket tiia Day la mdt trong nhung phuang phap dang dugc SIT dung rdng rai dl tdng hgp vat lieu. Phuang phap
nay cho phep khuech tan cac chat tham gia phan img kha tdt, tang dang ke be mat tiep xiic ciia cac chat phan irng do dd cd the dieu che dugc vgt Ii?u mong mudn.
Phuang phap ket tiia cd uu diem sau; cho san pham tinh khiet; tinh ddng nhat cua san pham cao.
Ben cgnh dd, vi^c thay ddi cac ti'nh chat, hinh thai ciia vat li?u cd the thuc hien dugc de dang thdng qua vi?c dieu chinh cac ylu td anh hudng nhu: pH, nhi^t dg, ndng do, tdc dg thuy phan ....
Dung djch Cu^* cd ndng dg xac djnh dugc khu§y gia nhiet tren may khuay tir ARE (Y) d nhi?t do thi'ch hgp. Sau dd, nhd tir tir tirng gigt dung djch S^
Ket tiia CuS tgo thanh cd mau den dugc dem lgc, riia bang nudc cat ndng d l logi bd ion NHj*, U0{ con du trong mau.
Cu(N03)2 + (NH4)2S = CuSi + 2 NH^NO, (1) Mau thu dugc dem say khd d lOS^C trong 8 giir trong khdng khi rdi dem xac djnh thanh phan pha ket tinh tren may Siemens D-5000, hinh thai hgc xac djnh tren kinh hiln vi dien tir quet (SEM) S-JED- 2300.
2.3. Phuong phap nghien ciru
Gian do nhieu xg Ronghen ciia cac mau nghiSn ciru dugc ghi tren may Siemens D-5000 (CHLB DO-c), buc xa CuK,, vdi budc sdng I = 1,5406 A.
Viec ghi anh hinh thai hgc ciia mlu dugc thirc hien tren kinh hiln vi dien td quet (SEM) S-JEE^
2300 (Nhgt Ban).
TCHH, T. 51(1), 2013 3. KET QUA VA T H A O LUAN
Cd nhieu yeu td anh hudng tdi sy hinh thanh pha khi che tao CuS bang phuang phap kit tiia. Trong cong trinh nay chimg tdi khao sat mgt sd cac yeu to anh hudng nhu: nhi?t dg kit tiia, pH kit tiia, nong dg cac chat ket tiia. Cac kit qua nghien ciiru dugc trinh bay ngay sau day.
3.1. Khao sat anh huwng cua nhift dg kit tiia den hieu suat hinh thanh pha CuS
cac mau dugc tdng hgp d dieu ki^n: pH = 7; ty le mol Cu^^/S^" la 1/3; nhiet do ket lua thay ddi lan lugt la 40''C, eO^C, SO^C va lOCC. Kit liia dugc dem Igc, rira, rdi say khd d 105°C trong 8 gid. Tir gian do nhieu xg Ranghen tren hinh 1 ciia cac mau ket tua d nhi^t dg khac nhau thay rang chi khi ket tiia d 80°C thu dugc dan pha CuS vdi cau true covelit.
Vdi mau cd nhiet dg ket tiia la 40°C, pha CuS xuat
H2S + (1/2)02 = H20 + S (2) Lugng luu huynh sinh ra nay tac dung vdi (NH4)2S tgo thanh polysunfua (cd mau vang) va tiosunfat theo phuang trinh (3) va (4).
(x-1 )S + (NH4)2S -^ (NH4)2S, (3) 4S + 6NH3 + 3H2O = 2(NH4)2S + (NH4)2S203 (4)
Nguyen Dire Vdn vd cgng su Them vao dd, mgt phan S^" bj mat di mgt phan theo phuang trinh (5) va (6).
(NH4)2S = NH,HS+NH3 NHflHS=NH3+H2St
(5) (6) Khi sd mol ciia S^" ihicu thi sd mol ciia Cu'^ du SC phan irng vdi OH", S203^" trong dung djch tao thanh Cu(0H)2, CUSO4 theo phuang trinh (7), (8) va (9).
Cu^* + 20H- = Cu(0H)2 (7) CU^*+S203^' =CuS203 (8) CUS2O3 + (3/2)0; = CUSO4 + SO2 (9) Khi tien hanh ket tiia d SO^C, ngudi ta thu dugc dan pha CuS do d nhiet dg nay nhiet lugng cung cap dil de cho cac chat dau vao dugc hoa trdn ddng nhat va tham gia phan irng (1) mgt each lire thdi. (5 cac nhiet do ket tiia cao han va thap ban nhiet do nay, nhiel lugng cung cap tgo nen sir bat ddng nhat cung nhu lam thay ddi ve ndng dg cac chat dau vao. Vi vgy, nhiet dg ket tiia dugc lya chgn cho cac thi nghiem tiep theo la SO^C.
3.2. Khao sat anh hudng ciia pH den sir hinh thanh pha cua CuS
Mau dugc tien hanh tdng hgp nhu phan tren nhung vdi pH ket tiia thay ddi tir I den 7 va ket qua do nhieu xa Ranghen dugc ghi lgi d hinh 2. Cd the
Hinh 1: Gian dd nhieu xa Ranghen ciia mau ket tiia d nhiet do khac nhau hien ciing vol pha CUSO4 5H2O. Cdn khi mau ket tua d eO^C, chii ylu thu dugc pha CuS04-3Cu(OH)2.
Cl nhiet do kit tua la lOCC, thu dugc hdn hgp hai pha CuS va CuS04-5H20 giong nhu Irudng hgp 40T. Su phy thudc rlt mgnh cila thanh phan san pham phan irng vao nhiet do kit tiia cd the hieu dugc la do CO hien tugng cgnh tranh giua cac qua trinh xay ra trong phan iing ddng ket tiia neu tren. Do dung djch (NH4)2S trong nudc la mdt chat Idng khdng mau cd miii amoniac va dihidrd sunfua nen cd hien tugng oxi hda dihidrd sunfua de tao thanh nudc va luu huynh theo phuang trinh (2).
Hmh 2: Gian dd nhicu xa Ranghen cua mau ket liiad pH khac nhau
nhan thly r^ng khi mau kel tua d cac pH khao sat deu ibu dugc dan pha CuS vdl cau true covelit. O pH = I thi do kit tinh cua tinh thi CuS va hieu suat thap nhat (dieu nay la do d pH nay mgt lugng S^' bj tac dung vdi axit du trong dung dich). De tranh triet dl dieu nay, pH ^ 7 se dugc chgn cho cac thi nghiem tiep theo.
3.3. Khao sat anh hudng ciia ty Ie mol Cu^VS^"
den SIT hinh thanh pha cua CuS
Anh hudng ciia ty le mol Cu^"'/S^" den hI3u Sv^ai hinh thanh pha ciia CuS dugc khao sat \ Yi :^c gi.. •
T C H H , T. 5 1 ( 0 , 2 0 1 3
ian lugt thay ddi ian lugt la 1/1; 1/2; 1/3 va 1/5. Cdc dieu kien thi nghiem l u a n g t y n h u c a c phan tren.
Gian do nhieu xg R a n g h e n d u g c ghi lgi d hinh 3.
Hinh 3: Gian dd nhieu xg R a n g h e n ciia nuiu ket tita d ly I? mol Cu"'Vs'" khac nhau
Tir hinh 3 cho thay khi mau ket tiia d ty le mol Cu"'/S" 1/1 va 1/2 mail thu d u g c ngoai pha C u S cau triic covelit la chinh cdn lan mot l u g n g nhd pha CuS04-3Cu(OH)2 d o cd mgt phan S^" lliam gia vao cac phan ung theo phirang trinh (5) va (6) va dan den sy hinh thanh ciia c a c tgp chat C u ( O H ) ; , CUSO4 theo p h u a n g trinh (7), (8) va (9).
Vi vay, ty le mol C u ^ 7 S " ' la 1/3 d u g c chgn cho cac thi nghiep tiep theo.
Hmh 5" Anh SEM ciia mau C u S mau d u g c tdng hgp d d i c u k i e n t d i u u ( p H = 7; ty l e m o l C u - * / S - " la 1/3;
nhiel d o k i t tiia 8 0 ^ )
Minh thai hgc va kich t h u d c hgt ciia m l u d u g c long hgp d dieu ki?n tdi uu (pH = 7; ly 1^ mol
Tdng hgp CuS cdu truc..\
Cu^VS^- la 1/3; nhi?t d g k i t t u a 8 0 ° C ) d u g c ghi l^j n h d sir d y n g kinh hien vi d i ? n tir q u e t ( S E M ) S- J E D - 2 3 0 0 . Ket q u a tren hinh 5 c h o t h a y m a u CuS co kich t h u d c d o n g nhat < 7 0 n m .
4. K E T L U A N
Da k h a o sal mgt sd y e u td d e c h i tgo CuS don pha vdi cau triic covelit va c d kich t h u d c nanomet ( < 70 n m ) b a n g p h u a n g p h a p ket tiia. Dieu ki?n toi uu d l e h l tgo C u S d a n pha vdi c a u true covelit va c6 kich t h u d c n a n o m e t la: ty Ig m o l Cu^VS^' la 1/3, nhigt d g k i t tiia S C C , p H = 7.
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K. Huang. Characterization of copper sulfide nanocrystal vi/V/i three-dimensional flower-shape, J Mater Sci, 42, 9181-9186 (2007).
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Lien he: N g u y e n Dire V a n Vien Khoa hgc vat lieu,
Vien Han lam K h o a hgc va C d n g nghe Viet N a m 18 Hoang Q u o c Viet, Cdu G i l y , Ha N g i Dien thogi: 0 4 6 6 7 4 7 8 1 6
Email: [email protected]
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