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Phase evolution from rod-like ZnO to
plate-like zinc hydroxysulfate during
electrochemical deposition
Lida Wang, Guichang Liu∗, Longjiang Zou, Dongfeng Xue Department
of Materials Science and Chemical Engineering, School of Chemical
Engineering, Dalian University of Technology, 158 Zhongshan Road,
Dalian 116012, China
Advisor：S.C.Wang
Student：Shih-Kai Shu
Outline
 Introduction
 Experimental
Procedures
 Results and Discussion
 Conclusion
 Future work
Introduction
 The effects of SO42− ion concentrations on the phase
evolution of electrochemical deposited films have been
investigated using scanning electron microscopy (SEM),
energy-dispersive X-ray (EDX), X-ray diffraction (XRD)
and Fourier transform infrared spectroscopy (FTIR).
 The results show that SO42− ion concentration plays a very
important role in directing the phase evolution of thick
films from rod-like ZnO to plate-like zinc hydroxysulfate
under fast hydroxylation.
 When ZnSO4 concentrations are below 0.54mM,the
oriented growth of ZnO rods tends to be enhanced with
the increase of ZnSO4 concentration.
 Otherwise, the vertically aligned zinc hydroxysulfate
plates can be formed by the introduction of SO42− ions in
nanocrystals.
Experimental Procedures
電解液為27mM KNO3 、3mM (CH2)6N4和濃度0.3mM~3mM ZnSO4的
混合水溶液
將FTO導電玻璃(2mm×1mm，片電阻15Ω/cm2)置入電鍍液中，並使用
三電極系統進行定電壓(-0.85V/SCE)電化學沉積5小時
沉積過程中電解意溫度維持在80°C下，並使用稀釋硫酸溶液調整pH值，
維持在3.0-4.0的範圍
使用SEM、EDX、XED和FTIR做分析
另外也討論電解液為27mM KNO3 、3mM (CH2)6N4和濃度0.3mM
ZnSO4的混合水溶液再加入濃度3mM~24mM K2SO4，觀察硫酸鹽對
ZnO薄膜成長的影響

電化學沉積氧化鋅主要分為兩部分：電化
學過程和化學過程
NO3− +2e + H2O ↔ NO2− +2OH−
 Zn2+ +2OH−↔ Zn(OH)2
 Zn(OH)2 = ZnO + H2O

(1)
(2)
(3)
Results and Discussion

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SEM images of the asprepared films (a–d) rod,
(e) mixture of rod and plate,
(f–h) plate synthesized at
various ZnSO4
concentrations.
(a) 0.3mM
(b) 0.36mM
(c) 0.48mM
(d) 0.54mM
(e) 0.6mM
(f) 1.2mM
(g) 1.8mM
(h) 3mM
temperature 80◦C for 5 h.

EDX spectra of marked regions (I) rod and (J) plate in
film prepared at 0.6mM ZnSO4 at the temperature 80◦C
for 5 h.
XRD patterns of the as-prepared films synthesized at
various ZnSO4 concentrations (a) 0.3mM, (b) 0.36mM,
(c) 0.48mM, (d) 0.54mM, (e) 0.6mM at the temperature
80◦C for 5 h.
 The standard diffraction patterns of ZnO are shown as
reference. Asterisks (*) indicate the FTO substrate.

XRD patterns of the as-prepared films synthesized at
various ZnSO4 concentrations (a) 1.2mM, (b) 1.8mM,
(c) 3mM, at the temperature 80◦C for 5 h.
 The standard diffraction patterns of 6Zn(OH)2
ZnSO4·4H2O are shown as reference.
 Asterisks (*) indicate the FTO substrate.

FTIR spectra of the as-prepared films synthesized at
various ZnSO4 concentrations.
 (a) 0.3mM, (b) 3mM, at the temperature 80◦C for 5 h.
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SEM images of the asprepared films (a)
mixture of rod and
plate, (b–d) plate,
synthesized at various
K2SO4 concentrations.
(a) 3mM
(b) 6mM
(c) 12mM
(d) 24mM at the
temperature 80◦C for 5
h.
XRD patterns of the as-prepared films synthesized at
various K2SO4 concentrations, (a) 3mM, (b) 6mM, (c)
12mM, (d) 24mM at the temperature 80◦C for 5 h.
 The standard diffraction patterns of ZnO and 6Zn(OH)2
ZnSO4·4H2O are shown as reference.
 Asterisks (*) indicate the FTO substrate.

Conclusion
 In present work, we demonstrate that SO42− ion
concentration plays a very important role in
controlling the phase evolution of films from ZnO
rods to zinc hydroxysulfate plates under fast
hydroxylation using electrochemical deposition.
 At lower ZnSO4 concentrations, vertically aligned
ZnO rods tend to dominate the film morphology.
 On the contrary, SO42− ions can participate in the film
growth under fast hydroxylation, thus leading to the
formation of vertical aligned zinc hydroxysulfate
plates.
 Most importantly, this work facilitates not only the
researches about the nature of chemical reactions
under electric field, but also the applications in
optoelectronics, field effect transistor and solar cells.
Future work
 Paper
review