There are two possible reasons to explain the increase of capacitance. First, when ethanol added in the deposition bath, the effective current was increased that increased the amount of deposition of oxides. Secondly, the structure of the coating surface initially might be too compact for the electrolysis to pass through. However, there are many cracks on the surface of coating after adding ethanol which increased the utilization of ruthenium oxide coating.
In advanced, anodic oxidation can enlarge the fissure of coating, which the electrolysis would unobstructed working. Anodic oxidation can also transfer some part of ruthenium metal to ruthenium oxides, which increased the capacitance measurement.
After anodic oxidation, the weight of coating will changed a little, indicating that the some of coating has been oxidized and became to oxide. The CV curve was shown in Figure 4-3, showing that capacitance per unit area did not apparent increased.
Observed the result of specimen with ethanol added, the capacitance was not increased by the charge of oxidation of ruthenium metal. The capacitance was found decreased from 428 F/g to 381 F/g. Therefore, the second explanation would be the reason. The effect of cracking was limited by forward anodic oxidization. However, the CV curve was become squarely and tends to the theoretic mode after anodic oxidation treatment.
Generally, to increase the capacitance of electrode, it is important to control the amount of coating. It was found that adding surfactant is the most popular method to control the amount of deposit. In this study, the effect of adding surfactant Triton X-100 was observed. It is well-known that adding surfactant Triton X-100 makes the substrate moistly, which the coating material will deposited onto the substrate surface easily. The weight of ruthenium oxide deposition when surfactant was added is 0.926
surfactant. The surfactant is certainly conduced the coating to deposit. The capacitance was measured to be 343 F/g. The higher amount of deposits does not represent the high capacitance. Figure 4-4 shows the structure of the coating layer of ruthenium oxide by electrode C demonstrate compact structure on this deposition condition. Figure 4-5 shows the change of capacitance after anodic oxidation. It is found that the capacitance change was limited after anodic oxidation treatment.
Controlling pH is an important factor in deposition process. The chloride ruthenium solution must work in acid environment. When pH was higher than 1.5, black suspending ruthenium particles would be produced in the bath and only a little deposit can be found on the substrate. Figure 4-6 depicts the capacitance measurement of ruthenium oxide coating under different pH environment. Controlled the pH=1, the weight of coating will be 0.510 mg. On the other hands, the weight of coating will be 0.782 mg when pH is controlled to be 1.5. The corresponding capacitance will be 0.084 F/cm2 and 0.261 F/cm2 respectively. The pH value of 1.5 was found to be the best condition in this study.
4-1-1-1 Effect of Capacitance of Hydrous Ruthenium Oxide by Anodic Oxidization
Hu et al. have used the anodic oxidization method to obtain the ruthenium oxide [45, 54].
The capacitance was measured to be 0.150 F/cm2 when 0.5 ASD of anodic oxidization is applied. The capacitance was decreased 28% compared to the specimen without applying anodic oxidization. The capacitance in weight was measured to be 390.630 F/g which was only declined by 0.05% as comparing to that without anodic oxidization. Since, the weight of specimen experienced anodic oxidization was
decreased tremendously. The weight of specimen experienced anodic oxidization was 0.384 mg comparing to 0.536 mg before anodic oxidization. The capacitance measurements of specimen experienced 0.5 ASD anodic oxidization are shown in Figure 4-7, 4-8, and 4-11.
The capacitance was measured to be 0.140 F/cm2 when 1 ASD of anodic oxidization is applied. The capacitance was decreased 26% compared to the specimen without applying anodic oxidization. The capacitance in weight was measured to be 353 F/g which was not declined as comparing to that without anodic oxidization as shown in Figure 4-9 and 4-12.
The capacitance was measured to be 0.120 F/cm2 when 1.5 ASD of anodic oxidization is applied. The capacitance was decreased 26% compared to the specimen without applying anodic oxidization. The capacitance in weight was measured to be 345.820 F/g which was declined by 5% as comparing to that without anodic oxidization as shown in Figure 4-10 and 4-13.
It was found that anodic oxidization can cause the hydrous ruthenium oxide coating having theoretical capacitance behavior. Figure 4-14 reveals the difference of electrical capacity characteristics of specimens with various anodic oxidization treatments. It was also found that the coating layer will peel off after the treatment which is the main reason of weight reduction. Therefore, the function of anodic oxidation can increase the utilization rate of ruthenium compounds, and then get the purpose of lightening.
4-1-1-2 The Effect of Thermal Treatment on Capacitance of
Hydrous Ruthenium Oxide Coating
Heat treatment was also applied in this study to investigate change of capacitance of coating. The specimen was heat treatment at 50 , 100 , 150 , 200 , 250 , ℃ ℃ ℃ ℃ ℃ and 300 , respectively℃ . The period of time of heat treatment is 1 hour and followed by room temperature cooling.
It was found that the effect of heat treatment is similar to that of anodic oxidization.
The measured capacitances of specimens about between 50℃-150 were not ℃ improved distinctly as shown in Table 4-7, 4-8.
The capacitance was measured to be 0.220 F/cm2 when 50℃ heat treatment is applied. The capacitance was decreased 21% compared to the specimen without applying heat treatment. The capacitance in weight was measured to be 274.050 F/g which was declined by 23% as comparing to that without heat treatment. Since, the weight of specimen experienced heat treatment was increased. The weight of specimen experienced heat treatment was 0.794 mg comparing to 0.770 mg before heat treatment. The capacitance measurements of specimen experienced 50 heat ℃ treatment are shown in Figure 4-17, and 4-23.
The capacitance was measured to be 0.160 F/cm2 when 100℃ heat treatment is applied. The capacitance was decreased 35% compared to the specimen without applying heat treatment. The capacitance in weight was measured to be 216.600 F/g which was declined by 37% as comparing to that without heat treatment. Since, the weight of specimen experienced heat treatment was increased. The weight of specimen experienced heat treatment was 0.759 mg comparing to 0.737 mg before heat treatment. The capacitance measurements of specimen experienced 100 heat ℃ treatment are shown in Figure 4-18, and 4-24.
The capacitance was measured to be 0.110 F/cm2 when 150℃ heat treatment is applied. The capacitance was decreased 56% compared to the specimen without applying heat treatment. The capacitance in weight was measured to be 174 F/g which
was declined by 48% as comparing to that without heat treatment. Since, the weight of specimen experienced heat treatment was increased. The weight of specimen experienced heat treatment was 0.648 mg comparing to 0.655 mg before heat treatment. The capacitance measurements of specimen experienced 150 heat ℃ treatment are shown in Figure 4-19, and 4-25.
At this thermal range, it was beginning to produce the ruthenium dioxides, which has stationary electron pairs, and the area of CV curve will be smaller.
Compared specimens at heat treatment 200 and ℃ 250 with 100 and 150 , ℃ ℃ ℃ the measured capacitances were not only raised a few, but also tend to theoretical capacitance behavior.
The capacitance was measured to be 0.180 F/cm2 when 200℃ heat treatment is applied. The capacitance was decreased 31% compared to the specimen without applying heat treatment. The capacitance in weight was measured to be 241.620 F/g which was declined by 33% as comparing to that without heat treatment. Since, the weight of specimen experienced heat treatment was increased. The weight of specimen experienced heat treatment was 0.740 mg comparing to 0.723 mg before heat treatment. The capacitance measurements of specimen experienced 200 heat ℃ treatment are shown in Figure 4-20, and 4-26.
The capacitance was measured to be 0.17 F/cm2 when 250℃ heat treatment is applied. The capacitance was decreased 31% compared to the specimen without applying heat treatment. The capacitance in weight was measured to be 224.400 F/g which was declined by 35% as comparing to that without heat treatment. Since, the weight of specimen experienced heat treatment was increased. The weight of specimen experienced heat treatment was 0.770 mg comparing to 0.729 mg before heat treatment. The capacitance measurements of specimen experienced 250 heat ℃
Experienced 200 heat treatment℃ , the CV curve will become squarely which tend to the theoretic capacitance. It is surmise that heating temperature was above 200℃, which will make theoretic capacitor behavior. At 200 and 250 heat treatment, ℃ ℃ some part of hydrous ruthenium oxide become to ruthenium dioxide (RuO2). At opportune heating treatment could change and increased the percentage of crystalline structure of hydrous ruthenium oxide. However, the proportion of hydrous ruthenium oxide was decreased relatively, and it was found the reason of decaying capacitance.
At 300 heat treatment, the capacitance was immensely gliding dropp℃ ed. The capacitance was measured to be 0.10 F/cm2 when 300℃ heat treatment is applied.
The capacitance was decreased 63% compared to the specimen without applying heat treatment. The capacitance in weight was measured to be 70.080 F/g which was declined by 79% as comparing to that without heat treatment. Since, the weight of specimen experienced heat treatment was increased. The weight of specimen experienced heat treatment was 0.727 mg comparing to 0.765 mg before heat treatment. The capacitance measurements of specimen experienced 300 heat ℃ treatment.
Figure 4-22, 4-28, and Table 4-7, 4-8. Figure 4-29 reveals the difference of electrical capacity characteristics of specimens with various heat treatments. Figure 4-30, 4-31 reveals the distribution of capacitance. It was found the higher the heat temperature the greater the decreasing percentage of capacitance.
4-1-2 Carbon Nanotube Added into the Deposition Processes
In this study, carbon nanotube was added in the electrolyte. Since carbon nanotube has high electric conductivity, high specific surface area, it is expected that the capacitance can be increased by adding carbon nanotube in the deposition processes.
Added the carbon nanotube in the deposition solution, which had the characteristics of higher conduct electricity and higher specific surface area, it can also be expected that the reactionary potential was reduced and thus shorten the deposition period. The deposition time of those specimens was set at various deposition periods, which were 5 minutes, 10 minutes, 15 minutes, 30 minutes, and 60 minutes, respectively. The concentrations of adding carbon nanotube were 0.05wt%, 0.1wt%, and 0.25wt%, as show in Table 4-9.
Figure 4-32 reveals the difference of electrical capacity characteristics of specimens added 0.05wt% carbon nanotube at various deposition periods. The measured capacitances of specimens at various deposition periods were: 288.320 F/g, 385.830 F/g, 439.100 F/g, 370.600 F/g, and 442.460 F/g corresponding to 5 minutes, 10 minutes, 15 minutes, 30 minutes, and 60 minutes, respectively. It should be noted that the longer deposited time was not corresponded to high capacitance. From the result, the best coating efficacy on capacitance was the specimen deposited at 15 minutes.
Figure 4-33 reveals the difference of electrical capacity characteristics of specimens added 0.1wt% carbon nanotube at various deposition periods. The measured capacitances of specimens at various deposition periods were 329.240 F/g, 515.160 F/g, 378.400 F/g, 462.650 F/g, and 381.700 F/g corresponding to 5 minutes, 10 minutes, 15 minutes, 30 minutes, and 60 minutes, respectively. In this consistence, the capacitance of specimen at shorter deposited period was better than the specimen at longer deposited period. Especially, the measured capacitance of specimen at 10 minutes deposited periods had the best outcome. Figure 4-34 reveals the difference of electrical capacity characteristics of specimens added 0.25wt% carbon nanotube at various deposition times. The measured capacitances of specimens at various deposition periods were 258.900 F/g, 589.970 F/g, 538.950 F/g, 473.700 F/g, and 361
respectively. The highest measured capacitance was at 10 minutes deposited periods.
Figure 4-35 reveals the distribution of capacitance as a function of carbon nanotube added.
Figure 4-36 reveals the difference of electrical capacity characteristics of specimens at 5 minutes deposited period with various carbon nanotube additives concentrations.
Figure 4-37 reveals the difference of electrical capacity characteristics of specimens at deposited period of 10 minutes with various added carbon nanotube concentrations.
Figure 4-38 reveals the difference of electrical capacity characteristics of specimens at deposited period of 15 minutes with various added carbon nanotube concentrations.
Figure 4-39 reveals the difference of electrical capacity characteristics of specimens at deposited period of 30 minutes with various added carbon nanotube concentrations.
Figure 4-40 reveals the difference of electrical capacity characteristics of specimens at deposited period of 60 minutes with various added carbon nanotube concentrations.
At these different deposition periods of 5 minutes, 10 minutes, 15minutes, and 30 minutes, it was found that the CV curve area of specimens with 0.1wt% of added carbon nanotube was larger than others. From the theory, the larger the CV curve area, the higher the capacitance. In fact, the specimen with 0.25wt% of added carbon nanotube was measured having the highest capacitance. The reason comes from the deposit weight. Because the capacitance was calculated in unit weight, the capacitance value was low when the weight of specimen was heavy. Figure 4-41 reveals the distribution of capacitance as deposition time with carbon nanotube additive. The measured capacitance was as we expected, which the capacitance should be the linear function. However, it shows some positive results of capacitance increased when carbon nanotube was added in the deposition solution.
Merely add surfactant Triton X-100 could not effectively exert the effect of carbon nanotube, as depict in observed the surface of coating structure by SEM. Figure 4-42
shows the microstructure of hydrous ruthenium oxide with adding 0.05wt% of carbon nanotube into the deposition process. Figure 4-43 shows the microstructure of hydrous ruthenium oxide coating with adding 0.1wt% of carbon nanotube into the deposition process. Figure 4-44 shows the microstructure of hydrous ruthenium synthesis coating with adding 0.25wt% of carbon nanotube into the deposition process.
It was found that very tiny hydrous ruthenium oxide particles were deposited on Ti substrate at deposition period of 5 minutes.
Due to short deposited time, small amount of carbon nanotube was co-deposited on Ti substrate. However, the deposition efficiency was enhanced after adding the carbon nanotube into the deposition processes. As a result, hydrous ruthenium oxide can be deposited on Ti substrate in shorten deposition period. And it was found that the quantity of hydrous ruthenium synthesis coating was increased when the time of deposition is increased. Moreover, bloom-type structure was observed when 0.1wt%
of carbon nanotube was added in the deposition processes at deposition time of 60 minutes.
In these observations, the deposited carbon nanotubes were found twist together.
The twining carbon nanotube can not distributed efficiently and deposited much carbon nanotube, that was can not effectively deposited hydrous ruthenium synthesis onto carbon nanotube surface. In this way, the useless weight will be increased, which the capacitance did not increase. It can explain why the capacitance can be increased as increasing the deposition periods.
It can also be observed that the measured capacitance can be increased very effectively when small amount of carbon nanotube added during deposition which leads to the increasing of the amount of hydrous ruthenium synthesis. However, it was found that the measured capacitance decreases when the deposition period of
measurement contains both the hydrous ruthenium oxide coating and the carbon nanotube.
4-1-3 Dispersed Carbon Nanotube Added into the Deposition Processes
In theory, under the huge energy of high effective ultrasonic, carbon nanotube will be dispersed forcedly. Moreover, non ion surface active agent Triton X-100 that can make dispersing carbon nanotube did not easily occurred to self-polymerization. As the results, the characteristic of high surface of carbon nanotube can be used.
In this section, the parameters of deposition were the deposited period and the concentration of carbon nanotube added. The concentrations of carbon nanotube additives were 0.0125wt%, 0.025wt%, 0.05wt%, and 0.1wt%.
Figure 4-45 reveals the difference of electrical capacity characteristics of specimens added dispersed 0.0125wt% of carbon nanotube at various deposition periods. The measured capacitances of specimens at various deposition periods were 201.400 F/g, 227 F/g, 243 F/g, 321.400 F/g, and 396.800 F/g corresponding to 5 minutes, 10 minutes, 15 minutes, 30 minutes, and 60 minutes, respectively. The highest measured capacitance characteristic is 396.800 F/g, which was less than that 429 F/g in specimen without added carbon nanotube. The reason is not added carbon nanotube enough to exert the affect.
Figure 4-46 reveals the difference of electrical capacity characteristics of specimens added dispersed 0.025wt% of carbon nanotube at various deposition periods. The measured capacitances of specimens at various deposition periods were 175 F/g, 283.800 F/g, 400 F/g, 417 F/g, and 397.700 F/g corresponding to 5 minutes, 10
minutes, 15 minutes, 30 minutes, and 60 minutes, respectively. The best measured capacitance of specimen was 417 F/g. This value is very close to that specimen without added carbon nanotube. However, the quality of added carbon nanotube was still not enough to enhance the capacitance.
Figure 4-47 reveals the difference of electrical capacity characteristics of specimens added dispersed 0.05wt% of carbon nanotube at various deposition periods. The measured capacitances of specimens at various deposition periods were 213.800 F/g, 406.500 F/g, 411.250 F/g, 713.600 F/g, and 718.800 F/g corresponding to 5 minutes, 10 minutes, 15 minutes, 30 minutes, and 60 minutes, respectively. It had the palpable increased capacitance, especially the measured capacitance of specimen at deposited period 60minutes. It should be mentioned that the capacitance of specimen at 30 minutes of deposition period was measured to be 713.600 F/g. This result is still very good. If the deposition period is a critical choice in the future, the condition of 30 minutes deposition is properly to use.
Figure 4-48 reveals the difference of electrical capacity characteristics of specimens added dispersed 0.1wt% of carbon nanotube at various deposition periods. The measured capacitances of specimens at various deposition periods were 366.800 F/g, 406.800 F/g, 390.600 F/g, 600.800 F/g, and 680.600 F/g corresponding to 5 minutes, 10 minutes, 15 minutes, 30 minutes, and 60 minutes, respectively. The maximum capacitance was only 680.600 F/g. The capacitance was found decreasing comparing to that specimen added 0.05 wt% of carbon nanotube. The reason would be that too much carbon nanotube was added.
Figure 4-49 reveals the distribution of capacitance as a function of added dispersed carbon nanotube. From the results, it can be found that the measured capacitance was increased when the quality of added carbon nanotube was added. However, there is a
carbon nanotube in the deposition bath, too heavy compound of hydrous ruthenium oxide with carbon nanotube was produced. In the our study, the highest capacitance was measured to be 718.800 F/g, which was added dispersed 0.05wt% of carbon nanotube at 60 minutes of deposited period.
Figure 4-50 reveals the difference of electrical capacity characteristics of specimens with various added dispersed carbon nanotube concentrations when deposition period is fixed to 5 minutes. Figure 4-51 reveals the difference of electrical capacity characteristics of specimens with various added dispersed carbon nanotube concentrations when deposition period is fixed to 10 minutes. Figure 4-52 reveals the difference of electrical capacity characteristics of specimens with various added dispersed carbon nanotube concentrations when deposition period is fixed to 15 minutes. Figure 4-53 reveals the difference of electrical capacity characteristics of specimens with various added dispersed carbon nanotube concentrations when deposition period is fixed to 30 minutes. Figure 4-54 reveals the difference of electrical capacity characteristics of specimens with various added dispersed carbon nanotube concentrations when deposition period is fixed to 60 minutes. It can be found that the area of CV curve of specimens with added carbon nanotube 0.1wt% at 5, 10, and 15 minutes of deposition periods were larger than others which corresponds to higher capacitance. In this case, the area of CV curve can represent the capacitance without considering the weight.
However, it can be also found that the measured capacitance was the highest although the area of CV curve was not the largest which occurred at specimen of adding 0.05wt% carbon nanotube at 30 minutes of deposition period. Figure 4-55 reveals the distribution of capacitance as a function of deposition time with added dispersed carbon nanotube. It shows the measured capacitance had positive proportion relation with the concentration of added dispersed carbon nanotube and the deposited