钨基化合物的制备、表征及催化性能研究
发布时间：2018-08-10 07:41
【摘要】：随着能源危机和环境污染问题日益加剧,可再生能源的开发迫在眉睫。太阳能是一种最具开发利用潜力的可再生能源。作为第三代太阳能电池,染料敏化太阳能电池(dye-sensitized solar cell,DSSC)由于其原材料来源广泛、制备成本低廉、制作工艺简单、环境友好和理论转化效率较高等优点,一直是国内外研究的热点。作为DSSC的重要组成部分,对电极主要负责收集外部电路电子以及催化还原电解质溶液中的I3-离子。Pt是最常用的对电极催化材料。然而,其价格昂贵且储量有限,严重限制了DSSC的商业化应用。因此,开发低成本、高催化性能的非铂对电极材料,具有重要的意义。钨基过渡金属化合物由于其充足的资源储备量、良好的离子和电子导电性、较强的催化活性及目标产物的可选择性,使其作为对电极催化剂材料在DSSC中显示出巨大的应用潜力。本文通过不同的制备方法合成了钨基化合物对电极催化材料,并将其应用于DSSC中。针对由钨基化合物作为对电极的DSSC进行了以下研究。(1)利用简单化学“一锅法”,成功制备一元钨基化合物(W_(18)O_(49)、WO_3和W_2N)电催化材料,并系统考察了其作为对电极催化剂在DSSC中的催化性能。研究结果表明:所制备的钨基化合物材料结晶度较好、物相纯度较高及尺寸分布均匀。钨基化合物对电极具有优秀的电化学性能与光伏性能。作为表征对电极催化剂催化性能的参数,W_2N、WC和WO_3的传荷电阻分别为20.04Ω,22.18Ω和25.32Ω,对应DSSC的光电能量转换效率分别为5.97%,5.20%和4.69%,相似于相同条件下的Pt对电极(10.81Ω,6.52%)。由于氧空位的引入,非化学计量比的W_(18)O_(49)获得了最优的催化性能(传荷电阻为2.52Ω),对应DSSC表现出最优的光伏性能(6.69%)。同时,电化学稳定性测试结果显示W_(18)O_(49)、W_2N、WC和WO_3可以稳定高效地催化还原I-/I3-。第一性原理密度泛函理论计算结果表明:W_(18)O_(49),W_2N,WC和Pt的带隙为零,而WO_3的带隙为1.7eV,这进一步阐明了影响钨基化合物优异电催化活性的本征因素。(2)利用低温水热法,合成了二元钨基化合物Ni_(0.19)WO_4和CoWO_4电催化材料。实验结果表明:所制备的Ni_(0.19)WO_4和CoWO_4材料具有组成均一且结晶性良好的特点。Ni_(0.19)WO_4和CoWO_4对电极显示了相近的串联电阻(16.21Ω和14.36Ω)和传荷电阻(35.08Ω和41.18Ω),即Ni_(0.19)WO_4与CoWO_4对I-/I3-有良好的催化性能。基于Ni_(0.19)WO_4和CoWO_4对电极的DSSC,获得光电能量转换效率分别为4.71%和4.55%,而同等条件下的Pt对电极的光电能量转换效率为6.27%。同时,电化学稳定性测试表明Ni_(0.19)WO_4和CoWO_4表现出良好的电化学稳定性。(3)利用均相共沉积法,成功的合成了Fe_2WO_4电催化材料。实验结果表明:所制备的Fe_2WO_4材料的粒度均匀且纯度较高。由Fe_2WO_4对电极组成的对称电池,其串联电阻与传荷电阻分别为16.1Ω和27.42Ω,对应DSSC的光电能量转换效率5.17%。Fe_2WO_4对电极利用了双金属间的协同作用,表现出了可与Pt电极相比的催化性能。同时,Fe_2WO_4对电极在I-/I3-电解液中具有优异的电化学稳定性。
[Abstract]:As the energy crisis and environmental pollution are increasing, the development of renewable energy is imminent. The solar energy is the most potential renewable energy. As the third generation of solar cells, the dye sensitized solar cell (dye-sensitized solar cell, DSSC) is widely used in the raw materials, and the production cost is low. As an important part of DSSC, the main responsibility of collecting the external circuit electrons and the I3- ion.Pt in the catalytic reductive electrolyte solution is the most commonly used electrode accelerating material. However, its price is expensive and the reserves are limited. The commercialized application of DSSC is seriously restricted. Therefore, it is of great significance to develop the non platinum electrode materials with low cost and high catalytic performance. The tungsten based transition metal compounds are used as the electrode catalysts due to their sufficient reserve of resources, good ionic and electronic conductivity, strong catalytic activity and the selectivity of the target products. Materials have shown great potential for application in DSSC. In this paper, tungsten based compounds have been synthesized by different preparation methods and applied to the DSSC. The following studies have been made for the DSSC of the tungsten based compounds as the electrode. (1) a single tungsten based compound (W_ (18) O_) was successfully prepared by the simple chemical "one pot" method. (49) (49), WO_3 and W_2N) electrocatalytic materials and their catalytic performance as an electrode catalyst in DSSC. The results show that the prepared tungsten based compounds have good crystallinity, high phase purity and uniform size distribution. The parameters of the catalytic performance of the catalyst, W_2N, WC and WO_3, are 20.04 Omega, 22.18 omega and 25.32 Omega respectively. The photoelectric energy conversion efficiency of the corresponding DSSC is 5.97%, 5.20% and 4.69% respectively, similar to the Pt pair electrode (10.81 Omega, 6.52%) under the same condition. The non stoichiometric ratio of W_ (18) O_ (49) is obtained because of the introduction of the oxygen vacancy. The catalytic performance (transfer resistance is 2.52 omega) shows the best photovoltaic performance (6.69%) corresponding to DSSC. At the same time, the results of electrochemical stability test show that W_ (18) O_ (49), W_2N, WC and WO_3 can stabilize and efficiently catalyze the reduction of I-/I3-. first principle density functional theory calculation results show that W_ (18) O_ (49), W_2N, WC, and Pt band gap is zero. The band gap is 1.7eV, which further clarifies the intrinsic factors affecting the excellent electrocatalytic activity of tungsten based compounds. (2) a two element tungsten base compound, Ni_ (0.19) WO_4 and CoWO_4, is synthesized by low temperature hydrothermal method. The experimental results show that the prepared Ni_ (0.19) WO_4 and CoWO_4 materials have a homogeneous and good crystallization characteristic.Ni_ (0.1). 9) WO_4 and CoWO_4 show similar series resistance (16.21 omega and 14.36 omega) and transfer resistance (35.08 omega and 41.18 omega), that is, Ni_ (0.19) WO_4 and CoWO_4 have good catalytic performance to I-/I3-. Based on Ni_ (0.19) WO_4 and CoWO_4 pairs of DSSC, the photoelectric energy conversion efficiency is 4.71% and 4.55% respectively, and the Pt pair electrode under the same condition The photoelectric energy conversion efficiency was 6.27%., and the electrochemical stability test showed that Ni_ (0.19) WO_4 and CoWO_4 showed good electrochemical stability. (3) the Fe_2WO_4 electrocatalysis material was successfully synthesized by homogeneous co deposition. The experimental results showed that the prepared Fe_2WO_4 material had a uniform particle size and high purity. The Fe_2WO_4 pair was used as the electrode. The symmetrical battery consists of 16.1 omega and 27.42 Omega resistance in series resistance and transfer resistance, respectively, and the photoelectrical energy conversion efficiency of the corresponding DSSC 5.17%.Fe_2WO_4 makes use of the synergism between the bimetallic electrode, showing the catalytic performance compared with the Pt electrode. At the same time, the Fe_2WO_4 has excellent electrochemical stability in the I-/I3- electrolyte. Sex.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM914.4
本文编号：2175411
[Abstract]:As the energy crisis and environmental pollution are increasing, the development of renewable energy is imminent. The solar energy is the most potential renewable energy. As the third generation of solar cells, the dye sensitized solar cell (dye-sensitized solar cell, DSSC) is widely used in the raw materials, and the production cost is low. As an important part of DSSC, the main responsibility of collecting the external circuit electrons and the I3- ion.Pt in the catalytic reductive electrolyte solution is the most commonly used electrode accelerating material. However, its price is expensive and the reserves are limited. The commercialized application of DSSC is seriously restricted. Therefore, it is of great significance to develop the non platinum electrode materials with low cost and high catalytic performance. The tungsten based transition metal compounds are used as the electrode catalysts due to their sufficient reserve of resources, good ionic and electronic conductivity, strong catalytic activity and the selectivity of the target products. Materials have shown great potential for application in DSSC. In this paper, tungsten based compounds have been synthesized by different preparation methods and applied to the DSSC. The following studies have been made for the DSSC of the tungsten based compounds as the electrode. (1) a single tungsten based compound (W_ (18) O_) was successfully prepared by the simple chemical "one pot" method. (49) (49), WO_3 and W_2N) electrocatalytic materials and their catalytic performance as an electrode catalyst in DSSC. The results show that the prepared tungsten based compounds have good crystallinity, high phase purity and uniform size distribution. The parameters of the catalytic performance of the catalyst, W_2N, WC and WO_3, are 20.04 Omega, 22.18 omega and 25.32 Omega respectively. The photoelectric energy conversion efficiency of the corresponding DSSC is 5.97%, 5.20% and 4.69% respectively, similar to the Pt pair electrode (10.81 Omega, 6.52%) under the same condition. The non stoichiometric ratio of W_ (18) O_ (49) is obtained because of the introduction of the oxygen vacancy. The catalytic performance (transfer resistance is 2.52 omega) shows the best photovoltaic performance (6.69%) corresponding to DSSC. At the same time, the results of electrochemical stability test show that W_ (18) O_ (49), W_2N, WC and WO_3 can stabilize and efficiently catalyze the reduction of I-/I3-. first principle density functional theory calculation results show that W_ (18) O_ (49), W_2N, WC, and Pt band gap is zero. The band gap is 1.7eV, which further clarifies the intrinsic factors affecting the excellent electrocatalytic activity of tungsten based compounds. (2) a two element tungsten base compound, Ni_ (0.19) WO_4 and CoWO_4, is synthesized by low temperature hydrothermal method. The experimental results show that the prepared Ni_ (0.19) WO_4 and CoWO_4 materials have a homogeneous and good crystallization characteristic.Ni_ (0.1). 9) WO_4 and CoWO_4 show similar series resistance (16.21 omega and 14.36 omega) and transfer resistance (35.08 omega and 41.18 omega), that is, Ni_ (0.19) WO_4 and CoWO_4 have good catalytic performance to I-/I3-. Based on Ni_ (0.19) WO_4 and CoWO_4 pairs of DSSC, the photoelectric energy conversion efficiency is 4.71% and 4.55% respectively, and the Pt pair electrode under the same condition The photoelectric energy conversion efficiency was 6.27%., and the electrochemical stability test showed that Ni_ (0.19) WO_4 and CoWO_4 showed good electrochemical stability. (3) the Fe_2WO_4 electrocatalysis material was successfully synthesized by homogeneous co deposition. The experimental results showed that the prepared Fe_2WO_4 material had a uniform particle size and high purity. The Fe_2WO_4 pair was used as the electrode. The symmetrical battery consists of 16.1 omega and 27.42 Omega resistance in series resistance and transfer resistance, respectively, and the photoelectrical energy conversion efficiency of the corresponding DSSC 5.17%.Fe_2WO_4 makes use of the synergism between the bimetallic electrode, showing the catalytic performance compared with the Pt electrode. At the same time, the Fe_2WO_4 has excellent electrochemical stability in the I-/I3- electrolyte. Sex.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM914.4
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