基于金属氧化物半导体的人工光合作用

发布时间：2018-03-25 15:54

本文选题：太阳能　切入点：半导体　出处：《中国科学院研究生院（上海应用物理研究所）》2015年博士论文

【摘要】：世界上大部分的能量来自于化石燃料的消耗，比如像天然气，石油和煤炭。然而，众所周知，这些能源是不可再生的，而且它们的燃烧产物对环境和人是非常有害的，比如雾霾天气的产生。因此，需研究者们寻找可再生和无公害的能源如太阳能来代替目前的化石能源，这一领域一直吸引大家广泛的兴趣。一般的，我们可以利用光伏电池收集太阳光，将吸收的太阳光可以直接转化为电能或者化学能，如通过分解水反应以氢气的形式收集起来。而且氢气是在燃料电池使用中的一种清洁能源。在发展可持续型能源方面，光电化学（PEC）电池时候通过吸收太阳光来分解水，有很大的应用前景。特别是作为PEC光解水的光阳极材料半导体氧化铁通过吸收可见光使水分解受到广泛研究。这主要是因为氧化铁比较容易得到，具有相对的稳定性，和合适的价带1.9eV-2.2eV来吸收可见光。通过制备氧化铁纳米结构可以提供一种有效的方式来增加氧化铁光解水的能力。主要体现在可以增加电荷的分离，增加半导体比表面积和光学吸收。在本论文中，研究工作主要集中在对氧化铁表面的修饰，氧化铁体相的修饰和氧化铁和导电玻璃的界面进行修饰。而且，我们通过设计，合成出了具有高效的三氧化钨和钒酸铋组成的异质结并达到了很高的光电流密度。首先通过在氧化铁和导电玻璃之间引入ATO纳米颗粒，形成核壳结构，减少电子复合的概率而使得氧化铁的光解水效率提高。我们在ATO纳米层上面生长氧化铁纳米棒，发现生长在ATO纳米结构上面的氧化铁纳米棒以抗高温烧结而保持很好的氧化铁纳米形貌，从而使得光电流密度增加达到了没有任何表面催化剂处理的最大值，，2.12mA／cm2。接下来，我们利用电沉积的方法在氧化铁的纳米结构中引入Zn和Ti元素。通过Ti来增加载流子的数目和Zn来提高氧化铁表面动力学共同作用使得氧化铁的光电流有所增加。而且，通过ALD方法和热扩散的方法我们首次获得了很均匀的Ti掺杂氧化铁纳米线，而且在经过Co离子处理后氧化铁光阳极材料光电流达到了2.6mA/cm2。这一光电流值可以和Michael组报道的APCVD方法合成氧化铁的方法可以比较。再次，我们利用ALD在氧化铁和导电玻璃之间引入超薄的TiO2纳米层，我们成功的将氧化铁的活化温度从800度降低到了600度。而且进一步的我们设计和合成出了具有三维结构的氧化铁支状形貌，这一形貌有利于氧化铁可见光的吸收，从而导致了光解水的效率有所提高。最后，我们首次合成出超薄的WO3片层结构，而且在利用BiVO4处理后，我们在没有催化剂的情况下利用复合结构获得光电流达到了4.2mA/cm2。我们通过设计和合成半导体纳米结构，再利用其他的方法将制备的半导体进行修饰，从而获得比较好的光电化学分解水的效率。我们有理由相信，在标准的模拟太阳光下通过加入高效催化剂等方法我们可以获得更高的光电流密度。这些努力有可能将对PEC实际应用方面做出贡献。
[Abstract]:Most of the world's energy comes from the consumption of fossil fuels, such as natural gas, petroleum and coal. However, as everyone knows, the energy is not renewable, and their combustion products is very harmful to the environment and people, such as fog and haze. Therefore, researchers need to find renewable and pollution-free energy such as solar energy to replace the fossil energy, this field has attracted widespread interest. In general, we can use the sun light collecting photovoltaic cells will absorb sunlight directly into electrical energy or chemical energy, such as through water decomposition reaction in the form of hydrogen gas and hydrogen is collected. Clean energy in the fuel cell is used.
In the development of sustainable energy, photoelectrochemical (PEC) battery time by absorbing sunlight to split water, has great application prospect. Especially as the photoanode semiconductor materials of iron oxide PEC photolysis of water by absorption of visible light water decomposition has been widely studied. This is mainly because the iron oxide is easy to obtain, with relative stability suitable to 1.9eV-2.2eV, and the valence band of visible light absorption ability. Through the preparation of iron oxide nano structure can provide an effective way to increase the photolysis of water. Iron oxide is mainly reflected in the increase of charge separation, increase the specific surface area and optical absorption of semiconductor.
In this paper, the research work focuses on the modification of the surface of iron oxide, iron oxide and iron oxide bulk modification and conductive glass interface modification. Moreover, we design, synthesized with heterojunction tungsten oxide and bismuth vanadate, consisting of up to the light and high current density.
First, through the introduction of ATO nano particles in between iron oxide and conductive glass, forming a core-shell structure, reduce the probability of electron recombination and the photolysis of water efficiency improvement. Our growth of iron oxide iron oxide nanorods on ATO nano layer, iron oxide nanorods grown on ATO nanostructures on top of sintered iron oxide nano morphology and keep good light, so that the increase of current density reached no surface treatment catalyst maximum, 2.12mA / cm2.
Next, we use the method of electrodeposition into the Zn and Ti elements in iron oxide nano structure. Through Ti and Zn to increase the number of carriers to improve the interaction of iron oxide surface dynamics makes light current iron oxide increases. Moreover, by means of ALD method and thermal diffusion for the first time we get a uniform Ti doped iron oxide nanowires, and after Co ion treatment after iron oxide anode photocurrent reached 2.6mA/cm2. the photocurrent value comparison method and Michael APCVD method can be group reported on the synthesis of iron oxide.
Again, we use ALD TiO2 nano layer into thin between iron oxide and conductive glass, we successfully iron oxide activation temperature from 800 degrees down to 600 degrees. And further we designed and synthesized iron oxide branched morphology has a three-dimensional structure, the morphology of iron oxide is conducive to the absorption of visible light. Which leads to the efficiency of photolysis of water is increased.
Finally, we first synthesized ultra-thin WO3 lamellar structure, and after BiVO4 treatment, we achieved the photocurrent of 4.2mA/cm2. under the condition of no catalyst.
We through the design and synthesis of semiconductor nanostructures, and then use other methods for preparation of semiconductor was modified to obtain better photoelectrochemical water splitting efficiency. We have reason to believe that, by adding high effective catalyst and method under simulated solar light under the standards we can obtain higher photocurrent density. Efforts may make a contribution to the practical application of PEC.

【学位授予单位】：中国科学院研究生院（上海应用物理研究所）
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TN304.21;TQ116.2

【共引文献】