随着现代社会和经济的迅速发展，出现了化石燃料的枯竭和环境恶化的危机。在这种情况下，人类迫切需要发展环境友好、经济低廉的可再生替代能源。氢气（H₂）由于具有高能量值、储量巨大、绿色清洁的优点，被广泛认为是一种可以替代传统碳基化石燃料的极具应用前景的新型替代能源。太阳能储量丰富，洁净无污染，因此利用太阳光的能量诱导分解水产氢气已经成为一种转换可持续能源的最有前景的方法。在光催化反应中，光催化剂起到极其重要不可或缺的作用，因为从太阳辐射到地球表面的光不能直接使水分解，必须借助光催化剂这一反应基体才可以实现能量的转化，因此各种类型的半导体光催化剂成为该领域的热门话题以及研究人员和学者们孜孜不倦探索的方向。钙钛矿型半导体材料因为拥有合适的能带结构和廉价、无毒、制备方法简便等诸多优点成为新型高效的非Ti系光催化剂，但是其仍然存在一些明显的缺点，如光稳定性差、电子空穴复合率高及表面区域小等。

针对钙钛矿型材料存在的问题，本文着力于探究LaNiO₃基纳米异质结复合材料的制备条件的优化及光催化性能的提高，我们采用溶胶凝胶法合成LaNiO₃纳米颗粒，采用程序升温焙烧法合成石墨相氮化碳g-C₃N₄，然后通过机械搅拌、超声分散及溶剂热法等手段合成LaNiO₃/g-C₃N₄系列Z-型异质结复合材料。我们通过X-射线衍射（XRD），扫描电镜（SEM），透射电镜（TEM），比表面积及孔分析仪（BET），X-射线光电子能谱分析（XPS），傅里叶红外（FT-IR）等表征手段对催化剂进行晶相结构、尺寸形貌、元素组成以及孔径结构和比表面积等方面的性质测试与比较讨论。我们通过定制的石英反应器和气相色谱仪分析手段进行光催化分解水产氢实验，保持氙灯光源强度、温度、投料用量等条件相同，测试不同掺杂比的异质结复合纳米材料的催化效果，从而探索出最佳的掺杂比。最后，进一步测试最佳掺杂比材料的光催化稳定性。主要内容如下：

（1）第二章合成LaNiO₃纳米颗粒、类石墨相氮化碳g-C₃N₄及LaNiO₃/g-C₃N₄系列Z-型异质结复合材料。g-C₃N₄的质量掺杂比分别为20,30,40,50,60,70,80%，并且依次命名为LNCN2-LNCN8。对系列催化剂进行性质表征和紫外光（λ =250~380 nm）催化产氢性能测试。测试实验结果表明，LNCN系列催化效果均有明显提升，其中LNCN7具有最优良的光催化产氢效果，5个小时的总产氢量为3392.5μmol·g^-1，最大产氢速率达到678.5 μmol·h^-1·g^-1，其催化效率约为纯LaNiO₃的5倍。我们还进行最优掺杂比材料LaNiO₃/70%g-C₃N₄的光催化稳定性和重复性测试，结果显示性质优良。

（2）第三章采用相同的手段合成另一个系列的LaNiO₃/g-C₃N₄。在这个系列中，g-C₃N₄为催化剂主体，LaNiO₃的质量掺杂比分别为1,2,4,8,10,12,20,80%，并且依次命名为CN1-CN80。对系列催化剂进行性质表征和可见光（λ =400~780nm）催化产氢性能测试。测试实验结果表明，掺杂后的材料催化效果相对于纯的g-C₃N₄虽然有小幅度的提升，但是效果不显著。其中CN2具有优良的光催化产氢效果，5个小时的总产氢量为7584.9μmol·g^-1，最大产氢速率达到1517.0μmol·h^-1·g^-1。2%LaNiO₃/g-C₃N₄光催化稳定性测试结果也显示性质良好。

（3）本论文还对合成的LaNiO₃/g-C₃N₄异质结复合材料光催化分解水产氢机理进行了模型建立与分析，钙钛矿材料LaNiO₃与g-C₃N₄结合形成异质结构复合材料，由于Z-型载流子转移途径的构建，能够使光生电子或空穴生成之后从一个半导体转移到另一个半导体，从而减少载流子复合率，获得更好的电荷分离效率和广泛的光响应区域，因此增强光催化活性。

With the rapid development of modern society and economy, there has been appeared the exhaustion of fossil fuels and environmental deterioration crisis. One form of environmentally friendly, economical and low cost renewable alternative energy was urgently needed under recent situation. Because of the high energy value and the benefit of green cleaning, hydrogen (H2) is a kind of the promising alternative new energy source that can become the substitute of the traditional carbon-based fossil fuels. Solar energy is abundant, clean and pollution-free, so the light-driven photocatalytic water splitting to produce hydrogen has become one of the most promising methods for converting sustainable energy. In the photocatalytic reaction, the photocatalyst plays an extremely important and indispensable role. Because the light radiated from the sun to the surface of earth cannot directly decompose water, and the conversion of energy might be achieved with the help of the photocatalyst. So the semiconductor photocatalyst has become a hot topic in this field, and the directions of researchers are tirelessly exploring. Perovskite-type semiconductor materials become a kind of new and efficient non-Ti-based photocatalyst because of their advantages such as owing suitable band structure, low cost, non-toxicity, and simple preparation methods. But they still exist some obvious disadvantages, such as poor light stability, the high recombination rate of photo electronic-hole and the limitation of surface area. 
Aiming at the problems of perovskite-type materials, this paper focuses on exploring the preparation and photocatalytic performance of LaNiO3-based heterojunction nanocomposites. We adopt the sol-gel method to synthesize LaNiO3 nanoparticles and adopt the programmed temperature roasting method to obtain g-C3N4. Then a series of Z-type LaNiO3/g-C3N4 heterojunction composites were synthesized by mechanical stirring, ultrasonic dispersion and solvothermal method. The structure, composition, morphology, size and specific surface area of as-prepared materials were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), specific surface area and pore analyzer (BET), X-ray photoelectron spectroscopy (XPS), Fourier infrared (FT- IR) and other characterization methods. We conducted photocatalytic hydrogen-production test using a custom-made quartz reactor and a gas chromatograph for data collection, and tested the photocatalytic performance of heterojunction nanocomposite materials with different doping ratios on the same condition. So as to select the best doping ratio catalyst, and we further tested the photocatalytic stability of it. The major research points are summarized as follows:
On chapter two, we prepared a series of photocatalyst including LaNiO3 nanoparticles, graphite carbon nitride g-C3N4 and LaNiO3/g-C3N4 heterojunction nanocomposites, the mass doping ratios of g-C3N4 were 20,30,40,50,60,70 and 80%，respectively, and named LNCN2-LNCN8 in turn. The series of catalysts were characterized by several means for their properties and tested the performance of hydrogen production under the irradiation of ultraviolet light (λ = 250 ~ 380 nm). The test results showed that the photocatalytic activity of the LNCN series had been significantly improved. Among them, LNCN7 had the high photocatalytic hydrogen evolution rate of 678.5 μmol?h-1?g-1, and the total hydrogen production in 5 hours was 3392.5μmol ? g-1 which was about 5 times than that of pure LaNiO3. LNCN7 also performed good stability in long-term photocatalyst test.
Chapter three synthesized another series of LaNiO3/g-C3N4 materials. The mass doping ratios of LaNiO3 were 1, 2, 4, 8, 10, 12, 20, 80%, respectively. They were named CN1-CN20 in turn. We had studied their photocatalytic performance under the irradiation of visible light (λ = 400 ~ 780 nm). The results showed that some doped materials had slight improvement compared to pure g-C3N4. CN2 catalyst had a high H2 evolution rate of 1517.0μmol ? h-1 ? g-1 and the total hydrogen production reached 7584.9μmol ? g-1 after 5 hours. In long-term photocatalyst stability test, CN2 also performed well.
Finally, we put forward Z-type carrier transfer mechanism of LaNiO3/g-C3N4 heterojunction nanocomposite. In this photocatalytic system, the Z-type carrier transfer pathway can enable photo-generated electrons or holes to be transferred from one semiconductor to another semiconductor. Thereby reducing the recombination rate of carriers, obtaining better charge separation efficiency and wide photo response region. Thus resulting in the enhanced photocatalytic properties.