复合固体推进剂是一种固体颗粒(氧化剂及金属燃料)填充高分子聚合物(粘合剂)的复合材料，是导弹、空间飞行器的各类固体发动机的动力源。本实验教学针对固体推进剂在载荷下容易发生“脱湿”，即粘合剂与填料表面之间分离，界面作用受到破坏的情况，通过可控自由基聚合设计了结构规整、分子量及组成可控的新型中性大分子键合剂，通过核磁氢谱及凝胶渗透色谱系统表征了其分子结构。本综合实验教学不仅加深了学生对固体推进剂领域的理解，提升了学生对于前沿高分子化学的基本原理及方法的认知，而且训练了学生的实验操作技能、大型仪器使用能力和结果分析能力，实现了前沿科学研究与国家重大需求在人才培养的结合。

Photoelectrochemical water splitting using semiconductor materials is one of the most promising methods for converting solar energy into chemical energy. Among the commonly used semiconductors, p-type CuBi₂O₄ is considered one of the most suitable photocathode materials and can allow a theoretical photocurrent density of about 20 mA·cm⁻² for photoelectrochemical water splitting. However, due to severe charge carrier recombination, the obtained photocurrent density is much lower than the theoretical value. Highly efficient photoelectrochemical performance relies on fast charge carrier separation and transport, and prompt reaction kinetics. In this study, we report the development of a polyoxometalate-modified CuBi₂O₄/Mg-CuBi₂O₄ homojunction photocathode to improve both the bulk and interfacial charge carrier transport in the photocathode. For the bulk of the photocathode, the built-in electric field originating from the CuBi₂O₄/Mg-CuBi₂O₄ homojunction promotes the migration of photo-excited electrons on the conduction band from pure CuBi₂O₄ to Mg-doped CuBi₂O₄. Additionally, the electric field facilitates the transfer of holes from the valence band of Mg-doped CuBi₂O₄ to pure CuBi₂O₄. This directional transfer of both photo-excited electrons and holes plays a significant role in promoting separation and suppressing the recombination of the charge carriers. On the surface of the photocathode, the reduced polyoxometalate co-catalyst Ag₆[P₂W₁₈O₆₂] (AgP₂W₁₈) was used as a proton sponge to accelerate surface reaction kinetics and suppress carrier recombination. These synergistic effects improved the photo-generated charge carrier transfer and reaction kinetics. As a result, the novel photocathode displayed excellent photoelectrochemical properties, and the photocurrent density was observed to be −0.64 mA·cm⁻² at 0.3 V vs. RHE, which is better than that of −0.39 mA·cm⁻² for a pure photocathode. Furthermore, the novel photocathode had an applied bias photon-to-current efficiency (ABPE) higher than 0.19% at 0.3 V vs. RHE. In contrast, the pure photocathode had an ABPE of ~0.12% under the same conditions. Additionally, when H₂O₂ was used as an electron scavenger, the photocurrent density was −3 mA·cm⁻² at 0.3 V vs. RHE, which is an improvement of approximately 1.5 times compared to the pure photocathode. Furthermore, the charge separation and charge injection efficiency of the novel photocathode were significantly improved compared with the pure photocathode. The experimental results conclusively indicate that the formation of the CuBi₂O₄/Mg-CuBi₂O₄ homojunction and AgP₂W₁₈ modification played a significant role in the improved performance of the CuBi₂O₄ photocathode. The performance of the novel photocathode was comparable with the results reported in previous studies, demonstrating its promising potential in real applications.