不断增长的能源需求与有限的全球化石燃料之间存在着激烈的冲突，开发可持续能源是人类面临的最紧迫的任务之一。考虑到氢气清洁、绿色的特性，在太阳光照下，通过半导体光催化剂进行光催化析氢反应对于缓解当下能源和环境危机具有重要意义。然而，传统的光催化制氢技术通常需要牺牲剂来降低氧化半反应的能量势垒从而提高析氢速率，导致光生载流子能量的浪费并产生无用副产物，造成整体经济效率下降。利用光生空穴进行特定的有机物转化反应不仅可以实现能量的最大化利用，也可以使整个制氢过程更具有经济价值。
       基于以上考虑，本论文设计了一种双功能光催化系统，实现制氢的同时进行硫醇的转化。该系统质子还原的氢气将自动逸散至气相，硫醇氧化的产物则留在液相，从而实现了生成物的快速分离，抑制逆反应的发生，提升了反应效率。论文的主要研究内容包括以下部分：
     （1）采用简单的溶剂热和煅烧法，成功制备了一系列Ni2P负载的具有异质结结构的CdS/P25/Ni₂P（SOP）光催化剂，并运用多种表征手段对其进行了详细的研究。考察了SOP在光催化产氢耦合硫醇分子间偶联转化反应中的活性，结果表明，最优的pH = 9，最优催化剂为CdS与P25/Ni₂P摩尔比为1:1时形成的复合催化剂S₁O₁P，转化率和选择性分别为97.47%和100%。此外，S₁O₁P还表现出良好的可见光光催化活性和普适性。将底物的浓度扩大到300 mM进行光催化实验，转化率仍然高达83.81%，表观量子产率AQY = 3.92%，产氢速率高达16697.86 μmol·g_cat^-1·h^-1。根据电化学表征、电子顺磁共振和同位素标记的结果提出了光催化产氢耦合硫醇分子间偶联转化的反应机理。
     （2）以具有双巯基的DL-二硫苏糖醇（DTT）为反应底物，考察了SOP在光催化产氢耦合硫醇分子内偶联转化反应的活性。结果表明，最优pH = 6，最优催化剂为S₁O₁P，最佳化剂用量为50 mg，转化率和选择性均为100%，产氢速率高达9949.4 μmol·g_cat^-1·h^-1。同样对DTT的浓度进行扩大实验，结果产率不升反降，这表明高浓度下DTT的转化存在分子内成环与分子间链聚合反应的竞争。此外，还进行了DTT与L-半胱氨酸混合溶液的反应，结果表明多组分下DTT仍是分子内偶联转化。根据EPR与同位素标记法等实验结果，提出了光催化产氢耦合硫醇分子内偶联转化的反应机理。
       本文设计制备了一种不含贵金属的双功能光催化剂，提出了充分利用光生载流子的策略，并从实际应用的角度出发，进行了底物扩大实验，取得了令人满意的成果，对光催化技术的发展具有一定的启发意义。
 

        Developing sustainable energy resources is one of the most urgent missions for human beings as increasing energy demand is in drastic conflict with limited global fossil fuels. Photocatalytic hydrogen evolution through semiconductor photocatalysts under sunlight irradiation is of great significance in alleviating the current energy and environmental crisis, considering the clean and green characteristics of hydrogen. However, the conventional photocatalytic hydrogen production technologies generally require sacrifices to reduce the energy barrier of oxidation half reaction for increasing hydrogen evolution rate, resulting in the waste of photogenerated carriers, generation of useless by-products and decline of whole economic efficiency. Using photogenerated holes to carry out specific conversion of organics can not only maximize solar energy but also make the whole process of hydrogen production more economically valuable.

        Based on the above considerations, a dual-functional photocatalytic system that can simultaneously achieve hydrogen production and thiol conversion was developed in this article. The hydrogen gas generated by this system will automatically escape to the gas phase, while the products of thiol conversion will remain in the liquid phase, thus achieving rapid separation of the products and suppressing the occurrence of reverse reactions, thereby improving the reaction efficiency. The main research contents of this paper include the following parts:

       (1) A series of Ni₂P-loaded CdS/P25/Ni₂P (SOP) photocatalysts with heterojunction structures were successfully prepared by a simple solvothermal and calcination method, which were investigated detailedly using a variety of characterization methods. The activity of SOP for photocatalytic hydrogen evolution and simultaneously intermolecular-converting thiols into disulfides was inspected. The results show that the the optimal pH, best photocatalyst, conversion and selectivity of this system are 9, S₁O₁P (molar ratio of CdS to P25/Ni₂P is 1:1), 97.47 and 100%, respectively. In addition, S₁O₁P also exhibits favourable photocatalytic performance under visible light and universality. The substrate concentration was expanded to 300 mM to carry out photocatalytic experiments, which significantly exceeded that of the usually reported benchmark for photocatalysis. The conversion of MPA is 83.81% and the apparent quantum yield AQY = 3.92% as well as the rate of hydrogen evolution reaches up to 16697.86 μmol·g_cat^-1·h^-1. Based on the results of electrochemical characterization, electron paramagnetic resonance (EPR) and isotope labeling, a possible mechanism of photocatalytic hydrogen evolution coupled with the intermolecular value-added coupling conversion of thiols has been proposed.

        (2) DL-dithiothreitol (DTT) with two sulfhydryl groups was used as the modal substrate to investigate the reaction activity of SOP for photocatalytic hydrogen evolution paired with the intramolecular value-added coupling of dithiols. The results show that the optimal pH of this system is 6 and the best photocatalyst formula is S₁O₁P as well as the dosage of photocatalyst is 50 mg. The conversion and selectivity of this reaction are both 100%. The rate of hydrogen evolution can reach up to 9949.4 μmol·g_cat^-1·h^-1. Similarly, the concentration of DTT was amplified in the experiment, however, the yield reduced instead of rising as expected. The above results show that the coupling of DTT in the high-concentration is a competitive process between intramolecular ring formation and intermolecular chain polymerization. Moreover, the reaction of mixed solution containing DTT and L-cysteine has been performed, indicating that the conversion of DTT is still an intramolecular coupling reaction in the multicomponent. Based on the results of EPR and isotope labeling, a possible mechanism for photocatalytic hydrogen evolution paired with the intramolecular value-added coupling conversion of dithiols has been proposed.

        A dual functional photocatalyst without precious metals was prepared and a strategy for making full use of photocarriers was provides in this paper. The experiments of high substrate concentration were carried out from the perspective of practical applications for photocatalysis technology achieving satisfactory results. This work will be inspirational for the development of photocatalysis technology.