人类工业化进程的高速发展是一把双刃剑，给人类生活带来便利的同时，也不可避免的对环境造成了损害。例如，化石燃料的大量燃烧，不仅造成不可再生能源的耗竭，大量排放的CO₂还引发了严重的温室效应。面对当下能源耗竭与环境失调的问题，平衡工业发展与环境保护是人类健康发展的重要前提。由此，开发新型可再生能源，基于催化反应促进CO₂还原，早日达成“碳达峰，碳中和”，成为当下解决该失衡问题的必由之路。值得一提的是，设计具有高效活性的催化剂以加速反应过程，明确催化剂的催化机理，对催化剂进行优化改进，以获得性能更优的催化剂，显得尤为重要。基于此，为了获得性能优异的催化剂，开展绿色催化应用研究，本文基于材料催化的调控电子途径，借助空位构建、金属掺杂、轴向配位等手段，综合开展纳米材料催化剂的性能调控，并基于多种分析表征手段，开展催化剂构效关系的探索，拓展其绿色催化应用研究。电子层面的微观研究可有效指导宏观催化性能的提升，将对设计高性能催化剂提供有效参考。

本论文包含的主要内容如下：

1. 构建非金属原子掺杂阳离子Ti空位，通过氧桥促进光电催化析氧反应（OER）。首先以金红石型TiO₂为基底，在其表面进行阳离子Ti空位构造，制备了V_Ti-TiO₂。进而，对空位进行微量非金属元素P、S掺杂，得到了P-V_Ti-TiO₂和S-V_Ti-TiO₂。研究表明，本工作成功构建了Ti-O-P和Ti-O-S结构，其中O原子起到桥梁作用，在OER开始前可以富集周围原子的电子，在反应过程中将储存好的电子直接传递给活性位点Ti原子，继而进行后续反应。该过程有效提升了载流子数量，并改善了局域电子分布，加速了反应进程。基于AC-TEM、XRD和PAS等多种表征手段，证实了阳离子空位的成功构造。并且借助XPS和XAFS技术，证实了Ti原子的配位环境和原子之间的电子转移方向。此外，还结合DFT计算，解释了P-V_Ti-TiO₂、S-V_Ti-TiO₂之间由于给电子机制的不同而导致的性能差异。该工作揭示了非金属掺杂阳离子Ti空位的构效关系，并拓展了其在绿色催化领域的应用。

2. 基于金属Ni轴向配位Mn单原子，调控电子自旋重新排布，增强了二氧化碳还原反应（CO₂RR）。基于单原子负载率有待提升、电子结构仍需优化的现状，本工作通过双溶剂法，利用两种溶剂极性的差异以及MOF表面疏水、内部孔道亲水的性质，将金属Ni、Mn分别引入到Mn MOF、Ni MOF的内部，经高温煅烧形成双单原子催化剂Ni→Mn SAC、Mn→Ni SAC。基于球差电镜（AC-TEM）表征，证实金属以单个原子形式分散，并且没有引起原子聚集，有效提升了单原子的负载率。研究发现，该单原子催化剂中被引入的金属以轴向配位的方式与锚定金属位点的N原子成键，并且两种双单原子催化剂中被引入金属的配位方式存在差异。进一步，基于XPS、XAFS等技术的综合表征，证实了Mn→Ni SAC中引入的Mn均与周围的N成键，而Ni→Mn SAC中Ni与Mn配位的N成键，并与周围的C成键。这种不对称的配位方式有效调控了电子结构，诱发了活性位点3d轨道的电子重排。此外，XPS、sXAFS和VSM表征，证实了两种双单原子催化剂中Mn的价态没有改变，但不同价态的Ni可以不同程度地调控Mn的电子自旋排布状态，使其由低自旋向高自旋转变。该高自旋电子排布也通过DFT计算进行了验证。实验和计算均表明，这种调控有利于在CO₂RR过程中给出电子，有效促进了高附加值产物CH₄的产生。该工作不仅从微观角度解释了电子自旋调控对金属催化剂性能的高效调节作用，也拓展了其在绿色催化领域的应用。

The rapid development of human industrialization is a double-edged sword for human beings. It has brought significant convenience to human social life, while has inevitably caused damages to environments. For example, the burning of large number of fossil fuels has not only depleted non-renewable energy, but also induced serious greenhouse effect for emission of large amounts of CO₂. Given the current energy depletion and environmental imbalance, balancing the industrial development and environmental protection has become an important premise for human development. Consequently, the development and utilization of new renewable energy and the promotion of CO₂ reduction have become the crucial ways to solve the imbalance problem. This would facilitate to achieve the goal of “carbon peak and carbon neutrality” as soon as possible. What’s more, the design and preparation of catalysts with high activities, the revealing of reaction mechanism and the improvement of catalyst are particularly important. Therefore, in this thesis, to obtain the highly efficient catalysts for green catalysis applications, electron regulation of nanomaterials has been carried out upon series strategies, including constructing vacant sites, doping metallic elements, and metal axial coordination of single atoms. In addition, the structure-activity relationship of the catalysts has been explored by series of characterizations, which initiated the application of green catalysis. The fine structure-based examinations at the electronic levels would effectively guide the improvement of catalytic properties, obtaining the highly efficient catalysts for better applications.

The main contents of the thesis are as follows:

1. Doping nonmetallic atoms into cationic vacancies of the TiO₂ surface was successfully achieved to accumulate electrons via an oxygen bridge, facilitating the enhancement of the oxygen evolution reaction (OER) performance without bandgap change. Initially, Ti vacancies on the TiO₂ surface (V_Ti-TiO₂) was prepared by constructing cationic Ti vacancy structure on the surface of rutile TiO₂. Thereafter, P-V_Ti-TiO₂ and S-V_Ti-TiO₂ were prepared by doping of trace nonmetallic elements P and S at the V_Ti-TiO₂. As demonstrated, Ti-O-P and Ti-O-S structures were successfully constructed, in which O atom played a bridging role to enrich the electrons of the surrounding atoms. The stored electrons can be directly transferred to the active sites of Ti atoms for subsequent reactions. This effectively increased the number of carriers and improved the local electron distribution, efficiently accelerating the reactions. Based on AC-TEM, PAS and XRD characterizations, the successful construction of cationic vacancy was confirmed. In addition, XAFS and XPS characterizations have confirmed the coordination environment of Ti atoms and the direction of electron transfer between atoms. Besides, DFT calculations have revealed the different performance caused by the different electron donating mechanisms between P-V_Ti-TiO₂ and S-V_Ti-TiO₂. This work not only demonstrated the structure-activity relationship of nonmetallic atom-doped cationic Ti vacancies, but also enlarged their applications in the field of green catalysis.

2. Based on the Ni-axial coordination to Mn single atoms, the electron spin was regulated to enhance CO₂ reduction reaction (CO₂RR). Currently, the single atom catalysis is still encouraged to be improved by increasing loading rates of single atoms and improving electronic structures. Therefore, in this work, Ni and Mn were respectively introduced into the internal nanomaterials of Mn MOF and Ni MOF, based on the polarity difference of two solvents and properties of surface hydrophobic and internal pores hydrophilic of MOF. In this way, the nanomaterials of Ni→Mn MOF and Mn→Ni MOF were obtained, respectively. Thereafter, the double monatomic catalysts were calcined at high temperature to obtain the double-single atom catalysts of Ni→Mn SAC and Mn→Ni SAC. The dispersion of metal in the form of single atom was confirmed by AC-TEM, which effectively increased the loading ratio of single atom and did not cause the atomic aggregation. As demonstrated, the introduced monatomic metals were anchored to the metal sites through axial coordination to the around N atoms and the coordination modes of two catalyst were different. In addition, XPS and XAFS characterizations have revealed that the introduced Mn in Mn→Ni SAC was linked to the N in the upper and lower layers. However, in Ni→Mn SAC, Ni bound to both N of Mn coordination and the lower C. This efficiently regulated the electronic structures to induce the electron rearrangement of active metals. In addition, demonstrated by XPS, sXAFS and VSM characterizations, the valence state of Mn in the two double monatomic catalysts did not change. While the different valence states of Ni can regulate the electron spin configuration of Mn at different degrees, which induced electrons to a higher spin state. The corresponding configuration of high spin electrons has also been verified by DFT calculations. This was conducive to provide electrons in CO₂RR and effectively promote the production of CH₄ at high values. This work not only explored the efficient improvements of catalytic performance upon electron spin regulation, but also enlarged their applications in green catalysis.