活化氮气分子用于常温常压下合成氨的缺陷电催化剂研究

In order to achieve ammonia synthesis from N2 reduction through electrocatalytic method at ambient condition but not unsustainable Haber-Bosch way, the key issue is catalysts. However, in almost all of the related publications, the current efficiency for ammonia synthesis in aqueous solution is quite low due to the predominant H2 evolution. To address the scientific issue, we propose that the catalysts which are sluggish to H2 evolution and able to activate N2 with the presence of defects may work well. In initial exploration, it is found that TiO2 with oxygen vacancy has such two functions. Preliminary results show that the Faradaic efficiency of ammonia synthesis in aqueous solution under ambient condition for this catalyst is better than the most data published in literatures. To apply the rule for this new catalyst to the design and preparation of new and highly efficient electrocatalysts for ammonia synthesis, we will optimize all of the experimental conditions for the electrocatalytic process over the TiO2 with oxygen vacancy. Additionally, the controllable preparation of TiO2 with different nanostructures and defects, and the relationship between the structure and performance for the different prepared TiO2 will be explored. Furthermore, the mechanism for the activation of N2 molecular by catalyst defects and the effect of N2 activation on the ammonia synthesis will be investigated theoretically and experimentally. Based on the above study, several new and efficient non-noble metal electrocatalysts with defects are expected to be prepared for ammonia synthesis. As such, we hope that this proposal can provide the base for future practical application of sustainably electrocatalytic ammonis synthesis under ambient condition.

为了实现N2还原合成氨从不可持续的Haber–Bosch法到可再生的常温常压电催化法的飞跃，高效的催化剂是关键。然而已报道的水溶液体系中电催化剂都因有利于H2析出而使合成氨的电流效率低下，为了解决该科学问题，本申请项目提出使用能抑制H2析出并活化N2分子的缺陷电催化剂，并发现带有氧空位（OVs）的TiO2能同时实现上述两种功能，初步实验结果显示该电催化剂常温常压下合成氨的电流效率高于绝大多数水溶液体系固氮文献中的数据。为了将其规律应用于新型高效合成氨电催化剂的研制，本申请项目拟系统优化含有OVs的TiO2电催化合成氨的实验条件，研究不同纳米结构和不同表面缺陷结构TiO2的可控制备及其构效关系，从理论和实验两方面深入探讨OVs以及其他缺陷活化N2分子的机理及其对合成氨反应过程的影响规律，并在此基础上研制出几种高效的缺陷非贵金属电催化剂，为未来常温常压下电催化合成氨的规模化应用提供理论依据。

为了实现未来的“双碳”目标，本项目系统研究了电解水和电催化还原CO2中必需的高效稳定催化剂，即构筑和研究了纳米结构电催化材料用于分解水/海水制氢和产氧，深入探索了电、光电和光催化还原CO2的催化剂。并额外创制了新型储能器件，探讨了水系锌离子电池活性和稳定性增强的规律。取得的重要结果如下：1）针对能耐受海水腐蚀的高效稳定催化剂非常缺乏的难题，我们在泡沫Ni基底上制备了NiMoN@NiFeN三维核壳纳米结构电极，该电极在电解海水的OER过程中表现出优异的电催化活性和稳定性。将该OER催化剂和HER催化剂NiMoN组合搭建了碱性电解槽用于全分解海水，在60℃、电流密度达到工业要求的500和1000mA/cm2时，所需电压仅分别是1.608和1.709V，该性能优于当时所有全分解海水的电解槽。该工作发表在了Nat. Common.上，被引用了390次，入选ESI热点和高被引论文。此外，我们还创制了铁修饰的羟基硫化镍纳米片阵列催化剂，该催化剂中的S原位析出加速了电极自重构，促进生成了高活性的高价镍（Ni4+），从而促发晶格氧机理，最终导致该催化剂能够在商用电流密度下稳定工作1100小时，并在碱性海水中、500mA/cm2下稳定运行超过了900小时，具有很好的应用前景。该工作发表在了Energy Environ. Sci.上。2）针对含氧铜的结构不清晰，其有利于C-C耦合的机理不明确等问题，我们利用具有分级孔和富晶界的CuO前驱体成功合成了稳定的非典型含氧铜结构，通过一系列原位和准原位材料表征技术和方法，发现其为亚稳态低值氧化铜Cu4O，该结构有利于C-C偶联以及二聚反应。该工作发表在J. Am. Chem. Soc.上，入选ESI高被引论文。3）我们提出了“整合电容”的新概念，并首次报道了在溶液体系中实现可逆循环的高性能铜锌电池。本项目的研究结果在SCI源刊物上发表了35篇论文，并被引用超过1800次。并申请了6项发明专利，有2项已获得授权。