氧化物表面结构调控常温常压电催化合成氨反应活性研究

Ammonia synthesis is among the most important processes in the chemical industry, leading to sustainable world food production for the human population. Today, a new challenge of ammonia synthesis lies in developing alternative approaches to the conventional Haber-Borch process, especially exploring the possibility of ammonia synthesis at ambient temperature and pressure. The introduction of electricity into ammonia synthesis under ambient conditions has attract much attention in recent years. However, a lack of catalysts with high activity and high selectivity hinders the progress of this field. Herein, we propose that nano-sized iron oxide can be used for electrochemical ammonia synthesis under ambient conditions and focus on the critical scientific issue of the relationship between structure and catalytic activity of such catalyst. Based on controllable synthesis of nano-sized iron oxide based materials, strategies including doping, defect engineering and crystal facet engineering will be used to realize the development of catalysts with specific surface structure. Hence, reasonable design and structure-property optimization of the catalyst material can be achieved through in-depth understanding of the relationship between surface structure and catalytic activity. This proposal may open a new avenue for the development of catalysts with both high reactivity and high selectivity toward artificial ammonia synthesis through a mild electrochemical approach and provide new insights into fundamental and practical aspects of this field.

合成氨是化学工业的重要支柱，为人类社会粮食的可持续供应提供了有效保障。寻找合成氨新方法，探索常温常压合成氨的可能性，是催化合成氨技术面临的新挑战。电能驱动下的常温常压合成氨是近年来备受关注的研究领域，然而具备高活性与高选择性的常温常压合成氨催化剂体系十分罕见。本课题提出采用纳米氧化铁催化剂体系实现常温常压电催化合成氨，并针对该催化剂体系的构效关系展开研究。基于纳米氧化铁的可控制备技术，通过掺杂、缺陷调控和晶面调控，实现具有特定表面结构的催化剂的制备；进一步通过对纳米氧化铁表面结构与合成氨催化活性之间关联的深入理解，实现对催化剂材料的合理设计与对结构和性能的优化。课题研究有望在基础与应用方面为开发具有高活性和高选择性的常温常压合成氨催化剂提供新思路。

合成氨工业是化学工业的重要支柱，改变了世界粮食生产的历史，奠定了多相催化和化学工程科学的基础。常温常压电催化合成氨是近几年来电催化领域的研究热点。本课题围绕氧化物纳米结构的可控合成与电化学合成氨催化性能的调控开展工作，实现了氧化铁纳米颗粒表面结构和表面缺陷的可控调控，建立了氧化物表面结构与电化学合成氨催化活性间的关联，据此对催化剂材料进行合理设计，构筑了氧化物纳米粒子-超薄碳层界面，提高了常温常压电催化合成氨催化剂的活性和选择性。复合催化剂在-1.0 V vs RHE下达到最佳氨氮产率7.56 μg h-1 cm-2，在-0.8 V vs RHE下达到最佳法拉第效率14.78%。从复合结构的设计角度为高性能电催化合成氨催化剂的制备提供新的思路和指导，从痕量氨氮定量检测手段的完善方面（NMR 1H谱定量测定15N铵根离子浓度0.01 ppm至0.1 ppm范围内）为氮气还原合成氨反应的评测提供了有力支撑。