过渡金属原子掺杂激活二维氧化钛电催化析氧性能的研究

Fabrication of low-cost and efficient electrocatalysts for oxygen evolution reaction (OER) is one of the key issues in the scale-up deployment of electrochemical water splitting or CO2 reduction for the renewable energy storage and conversion. Recently, two-dimensional metal oxides (2D-MO) have attracted numerous research interesting in many electrocatalytic reactions, which usually exhibit superior catalytic performance compared with the micro- and nanostructured catalysts due to their unique physicochemical properties. However, the understanding in the intrinsic microsturcture of 2D-MO, and their dependence on the electrocatalytic activity for OER still remained a challenge task, which strongly hindered their further practical application. In this study, the electrochemical oxidation-toleranced 2D-titanium oxide catalysts (2D-M-TiO2，M=Cr、Mo、Mn、Fe、Co) will be prepared by bottom-up exfoliation of layered titanate with transition metal dopnants. The crystal microstructure of 2D-M-TiO2, in particular the activation centers contained with transition metal sites, and their interaction with 2D-titanium oxide support will be comprehensively investigated by spherical aberration-corrected transmission electron microscopy (AC-STEM) and X-ray absorption spectrum based on synchrotron radiation (XAFS). Then, combined with the results of electrochemical testing and theoretical simulations, the mechanism about the effect of microstructure of 2D-M-TiO2 on their OER electrocatalytic performance will be revealed. Finally, the significant optimization of the OER electrocatalytic performance of 2D-M-TiO2 could be achieved through designing and tuning their microstructure. It is expected that this study might provide an efficient and universal approach to develop a series of novel and more practical 2D non-noble metal active materials for OER electrocatalysis, which have important implications for both basic research and industrial applications.

开发廉价高效的电催化析氧（OER）活性材料对发展电解水制氢、CO2还原等清洁能源技术至关重要。近年来，二维金属氧化物（2D-MO）由于其物化性质独特，在各种电催化反应中展现出了优异性能。然而，目前对该类型材料的微观结构与OER催化特性之间的关联缺乏深入理解，这阻碍了2D-MO在OER催化中的进一步发展。本项目拟通过剥离过渡金属原子掺杂的层状钛酸盐，自上而下地制备一系列新型二维氧化钛基催化剂（2D-M-TiO2，M=Cr、Mo、Mn、Fe、Co）；应用球差校正扫描透射电子显微镜和同步辐射X射线吸收精细结构谱等实验技术对材料表界面原子结构和电子态进行分析，系统研究其OER性能；结合理论计算探究反应活性位点，分析反应中间体在该材料表面的吸附行为及反应路径，揭示微结构与催化活性之间的关联规律，为发掘及强化其OER催化性能提供思路；此项研究将为发展高性能二维OER催化剂提供一定的理论依据和实践指导。

开发廉价高效的电催化析氧（OER）活性电极对发展电化学制氢、CO2还原等清洁能源技术至关重要。近年来二维结构催化材料由于其独特的物化特性，在诸多电催化反应中展现出了不同于普通纳米催化剂的优异性能。然而，1）目前对该型材料的本征微观结构与其析氧催化特性之间的内在关联缺乏深入理解，2）多数研究仅集中于催化剂开发，对不同尺度下电极结构与反应体系对OER催化性能的影响规律却鲜有探究，这极大阻碍了现有OER活性电极的发展与实际应用。.针对上述问题，本项目1）通过剥离过渡金属原子掺杂的层状钛酸盐，制备一系列二维氧化钛基催化剂（2D-M-TiO2，M=Cr、Mo、Mn、Fe、Co）；以2D-Co-TiO2为前驱体，通过热诱导相分离法制备了高氧化态的亚纳米CoOx团簇，其取代性掺杂在金红石型TiO2载体（Co-TiO2）的晶格中。Co-TiO2对电催化OER表现出较为优异的本征催化活性和稳定性；其中，Co位点与相邻Ti原子之间形成了大量的电荷传导，诱导形成高效Co-Ti协同催化中心并对中间体具有更为合理的吸附能，从而降低了O2生成能垒。2）通过在镍纳米棒阵列（Ni-NRAs）上化学沉积二维过渡金属物种，制备了具有自支撑结构的Ni/Ni-M（M=Fe，Co，Mo）双金属氧化物核/壳纳米棒阵列电极；NRAs结构有效提升了电催化阳极的电荷转移效率和电化学活性表面积（ECSA），在相同的Ni-M双金属活性位点负载条件下，其催化电流约为传统碳纸基气体扩散电极的2-6倍。3）通过原位拉曼光谱，深入解析了Ni基界面上电催化OER与醇类氧化（AOR）之间存在的协同互补机制；OER为阳极氧化提供了关键活性位点NiOOH；而AOR则大幅提升了催化界面的电化学氧化稳定性；在OER与AOR并存的反应体系下，电催化阳极整体效率可达到较高水平。上述研究将为设计构建高性能非贵金属OER催化电极提供理论依据和实践指导。