高度交联多孔掺杂氧化锡/铱基核壳结构复合氧析出反应催化剂及其协同机制

Proton exchange membrane water electrolysis is a highly efficient energy storage route which is stuck in the bottleneck during its industrialization process. Due to the sluggish kinetics of the oxygen evolution reaction (OER) on anode, the electrocatalyst excessively depends on the Ir or Ru precious metal. Even though used the noble metals, the stability still can’t meet our expectation. Therefore, it is very urgent to explore an efficient and superiorly durable Ir or Ru-lean electrocatalyst for OER. Here, from the view of composition and nanostructure, a highly cross-linked porous network of conductive support, M-doped SnO2 which would improve the mass and charge transfer will be fabricated at first, and then an Ir-transition metal oxide with core-shell structure will be anchored on the surface of the as-prepared support in order to enhance the intrinsic activity and tolerance with cost reduction. By adjusting synthesis parameters, the template, the ratio of M to Ir and so on, a formation mechanism and controllable synthesis protocol of the porous support and core-shell structure will be established. It is planned to probe the influence coming from the composition, pore size, surface area and conductivity of support, and the component, depth and crystal structure of the core-shell catalyst on the activity and stability. The impact mechanism on OER kinetics and stability caused by the charge transport, microstructure and solid-liquid interface features will also be investigated. Furthermore, the synergic effect between the support and active component will be focused on by making the activity-stability trend clear. The results will provide theoretical and experimental basis for designing and screening the advanced OER catalysts.

质子交换膜水电解是一种高效的能源存储方式，其发展的瓶颈是阳极氧析出反应（OER）动力学缓慢，催化剂依赖于Ir、Ru等贵金属且稳定性也不理想。开发高效稳定的低贵金属催化剂是关键。本研究从组成与纳米结构出发，首先构建高度交联多孔M（Sb, In, F）掺杂SnO2导电骨架促进传质与电荷传导，然后负载具有核壳结构的Ir-过渡金属（Co, Fe, Sn等）氧化物以提升本征活性与稳定性，同时降低成本。通过改变模板剂、Ir与过渡金属配比等参数，获得多孔载体与核壳结构的形成机制与微结构控制方案；考查载体组成、孔径、表面积、电导率及催化剂核壳层组成、厚度、晶面结构等对活性与稳定性的影响；探讨载体与活性组分间的电荷传输机制、微结构特性、活性组分的固-液界面特性等对OER动力学及稳定性的影响机理；通过比较活性-稳定性趋势，探讨载体与活性组分的协同作用机制，以期为OER催化剂的科学设计与开发提供一定的理论基础。

氧析出反应（OER）是许多能源存储与转化过程的关键反应，其动力学缓慢，需要高效稳定且低成本的催化剂进行催化。尽管Ir及其氧化物是目前优良的OER电催化剂，但储量稀少和高昂的价格制约了其大规模应用。因此，设计极低Ir含量或非贵金属OER催化剂对于清洁能源转化与存储意义重大。本研究从调控组成与构建多孔纳米复合结构两个角度，设计合成了系列负载型Ir基电催化剂，包括meso-Sb-SnO2/IrO2，TiN/IrO2与Co3.2Fe0.8N/Ir以及Co3.2Fe0.8N、Co3.2Fe0.8N/MNC、二维异质结构NF/CoMoP/NiFe-LDH等高活性的非贵金属电催化剂。提升催化活性的方法主要有：多孔导电骨架的分散效应及高效的传质与电荷传导、第二种过渡金属的电子调控作用促进反应中间体的吸/脱附过程、二维纳米片构成的交联多孔结构提供高密度且暴露的活性位点、过渡金属引入新的反应位点、复合结构中各种界面的化学耦合与协同作用等。在所得的系列电催化剂中，TiN/IrO2（31wt%）具有最高的质量归一化活性（1.6 V时为874.0 A g-1IrO2，是纯IrO2的5.0倍（176.0 A g-1IrO2），超过绝大部分文献结果。其他复合催化剂也具有接近或超过文献值的高催化活性，如Co3.2Fe0.8N/MCN（ηOER@10mA cm-2=350 mV，ηHER@10mA cm-2= 315 mV，E1/2,ORR=0.846 V, 1 M KOH）、Co1Ni1@NC（ORR/OER, △E=0.91 V, 0.1 M KOH）及NF/CoMoP/NiFe-LDH（ηOER@50mA cm-2=225 mV，ηHER@10mA cm-2= 98.9 mV）。此外，Co3.2Fe0.8N/Ir在酸性电解质中具有最佳的OER稳定性，为非贵金属在酸性水电解中的应用开拓了新的思路，同时NF/CoMoP/NiFe-LDH电极也具有27 h以上的长期操作稳定性。我们的研究表明，通过上述方法，可以实现贵金属甚至非贵金属对于能源相关反应的高效催化活性与稳定性，从而为电催化材料的设计提供参考。