Wang Lina, Du Ruofei, Liang Xiao, Zou Yongcun, Zhao Xiao, Chen Hui, Zou Xiaoxin
State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, 130012, China.
Key Laboratory of Automobile Materials of MOE, School of Materials Science and Engineering, Jilin University, Changchun, 130012, China.
Adv Mater. 2024 Apr;36(16):e2312608. doi: 10.1002/adma.202312608. Epub 2024 Jan 12.
Improving catalytic activity of surface iridium sites without compromising catalytic stability is the core task of designing more efficient electrocatalysts for oxygen evolution reaction (OER) in acid. This work presents phase transition of a bulk layered iridate NaIrO in acid solution at room temperature, and subsequent exfoliation to produce 2D iridium oxide nanosheets with around 4 nm thickness. The nanosheets consist of OH-terminated, honeycomb-type layers of edge-sharing IrO octahedral framework with intrinsic in-plane iridium deficiency. The nanosheet material is among the most active Ir-based catalysts reported for acidic OER and gives an iridium mass activity improvement up to a factor of 16.5 over rutile IrO nanoparticles. The material also exhibits good catalytic and structural stability and retains the catalytic activity for more than 1300 h. The combined experimental and theoretical results demonstrate that edge Ir sites of the layer are active centers for OER, with structural hydroxyl groups participating in the catalytic cycle of OER via a non-traditional adsorbate evolution mechanism. The existence of intrinsic in-plane iridium deficiency is the key to building a unique local environment of edge active sites that have optimal surface oxygen adsorption properties and thereby high catalytic activity.
在不影响催化稳定性的前提下提高表面铱位点的催化活性是设计更高效的酸性析氧反应（OER）电催化剂的核心任务。这项工作展示了块状层状铱酸盐NaIrO在室温下于酸性溶液中的相变，以及随后的剥离过程，从而制备出厚度约为4纳米的二维氧化铱纳米片。这些纳米片由具有本征面内铱缺陷的、以OH为端基的、边缘共享的IrO八面体框架的蜂窝状层组成。这种纳米片材料是已报道的用于酸性OER的最具活性的Ir基催化剂之一，与金红石型IrO纳米颗粒相比，其铱质量活性提高了16.5倍。该材料还表现出良好的催化和结构稳定性，并能保持催化活性超过1300小时。实验和理论相结合的结果表明，该层的边缘Ir位点是OER的活性中心，结构羟基通过非传统的吸附质演化机制参与OER的催化循环。本征面内铱缺陷的存在是构建具有最佳表面氧吸附性能从而具有高催化活性的边缘活性位点独特局部环境的关键。
