纳米多孔镍/镧基钙钛矿氧化物复合材料的形成机制及其电催化析氧性能研究

Perovskite oxides are excellent candidates for oxygen evolution reaction (OER) electrocatalysts, due to their tunable compositions and physicochemical properties, high intrinsic OER catalytic activity, as well as low cost. However, their inferior electronic conductivity and low specific areas restrict the release of their activity. It is expected to improve the activity and stability of the catalysts, by constructing nanoporous metal/perovskite oxide electrocatalysts with the assistance of high electronic conductivity and special three-dimensional structure of nanoporous metals. In this project, nanoporous Ni with tunable channel sizes will be synthesized via dealloying. We will investigate the formation behavior of La-based perovskite oxide in the confined space of nanoporous Ni with various sizes, as well as the structure evolution of nanoporous Ni during the phase formation of perovskite. Moreover, through analyzing the element diffusion and phase compositions in the boundaries between two materials, the formation mechanism of the composite will be revealed. By probing the structural features and OER performance of the composite, we will study the inherent relationship between OER activity and microstructures, compositions, as well as boundary phases. Based on the results, the synergistic effect of the two materials towards OER will be clarified. The proposed results of this project will provide novel route of developing OER electrocatalysts based on perovskite oxides, and have great significance in reducing the cost of electrocatalytic water splitting.

钙钛矿氧化物具有成分和物化性能易于调节，本征析氧催化活性高，且成本低廉等优势，是优良的水分解析氧电催化剂。但同时也存在电子电导低、比表面积小等缺点，制约了其活性的释放。借助于纳米多孔金属较高的导电能力和独特的三维孔道结构，构建纳米多孔金属/钙钛矿氧化物复合材料，可赋予催化剂更高的活性与稳定性。本项目拟通过脱合金法，获取孔道尺寸可调的纳米多孔镍，通过复合镧基钙钛矿氧化物，阐明钙钛矿在不同孔径镍限域空间的生长规律，以及纳米多孔镍在钙钛矿成相过程中的结构演化；探究两种材料界面间元素互扩散与界面相组成，揭示复合材料的形成机制。利用电化学手段，结合材料结构特征，探明此复合材料的微观结构、组分、界面相组成等因素与析氧电催化活性的内在关联，揭示其电催化协同作用的根源。本项目的顺利开展将为开发基于钙钛矿氧化物的析氧催化剂提供一种新途径，对降低电催化水分解成本具有重要意义。

钙钛矿氧化物具有成分和物化性能易于调节，本征析氧催化活性高，且成本低廉等优势，是优良的水分解析氧电催化剂。借助于纳米多孔金属或金属纳米颗粒较高的导电能力和电催化性能，构建纳米金属/钙钛矿氧化物复合结构，可赋予催化剂更高的活性与稳定性。本项目围绕纳米多孔金属和钙钛矿氧化物，首先探讨了自支撑纳米多孔金属箔的设计；其次研究了纳米多孔金属以及纳米金属颗粒在与钙钛矿氧化物复合时的界面效应，揭示了钙钛矿氧化物和纳米金属之间的相互作用以及电催化增强机制；最后扩展到钙钛矿氧化物的结构调控上，揭示高价金属掺杂等因素对其结构和催化性能稳定性的影响。在纳米多孔金属箔的设计上，通过表面合金化-脱合金法，获得了纳米柱阵列结构的镍箔和纳米多孔结构的铜箔，为复合镧基钙钛矿氧化物奠定了基础；在纳米金属与钙钛矿氧化物的复合上，通过实验结合计算机模拟，阐明了钙钛矿B位元素对钙钛矿脱溶过程的影响，发现Ru元素掺杂可以促进B位金属颗粒析出，形成纳米合金颗粒/钙钛矿氧化物复合结构，获得较高的电催化OER性能提升；在纳米多孔Ag与钙钛矿氧化物复合的研究中，发现通过热处理可实现多孔金属和钙钛矿氧化物之间界面处元素扩散，从而形成高活性界面，有助于电催化活性的提升；最后探讨高价元素掺杂对钙钛矿氧化物稳定性的影响，通过实验结合DFT计算，探讨稳定性增强的根本原因，发现O 2p带中心的降低和Co 3d-O 2p共价键的减弱是钙钛矿稳定性增强的内在原因。本项目的成功开展为开发基于钙钛矿氧化物的析氧催化剂提供了指导方向，对深入研究钙钛矿氧化物的催化机理打下一定的理论基础。