Co3O4-Co2P自支撑多孔梯度膜结构调控及其析氧性能强化机制

Co3O4 is the most promising oxygen evolution reaction (OER) catalytic material to be practically applied. As the present Co3O4 is mostly powdery, adhesion agent should be coated on the substrate, which would make the structure and composition of the catalyst uncontrollable. And the binder coating would cast off due to the strong attack of bubbles. Therefore, it’s desirable to develop self-supporting porous films to improve the oxygen evolution properties. Co3O4-based film has the defects of low conductivity, single electronic structure and weak binding force, and it’s hard to meet the demand of practical industrial application as the OER performance is restricted by the structure of materials. In this research, the phase structure of CoP self-supporting porous film was adjusted by using phase separation-selective oxidation heat treatment method. The formation mechanism of Co-Co2P gradient film was analyzed, through exploring the effect of phase separation-oxidation heat treatment on the phase structure evolution and the diffusion behavior of P during phase separation process. The influence rules of oxidation heat treatment on the phase structure evolution of Co, Co2P and Co-Co2P were studied. Selective oxidation mechanism was illustrated and the phase structure controllable regulation of Co3O4-based self-supporting porous film was realized. The correlation of the phase structure gradient and physical-chemical properties (binding force, conductivity, oxygen vacancy), oxygen evolution properties of Co3O4-based self-supporting porous film was researched. And the strengthening ORE mechanism of phase gradient structure was analyzed, which provided theoretical basis and technological guidance for designing new-type oxide-based OER catalytic electrode with high efficiency and stability.

Co3O4是最有望应用的析氧催化剂，而现有Co3O4主要为粉末状，需加入粘结剂涂覆到基底上，导致催化剂表面结构、成分不可控，粘结剂涂层难以承受强烈气泡冲击而脱落。因此，需开发自支撑多孔膜提高析氧性能。由于Co3O4自支撑膜电导率低、电子结构简单、结合力差，其析氧性能提高仍受限于材料结构，难以满足工业化需求。本项目提出利用相分离-选择性氧化热处理调节CoP自支撑多孔膜相结构新方法，通过考察热处理工艺对相结构演变作用规律，掌握相分离过程中P元素扩散行为，分析Co-Co2P梯度膜生成机制；通过研究氧化热处理对Co、Co2P及Co-Co2P相演变影响规律，阐明选择性氧化机制，实现Co3O4-Co2P自支撑多孔梯度膜相结构可控调节；研究自支撑多孔膜相结构与其物化性能（结合力、电导率和氧空位）和析氧性能关联性，解析相结构强化析氧机制，为制备自支撑多孔梯度膜高效、稳定析氧电极提供理论基础和技术指导。

铁族金属基（主要为铁、钴、镍）自支撑多孔梯度膜结构、组分可控，导电性好，活性高，无需粘结剂，跟基底具有良好的结合力，展现出高效、稳定的电化学活性。本项目发展了气泡模板法电沉积-相分离热处理-（选择性刻蚀）-选择性氧化热处理制备调控铁族金属基自支撑多孔膜电催化电极多结构的新方法。围绕热处理工艺条件等对电沉积的铁族基自支撑膜相结构、元素组成和形貌等的作用规律开展研究，研究了溶液pH、添加剂和超声外场等对电沉积铁族合金薄膜多结构的作用规律，认识了不同铁族合金多孔薄膜相结构热力学和动力学调节规律，明确了薄膜中各元素的迁移和物相演变历程，确定了自支撑膜相分离、选择性刻蚀和选择性氧化实质；重点以电沉积的CoP、FeP等单金属磷化物合金和NiCoP双金属磷化物合金为对象，进行相结构调控，及其多结构与电化学性能（析氧、析氢和储锂性能等）构效关系研究。通过相分离和氧化热处理，制备了多相结构梯度膜，实现了铁族金属合金相结构分布精准调控，解析了不同铁族金属元素合金相分离，选择性刻蚀和选择性氧化过程中相结构（如尖晶石结构等）和元素分布演变的调节规律与机制，及其对自支撑膜微观结构演变的影响规律；在系统研究的基础上，解析了电沉积-相分离热处理-（选择性刻蚀）-选择性氧化热处理法制备和调控自支撑多孔梯度膜结构的共性科学机制，掌握了制备铁族金属基各类型自支撑多孔梯度薄膜的通用方法；在此基础上制备了高效稳定的铁族金属基自支撑多孔梯度薄膜析氧、析氢和储锂电极。研究成果将为发展铁族金属基自支撑多孔梯度薄膜的普适性方法和实现其在能源存储与转化器件中的应用，奠定理论基础和技术支撑。本项目总计发表期刊论文16篇，其中SCI论文15篇（最高单篇IF29.369）；在国外学术会议上口头报告2次；申请发明专利1项。