一维铱基氧析出催化剂氧空位的调控及其在质子交换膜水电解中应用研究

The proton exchange membrane water electrolysis (PEMWE) has been regarded as one of the most potential technology in hydrogen production due to its high efficiency, high purity and environment-friendly feature. However, the high anodic overpotential, unsatisfactory stability and high catalyst loading seriously hinder the development of PEMWE. This proposal will focus on the construction of nanostructured catalysts and catalyst layers. The one-dimensional Ir-based catalysts with controllable morphology, tunable oxygen vacancies and stable structure will be synthesized via combining sacrificial template method and reduction method with alkalis. The effect of concentration of oxygen vacancy on the electronic structure and coordination environment of the catalytic active sites in Ir-based catalysts will be investigated, which will help to explore the mechanism of the enhanced catalytic activity and to instruct the controllable fabrication of one-dimensional Ir-based catalysts with oxygen vacancies. The ordered nanostructured catalyst layers based on one-dimensional Ir-based catalysts will be constructed through external field assisted method and in-situ growth. Then the relationship between the structure parameters and the performance of the catalyst layers will be researched, followed by the exploration of rules to fabricate membrane electrode assemblies for PEMWE. This proposal will develop controllable preparation methods for Ir-based catalysts with high activity and stability and membrane electrode assemblies with high performance, long-life, and low cost, providing theoretical basis and technical support for the development of PEMWE.

质子交换膜（PEM）水电解技术具有高效、环保、气体纯度高等特点，然而阳极高的过电位、不足的稳定性和高的贵金属用量等问题阻碍了其规模应用。本项目从纳米结构催化剂和纳米结构催化层可控构筑两方面入手，通过模板法结合碱金属还原方法可控合成形貌可控、氧空位可调、结构稳定的一维铱基氧析出催化剂，研究氧空位浓度对铱基催化剂活性位电子结构和配位微环境的影响规律，探索氧空位对电催化剂活性的增强机理，阐明一维富氧空位铱基催化剂的可控构筑规律。通过外场诱导辅助、原位生长等构筑基于一维铱基催化剂的有序化纳米结构催化层，研究催化层中催化剂的取向、分布、孔隙结构等参数与电催化动力学和传质动力学之间的关系，阐明适用于PEM水电解膜电极催化层的构筑规律。发展高活性和高稳定性铱基催化剂的可控制备方法以及高性能、长寿命、低成本纳米结构膜电极构筑新策略，降本增效，为PEM水电解器的发展提供理论基础和技术支撑。

阳极析氧反应(OER)的高过电位和膜电极(MEA)的高贵金属用量等问题阻碍了质子交换膜电解水制氢的规模应用。本项目聚焦高活性析氧催化剂和低贵金属用量MEA研究，取得以下进展：1）设计和合成出一种具有独特OH配位的IrO2/TiO2催化剂，通过改变热处理时间可以实现表面OH数量可控制备，从而对Ir5+的形成电位进行有效调控；与Ir键合的OH直接参与反应，促进高活性的Ir5+反应位点原位形成，提高析氧活性；2）通过低温氟化策略将F掺入烧绿石晶格中，制备出系列高活性Y2Ru2O7-δ-xFx催化剂，结果表明F掺杂可以调控烧绿石中氧空位（VO）的产生，从而极大地促进了OER动力学；3）创新地提出利用纳米压印技术结合静置法制备一种阳极兼具梯度化锥形阵列及三维膜/催化层界面的新型有序MEA。这种新型有序MEA在Ir载量低至0.2mg/cm2时，仍表现出1.801V@2A/cm2的优异性能，与Ir载量是其十倍的传统MEA（2mg/cm2）相当；4）结合纳米压印技术和离子溅射在有序阵列结构MEA中引入Pt薄层并原位生长Pt纳米线制备了一种多级纳米结构MEA，多级纳米结构MEA阳极具有超亲水特性，接触角低至8.74°，多级纳米结构MEA仅使用0.1mg/cm2的IrO2即可实现1.885V@2A/cm2的良好性能，与IrO2载量是其二十倍的传统MEA（2mg/cm2）相当。本项目的研究成果可为质子交换膜电解水制氢的发展提供一定的理论基础和技术支撑。