二维层状介孔过渡金属-氮-碳/掺氮石墨烯纳米杂化电催化剂的构筑与电催化性能研究

To overcome the shortcomings of electrocatalytic activity loss of non-precious metal electrocatalysts induced by severe aggregation, low dispersion of active site, and less capable of controlling particle size, morphology, and structure with current synthetic strategies, this project aims to create a well-controlled methodology to construct a new type of nanostructured hybrid electrocatalysts of transition-metal-nitrides-carbrides/nitrided-graphene (TMNC/NG) with two-dimensional layered mesoporous structure via a nanocasting route using a in-situ formed mesoporous silica (KIT-6)/nitrided-graphene as a template. The electrocatalytic performance of two-dimensional layered mesoporous TMNC/NG electrocatalysts for oxygen reduction reaction in photon exchange membrane fuel cells (PEMFCs) will be systematically studied. The development of new methodology for constructing two-dimensional layered mesoporous TMNC/NG electrocatalysts and the investigation of correlation on composition-structure-property of the electrocatalysts will be mainly focused on. The ORR electrocatalytic performance of two-dimensional layered mesoporous TMNC/NG electrocatalysts may be largely enhanced due to the augment of metal-N active site, the formation of two-dimensional layered configuration and mesoporous structure, the synergistic effect arisen from graphene hybridization, and the generation of active pyridine nitrogen due to the nitridation of graphene. The obtained two-dimensional layered mesoporous TMNC/NG electrocatalysts may have comparable or even superior electrocatalytic performance over commercial noble metal Pt/C electrocatalysts for ORR, thus representing the prospect for practical application in PEMFCs. The methodology is universal and robust for constructing other two-dimensional layered mesoporous nanostructured electrocatalysts.

本项目针对目前非贵金属电催化剂合成过程中颗粒尺寸、形貌和结构较难控制、易发生团聚导致活性和稳定性降低、催化活性位点分散度低、组分单一且协同催化效应不强等问题，拟以原位组装的二维层状介孔KIT-6/掺氮石墨烯为模板，利用纳米浇铸方法，制备二维层状介孔过渡金属-氮-碳/掺氮石墨烯纳米杂化电催化剂，并系统研究其对质子交换膜燃料电池阴极氧还原反应的催化性能。重点开发二维层状介孔过渡金属-氮-碳/掺氮石墨烯纳米杂化电催化剂的构筑新方法，探索其结构-组成-性能的关联关系，阐明其过渡金属-氮活性位、二维层状构型、介孔结构、石墨烯协同催化、氮化产生高活性吡啶N位等所诱导的催化效应增强机理，提升其催化性能达到或优于目前商用贵金属Pt/C电催化剂，推进非贵金属纳米电催化剂在PEMFCs的实际应用。项目开发的二维层状介孔纳米电催化剂的构筑方法具有一定的普适性，可推广用于制备其他高效二维层状介孔纳米催化剂。

本项目针对目前非贵金属电催化剂合成过程中颗粒尺寸、形貌和结构较难控制、易发生团聚导致活性和稳定性降低、催化活性位点分散度低、组分单一且协同催化效应不强等问题，系统开展了二维介孔过渡金属基（Fe、Co、Ni、Mo、W碳化物、氮化物、磷化物等）纳米杂化电催化的制备方法开发和催化性能优化工作。项目开发了以二维层状介孔氮掺杂石墨烯杂化的KIT-6/N-G为模板，结合纳米浇铸和水热/溶剂热等方法，制备了二维层状介孔Fe/Co/Ni-N-C/N-G、Mo2C/N-C、(Mo2C)x–(WC)1-x/N-G、 (CoP)x–(FeP)1-x/G、CoxFe3-xO4@mSiO2等多个系列的纳米杂化电催化剂以及三维自支撑整体式CoNiP@N-C、MoP@N,P-C等多个体系的电催化剂，通过多种表征手段并结合理论计算，系统研究了这些电催化剂的组成、结构、相态、构造、表面结构、电子构型等物理化学特性，详细评价了其ORR、HER和OER等反应的电催化性能够，深度揭示了电催化剂的组分变化、晶相调变、掺杂效应、耦合作用、铠甲包覆、表面价态调控、表面电子相互作用等效应和作用对其电催化性能的影响，系统建立了不同系列电催化剂的组成−结构−性能关系，全面阐明了多个电催化反应过程中呈现的新催化现象和催化机制。研究为开发新型高效廉价的电催化剂提供了重要的合成方法，也为揭示电催化剂的催化作用机制、进而提升优化催化活性、稳定性和耐久性、解决电催化领域面临的关键问题提供了重要理论指导和技术支撑。所开发的合成方法和部分性能优异的电催化剂具有重要的应用潜力。在本项目支持下，累计在Adv. Funct. Mater.、Appl. Catal. B、Small、NPG Asia Materials、iScience、J. Mater. Chem. A等高影响力学术期刊发表论文14篇。