二维材料限域的非贵金属单原子复合体系的构建及氧还原/氧析出双功能电催化性能的研究

Exploring effective and low-cost electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a key and pressing issue to be solved for the commercialization of rechargeable metal−air batteries. Based on the two important strategies of increasing the number of active sites and enhancing the intrinsic reactivity in the designs of electrocatalysts, this program plans to prepare two dimensional (2D) materials (g-C3N4 and reduced graphene oxide (rGO)) confining non-precious metal (Fe, Co and Ni) single atom electrocatalysts by taking full advantages of abundant pyridine-like nitrogen in g-C3N4, high content metals resulting from the pyrolysis of metal–organic frameworks, huge surface area of rGO and N-doping of rGO. The efficacious routes for increasing metal loadings and stability of metal single atoms will be searched mainly based on the pyrolysis. The structure–performance relationships of the said single atom electrocatalysts toward the ORR and OER of rechargeable metal−air batteries will be systematically investigated by experiments, and the intrinsic connections of preparation processes, structures, components, morphologies and sizes, and electrocatalytic performances of composites will be disclosed. The precise catalytically active sites will be identified employing a series of characterization methods, and the electrocatalytic reaction mechanism will be explored in depth on the atomic and molecular levels. The success of this project will provide direction to the accurate and rational designs of more atomically dispersed electrocatalysts.

开发高效、廉价的金属空气二次电池氧还原(ORR)和氧析出(OER)电催化剂是加速其商业化进程亟待解决的关键问题。基于增加活性位点和提升本征活性这两个电催化剂设计中的重要策略，本课题拟充分利用g-C3N4丰富的吡啶氮、金属–有机框架材料热解后高含量的金属元素、石墨烯(rGO)巨大的表面积以及对rGO进行氮掺杂等手段制备二维材料(g-C3N4、rGO)限域的非贵金属(Fe、Co、Ni)单原子催化剂。探索以热解法为主的提高金属单原子负载量和稳定性的有效途径。从实验的角度系统研究单原子催化剂在金属空气二次电池ORR和OER电化学反应中的构效关系，揭示材料的制备工艺—结构、组成、形貌和尺寸—电催化性能间的内在联系，综合多种表征手段解析催化活性位点的精确结构，并从原子分子层面深入探讨复合材料的电催化反应机理。本项目的成功开展有助于指导准确合理地设计更多原子级别的电催化剂。

开发高效廉价与能量储存与转化相关的氧还原(ORR)、氧析出(OER)和氢析出(HER)电催化剂是加速金属空气二次电池、燃料电池和电解水商业化进程亟待解决的关键问题。本项目主要围绕着二维材料(g-C3N4、rGO)及其它碳材料限域的高性能的非贵金属(铁、钴、镍)单原子、纳米团簇及纳米颗粒复合材料的制备及其电催化性能开展相关的研究工作。以简便的热解法合成了二维g-C3N4、二维氮掺杂碳纳米片(带)和三维氮掺杂科琴碳(KB)限域的过渡金属(铁和钴)基复合材料Fe4N−Fe@N-C/N-KB和Co@N-C/N-KB，在碱性ORR以及作为空气电极组装的锌空全电池中表现出高于商业20wt% Pt/C的电催化性能，实验研究及密度泛函理论(DFT)计算揭示了电催化反应机理和具有优异电催化性能的原因。以简便的热解法合成了二维g-C3N4、二维氮掺杂rGO和一维氮掺杂CNTs限域的过渡金属(钴、铁和镍)基CoO@CoSe2@N-CNTs/rGO和CoS2−FeS2@N-CNTs/rGO复合物，表现出优于商业贵金属催化剂RuO2的OER电催化性能和良好的酸性HER电催化活性，通过实验和DFT计算探究了相应的电催化反应机理。通过简便的一步热解法制备了氮掺杂碳骨架限域的镍铂和钴铂合金纳米团簇复合材料，极大地提升了电催化HER和ORR铂的质量活性，作为空气电极组装的锌空全电池表现出高于20wt% Pt/C的电催化性能，实验及DFT计算揭示了电催化反应机理。开发了一种颠覆性的高温煅烧合成多孔碳负载普鲁士蓝及其类似物的新方法，进一步原位负载NiFe层状双金属氢氧化物纳米片阵列，表现出远高于RuO2的OER电催化性能。通过简便的热解法或湿化学法合成了以g-C3N4和N掺杂竹节状CNTs限域的CoFe-CoFe2O4、氮掺杂纳米碳片和KB限域的CoSe2/Ni3Se4、KB限域的高纯NiFe2O4和CoFe2O4、泡沫镍限域的自支撑(Fe-NiO、IrO2@NiO和NiFe(OH)x@NiFe2O4)、泡沫镍铜限域的自支撑富含氧空穴的Cu/Cu2O/NiO等各种电催化剂，综合性能均高于相应商业化的贵金属催化剂，并对其电催化反应机理进行了探究。以上工作为高效低成本的过渡金属基单原子、纳米团簇、纳米金属和纳米复合物以及过渡金属-贵金属催化剂的开发提供了有价值的合成策略和理论视野。