Seal Nilanjan, Karmakar Arun, Mondal Partha Pratim, Kundu Subrata, Neogi Subhadip
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
Inorganic Materials & Catalysis Division, CSIR-Central Salt & Marine Chemicals Research Institute, Bhavnagar, Gujarat 364002, India.
ACS Appl Mater Interfaces. 2024 Aug 14;16(32):41721-41733. doi: 10.1021/acsami.4c06804. Epub 2024 Aug 1.
Development of high-performing catalytic materials for selective and mild chemical transformations through adhering to the principles of sustainability remains a central focus in modern chemistry. Herein, we report the template-free assembly of a thermochemically robust covalent organic polymer (COP: ) from 2,2'-bipyridine-5,5'-dicarbonyl dichloride and 2,4,6-tris(4-aminophenyl)triazine as [2 + 3] structural motifs. The two-dimensional (2D) layered architecture contains carboxamide functionality, delocalized π-cloud, and free pyridyl-N site-decked pores. Such trifunctionalization benefits this polymeric network exhibiting tandem alcohol oxidation-Knoevenagel condensation. In contrast to common metal-based catalysts, represents a one of a kind metal-free alcohol oxidation reaction via extended π-cloud delocalization-mediated free radical pathway, as comprehensively supported from diverse control experiments. In addition to reasonable recyclability and broad substrate scope, the mild reaction condition underscores its applicability in benign synthesis of valuable product benzylidene malononitrile. Integration of 2,2'-bipyridyl units in this 2D COP favors anchoring non-noble metal ions to devise -M (M: Ni/ Co) that demonstrate outstanding electrochemical oxygen evolution reaction in alkaline media with high chronoamperometric stability. Electrochemical parameters of both -Co and -Ni outperform some benchmark, commercial, as well as a majority of contemporary OER catalysts. Specifically, the overpotential and Tafel slope (280 mV, 58 mV/dec) for -Ni is better than -Co (360 mV, 78 mV/dec) because of increased charge accumulation as well as a higher number of active sites compared to the former. In addition, the turnover frequency of -Ni is found to be 6 times higher than that of -Co and ranks among top-tier water oxidation catalysts. The results provide valuable insights in the field of metal-free tandem catalysis as well as promising electrochemical water splitting at the interface of task-specific functionality fuelling in polymeric organic networks.
通过遵循可持续性原则开发用于选择性和温和化学转化的高性能催化材料仍然是现代化学的核心焦点。在此，我们报道了由2,2'-联吡啶-5,5'-二羰基二氯和2,4,6-三(4-氨基苯基)三嗪作为[2 + 3]结构基元无模板组装的热化学稳定的共价有机聚合物(COP: )。二维(2D)层状结构包含羧酰胺官能团、离域π云以及带有游离吡啶基-N位点的孔。这种三功能化使该聚合物网络表现出串联醇氧化-Knoevenagel缩合反应。与常见的金属基催化剂相比， 通过扩展的π云离域介导的自由基途径代表了一种独特的无金属醇氧化反应，这得到了各种对照实验的全面支持。除了合理的可回收性和广泛的底物范围外，温和的反应条件突出了其在有价值产物苄叉丙二腈的良性合成中的适用性。在这种二维COP中整合2,2'-联吡啶单元有利于锚定非贵金属离子以设计出 -M (M: Ni/ Co)，其在碱性介质中表现出出色的电化学析氧反应，具有高计时电流稳定性。 -Co和 -Ni的电化学参数均优于一些基准、商业以及大多数当代的析氧反应催化剂。具体而言， -Ni的过电位和塔菲尔斜率(280 mV, 58 mV/dec)优于 -Co (360 mV, 78 mV/dec)，因为与前者相比，其电荷积累增加且活性位点数量更多。此外，发现 -Ni的周转频率比 -Co高6倍，跻身顶级水氧化催化剂之列。这些结果为无金属串联催化领域以及在聚合物有机网络中特定功能促进的界面处进行有前景的电化学水分解提供了有价值的见解。
