Block Copolymer Templating as a Path to Porous Nanostructured Carbons with Highly Accessible Nitrogens for Enhanced (Electro)chemical Performance

Abstract

The design of carbon materials for improved electrochemical systems should combine the preferential occurrence of pyridinic functionalities and a structure that maximizes their exposure to the surface. The carbonization of nitrogen‐rich polyacrylonitrile (PAN) retains a high level of nitrogen content, with a large percentage of the functionalities taking the form of pyridinic species at the graphene edges. A block copolymer precursor containing PAN and a second thermally sacrificial block can be converted to a nitrogen‐rich carbon material with a mesoporous network mimicking that of the precursor. Here, we highlight the structural advantages of this templating approach and their improvement in several electrochemical systems.

Common Carbons as Water‐Reducing Catalysts in Photo‐Driven Hydrogen Evolution with Nitrogen‐Dependent Activity

“…Additionally, the use of model catalysts allowed for more systematic variations and control of heteroatom composition, nanostructure, and microstructure. The PAN‐derived carbons exhibit well‐characterized variations in their graphitic domain sizes, meso/microporous structures, and nitrogen content . The first set of systematic photo‐HER studies used series of carbons derived from a block copolymer (BCP), polyacrylonitrile‐ b ‐poly (butyl acrylate) (PAN‐ b ‐PBA), pyrolyzed at different temperatures (Scheme ).…”

“…Consistent with prior work applying CTNCs as an electrocatalyst, 800 °C was the optimal pyrolysis temperature for catalytic performance . In accordance with the accepted carbonization mechanism of PAN,, pyrolysis at higher temperatures yielded carbons with lower nitrogen content and larger crystallite domains (Figure b). Specifically, the established view of structural changes occurring upon increasing the pyrolysis temperature of PAN, and in line with our previous results, graphitic domains progressively fuse through denitrogenation into more extended nanographitic sheets.…”

“…Using the optimal pyrolysis conditions determined above, PAN‐ b ‐PBA, high molecular weight (MW) PAN, and low MW PAN (RAFT PAN) were all assessed as WRCs. As shown in prior work, CTNCs have both mesopores and micropores . CTNC mesoporosity is the result of copolymer templating, in which PBA acts as a sacrificial porogen, volatilizing and leaving behind mesopores during the pyrolysis process.…”

Strategies towards Novel Carbon Fiber Precursors: the Research Results on the Synthesis of PAN Copolymers via AGET ATRP and on Lignin as a Precursor

“…This can be achieved by using immiscible sacrificial blocks with PAN such as poly(n-bulyl acrylate) (PBA): upon pyrolysis the PBA block chains are totally transformed to gaseous byproducts and the PAN chains are carbonized, leaving behind a porous material. The porosity of the residual depends on the morphology of the initial block copolymer [14]. This approximation seems quite promishing also for synthesizing block copolymers that could be oxidatively stabilized faster and more efficiently than the currently random PAN copolymers used as precursors for the production of CFs.…”

Reactive-Template Inducedin-situHypercrosslinking Procedure to Hierarchical Porous Polymer and Carbon Materials

“…与传统多孔聚合物的(准)无孔骨架不同, 这 些 HPPs 具有高密度羰基交联桥的共价有机聚合物骨架, 其内部含有独特的三维网络型微孔结构; 而且纳米颗粒 单元之间进一步交联堆叠可形成含有丰富中孔和大孔 的多级孔结构 [25] . 然而, 上述方法需要添加额外的交联 [26,27] . 图 5B 是 HPC 的拉 曼光谱图.…”